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blackburn mark
03-08-2010, 07:38 PM
Iv been having way too much fun researching, learning new skills and dreaming about how well it will all work out… I guess its time to put my penis back in my pocket and crack on with actually getting somewhere

This will be a small and hopefully stiff machine, I’m only really nervous about my choice of stepper driver kit (Chinese 5axis TB6560) I could do with the extra axis to run a 4th axis…… So….. If anyone can offer any optimistic words about these Chinese driver kits pushing a router like this through ally and delrin I would be much obliged.

Ballsrews 1605s
THK-HSR25 pre-loaded for the X and Y
NSK-LH20 for the Z axis but I’m not to sure I want to use these as they are not pre-loaded but I couldn’t resist them at £16 for 4 (new)

The spindles I’m in the process of building... the small one I’m trying skate bearing on with Belleview washers (not to optimistic about those but A/C bearings with an 8mm id are hard come by) it runs at 10000rpm flat out with 12v
The larger motor runs 2800rpm flat out on 12v and maintains loads of torque down to about 1000rpm, Iv an ER11 collet chuck with a 10mm shaft on its way which should drop straight in with the double row a/c bearing at the nose
Anyway… cheers to anyone who has ever posted on mycncuk, Iv had a lot of fun reading of your trails and tribulations
Ps the gantry sides are heavy extrusions… I couldn’t be arsed drawing them in :)
25512554 25522553





http://www.mycncuk.com/forums/images/misc/pencil.png

Ross77
03-08-2010, 09:48 PM
Nice design, I'm not sure I can find anything wrong with it :smile::smile:

maybe a slight tweak here and there but everthing seems to be where it should be, I like the Z axis thats how I think is the best way to do it, rails top and bottom on the gantry keeps the Z in nice and close and the wrap around connector is good to.

The only thing is wether the RC motor will cut Ali !!! engrave yes but cutting ???

Nice work cant wait to see it built and running

routercnc
03-08-2010, 09:58 PM
Hi Mark,

I'm struggling to get past the first paragraph - did you mean pens back in your pocket !

As for the machine, looks good, with some good features - upside down Z axis, Y axis ballscrew low down to reduce gantry side bending, twin X axis ballscrew, very stiff frame etc. etc.

You can always sell the Chinese board when you outgrow it, safe in the knowledge that the basic m/c is sound.

blackburn mark
03-08-2010, 10:01 PM
cheers ross,,, i spent bloody ages trying to find a way to get the overhang down, i had the Y screw on the back of the gantry to kick off with but there is quite a bit of drag with the linear bearings and it seems to make sence to off set some of it with the screw at the front...... errrr if that makes sense:)

GeorgeD
03-08-2010, 10:14 PM
Personally I don't like the motors showing on the sides of a CNC,so I've takenthe liberty of relocating it.

This would mean its belt driven and would have to have some clearence between Y axis and rail support.

blackburn mark
03-08-2010, 10:14 PM
sorry man.. yea i really did mean penis :wink:
for 5axis the chinese boards are hard to ignore
iv read plenty about them on this sight but i have no idea how much they lag behing the so called good stuff

routercnc
03-08-2010, 10:19 PM
Hi Mark

You could add another worktable on top of that one, but a bit wider, to protect the expensive X axis bits from dust and debris to some extent.

By the way, one of the x axis motors is making a break for it!

Anyway, nice one.

blackburn mark
03-08-2010, 10:23 PM
i know exsactly what you are saying about the motor hanging out and iv scratched my head over and over trying to tidy them away but at this point the design is an order parts and bolt together job, there is very little machining needed to get this one up and running... i can always make it look posh when iv got the ability to machine:naughty:

irving2008
03-08-2010, 10:29 PM
what power output do those spindles give?

Other than the machine rigidity, which looks quite reasonable (tho if you wanted to improve it take the side panels down under the table and crossmember there with a diagonal gusset) the main limitation on machining ally with any reasonable effectiveness will be spindle power.

blackburn mark
03-08-2010, 10:30 PM
i was thinking of a rubber skirt attached to that bed to protect the rails

i know the drawing isnt perfect but the meat of the idea is there and i had to start buying in the gear before i started putting go faster stripes on my drawing!!! :heehee:

blackburn mark
03-08-2010, 10:52 PM
Ah.. irving2008, iv read a thousand and one of your posts,, you always seem to go above and beyond the call of duty... mucho respect xx
the large motor is 1700W at 37v and the smaller one is 700w at 22v
im not to bad an engineer but the electic stuff is a bit rocket science to me

i have thought about going all the way around with the gantry but i do like the simplicity of it at the moment

irving2008
03-08-2010, 11:03 PM
Well 1700W input is 850W+ output, ~1HP theoretically you have the power to take around a 5mm deep cut with a 8mm 2 flute cutter at a feed rate of 500mm/min... but in reality your rigidity probably won't be up to that... but I reckon 0.5mm cuts would be possible, maybe a little more with a brand new very sharp cutter...


thanks for the compliments

Ross77
03-08-2010, 11:10 PM
Personally I don't like the motors showing on the sides of a CNC,so I've taken_ the liberty of relocating it PS.ive taken the liberty of adding spaces to your post so its easier to read.....:naughty:

George (what are we going to do with you?:heehee:) CNC machines are not Art and don't have to be pretty just functional. Direct mounting a motor is the best solution as far as backlash and accuracy are concerned, all the professional machines Ive seen use this setup.

Its is only worth while using belt drive if you need to change the gearing.



i can always make it look posh when iv got the ability to machine:naughty:
Damm right, get it working first. If your milling Ali have you looked at the coolant side? Pumps, catch tray etc...After a few uses you wont care what it looks like only be amazed at the pieces you make with it.

blackburn mark
03-08-2010, 11:15 PM
nice one irving ! it sounds possible then

most of the work done on it will be in acetal delrin type plastics but i do need the odd ally bits and bobs

them motors nice and quiet!! :smile:

blackburn mark
03-08-2010, 11:24 PM
iv been collecting surgial tube at work to make a peristaltic pump with,
they have a low flow rate but must be worth a try for a giggle
they look pretty simple to make
i am sort of worried about coolant though... i wanted to put all my electrics under the base

routercnc
04-08-2010, 07:59 PM
Hi Mark,

Those brushless motors look like the type I use in my model aircraft. I was wondering how you are controlling them, and what power source you are going to use. Looking at your stats for the big motor:

2800rpm for 12v is a 233Kv motor. This will obviously give you 8633rpm at 37v no load.

1700W is achieved at 45A for 37v. Do you have a 37v supply, and more to the point, can it give out 45A at the same time? The 12v 60A supply we have at work is the size of a suitcase, and probably cost us a bit, so I'm interested in the bench supply you have in mind. If you have simply read the motor spec, then you might like to know that on aircraft, when run from Lipo cells (37v) these motors run at about 45A on average (depending upon prop and throttle), and last for 8 - 9 minutes before a recharge is required. If your bench supply can't give this kind of current, then your actual power will be down (plus not so efficient), and you may have to back off on the ali cuts. But then maybe you have a cunning plan for all this . . .

I assume you are using a speed controller to run the brushless from. What amp rating are you running on that, and are you using a servo simulator to control the speed on a dial?

If you can get this all to work, then you're right about the noise, very quiet. I did consider this route myself, but the above put me off. Keen to see more . . .

z3t4
04-08-2010, 10:40 PM
...to make a peristaltic pump with,
they have a low flow rate but must be worth a try for a giggle
they look pretty simple to make

Hi Mark.

You can get peristaltic pumps on the 'bay reasonably cheaply. Do a search for 'condensate pump' or 'Aspen peristaltic'. I got one a couple of years ago for a tenner. For the last week it's been pumping dilute citric through a crudded-up coffee machine heat exchanger.*

Sorry, rambling again. Where did I put the Jaffa cakes?

John

*another ebay win.

irving2008
04-08-2010, 10:50 PM
5 of those cheap 50v supplies from ebay in parallel will give 43v-56v @ 50A for £12 each, not bad for £60...

GeorgeD
04-08-2010, 11:00 PM
lol Irving,how much will the electricky bill be?

blackburn mark
04-08-2010, 11:11 PM
im using a servo tester with an 80A speed controller

i bought the motor as a 250kv at 2000w but a review i read has it at more like 1700w

i have two server power supplies at 12v 45A each... im hoping to stick with 12v to keep
the speed down for ally

i can use the smaller motor at 12v for up to 10000rpm

im also hoping to replace a 3.17mm shaft in a 4000kv helli motor with a 3.18mm shafted
engraving bit... not sure how practical this will be as ill have to strip the motor every time the bit wears out... worth a try if im desprate to do some really fine work
this one should run up to 48000rpm on 12v (i think) it will be interesting to see
how the bearings hold up

feel free to critiqe... im sure youll know more about these rc motors than i do

blackburn mark
04-08-2010, 11:18 PM
ha,,,, sod off George... i got the server power supplies for nowt!!
the speed controller was 15 quid and the servo tester was a fiver.... maybe a teners worth of postage

EDIT: sorry george, i miss read you,,, electricity bill !!
dont put me off now man im on a roll :)

blackburn mark
04-08-2010, 11:31 PM
Irving,,, you seem to have it all worked out,
if i have any dastardly electrical plans im hoping youll stop me from blowing myself up :)

blackburn mark
04-08-2010, 11:39 PM
cheers z3t4
iv been keeping my eyes open on ebay,,, iv never searched for 'condensate pump' ill give it a go

Errrrr... dilute citric ?? heat exchanger??? are you making rocket fuel to dip your jaffa cakes into !!

z3t4
05-08-2010, 10:55 AM
cheers z3t4
iv been keeping my eyes open on ebay,,, iv never searched for 'condensate pump' ill give it a go

Good luck!


cheers z3t4
Errrrr... dilute citric ?? heat exchanger??? are you making rocket fuel to dip your jaffa cakes into !!
lol
The ex-commercial ones get really badly scaled. Citric is a really good, food-safe descaler and is gentle with copper boilers and HX's; you just have to be patient, which is where the peri pump helps.

I would never knowingly so abuse any Jaffa Cake in my care.

John

routercnc
05-08-2010, 02:02 PM
Hi Mark,

Sorry this thread is splitting in two. Referring back to your earlier reply, 80A S/C is OK, and for £15 is probably the low voltage type so don't run it at the 37V (12V is OK). Servo tester is OK and at some point I expect this could be speed controlled from the PC since there is a pot behind the dial. Not done speed control from a PC myself, but plenty of experts on here who could help . . .

I only use outrunners, so don't know about the inrunners or high Kv motors you are considering (from helis and ducted fan models). Nice idea about the engraver using the motor shaft.

Watch out for the heat buildup since these motors are all normally in the airflow. Especially if you go down Irving's route and go for the full 1700W. Some inrunners have finned sleeves which you can buy and fit over the outside of the can. For outrunners you might be able to fix a fan to the outer case, since this rotates, and it will blow air down through the holes into the windings. Bit of noise i'm afraid, so you'll have to see how it goes.
Wonder if you bolted a prop adapter on the back face and added a very small prop, instead of a fan. Mind your fingers, or add a guard if you do!

blackburn mark
05-08-2010, 02:24 PM
cheers routercnc

will i be ok using the 80A speed controller on a much smaller motor... it would be nice if i could use all three motors without having to swap about with diffrent ESC's

im not sure ill bother linking my spindle to the PC, iv got an optical rev-counter, i think ill just dail in whatever speed i want and stick with the simple life

im considering a goverer speed controller.. iv heard they will hold the revs steady under diffrent loads

Jonathan
05-08-2010, 03:24 PM
cheers routercnc

will i be ok using the 80A speed controller on a much smaller motor... it would be nice if i could use all three motors without having to swap about with different ESC's


Yes, any motor up to 80A should be fine with that speed controller. Is the speed controller programmable? You may find that adjusting some settings (such as 'timing' and 'frequency') will make the ESC run different motors more efficiently.



im not sure ill bother linking my spindle to the PC, iv got an optical rev-counter, I think ill just dial in whatever speed I want and stick with the simple life


I wonder if mach3 can do this. The input to the speed controller is just a simple PWM signal and mach3 can output PWM for spindle control at a set frequency.

I've got a huge 130kv brushless motor I think I might try as a spindle when I've bought an ESC for it. It's rated for 48v and claims to be 6500W(!) ... hadn't thought of controlling the speed from the computer though.

I agree about using a fan - these motors do get hot even running with no load from my experience. If you've got a lathe then you could make a pretty nice heatsink just by starting with a bar, bore it to fit the motor and add fins using the parting tool...

blackburn mark
05-08-2010, 03:51 PM
nice one jonathan, yea iv programmed the ESC for soft start, 14 poles etc.

iv run both large motors for 5mins 12v no load without to much heat in the ESC or the motors
i exspected way more... we'll find out eventualy what they do under load

the huge 130kv brushless motor you have (if its the one im thinking it is) has a 12mm
shaft wich is good news as far as A/C bearings are concerned and if you have a butchers on ebay you should be able to find an ER11 C12 L100 straight collet shaft,, that should drop straight in:naughty:
cheak how much shaft you need though as these have only 100mm of shaft!

Jonathan
05-08-2010, 04:06 PM
Yes it's the motor you're thinking of! It's currently in pieces since I'm altering the wiring so that I can change it between star/delta for higher torque/rpm etc. You may mant to consider this for your motors? Easier to swap a few wires than change the motor, perhaps.
I've found the straight collet holder - that looks ideal (thanks!), except the shaft is a bit short! I'd prefer ER25 though since I've just bought a set of ER25 collets for my milling machine. I'll have a look around for one / make one if necessary.

The bearings in the motor are already pretty huge. The one at the 'back' is a large thin section bearing about 65mm diameter if I recall correctly.

Maybe create a thread about using these motors?

blackburn mark
05-08-2010, 04:31 PM
jonathan... good luck with the ER25, iv seen a few of these ER straight shafts with 150mm to play with,,
cant remember seeing an ER25 though
if you get chatter i would consider at least a double row A/C bearing at the sharp end,
they are already pre loaded and ready to go

z3t4
05-08-2010, 04:47 PM
Maybe create a thread about using these motors?

Yes please!

There was an article in MEW (Feb 2008 issue, No 135 ) about making outrunner motors but there wasn't much about how to power them. I'm guessing that the 'servo tester' provides a PWM pulsetrain and the speed controller (is this aka an 'ESC'?) sees the pulsetrain and uses electromagick to provide a 3-phase supply to the motor.

John

blackburn mark
05-08-2010, 05:02 PM
[QUOTE=z3t4;14653]Yes please!

it will be a while before i can report any findings on mine... i cant wait to see how jonathan gets on with that monster motor of his:smile: and what he gets with the "star/delta" wiring (i have no idea what that is and im just about burnt out on research)

routercnc
05-08-2010, 08:21 PM
Quickly sketched this to show aircraft vs cnc application for those interested:

(You could probably delete the 4.8V supply if using a BEC ESC)

blackburn mark
05-08-2010, 08:40 PM
nice one... im not so good with the electronics but all this stuff is nice and modular,, for those that dont know BEC is just a set of 5v power leads coming out of your Electronic speed controller to run your servo tester

anyone using small motors (engraving) might get away with an old PC power supply... they have 5v and 12v coming out of them

Jonathan
05-08-2010, 09:10 PM
anyone using small motors (engraving) might get away with an old PC power supply... they have 5v and 12v coming out of them

If you're careful you could even put the computer PSUs in series. Just need to make sure they're isolated. I considered doing this for my stepper motors since I've got plenty of 350W (or so) PSUs from the local car boot and if I put 6 in series that would have given a nice 72v for my stepper motors. I decided against this as 6 of those would have been a bit bulky and a good toroidal transformer came up on eBay.

A cheap way of providing the 5v supply is just using a 5v voltage regulator. Any would probably suffice since it's only providing a few miliamps in this application.

With regards to my big motor I think I could get away with the 100mm shaft collet holders. I'd probably get the 1/2" one and reduce it down to 12mm. The motor contains 4 bearings, 3 of which are 2112 bearings and one big 6089. I shouldn't be too difficult to change them but it is worth it? The biggest external diameter bearing that would fit without doing something imaginative is maybe 24mm. I can't find any angular contact bearings that would fit there.
I've been thinking of using this motor for a 4th axis / lathe but I wont go too off topic!

blackburn mark
05-08-2010, 09:41 PM
yo jonathan,

i was terrified of turning down an over sized shaft so i spent weeks looking for the right size, its being shipped as we speak

im gutted you didnt find a 150mm one, im convinced it would have been easy to stick double row A/C on the nose in a shallow housing,, ill find out as soon as my shaft turns up ill start doing a bit of turning

im not totaly convinced a double row A/C bearing will be tight enough for ally, the ones iv got dont feel like they have that much pre-load, i might end up stacking the two of them

4th axis... mmmm im thinking a 100mm rotary table with my 5th stepper melded to it

im not sure anything is off topic,, is it?

Jonathan
05-08-2010, 10:25 PM
i was terrified of turning down an over sized shaft so i spent weeks looking for the right size, its being shipped as we speak


Hah, I was pretty scared dismantling this motor. It was all glued/loctited together and needed some persuasion with a hammer.



im gutted you didnt find a 150mm one, im convinced it would have been easy to stick double row A/C on the nose in a shallow housing,, ill find out as soon as my shaft turns up ill start doing a bit of turning


There are 150mm ones, but they're more than twice the price of the 100mm. I could probably extend the 100mm one if it came to it - definitely some thinking to do before I buy anything!



im not totaly convinced a double row A/C bearing will be tight enough for ally, the ones iv got dont feel like they have that much pre-load, i might end up stacking the two of them


I see, so you don't think the ones that are currently in my motor would be up to it? Maybe I could link this motor to the existing milling machine spindle via a pulley...then I needn't worry about angular contact bearings. Having said that I don't know if the bearings in the spindle of my machine are up to 6000rpm.



4th axis... mmmm im thinking a 100mm rotary table with my 5th stepper melded to it


Yep, that's what I did except with a 150mm vertex rotary table. It's excellent for making pulleys:

2562

And making 4th axis'

2566



im not sure anything is off topic,, is it?


:) well in that case this is the 4th axis/lathe design I've started making:
2561
2563
2564
2565

I'm using two tapered roller bearings in that. The gold things are solenoids to create a sort of disk brake which I'm hoping will hold it steady enough for me to mill will it aswell as using it as a lathe by swapping to a bigger motor...the brushless one.

blackburn mark
05-08-2010, 10:45 PM
SWEEEET!!!! im intimidated,,, and its not just a drawing, youve made a start

are you not happy with the rotary table?

are the solenoids air?

EDIT: iv just spotted the wires

Jonathan
05-08-2010, 10:58 PM
Thanks!

I'm happy enough with the rotary table - it's very well made. If you get one I'd advise a vertex one as I've used this and a bigger one at school and they're both good. It's good in that it uses a worm gear (90:1) which means it wont move when milling but equally the worm gear is bad as it severely limits the rpm I can run the table at. I'm making the new axis because I want it to double up as a CNC lathe. My mini lathe (C3 from arc euro) isn't up to much so I'm hoping this will be sturdier.

I've machined the shaft of the axis the same as the mini-lathe so it can take the same chucks. Ideally I would have gone for bigger than 80mm diameter for the shaft...but turning that down to 35mm for the bearings took long enough and annoyed my teacher at school a bit... any bigger would have been pushing my luck I think!!

Any ideas for materials to use for the disk brake are welcome. The brake will only be used to hold in position, not for stopping, so heat build-up isn't an issue.

I'll go and take another photo...

P.S. Someone's bound to point this out, so before they do...If you look carefully on the renders of the 4th axis you'll see the disk brake is impossible to assemble! I've since fixed that by putting the disk the other side of the flange.

blackburn mark
05-08-2010, 11:33 PM
Ah, im with you on the speed issue, i think i get you with the large motor to,, im guessing you would be fitting a rotory encoder for position feedback if you use the large DC motor ? (im no expert with these)

for the brake i would be looking at a motorcyle cluch plate maybe, im not sure youll get the force with electric solenoids to lock it for milling though but thats my guesstimation... id be tempted to consider an actual disk brake and caliper... the caliper would have to be beautfully fitted and have oposing pistons (you couldnt have it floating like you do on a vehicle)
im really not sure though im just thinking out loud :)

Ross77
05-08-2010, 11:37 PM
I'm just looking at spindle design and A/c bearings so I'm intrigued if you know of a cheap type.



im not totaly convinced a double row A/C bearing will be tight enough for ally, the ones iv got dont feel like they have that much pre-load, i might end up stacking the two of them


Do you mean rigid enough for milling Ali? If so be careful adding addition preload to a factory set tandem one as I believe you just end up un loading one side!!! if its a double row then lock it to the sharp end and fit a floating bearing at the other end.

According to SKF the distance between the CL of the bearings should be 3 to 3.5 time the shaft dia, so 12mm shaft = 36 to 42mm so a 100mm shaft should be way long enough.

The optimum design seems to be to use 2 opposing A/C bearings with a spring loaded pre-tensioner.

Have you seen the "DIY spindle design" on here, or these?
http://www.cnczone.com/forums/showthread.php?t=12184&page=6
http://www.cncathome.com/spindles.html

It seems this has been done many times and the problems are mounting the motor to the spindle, the first link post no. 64 and 65 shows a flexible mount and water cooling for the motor.

I also have an ER11 collet and a RC motor to power it but as its for machine No. 2 I haven't got around to doing anything with it yet. so I will be watching with interest.

Good luck

Jonathan
05-08-2010, 11:55 PM
Ah, im with you on the speed issue, i think i get you with the large motor to,, im guessing you would be fitting a rotory encoder for position feedback if you use the large DC motor ? (im no expert with these)

Err I hadn't really thought about feedback. I was thinking something along the lines of using a stepper motor and the big brushless motor and switching between the two. For instance start by using the big motor for CNC lathe then switch to stepper motor to perform any milling on the part.
It would be good to switch back and forth between the big motor and the stepper but that of course requires the motors to engage at precisely the same point. Maybe get the brushless motor to stop at a set position (doable) and have another solenoid push a pin in the shaft to engage the stepper (tricky) ... the best would be to just use a servo but that's very very expensive to get anywhere near the power of this brushless motor.



for the brake i would be looking at a motorcyle cluch plate maybe, im not sure youll get the force with electric solenoids to lock it for milling though but thats my guesstimation... id be tempted to consider an actual disk brake and caliper... the caliper would have to be beautfully fitted and have oposing pistons

I'm not sure about the solenoids either, hence how I've milled spaces for several of them.
Clutch plate... that looks promising.

An actual brake disk and calliper would be very nice. Sounds expensive though. I don't know much about them - what would be required to actuate/use it? Are they available with small enough disks since the biggest disk I would want to use is realistically 6".

blackburn mark
06-08-2010, 12:10 AM
I'm just looking at spindle design and A/c bearings so I'm intrigued if you know of a cheap type.

"5200 zz z 2z ball bearing 10mm A/C" ebay aprox £16 for two... they might be to good to be true


just end up un loading one side!!!

och!! i hadnt thought of that... i hadnt decided if id just throw two in for good measure or pre-load them against each other
iv decided now!! cheers ross


According to SKF the distance between the CL of the bearings should be 3 to 3.5 time the shaft dia, so 12mm shaft = 36 to 42mm so a 100mm shaft should be way long enough.


i think you misunderstand, jonathan has a motor that has a 100mm long body so with a 100mm shaft there is no room left to add an A/C bearing and housing


yea iv seen those thread, they make interesing reading, one of those guys has his own ballancing machine!! to posh for me:)

blackburn mark
06-08-2010, 12:29 AM
i thought a servo motor was just that "a motor with a rotary encoder" maybe somone can jump in and help us on that one

you could make your own disk easy enough... the calipers would take to much effort compared to going to a bike breakers
you need to look over some motorcycles and posh mountian bikes for inspiration :) im sure some of the mountain bike disk brakes are machanical,,, could be worth a look.. the hydraulic ones would need a cam and lots of torque to actuate

black5f
06-08-2010, 08:37 PM
Penis in pocket when around cnc machines is is a very good safety tip, no one wants to miss a tip :-)

z3t4
06-08-2010, 09:20 PM
Quickly sketched this ...
Thanks for the explanation. It's good to have it presented so clearly.

blackburn mark
06-08-2010, 10:01 PM
iv got some 8mm id A/C bearings but they are open (as apposed to sealed) so for now ill stick with the skate bearings
it would be nice to seal the nose and have a nice light oil swishing around in there :)
257025712572
still a bit of work to do on this but it will give those that are interested an idea of what we have been on about

blackburn mark
12-08-2010, 12:54 PM
My ER11 10mm shaft turned up,, nice tight fit.. i may loctite it when im happy
2616
Iv decided on one double row A/C bearing for now... i left room in the housing for two just in case :)

i ran it no load for ten mins... the bearing gives off more heat than the motor but nothing to drastic, if i remember correctly up tp 110 degrees is passable... it was nowhere near that
2617
I tried to keep the housings 43mm but it wasnt really pactical
i havnt fully decided on how to setup the small motor, iv considered inserting an engraving bit straight throgh the motor but im struggling to find engraving bits with enough length to allow for more bearings on the nose... i may modifiy a needle vise....
anyway the engraving motor is not overly inportant to me but Its killing time while i wait for parts for the main build

just got to hope they will work as well as they look :)

GeorgeD
12-08-2010, 01:02 PM
http://www.arceurotrade.co.uk/Catalogue/Cutting-Tools/Engraving-Cutters

irving2008
12-08-2010, 01:03 PM
Yes please!

There was an article in MEW (Feb 2008 issue, No 135 ) about making outrunner motors but there wasn't much about how to power them. I'm guessing that the 'servo tester' provides a PWM pulsetrain and the speed controller (is this aka an 'ESC'?) sees the pulsetrain and uses electromagick to provide a 3-phase supply to the motor.

John


Quickly sketched this to show aircraft vs cnc application for those interested:

(You could probably delete the 4.8V supply if using a BEC ESC)
1/ Whats the PWM signal characteristics?

2/ 'Servo Tester' sounds an expensive beast

3/ Surely you'd want a 0-10v input so you could control spindle speed from MACH3?

blackburn mark
12-08-2010, 01:14 PM
Cheers George.... i had my fingers crossed... but no joy. the motor body is 30mm i could do with at least 15mm to play with for a housing and bearings,,, those you linked are 38mm and a good bit of that length is taken with the knife,, nice try though xx

irving... the servo testers are between a fiver n tenner ebay... the rest of what you ask is errr... rocket science..
i have read somwhere that the puls rate is way to high for mach3 and would need some kind of conversion

im sure a man like you could rustle one up in your dinner break :)

ecat
12-08-2010, 01:43 PM
I'm guessing we are talking about standard RC parts here so, the servo tester most likely outputs a signal of 20ms period. The width of the pulse within this 20ms period determines the output of the ESC. Actual values and their relation to each other depend on the hardware used.

Can the ESC be driven from a 0 to 10v signal? Not directly. I'm sure there'll be something on the web to suit or maybe this is another job for a friendly PIC.

blackburn mark
12-08-2010, 02:11 PM
if you guys dream up a simple way of of conecting to mack3 ill have some of that :naughty:

im thinking of basterdising a lazor rev counter... can anyone tell me... will i get away with removing the lazor diode and pickup and extending them out onto my z axis and put the lcd somwhere more sociable?

irving2008
12-08-2010, 02:45 PM
im sure a man like you could rustle one up in your dinner break :)


I'm guessing we are talking about standard RC parts here so, the servo tester most likely outputs a signal of 20ms period. The width of the pulse within this 20ms period determines the output of the ESC. Actual values and their relation to each other depend on the hardware used.

Can the ESC be driven from a 0 to 10v signal? Not directly. I'm sure there'll be something on the web to suit or maybe this is another job for a friendly PIC.

This is an easy job for a single 14pin PIC, two small potentiometers (to set min and max speeds), a diode, a couple of resistors and two capacitors. The diode/resistor/capacitor combo forms a charge pump that converts the fast PWM signal from MACH3 into a voltage which is sampled by the analog-digital converter in the PIC. The same A/D converter samples the settings of the two pots to determine high and low speed limits. The PIC then generates a PWM output that varies according to the incoming voltage from MACH3. A speed sampler could be included in the same device and closed loop functions could be added to maintain set speed against load... With a bigger 20pin PIC the rev counter display could be added... price of the PIC, about £1, total cost <£15 if built on stripboard or enough were built to make setting out a PCB viable. Basic software would take a few days... bit longer for the closed loop stuff...

routercnc
12-08-2010, 02:46 PM
Hi Irving,

1. This explains far better than I could:
http://www.servocity.com/html/how_do_servos_work_.html

2. Servo tester is £5 - £15
http://www.fast-lad.co.uk/store/product_info.php?products_id=1716
The potentiometer on the tester controls the width of the pulses, and replaces the signal it would otherwise get from the reciever. This signal moves the output arm of the servo motor to the required position, or for the throttle, the engine to the required speed. It is fully proportional.

I wondered, with my limited electronics knowledge, whether the pot could be removed (which must just provide the pulse generating part of the servo tester with a 0 - 4.8v output) and via a magic box the Mach3 0-10v could be connected instead.
I'm sure you could come up with something along these lines or better !

Does this help you with a better plan?

Ah, you've already replied. Looks like you have it in hand!

irving2008
12-08-2010, 02:49 PM
if you guys dream up a simple way of of conecting to mack3 ill have some of that :naughty:

im thinking of basterdising a lazor rev counter... can anyone tell me... will i get away with removing the lazor diode and pickup and extending them out onto my z axis and put the lcd somwhere more sociable?
dont bother... the prpoblem with the laser diode ones is that they are sampling devices... press to read... as the laser diode cant handle continuous operation. Its a lot simple to do a slotted vane type approach and one of the many solutions discussed in Rick's Boxford 260VMC thread

irving2008
12-08-2010, 02:54 PM
Hi Irving,

1. This explains far better than I could:
http://www.servocity.com/html/how_do_servos_work_.html

2. Servo tester is £5 - £15
http://www.fast-lad.co.uk/store/product_info.php?products_id=1716
The potentiometer on the tester controls the width of the pulses, and replaces the signal it would otherwise get from the reciever. This signal moves the output arm of the servo motor to the required position, or for the throttle, the engine to the required speed. It is fully proportional.

I wondered, with my limited electronics knowledge, whether the pot could be removed (which must just provide the pulse generating part of the servo tester with a 0 - 4.8v output) and via a magic box the Mach3 0-10v could be connected instead.
I'm sure you could come up with something along these lines or better !

Does this help you with a better plan?

Ah, you've already replied. Looks like you have it in hand!


Thanks... I know how RC systems work, just wasnt sure on the PWM characteristics, its 30+ years since I built and flew anything (but my 10y old nephew is showing an interest so maybe I'll resurrect that... along with the 47000 other projects)

MACH3 doesnt produce a voltage just its own fast PWM train, which has to be converted to a voltage. My solution does that, tho it would be possible to use the PWM/ECCP (count and compare) function in the PIC to measure it directly, but that needs a PIC with two PWM channels and the 14pin ones only have one. Needs more software to be written too!

blackburn mark
12-08-2010, 02:55 PM
cheers irving, ill have a butchers

Jonathan
15-08-2010, 09:25 AM
I'll post more on Tuesday (I'm on holiday at the moment so no internet!) but I'm pretty sure mach3 will do the PWM. As ecat said the period for the ESC is 20ms, so 1/0.02=50hz. This next bit may be wrong, but anyway...running mach3 on 25khz kernel speed with 50hz PWM gives 25000/50=500. So that means you get 500 'steps' between 0% and 100% duty cycle. The ESC is probably 255 steps anyway, and if it's 1023 then it's not really an issue.

You'll probably want to put an optocoupler between the parallel port pin and the ESC just to be safe if the ESC doesn't already have one. Oh also if mach3 is 0 to 10v then just use a voltage divider to reduce that to 0 to 5v. Two 10k resistors should do the trick, or anything really it's not critical.

If that doesn't work then I'd go for the PIC option. I've had a PIC controlling servos before from a potentiometer...it shouldn't be difficult.

Jonathan
PS Have a look on eBay for servo testers. I think you'll find them cheaper.

blackburn mark
15-08-2010, 12:52 PM
yo jonathan.... sounds interesting, a bit complex for a simple soul like me id need walking through the whole procedure

have you had any joy with the brake ? i found a vid on youtube where someone had used a mechanical calliper on a disk
Actuated pneumatically,,, id prefer to use a motor and screw with a spring as a buffer

if you have any old slit saws you could use one of these as the disk
i havnt desided whether ill take the simple road and use a rotary table or build a fast mover with a disk brake

blackburn mark
09-10-2010, 07:37 PM
though id have a play with my attempt at an engraving spindle
the motor is 4000kv so in theory it should run at 48000rpm at 12v
i managed to find an extra long engraving bit 115mm and mounted it straight through the motor and put three plain ball bearings at the nose


3166316531683167

i ran it flat out for a couple of min's and both the motor and the bearing housing got pretty hot pretty quick
im not overly worried about the motor getting hot its to be exspected IMO but i think the bearings on the nose are soon going to be way above 110 degrees..... i think ill test it to destruction before i look at water cooling i just cant bring myself to do it just yet, ill admire its simplicity and form for a while longer and have a think about it :)

another problem i might have... when i run it up i can hear a bearing skidding now and again, im pretty sure its one of the motor bearings (only paid £7.50 for it new) so that will need upgraded bearings pretty soon

has anybody had a go at sharpening an engraving bit ?????? this one cost me more than the motor
http://www.mycncuk.com/forums/images/misc/pencil.png

blackburn mark
30-10-2010, 09:33 PM
Why is it that no matter how careful i am measuring and marking out i allways end up having to oval a slack hand full of holes, each time i start a new project i think " this is it now, im on it, iv learned by my mistakes and THIS time its all gona work like a bobby dazzler"...........Bollocks!!! there must be a tare in the space time continuum cause im buggard if its me! :)
3273
anyway, its starting to look like my drawing now, i drilled all the holes using my larger diy spindle and my Y axis up-ended as a sort of pillar drill (didnt want to be swinging around with a hand held)

im pretty sure ill have to oval a couple more holes when it comes to trueing it up but iv got a sh*t load to do before its finished and i dont want to think about it :)

(anyone thinking of useing helli mode on a RC speed controller, dont bother, it dosnt seem to hold revs any better than standard and it has a slow wind up to speed so every time you jam your drill you have to pause for it to catch up)

blackburn mark
30-10-2010, 11:57 PM
Nice one Chip... it helps knowing im not the only one trying to drill around corners
bad luck on the Z plates, im going to start marking mine out tomorow
ill try some Zen meditation in the morning....... OMMMMMMMMMMMM

ps: do you think id get 20mm alli plate through my printer :)

Lee Roberts
31-10-2010, 12:16 AM
I guess its time to put my penis back in my pocket and crack on with actually getting somewhere

LMAO, im glad im not the only one who makes good use of a chest mounted, shirt pocket :naughty:!

blackburn mark
31-10-2010, 04:53 PM
LMAO, im glad im not the only one who makes good use of a chest mounted, shirt pocket :naughty:!

well just make sure you NEVER put your scribe and your penis in the same pocket lee.... worse than a stainless splinter under the finger nail :)

youve done alright getting the hobnob crew to cnc your gantry sides man!!! me n chip can only hope you got the drawing wrong :) xx

Lee Roberts
31-10-2010, 06:53 PM
me n chip can only hope you got the drawing wrong :) xx

Why ?

I don’t think it is, I spent ages working everything out and it looks right to me. I didn’t have the privileges of software to model everything first and check everything that way. So I had to do it all on paper and in my head, then draw each part using an image editing/design program I use for my web work.

Steve has then worked from those drawings and done well too, or did you mean something else?

Lee

blackburn mark
31-10-2010, 09:23 PM
steady on lee... im just yanking your chain.... hope it fits together like a glove, theres nowt worse than having to re-work holes (or in laymans terms, re-insert the drill and swing around a bit)

mucho respect for drawing yours out on paper, thats got to take some mental accrobatics, i would have struggled without the 3D drawings... its soooooo easy to re-work a drawing compared to re designing during a build but, like i said marking out by hand always manages to catch me out a mm or two hear and there no matter how careful i try to be, hopfully steve has saved you the pleasure :)

Swarfing
31-10-2010, 10:33 PM
Mark if you don't have a pillar drill and vice, drill a hole the size you want a spare piece metal and clamp that over your intended spot then use that as your guide

Lee Roberts
01-11-2010, 01:56 AM
No offense taken Mark, when I said “privileges of software” I meant literally that because your right it was a night mare trying to concentrate and do it all on scrap bits of paper and so on. It would only take one of my kids to walk in and say something and I would have to start over again hehe.

I know what you mean by “marking out by hand”, this is another reason I wanted the plates made on a cnc, I’ve got a steel ruler and an engineer’s scribe but I really didn’t want to even try it. Plus ordering Ali you’re not getting the shapes you want ether and that is another “issue” if you don’t have a proper saw or guillotine to cut with.

I need to find a CAD program I can afford that will allow me to build 3d models, parts and make assembles, what did you use for your drawings Mark?

blackburn mark
01-11-2010, 10:06 AM
hi lee, iv been giving solidworks a go, i quite like it but it is a tad exspensive, its a lot to take in if its your first go in cad but if you press on with it long enough you will get into it

i want to give the solidcam sofware a go to make g-code but iv not got that far yet

blackburn mark
01-11-2010, 10:12 AM
Mark if you don't have a pillar drill and vice, drill a hole the size you want a spare piece metal and clamp that over your intended spot then use that as your guide

im thinking it was my marking out skills that let me down, i was drilling through 40mm in one go and my holes were bang on square

Jonathan
01-11-2010, 09:43 PM
(anyone thinking of useing helli mode on a RC speed controller, dont bother, it dosnt seem to hold revs any better than standard and it has a slow wind up to speed so every time you jam your drill you have to pause for it to catch up)

Slow wind up to speed - isn't that the govenor setting, if so surely it can be switched off?
I think the only way to hold revs if to have some sort of direct feedback (optical or something) of the motor RPM, and get mach3 to control the RPM as I detailed earlier.

I should really buy the ER25 collet for my massive brushless motor....it's occured to me that I can still get the 100mm one and make it longer. Drill an 8mm hole in one end, and whack a piece of 12mm with one end turned down to 8mm and knurled into the hole. The annoying thing is the motor only does 6000prm, which isn't so good as a router...but nice for machining aluminium.

Oval holes: same here, the worrying thing is I *did* use the CNC mill for the holes! I didn't make them oval though, just drilled the 8mm holes out to 9mm

blackburn mark
01-11-2010, 10:15 PM
your right jonathan, i meant a helli ESC in govenor mode... iv switched it off, i read somwhere that it would hold revs under diffrent loads, sadly, no joy on that one, its just a slow wind up to speed to stop all the power stripping gears betwean the motor and the main helicopter rotor... maybe it will hold revs when it is flat out?

on the brighter side, my motor has enough power to drill 10mm holes through 40mm of alli without getting particularly hot :) the ESC gets a bit warm though but nothing to drastic... fingers crossed

that motor you have would be wasted as a router !! it may even be over kill for milling alli on your 3 axis... id stick that one on a bike and start doing wheelies up and down your street and use a similar size as mine to mill alli, i really cant see my 3 axis out performing a 2000w spindle

ps: you get extra points for getting your holes wrong on a CNC :) yeeeee Haaaaaawww !!!

Jonathan
07-11-2010, 10:59 PM
on the brighter side, my motor has enough power to drill 10mm holes through 40mm of alli without getting particularly hot :)
Is that without a pilot hole? i.e. removing a 10mm diameter cylinder? If so that requires roughly 310W (at 'reccomended' rpm). What rpm did you use?


that motor you have would be wasted as a router !! it may even be over kill for milling alli on your 3 axis... id stick that one on a bike and start doing wheelies up and down your street
Yeah, I bought it to put on my bike, but that's not happened. I'm thinking of replacing the pathetic motor on my sieg C3 lathe with it. I still think it'd be good on my router for aluminium.[/QUOTE]



ps: you get extra points for getting your holes wrong on a CNC :) yeeeee Haaaaaawww !!!
I think I got a dimension slightly wrong, either that or I should have used a bigger clearance hole in the first place.

A long time ago in this thread I mentioned a method of controlling the ESC from mach3 using the spindle PWM output....so I thought I'd give it a go.

Basically I connected the ESC up to my normal radio system on the model car and used multimeter to measure the duty cycle, and frequency, of the signal at neutral, full reverse and full throttle. I measured 45.6Hz and 5%-6.7%-8.5%. That's a bit annoying as it's only using a small range, but nevermind.

So then in mach3 I ticked 'PWM control', 'Use spindle motor control output' and set 'PWMBase frequ.' to 46hz, and finally set 'Minimum PWM' to 5% (i.e. full reverse).
Then on the motor outputs tab I enabled the spindle and just set the step pin to the one I wanted (in this case pin 2).

Then I went to Config-->Spindle pulleys and set the max rpm to 1000 and left the rest. (more on why I chose 1000 rpm later)

Next I connected multimeter to the parallel port pin to check it was outputting the right frequency, and that the max voltage didn't exceed 5v since more would damage the ESC. Both were fine (I'm using laptop to test, which probably explains the port being 5v) so typed in 'S100 M3' to set the spindle moving at 100rpm. That way if I use the override slider 100rpm corresponds to 10% duty cycle, or more usefully 67rpm is 6.7% ... i.e. neutral.

Now I set it to 67rpm connected one of the parallel port ground pins to the black (ground) wire on the ESC signal connector, and pin 2 to the signal wire (the other side of the 3 pin connector). Esc initialised fine, so I upped the spindle speed a little with the override thing in mach3 and the car promplty shot off the desk :exclaim: and drew briefly half a kilowatt from the battery.
Connected it back up, and yes it works fine.

There's one issue though, at the moment 67rpm is motor stopped, and 85rpm is full speed - in this test 85,000rpm!

I think in my case I'm not going to be too worried about sending the motor backwards, so clearly I can use the forwards only setting on the ESC which makes things a bit simpler. You'll find the duty cycle values for your ESC will be slightly different - use my neutral (6.7%) as a starting point and you can do the normal calibration thing on the ESC to set the endpoints.

I'm sure with a bit of fiddling I should be able to get the RPM values in mach 3 to correspond to actual motor RPM, I'll have a think on that one and let you know.

Hope that helps, ask me if something isn't clear...

PS It took me a grand total of two bits of wire stuck in the parallel port to do this - you MUST check that the parallel port doesn't output more than 5V (5.1 in my case but that's close enough). If it's more then use a couple of resistors as a voltage divider to reduce it. Either way I strongly advise optically isolating the thing.

blackburn mark
08-11-2010, 12:01 AM
Is that without a pilot hole? i.e. removing a 10mm diameter cylinder? If so that requires roughly 310W (at 'reccomended' rpm). What rpm did you use?



haha! no chance! im using an old pc power supply at the moment thats probably only putting out 300w on 12v, besides that i cant get the levarage to drill 10mm in one go... im using one of my linear slides up-ended with a live centre attached just to guid me in straight :)

if i push the motor hard the pc power supply trips out... iv got a 12v 30a supply and two 12v 45a power supplies but iv not got around to sorting them out and as im getting by with the one im using iv percivered with it... the large motor dosnt get warm at all... the ESP worries me now and again, its a turnigy 85a so im thinking the heat is normal



Yeah, I bought it to put on my bike, but that's not happened. I'm thinking of replacing the pathetic motor on my sieg C3 lathe with it. I still think it'd be good on my router for aluminium


im thinking of buying another of the larger motors i have to run my cowels 90 lathe, it knocking on a bit now and the motor bearings are a tad noisy

Some nice research there Jonathan!!!!!!!! im going to have to pick your brain when iv absorbed what you have up to now... sounds like your nearly there, it would be a winner if it can be sorted... im still on the mechanical side of things at the moment but another week or so and i should be mounting my steppers and wiring the whole thing up

iv built a low profile pc out of my scrap box that im fitting into the base, im just hoping the hard drive can handle a bit of vibration

blackburn mark
08-11-2010, 12:07 AM
What rpm did you use?



i didnt clock the revs... just dailed until it was cutting sweet, less than 1000rpm id guess

Jonathan
08-11-2010, 12:58 AM
Double post...

Jonathan
08-11-2010, 01:01 AM
I remember trying 12mm drill with 5mm pilot hole in steel on my mill ... at 2150rpm as I couldn't be bothered to change it. That was fun, but right at the limit of the motor.

Anyway I've concluded that there's no way to get mach3 to read the actual motor rpm with this method, so instead you're going to have to use the following formula I just worked out to convert.

Spindle rpm = (u*x-v*Kv*L)/(u-L)

Or rearranged for x:

x=(rpm*(u-l)+v*kv*l)/u

Where:
u=max duty cycle, so in my case 8.5.
L=neutral duty cycle, 6.7 for me.
v=voltage to motor
Kv=motor rpm/volt
x=rpm mach 3 reads out
rpm=actual spindle rpm
(formula simplifies nicely once you've got the values, tell me what they are and I'll do it for you in Excel if you like)

For that formula to work you need to set the 'Max speed' in 'Spindle Pulleys' dialogue to:
v*Kv*100/L

So for instance with the 7700kv motor I was testing with earlier, on 11.1v ... that's 11.1*7700*100/8.5 = just over a million rpm. Putting that value in means that if you put the correct max rpm of your motor in the spindle speed, then the motor will spin at that speed. It's only true for the max speed though, for other speeds you need to use the other formula.

More to follow, my posts are getting long...

blackburn mark
08-11-2010, 01:20 AM
7700kv motor


youll be able to drill holes in alli with a human hair at that speed!!!!!

its a shame its so complex... (it is to me)

im sure i read somewere that the servo tester pot might possably be removed and driven by mach but no more was said about it... any chance of you casting your skills on that one jonathan?? :)

blackburn mark
08-11-2010, 01:46 AM
I wondered, with my limited electronics knowledge, whether the pot could be removed (which must just provide the pulse generating part of the servo tester with a 0 - 4.8v output) and via a magic box the Mach3 0-10v could be connected instead.
I'm sure you could come up with something along these lines or better !

Does this help you with a better plan?


i didnt realise it was mentiond in this thread :whistling:

also irving came up with ideas but again its all a bit rocket science to me at the moment

Jonathan
08-11-2010, 11:03 AM
The 7700kv motor is only for use in my model car!


i didnt realise it was mentiond in this thread :whistling:

also irving came up with ideas but again its all a bit rocket science to me at the moment

Yes modifying the servo tester is a good way of doing it. The problem is we'd need no know what the pot is connected to first..i.e the circuit diagram of the servo tester. I don't have any servo testers so I can't really help there yet.

The servo tester could be as simple as the one here:
http://pcbheaven.com/wikipages/How_RC_Servos_Works/
(There's some good info there on how servo signals work. It's the same for the ESC so worth reading.)
In which case you can't easily change the pot.
Maybe open up your servo tester and take a picture...

Going back to the connecting the parallel port directly to the ESC idea, I must just be explaining it badly.

Have you got a multimeter/voltmeter?
If so connect it between the pin you want the spindle on and ground on the parallel port. Set the spindle to full speed in Mach3 and check that the voltage is around 5v (definitely no more than say 5.5v).

If that's the case then for testing purposes just get two bits of wire, connect one wire from the ground (black/brown) wire on the ESC 3 pin connector to ground on the parallel port (any pin from 18 to 25). Connect the other wire from the output pin on the parallel port to the signal wire on the 3 pin connector (white/yellow/orange). DON'T connect anything to the red wire on the 3 pin connector.

From there just try the settings I mentioned earlier in mach3 and see what happens. I'm sure it'll become clearer once you've got it connected.


Do you use anything like windows messenger/Skype etc? If so that could be an easier way for me to explain this.

blackburn mark
08-11-2010, 07:43 PM
Maybe open up your servo tester and take a picture...

3353335233513350

dont know if you will make any sense out of these... its just a magic box to me :eek:

i do have a mulimeter but the pc with mach on it is in bits ready to go in my base but i will take you up on the offer of help when i get to that point in the build, iv only had a quick play with mach up to now.

iv just orderd a "MICRO MAESTRO 6-CH USB SERVO CONTROLLER ASSEMBLED" £12 ebay
im not sure if it will solve our mach spindle problem but i thought id give it a punt
335633543355
im hoping mach will know what to do with it :question:

blackburn mark
08-11-2010, 07:56 PM
micro maestro 6-ch usb servo controller

3357

Jonathan
09-11-2010, 01:09 AM
I don't think mach3 will interface with the thing you've bought, not without a lot of effort. I might be wrong though. You could just run it in the background and adjust it manually on the computer anyway?

Servo tester, still trying to trace the PCB. I think it'll work with the parallel port...

Jonathan
09-11-2010, 01:20 AM
Ok disregard that, just had another look. It should be simple to get the servo tester connected.

:idea: Here's a step by step guide.


Remove the potentiometer, or just desolder the pin connected to R32.
Solder a wire to the pin of R32 that was connected to the potentiometer.
Connect the other end of that wire to the chosen output pin on the parallel port...say pin 14.
Solder a wire to the negative of the circuit board, e.g. pin labled '-' on connector JIN, and connect it to any ground pin on the parallel port.
Set PWM frequency in mach3 to something high, like 1000.
Under Config-->Spindle Pulleys set max speed to the max RPM of your motor.
Cross fingers...it should work as normal with the rpm show in mach3 corresponding correctly.

Jonathan
09-11-2010, 01:24 AM
Hmm, before you do that measure the voltage between the pin of R32 that's not connected to the pot and ground whilst twiddling the potentiometer and see what the range is...


Ooh, is that a programming connector I spy on the PCB! Could be handy for something.

Jonathan
09-11-2010, 02:10 AM
Disregard steps 1 and 2, that's not safe to do if the parallel port outputs over 5v. Measure the max voltage as I said in the previous post then just desolder the switch and solder the signal output wire from the parallel port to the PCB pin of the switch which was connected to R31. Then adjust the pot untill it gives the same reading for voltage with mach3 at 100% spindle speed as it did with the pot at 100%. Good idea to remove R32 whilst you adjust the voltage, then put it back when you're sure it's right - that guarantees not to break anything. Quite tricky soldering though!

blackburn mark
09-11-2010, 10:44 AM
hahaha!! yove been busy jonathan... hope you werent late up this morning

iv still got loads of drilling to do so i cant afford to pull my servo tester apart at the mo but iv orderd one exsactly the same for you to experiment with (if you agree) , PM me your address and ill send it over to you once it turns up here.

if you manage to solve the issue then let me know how you did it and we'll call it even :smile:

ps: dont worry about it if its more than you can be botherd with :)

blackburn mark
09-11-2010, 11:26 AM
just for a refrence iv mesured the voltage between both sides of R32 with the resistor still in place

0.24v both sides 0 speed
3v both sides flat out

thats with 5.57v coming in from the ESC battery eliminator

Jonathan
09-11-2010, 08:21 PM
iv orderd one exsactly the same for you to experiment with (if you agree) , PM me your address and ill send it over to you once it turns up here.

if you manage to solve the issue then let me know how you did it and we'll call it even :smile:


That sounds like a good plan :) I've sent the PM. I'll work it all out properly and take some photos of what I do when I get it.

If that voltage is 3v max then we can use the existing potentiometer to scale the voltage from your parallel port to be the same.

Jonathan
09-11-2010, 10:24 PM
jonathan double check youve sent him the pm as ive some how ended up with it,your address etc..

Sorry about that! I've sent it to the right person now :redface:

blackburn mark
09-11-2010, 11:14 PM
ok jonathan the pm got to me :) ill get it off to you as soon as it turns up to mine and we can all look forward to you smoking the thing :eek:

no pressure :lol:

templecorran
11-11-2010, 05:19 PM
Excuse me,
The PC parallel port outputs a binary signal, meaning it has two levels, off / on; or 0 / 1. The 0 is represented by a voltage less than 0.8v The 1 represented by a voltage greater than 2.4v.
Because the signal of interest is a PWM waveform, the voltmeter will be showing the average of the highs & lows of the signal. PWM means Pulse Width Modulation. By varying the proportion of ON time to OFF time in a given interval (20ms) the resulting effect is an analogue voltage. If the ESC wants a true analogue voltage input, a small value capacitor (1μF) between signal pin and ground will help.
If you have access to an oscilloscope this would all be really clear.
Thank you class for being attentive. Now, run along and play with your nice machines!

Oh! I just answered my own problem! Use the oscilloscope to monitor the output of the PWM line (from Mach3), and see how similar it is to the DCBLM drive module requirement!!

blackburn mark
11-11-2010, 08:04 PM
Oh! I just answered my own problem! Use the oscilloscope to monitor the output of the PWM line (from Mach3), and see how similar it is to the DCBLM drive module requirement!!


errrr.... let us know if you make any sense of the problem or if you use the capacitor, im asuming you already have an ESC and servo tester ?

Jonathan
11-11-2010, 10:18 PM
...signal of interest is a PWM waveform, the voltmeter will be showing the average of the highs & lows of the signal...If the ESC wants a true analogue voltage input, a small value capacitor (1μF) between signal pin and ground will help

The ESCs we're using require a PMW signal with 20ms period. The range of the duty cycle used by the ESC is only roughly 5% to 10% - which means you don't get a very high resolution with mach3 connecting it directly. Only a handful of speeds in fact. Still probably sufficient in reality, but not ideal - hence why I'm still interested in investigating the servo tester adaptation. I agree a capacitor will certainly be required here, since the PWM signal is being fed into an ADC.

Just out of interest I connected my model car transmitter up to the parallel port yesterday in a similar fashion - it works fine which implies the servo tester conversion should also. I'm trying to control the parallel port in C now, so I can get the car driving itself around...

blackburn mark
14-11-2010, 09:36 PM
there are two things im dreading on this build....
hole sawing 25mm for the Y screw and drilling and tapping the bed plate

up to now iv used my diy spindle to do all my drilling and i was gagging to to be able to say id done the whole build with it and a tiny cowells 90 lathe:dance: however.... i think i may need to stop f***ing around and borrow a heafty drill

there is probably loads more stuff i should be flapping about but at this point i cant see past the drilling and tapping..... more drilling and tapping.... and!!!..... b***cks!!

336933713370
for now i decided not to support the floating bearing on the Z screw, the housing that came with it seem such a waste of valuable space... ill make a low profile one if i have trouble with it whipping around

Jonathan
16-11-2010, 11:41 PM
Servo tester arrived :)
I dismantled it straight away and sadly the PCB is different. I guess it's not surprising, hobbyking.com are allways changing their inventory.
We will still be able to do the same modification to both of them though - the voltages are similar.

I'll let you know as soon as I've done it - got a fair bit of work to do at the moment :(

blackburn mark
17-11-2010, 12:21 AM
dont be rushing it, i dont think either of us are in dire need of mach spindle control at the mo

have a crack at it in your own time jonathan, dont feel any pressure from me... im at least slack hand full of skinned knuckles away from fitting steppers never mind anything else

good luck when you do get to it :)

Jonathan
17-11-2010, 12:34 AM
Ok then, it's just you sent it special delivery so I thought you were in a hurry!

'im at least slack hand full of skinned knuckles away'
You do think up some good expressions!

I'm going home for the weekend and I intend to get my router to the point of cutting stuff. I intended that last time I went home, but as is always the case with these things they take longer than expected and I ran out of metal.

Anyway, where did you get the long 1/8" cutter from for your little brushless motor? I'm warming to that idea for making PCBs...could use a really high feedrate with the cutter going at 60krpm (or more..) with one of the in-runner motors I've got.

Can't you get the existing spindle to drill nice grid of holes in the bed plate when it's all set up? That's what I'm intending to do.

blackburn mark
17-11-2010, 01:16 AM
i got one from germany (ebay) "Gravierstichel 3,175x115mm 60°x0,32mm VHM f. Pantograph"

then i found some cheeper ones in france (ebay) "1 fraise à graver(long taille) 3,175*60°0,25mm V-type"

iv been looking into sharpening them whilst still in the motor... it would need a jig making.... should get some good use out of them if they can be sharpend without to much hassle

the worry for me are the bearings on the nose, im convinced they will need cooling unless you splash out on ceramic ones and at those prices id still want to cool them, at 48000rpm they were very hot in under a minute, it might stay cool if you use one bearing but i think the runout will suffer, it needs some research

the other spindles are fine, i managed to hole-saw 25mm for my Y screw with the large one... had to take my time though, it keept tripping out my power supply

blackburn mark
17-11-2010, 01:27 AM
could use a really high feedrate with the cutter going at 60krpm


look on ebay for ceramic dental drill bearings(china), if i remember correctly about £25 for 5... iv not commited to those yet, my high speed spindle is way down my list at the mo but im looking forward to having a crack at making it work



Can't you get the existing spindle to drill nice grid of holes in the bed plate when it's all set up? That's what I'm intending to do.


im considering it........ im sh*t scared ill press go and end up with a road runner carved into my nice plate lol

ill need to stick a biro in my spindle and work on my confidence :)

blackburn mark
22-11-2010, 09:24 PM
im starting to wonder if i know what im doing with this thing
3390
iv got a 12v 30A power supply in there for the spindle (couldnt fit the 45A in)
a 24v 15A for the steppers and a 5 axis china special :)
an old pentum4 system shoe horned in with a low profile cooler and a right angle riser for the graphics card, looks like it might get a bit warm in there and im right glad iv used sheilded cable for home switches and steppers

i used to throw this motherboard out of my way a couple of months ago :whistling: iv been holding it with two hands and tiptoing back n forth with it like its a new born baby.... i did test it before i comssioned it for a new life, in fact all the gear has been tested but im still going to squint my eyes first time i flick the on switch :eek:

can anyone tell me if ill be ok leap frogging the mains on all three power supplies and using a 220v 16A switch to turn the whole thing off (after the pc side of things has shut down of course)

ptjw7uk
22-11-2010, 09:44 PM
At full rating and 100% efficient thats only 1 kw so at 50% efficiency 2KW at max, I expect most times it will draw a lot less.
Peter

blackburn mark
22-11-2010, 09:49 PM
2KW at max, I expect most times it will draw a lot less.
Peter

cheers man, wiring isn't my strong point

Jonathan
22-11-2010, 10:44 PM
I would put a separate fuse on each power supply. Whatever is standard for the computer (3A?), and probably similar for the power supplies. Bear in mind the surge current when you switch it on will be quite high. In my case switching on the stepper motors briefly dims the light in my workshop.


Oops, just realised you're talking about a switch not a fuse :redface: Nevermind I'll leave this here.

I'm liking where you've chosen to mount the electrics.

blackburn mark
22-11-2010, 11:01 PM
dims the light in my workshop


youve got heafty setup compared with mine

should i also run an earth to my frame, the power supplies are bolted to the frame but iv no idea how conductive the surface of anodised aluminium is ?

M250cnc
22-11-2010, 11:07 PM
I'm liking where you've chosen to mount the electrics.

The electrics look nice but really should be as far away from dust as possible.

There are people on the zone that have put the controls in a separate room with air from outside to cool the electrics.

Phil


Sent from my HTC Desire using Tapatalk

blackburn mark
22-11-2010, 11:15 PM
as far away from dust as possible.




ill not be cutting wood on this one (acetal/delrin) so i shoulden't suffer the unusual levels of dust that some of you lads have

Jonathan
22-11-2010, 11:15 PM
I thought our drivers were the same? I've got 4 PM752 drivers on a 500VA (I think) toroidal transformer. Maybe it's the big capacitors that cause it...

I think the surface should be conductive enough for an earth. Whether it's a good idea or not I'm not sure. I'd be inclined to say yes.

Good point about the dust. Any fans in there are going to blow in a lot of dust. I found about a 5mm layer of wood dust (and some metal swarf!) in my computer when I cleaned it out on Friday. Probably should have made sure the case side didn't keep falling off, but still...

Edit: didn't see your last post in time :(

blackburn mark
22-11-2010, 11:35 PM
I thought our drivers were the same?


no, im on a chineese 5 axis TB6560, iv no idea if they will be enough, its a small machine but the gantry weighs almost as much as i do :) .... i think in some parts its over engineerd, i was trying to play it safe, the 20mm plate on the gantry sides are the week link.... i designed it with 200mm x 40mm extrusion but valuframe ran out of stock and couldn't find any

its amazing how much more the gantry sides flex in the Y axis compared with the X axis
ill stick some sort of buttress on them if its a problem

Jonathan
22-11-2010, 11:43 PM
I thought the forum had something to stop double posting...oops. That's the problem with having a really slow internet connection.

Jonathan
22-11-2010, 11:44 PM
no, im on a chineese 5 axis TB6560...
its amazing how much more the gantry sides flex in the Y axis compared with the X axis
ill stick some sort of buttress on them if its a problem

I'm not thinking today am I, you mentioned the driver only a couple of posts ago, sorry!

Plate is the worst possible cross section for bending in the Y direction. Maybe you could securely bolt some bigish aluminium angle to the plate to make it a bit stronger...ideally get it welded on.
All that aluminium profile must have cost a lot.

I intend to look at the servo controller on Wednesday, or this weekend at the latest.

blackburn mark
22-11-2010, 11:59 PM
i was thinking a 20mm arch bolted at 90 down the gantry sides, i need to work out where the torsion might be acting... im pretty sure it wont be a staight line top to bottom


All that aluminium profile must have cost a lot

Owch!! £100 meter, it did hurt spending that much but it is easy stuff to work with and its flat enough not to need machining



I intend to look at the servo controller on Wednesday, or this weekend at the latest.


have you got an ESC for that monster motor yet ?

Jonathan
23-11-2010, 12:33 AM
i was thinking a 20mm arch bolted at 90 down the gantry sides, i need to work out where the torsion might be acting... im pretty sure it wont be a staight line top to bottom

Have you had a look at irving's spreadsheet on this? It's interesting comparing the different sections with it.


Owch!! £100 meter, it did hurt spending that much but it is easy stuff to work with and its flat enough not to need machining
Yikes, that's a ridiculous price when you compare it to the material cost.



have you got an ESC for that monster motor yet ?
Not quite. According to the website I need at least 100A and 48v ESC, which is going to cost a lot even from hobbyking! I think a lower current ESC should survive as I'll never need that much power. I'm thinking of replacing the mosfets on a really cheap 100A 24v ESC I have for some much higher voltage ones...that should do the trick for very little money.

Alternatively a friend of mine has randomly acquired a 5.5 KW 400v variable frequency motor inverter from a lift. I think it might be adaptable...

blackburn mark
23-11-2010, 12:58 AM
try "giant cod"
as cheap as ebay for some stuff



irving's spreadsheet

ill have to have a look for that

im not going to use mine at 1700w, i really cant see me needing that much, im not sure the 360w power supply im using will be enough... we'll have to see how it pans out, it would be interesting to see how it dose at 1700w
it has been a real work horse though and the windings dont get very hot

it'll be interesting watching your workshop lights when you fire up that 6000w job :)

blackburn mark
27-11-2010, 01:16 AM
Errrr..... has anyone had any experience with wiring home switches to an X axis thats driven with two steppers ?

in mach setup documentation it recomends putting a homing switch on each of the two x-axis drives to correct for lost steps and racking which im getting plenty of as im in the tuning stages of my setup... i only have enough inputs for 3 homing switches and an e-stop on my driver board

how do i conjure up a forth input ???????

Jonathan
27-11-2010, 01:58 AM
A PCI parallel port card would get you plenty more inputs. There's probably a more elegant way to do it though...
Theoretically 3 inputs is enough if you put the switches in series/parallel etc with each X home switch on separate input - it's a matter of if mach3 can handle it. I'd like to know for my router...

I had a look at giant cod (what an odd sentance!). There's some interesting things but it's still a bit more expensive than www.hobbyking.com. Maybe I could use an E-bike controller on my motor.

HiltonSteve
27-11-2010, 10:25 AM
Jonathan - Just noticed that your after a 100A 48v motor controller, I have got a few kicking around if you want one.

The ones I have take any voltage from 24 up to 48 and also can cope with anything up to 200A, fully programmable through 3 buttons on the front.

Let me know if you want some more information.

Oh, and I am sure the price will be right!

blackburn mark
27-11-2010, 11:44 AM
A PCI parallel port card would get you plenty more inputs.


i was worried someone would say that... my graphics card is blocking all my PCI slots... ill find a way.
im not going down the "series/parrallel" route with switches, homing and soft limits makes the most sense to my eyes



Just noticed that your after a 100A 48v motor controller

might be a winner :)

M250cnc
27-11-2010, 12:42 PM
Mark i have not used a slaved axis but you can have all limits on one input, then maybe just the slaved axis on a separate input.

To anyone who wants more IO i use a PoKeys device http://www.poscope.com/product.php?pid=3

I have control panel with hardware buttons controlled through this device even does Speed and feed override via pots, MPG's etc

Phil

blackburn mark
27-11-2010, 01:10 PM
PoKeys55

looks interesting, cheers phil ill do some research

Jonathan
27-11-2010, 01:35 PM
Jonathan - Just noticed that your after a 100A 48v motor controller, I have got a few kicking around if you want one.
The ones I have take any voltage from 24 up to 48 and also can cope with anything up to 200A, fully programmable through 3 buttons on the front.
Let me know if you want some more information.

I'm definitely interested - those ratings should make it pretty indestructable! Do you have a datasheet or something for them? Is it sensored or sensorless?


Oh, and I am sure the price will be right!
Hehe, I hope so - just spent £274 on linear bearings and ballscrew so I've not got much money left!

P.S. I vaguely recall you posting about these before..?


PoKeys
That does look good, but very expensive compared to PCI parallel port card on eBay for £3.52.

ecat
27-11-2010, 02:45 PM
Mark, I don't know how much control the software you are using allows but one thought on conjuring up a second X home switch is to mount a single switch on the Z axis such that it 'makes' against an edge at the 'home' end of the table.

Drive the Z to the far left and you have a 'home' for the left X screw, drive the head to the right and you have a 'home' for the right screw. Not ideal for the final design perhaps but it certainly gives you some way of tracking the racking while messing around :)

M250cnc
27-11-2010, 03:12 PM
That does look good, but very expensive compared to PCI parallel port card on eBay for £3.52.

Jonathan while it is correct that you can buy cheap PCI Parallel Port cards on Ebay they don't all work with Mach3 some don't have the option of using pins (2-9) for input or output. The PoKeys has dedicated drivers for Mach3 it even has a sub forum on the Mach3 support site.

A bit like comparing a Tata Nano against a Ferrari they both have four wheels, one is a lot more expensive which one would you prefer. ?

Phil

Wobblybootie
27-11-2010, 03:35 PM
Just a quick question ... Any idea if it works with EMC2??

M250cnc
27-11-2010, 03:43 PM
Just a quick question ... Any idea if it works with EMC2??

If you are talking about the PoKeys in theory yes as it is classed as a standard USB device.

But it would need someone to build the the driver whatever and i am not that person, the EMC2 has other options that mean the best guys do not want to bother and Boris the seller of the Pokeys doesn't have the desire either sadly as i have already asked him.

Phil

Wobblybootie
27-11-2010, 03:54 PM
Cheers Phil, I know a EMC guru ... next time I catch him back in the UK I will ask him ... could be an interesting exercise ...

M250cnc
27-11-2010, 04:11 PM
Cheers Phil, I know a EMC guru ... next time I catch him back in the UK I will ask him ... could be an interesting exercise ...

I have had a good look at EMC2, being a guru is a minimum requirement. LOL

I am on the mailing list, i think they talk Klingon, goes way over my head.

Phil

Wobblybootie
27-11-2010, 04:27 PM
Same here ... that's why having a guru around is useful, that is if only he would stay in one country for long enough to have a conversation!!

blackburn mark
28-11-2010, 11:55 AM
Tata Nano against a Ferrari

think ill go for the nano, i can afford it :smile:

iv weighed up all your posts and its all getting a bit rocket science so im going for the simple and cheap option
iv orders a pci ribbon extender and a pci parallel port, i should be able to sneak under my graphics card with that

all that for one more input :wink:

M250cnc
28-11-2010, 12:15 PM
Mark list all your inputs and how you are using currently using them.

Phil

blackburn mark
28-11-2010, 12:32 PM
off the top of my head..... mach setup is saying iv 4 inputs i can use... that would have been fine if i didnt have the slaved x axis
i need one for E-stop two for Z home one for Y home and one for Z home

i know there are other exotic ways of running switches parrallel/series etc but i woul like my "home" away from the extream edeges of my machine so i can easily keep an eye on lost steps

im assuming another port will give me another 9 inputs ???? cant remember,,,, my brain is melting :)

Swarfing
28-11-2010, 05:05 PM
Not true guys? if you want compatibility out of a cheap card they say go for one using 'NetMos' driver chips onboard. I bought a second card that cost less than a tenner and it works with EMC2 fine and others have reported this chip to work well with Mach3 also. I used the details here http://wiki.linuxcnc.org/cgi-bin/emcinfo.pl?NetMos to help me decide which card to buy and Linux picked it up no problem. You have to specify the address in the config file and it was this guy off Ebay i got the card i used from http://myworld.ebay.co.uk/fullspeedit.

Swarfing
28-11-2010, 05:06 PM
Doh just realised i was replying to the previous page on this thread. Oh well

blackburn mark
28-11-2010, 06:48 PM
http://cgi.ebay.co.uk/PCI-IEEE-1284-Parallel-Printer-LPT-Port-I-O-Card-EEP-/290477035425?pt=UK_Computing_ComputerComponents_In terfaceCards&hash=item43a1c7cfa1

to late now, its orderd
ill find out soon enough :)

i might wire up without a Z home for now and add it when i can

f750
28-11-2010, 10:09 PM
Hi Mark just read ball the thread,very interesting I use a 650kv outrunnnermotor on a mill with a 80 amp speed controller, servo tester and a 15volt psu supplly. I have run it on mach3 to cut some small bearing pockets taking a 1mm cut with a 6mm cutter Ihave not had any problems with heat build up. I have fitted a fan on top of the speed controller bolted to the main frame of the mill.

Tony

blackburn mark
29-11-2010, 12:14 AM
Hi Mark just read all the thread

hahaha!!! that must have took some doing :)
i dont have any heat trouble with the larger two motors, its the tiny 4000kv spindle thats giving the bearings im using a hard time m250cnc(phil) thinks it may help if i run them in bit by bit not alowing them to over heat or trying lighter grease, ill give those a try when i find the time

thank god somone has a rc brushless motor spindle working for them, loads of people seem to have a go at building them but iv had no reports of any useful results untill yours, are you running it 1:1 or are you on pullys and belts??

f750
29-11-2010, 11:12 PM
Hi Mark I use a Arceuro ER16 which is 1:1, the motor is actualy a 800kv have loaded a photo
Tony

blackburn mark
29-11-2010, 11:36 PM
Splendid!!! 1000w (ish) ??

i might need to fit a fan to my esc, it gets to hot to touch now and again

are you not finding the 800kv a bit quick to cut aluminium?

f750
30-11-2010, 05:57 PM
I use good quality aluminium and spray a small amount of WD40 to lubricate.

blackburn mark
22-12-2010, 07:39 PM
iv now got a problem with my machine tripping the power
iv got 1 12v power supply 1 24v power supply and one pc power supply
they all work fine when i wire them up individualy
when installed together in my machine more often than not when i hit the on switch everything tripps

a mate of mine said i may have an earth leak (somthing to do with the diffrent power supplies interacting) and the breaker is seeing this as a fault
has anyone any ideas how i might get around this ????

Jonathan
22-12-2010, 09:08 PM
Could it be the initial surge when you switch it on? Can you switch each power supply on individually? The lights in my workshop dim briefly when I switch my steppers on.

blackburn mark
22-12-2010, 09:17 PM
i was hoping id missed somthing simple... ill give that a try jonathan
its really holding the job up now and i want to get started cutting things to bits :)

FatFreddie
22-12-2010, 09:22 PM
Is it a current trip or an earth leakage one?

blackburn mark
22-12-2010, 09:33 PM
Is it a current trip or an earth leakage one?

i cant be 100% sure i share a house with ten other people and the breaker is in somone elses part of the house (i dont want them sussing it me that keeps blowing the power ill get the shit kicked out of me :)

im pretty sure its an earth leak because of the three switching power supplies (all of them will be leaking a bit i guess)
i was thinking ill get a cumalative spike as they all come on at the same time

i have had the thing running and all seems well, it only trips when i power up

FatFreddie
22-12-2010, 10:44 PM
Hmm, separating the switch on times sounds your best bet then - at least it's a fairly easy one to try.

You could try putting a lower current rating RCD and or breaker between it and the fuse board to reduce your chances of injury (flat mate induced, not electrical) but I suppose they'd need to be faster reacting to be sure they tripped in advance of the main one...

blackburn mark
22-12-2010, 10:54 PM
flat mate induced

hahha!!
yep, id give it a go if a knew it would trip before the main one
i need to take it off the surge protector as well, iv read they leak as well

m_c
23-12-2010, 01:26 AM
Are switching live and neutral, or just live?

I know that VFD's are prone to tripping RCDs if you switch both on at the same time, and given that VFDs are basically a very fancy switch mode power supply...

Jonathan
23-12-2010, 01:37 AM
Are switching live and neutral, or just live?

I know that VFD's are prone to tripping RCDs if you switch both on at the same time, and given that VFDs are basically a very fancy switch mode power supply...

Slightly off topic but that reminds me...my router had a switch in it which switched both live and neutral. Is it safe to connect the neutral permanently and have the live on a relay (solid state)?

templecorran
23-12-2010, 03:54 PM
If you think about it ... the mains plug only switches the live, the neutral is unswitched. you can happily feed through the relay. Solid State relays are prone to not switching off though. I use a 4PDT relay with all 4 poles switching the current. I was concerned with the inductive load of the router causing contact burn with just one pole. my 1020W motor is capable of drawing over 4 amps on load, I lacked confidence that my relay contacts were up to that :-)

Jonathan
23-12-2010, 05:31 PM
If you think about it ... the mains plug only switches the live, the neutral is unswitched....Solid State relays are prone to not switching off though

Thanks for clarifying that. I got a SSR as I thought solid state generally means more reliable. It's not a huge issue if the spindle doesn't turn off I don't think since I'll have a normal switch nearby on the mains in addition to the relay. It's a 25 amp relay.

blackburn mark
23-12-2010, 06:27 PM
Are switching live and neutral, or just live?

interesting

im using a cheap 16A switch to switch both live and neutral... are you saying i should be useing a relay and only switching the live ? ill comence experimentations when its not so dark

iv bought a plug in rcd adapter so hopefully it will win the race against the main one and save my house mates missing flash gordon on the telly :)

blackburn mark
25-12-2010, 01:31 AM
ok i removed the surge protector, ran the neutral passed the power switch and bought a rcd adapter
no joy :(
tripped the building out a couple more times (house mates cursing and growling)
stripped the whole thing down looking for a short
i managed to norrow the problem down to some kind of interaction betwean my 24v supply and the driver board
took them over to my girlfreinds house, tripped her power out a dosen times before i twigged than one of the brass risers i was using to mount my driver board to the power supply was reaching through the supply case and touching the top of one of the large caps in there
FFF***nvpkdjsdkcning Hell!!!!!!

thats what i get for being lazy and not making sure they were clear... three days with my thumb up my arse!

ill have to keep my fingers crossed that i havnt damaged the board

h4ppy-chris
26-12-2010, 11:30 AM
glad you found the prob mark on wards and up :)

blackburn mark
08-01-2011, 08:48 PM
its a bit scruffy at the mo but it is working well :)

3570

iv been looking at ways of clamping work to the bed without drilling and taping hundreds of blind holes that will inevatably clog with shit
im thinking i will drill and tap some choice holes as and when things develop

i may have a job with a hundred or so small control panles to engrave so iv been looking at ways to clamp easily and with repeatability

3573
20mm o/d o-ring with 0.34mm protruding above face
3571
one way valve
3572
one way valve holding the vacuum,, at 20mm O/D it only just holds onto this alli plate

3574
35mm o/d o-ring 0.3mm protruding above the face
3575
valve holding the vacuum
3576
takes quite a bit of effort to get this one to pull off
i left it stuck there like that for an hour and i had to give it a good pull to get it off, i wouldnt trust it to hold while on the cnc but it gives a good indication of how well the valve holds the vacuum

very simple and cheap to make in any size , im looking at machining both sides and just placing them between my bed and work peice out of the way of the cut

once iv proven the cocept i may use a peristatic pump (nice and quiet) to pull the vacuum
iv also orderd some transparent valves so i can see which modules are failing to seal

cant see it not working at least for engraving :)

M250cnc
08-01-2011, 08:55 PM
Mark

Another tip is double sided tape for your application.

Phil

Sent from my HTC Desire using Tapatalk

blackburn mark
08-01-2011, 09:06 PM
Mark

Another tip is double sided tape for your application.

hi phil
sounds messy and not quite as elegent for 100+ pices ... iv used bu-tac before now for engraving :) worked ok

M250cnc
08-01-2011, 09:15 PM
hi phil
sounds messy and not quite as elegent for 100+ pices ... iv used bu-tac before now for engraving :) worked ok

It's only messy if you machine through the tape.

It is the number one method used for holding down small flat thin components.

Carpet tape is the best type.

Phil


Sent from my HTC Desire using Tapatalk

blackburn mark
08-01-2011, 09:21 PM
It is the number one method

:eek:
well maybe i can change all that nonsense lol

M250cnc
08-01-2011, 09:32 PM
iv used bu-tac before now for engraving :) worked ok

Well I've never heard of that method. You must like doing things the hard way lol

Phil

Sent from my HTC Desire using Tapatalk

Jonathan
08-01-2011, 09:34 PM
It's only messy if you machine through the tape.

It is the number one method used for holding down small flat thin components.


I've used it on countless occasions at school with the small Roland PNC2300 engraver.
It doesn't leave a mess iff you get the right tape...found that out the hard way :(


I don't like the sound of blu tack - difficult to get it level! More environmentally friendly though I guess.

blackburn mark
08-01-2011, 09:37 PM
Well I've never heard of that method. You must like doing things the hard way lol

what are you like phil ? ... if there was a vice handy or a vacuum bed or a t-nut............. no, there was a lovely peice of blu-tac just sitting there looking at me :) so i used that and got on with my day

blackburn mark
08-01-2011, 09:42 PM
difficult to get it level

hi jonathan, i used the bottom of my Z to press it level :) when iv used it on the lathe face plate i did the same again but with the stock,,, where theres a will :)

Edit: dont try this at home unless you have the magic spell off Gandalf !!!!

Jonathan
08-01-2011, 11:05 PM
when iv used it on the lathe face plate i did the same again but with the stock,,, where theres a will :)

Wait. Did I read that right, you attached something to the lathe using blu-tack!! That sounds a bit dangerous, even by my 'accident waiting to happen standards' :lol: I guess if you went really slow, but surely blu tack wouldn't take the cutting force...

I do like the look of your vacuum thingy. Where do you get the valves?

blackburn mark
08-01-2011, 11:18 PM
even by my 'accident waiting to happen standards' :lol:


yep ! even by your crazy arsed standards :)
i made a nema23 stepper motor mount out of delrin... i didnt have the swing to use a normal chuck but with the face plate i could just squeese the bugger in........ the art of engineering :)
thats why you dont get any saftey tips from me jonathan, dont get me wrong, your fingers are well useful so dont go losing any however somtimes you have just got to go for glory and keep the buggers crossed

blackburn mark
09-01-2011, 12:08 AM
I do like the look of your vacuum thingy. Where do you get the valves?

nice one jonathan, i was starting to think i was on my own with this one

they are fish tank check valves 10 for £3 ... bargain ebay :)
i havnt tested these ones yet but they do the same job as the one iv already got
(fingers crossed they will hold a vacuum without collapsing the diaphragm) ill let you know.
get the transparent ones, they may indicaite to some exstent the state of the vacuum
let me know if you want a syringe ill send you one across

blackburn mark
11-01-2011, 08:53 PM
some developments :) another 4 pads to make and im ready to give them a try
360736083609
its probably wise to keep the lose air to a minimum, small bore pipes etc that way you can pull a harder vacuum
i will be using a one way valve between each pad and the manifold (makes sense if you think about it)
iv oppted for the 35mm o-ring size for now they have a good holding force but not enough to bend/warp 2mm alli (i think) i may make some 60mm pads for heavier material cutting if these work out well
the glue im using is the heat type, iv had no leaks so far :)
you could use two o-rings (one smaller and inside the other) to clamp over holes
you could make up some exelent kits with this stuff
but we will see when it comes time to do some cutting on them:eek:

Jonathan
11-01-2011, 11:22 PM
Interesting stuff. You could stick a sheet of whatever plastic you're using down to the bed and mill slots/holes for the air ... then flip it over and cut out a grid of rings to fit your O-rings. Might be worth thinking about what pattern of rings would hold things best - some bigger than others? Could have rectangular ones, all sorts!

I might have a go at this, got some 6mm acrylic that would do the trick. Got plenty of O rings from £1 shop. Some might be big enough.

With a sufficiently big syringe how many pads do you think could be served? Or are you sucking the air out of one at a time and swapping the syringe round?

I'm looking at the servo controller now. I've traced the PCB and drawn circuit diagram of the interesting bits. The problem is the one you sent me has one significant difference to yours - mine gets 3.3v for the microcontroller and potentiometer via a 3.3v voltage regulator. I think yours is either a 5v microcontroller, or they're getting 3.3v via a voltage divider....

Could you measure the maximum voltage from between R32 and ground on the PCB please? I may have asked you to do that already, this thread is so long I'm not sure!
Also what resistance is your potentiometer - it says on the metal case (FB5k ... i.e 5k ohms for mine)?

Edit: don't worry about the voltage, post #90! Except was that definitely the voltage from the resistor to ground, not across the resistor?

blackburn mark
11-01-2011, 11:46 PM
You could stick a sheet of whatever plastic you're using down to the bed and mill slots/holes for the air

iv considered it for long runs, might be a pain to get the holes routed to each o-ring if its a complex pattern

the problem with mixing diffrent size o-rings is the diffrent surface arias would compress the o-rings diffrent amounts



With a sufficiently big syringe how many pads do you think could be served? Or are you sucking the air out of one at a time and swapping the syringe round?

im going to try using one syringe and fix one of the one way valves as an exsaust so you could pull the initial vacuum the pad valves will hold the vacuum ill press the syringe home and the air iv removed from the pads will be routed through the exsaust one way valve ?????? if you can get your head around that :)

i need to do a drawing to show you what i mean.... imagine you have two one way valves attached to the end of the syringe, youll work it out :)

am i sending you a large syringe ? (iv got a few from work)

Jonathan
11-01-2011, 11:55 PM
imagine you have two one way valves attached to the end of the syringe, youll work it out :)

am i sending you a large syringe ? (iv got a few from work)

Oh, two valves ... you're using the syringe as a pump!
If you could send me a syringe that would be great, I've not got any that seal any more - found out they don't like concentrated sulfuric acid. I can papal you something for it.

I had better buy some valves and tube. What diameter are you using?

blackburn mark
12-01-2011, 01:31 AM
I can papal you something for it.


dont worry about it man, work was scrapping old stock so i didnt pay anything myself :)


found out they don't like concentrated sulfuric acid

they dont like WD40 either

i didnt manage to get much of the surgical tubing, i need to buy some more myself, it looks like 1.5 or 2mm ID and the brass tubing is 3mm
i just used what i had lying around, if i was buying id go for the smallest diameter i could get

Ps: the only reason you would need to use the syringe like a pump is if it failed to seal on the first draw, it would save you having to remove the syringe and start again, im pretty sure you could pull a pretty good vacuum on 4 double sided pads all in one stroke
the 30mm pad held onto a un-polished block of alli for hours without the need for a top up, id top up every now and again if it was on the cnc though :)

blackburn mark
12-01-2011, 01:45 AM
I'm looking at the servo controller now. I've traced the PCB and drawn circuit diagram of the interesting bits. The problem is the one you sent me has one significant difference to yours - mine gets 3.3v for the microcontroller and potentiometer via a 3.3v voltage regulator. I think yours is either a 5v microcontroller, or they're getting 3.3v via a voltage divider....

Could you measure the maximum voltage from between R32 and ground on the PCB please? I may have asked you to do that already, this thread is so long I'm not sure!
Also what resistance is your potentiometer - it says on the metal case (FB5k ... i.e 5k ohms for mine)?

Edit: don't worry about the voltage, post #90! Except was that definitely the voltage from the resistor to ground, not across the resistor?

ill try to get another the same as yours
this thread is getting a bit long :redface: i guess i should have split it up into spindles router and vacuum stuff

Jonathan
12-01-2011, 02:11 AM
ill try to get another the same as yours
this thread is getting a bit long :redface: i guess i should have split it up into spindles router and vacuum stuff

Wait a second. I can just make you one using a PIC ... it'll save you buying one and you won't have to modify it.

If you just measure the voltage at the point I said earlier. Remove that resistor (R32), remove R31 and connect the parallel port pin to where R31 connected to the potentiometer, then set spindle in mach3 to highest, adjust the pot so you get the same voltage as measured at R32 earlier. Put R32 back in place and do not move the potentiometer ever again otherwise the microcontroller will probably break.

Measure that voltage, if it's ok then I'll scribble a diagram over the picture you posted.

It would be good if a moderator could split this thread up to save duplication? If not then I'll start a new one about the spindles.

ptjw7uk
12-01-2011, 09:45 AM
Just a note to say that the different size O-rings should all compress the same amount as long as they are all the of the same thickness, therein lies the problem getting the same thickness in different diameters.

Peter

blackburn mark
12-01-2011, 04:10 PM
Wait a second. I can just make you one using a PIC ... it'll save you buying one and you won't have to modify it.

If you just measure the voltage at the point I said earlier. Remove that resistor (R32), remove R31 and connect the parallel port pin to where R31 connected to the potentiometer, then set spindle in mach3 to highest, adjust the pot so you get the same voltage as measured at R32 earlier. Put R32 back in place and do not move the potentiometer ever again otherwise the microcontroller will probably break.

Measure that voltage, if it's ok then I'll scribble a diagram over the picture you posted.

It would be good if a moderator could split this thread up to save duplication? If not then I'll start a new one about the spindles.

great stuff, ill get on it as soon as i have time :)
ill probably buy another servo controller so i can run the spindles without mach and for a backup in case i fry the one iv got

blackburn mark
12-01-2011, 04:14 PM
Just a note to say that the different size O-rings should all compress the same amount as long as they are all the of the same thickness, therein lies the problem getting the same thickness in different diameters.


sounds to good to be true, ill have to do some maths, iv got plenty of o-rings from 18mm ID to 50mm ID and they are all 3.5mm section

ptjw7uk
12-01-2011, 06:34 PM
Your right it is to good to be true, must have been asleeop when I did the calcs!!

Peter

blackburn mark
12-01-2011, 08:21 PM
Your right it is to good to be true, must have been asleeop when I did the calcs!!


Darn it ! never mind, it would have been nice :)

ptjw7uk
12-01-2011, 08:25 PM
Yes Thats what you get when making quick calcs on the back of a fag packet while doing something else!
Took some time to find my error in th calcs!
Oh well seemed right at the time.
On some vac tables they have a cross hatch of grooves that you run a length of rubber around so its under the piece you want to hold and cut of any excess, can also be fitted with stops for repeat parts.

Peter

blackburn mark
15-01-2011, 12:56 PM
i've done some testing with these vacuum pads up to 50mm, they will work fine for engraving or fine cuts however due to the tiny footprint of the stiff o-rings the friction is a little low and there is the risk of the part slipping latteraly

jonathan, i've sent you a couple of syringes some tube (i found some more) and a one way valve, the valve is a medical job and it takes quite a bit of pressure before the seal is broken and it allows any flow so it needs to be mounted on the tip of the syringe to reduce pressure backlash, not perfect but it will give you something to experiment with, i'm leaning towards your idea of making a bolt down board unless i can find better seals, car oil filter seals might be much better for individual pads, they have a square section and a much larger contact area

i've sent it to your uni address

blackburn mark
16-01-2011, 03:10 PM
75mm oil filter seals, iv no idea why i save them when i service my car?

3627
1mm outside diameter hypodermic needles, i drilled the seals with a .75mm drill (by hand)
3626
squash for unusual shape
3625
plenty of holding force, the first seal is happily holding the weight of the second two blocks, i can slide each block around to square up but there is enough resistance for reasonable machining especially in acetal plate

i have used the smaller pads to cut 28mm washers out of 1mm alli, i had one failure with it creeping... it takes a light touch. they will be fine for my engraving job

templecorran
18-01-2011, 09:16 AM
Some where on this forum I had a thread about vacuum tables. I suggested cling film to mask off the unused holes.
However, I like your solution. simple, elegant, and best of all, QUIET!

blackburn mark
18-01-2011, 10:33 AM
I suggested cling film to mask off the unused holes

nice one ill give it a try, should work well with small holes, i was thinking latex but i guess over time you would build up a collection of anything that works
blu-tack might be an option for slighly larger holes, i think anything over 4 or 5mm would need a more sturdy plug


and best of all, QUIET!

high on my list, my router is running inside the house (thank god im not trying to cut wood)

Jonathan
18-01-2011, 11:12 AM
blu-tack might be an option for slighly larger holes, i think anything over 4 or 5mm would need a more sturdy plug

Rubber test tube bung?

I got the syringes yesterday - thank you :smile: Bigger than I expected - I'm impressed at the pressure (or lack of pressure!) that they can hold. I'll do some experimenting over the next few days...

blackburn mark
18-01-2011, 11:31 AM
yo jonathan, remember to put that one way valve as close to the tip of the syringe as you can, a mind like yours will work out why if you think about it, its not so important with the fish tank valves (almost zero resistance) iv had one of them fail so far, the one you have should be very robust
iv added the exsaust valve to my setup, makes life really easy :)
let us know if you have any eureka moments :)

Tenson
01-10-2012, 01:07 PM
Mark, I've just skim read this thread in one turn, so forgive me if I missed the details. Have you got the PSU sorted for the big motor?

I also built a spindle with a large 270KV motor (http://www.giantshark.co.uk/c506509-kv270-p-407464.html). I then modified a 750watt PC PSU to have a variable output voltage on what was originally the 12V line. Although I can make the PSU output any voltage unloaded, when the motor loads the PSU the voltage drops down the the point at which it can supply that amount of power*. I found that even driving the motor with 750watts didn't give a significant amount of cutting power; I can take 0.5mm cuts with a 6mm tool at 80mm/min but it is not very clean and the spindle RPM is too slow for 3mm cutters.

*The PSU will always limit at 750watts (this is a natural limit, not a protection circuit). Since the load of the motor is fixed (0.36 ohms), and the total power is fixed, the voltage must drop to 16.5V. I decided I need more power, but I'm not sure how to get it; even a budget ATX PSU >1000watts is not cheap.

blackburn mark
01-10-2012, 02:06 PM
Mark, I've just skim read this thread in one turn,

owch! that must have taken a bit of doing.... well done.


750watt
that should be loads! something not right there... i used a 300w pc supply for quite a while (managed to trip the supply out a couple of times while using a hole saw... besides that its managed ok?)

im now on a cheap 12v 350w china special iv not tripped that one so far

im assuming your saying its to slow for 3mm tooling in wood ?
90% of my cutting is 3mm single flute in acetal between 1mm and 3mm DOC aprox 2000rpm between 200 and 300 feed

at 270kv you would need 48v to get aprox 13000rpm ... might be a tad fast if your using double row A/C bearings unless you have them swishing around in a nice light oil ?
you might have problems with the esc and windings getting hot

id be tempted to make a second spindle with a higher kv rating .... 890kv would give you 10680rpm at 12v

Tenson
01-10-2012, 02:22 PM
Hi,

It doesn't do too bad in soft materials actually, but 3mm tooling in alu it didn't like. I assumed this was because the RPM was too low, but maybe it is just the CNC-3040 the spindle is attached to being too floppy for delicate tooling. Yes I think I should have gone for a higher KV motor; I had anticipated driving it with 30V.

Anyway here is a good tutorial I found about how to increase the PSU voltage - http://cyberfish.wecheer.com/blog/?p=769

Tenson
01-10-2012, 06:10 PM
Oh I also forgot to say, the surface of anodized aluminium is non-conductive, but the surface is easily scratched through to the conductive bulk. It is most definitely worth earthing the chassis so if any high voltage comes in contact with it, the power can sink to ground instead of the person who might be touching it. Wherever you connect the earth tag make sure it is well connected to the bulk of the material since the surface layer does not conduct.

Fivetide
03-10-2012, 11:24 PM
Love the vacuum pad idea Mark, will do something but a bit different, I am inspired though :) .. I went to school in Blackburn ...:surprise:

blackburn mark
04-10-2012, 01:04 PM
Oh I also forgot to say, the surface of anodized aluminium is non-conductive, but the surface is easily scratched through to the conductive bulk. It is most definitely worth earthing the chassis so if any high voltage comes in contact with it, the power can sink to ground instead of the person who might be touching it. Wherever you connect the earth tag make sure it is well connected to the bulk of the material since the surface layer does not conduct.

yea.. i sussed that one out in the end.. its kind of suprising that anodized aluminium is none conductive

blackburn mark
04-10-2012, 01:16 PM
I went to school in Blackburn ...


you poor sod... i went to boarding school in shropshire (not as posh as it sounds)


will do something but a bit different
if you can get your hands on a pump that will pull a good hard vacuum a vacuum plate full of o-rings might come in handy.
...we want pictures :)

Fivetide
04-10-2012, 02:47 PM
Ahhh now I have found something that may be a bit good lol waiting for the RTV to set then I'll show you, all because of a great guy at Tom Parker called Brian in Preston, he knows his shit and i think I have a pretty good solution.. fingers crossed and pics to come :)

blackburn mark
04-10-2012, 07:32 PM
Ahhh now I have found something that may be a bit good lol waiting for the RTV to set then I'll show you, all because of a great guy at Tom Parker called Brian in Preston, he knows his shit and i think I have a pretty good solution.. fingers crossed and pics to come :)

that might be a bit good !! depends how good you are with the dispenser.. stick a stepper motor on it :)
how long till it sets ?
or are you waiting double time just to make sure ?

Fivetide
04-10-2012, 09:50 PM
...we want pictures :)

done on my thread (http://www.mycncuk.com/forums/mills-routers-lathes-commercial-machines/5022-journey-begins-new-me-my-first-cnc-black-cat-4.html)

Fivetide
18-10-2012, 07:15 PM
Now I need some oil filter seals lol , going to try and tap some local gaurage see if they will keep them for me :)

m_c
18-10-2012, 07:30 PM
Now I need some oil filter seals lol , going to try and tap some local gaurage see if they will keep them for me :)

What do you want them for?

Could you not use a length of o-ring material?
You can buy kits for making o-rings, which are essentially a length of round rubber in rubber/viton/whatever spec, and some glue/bonding/vulcanising stuff.
I'm sure you can probably get lengths of square material aswell, which would be far better than oil soaked seals.

Fivetide
18-10-2012, 07:34 PM
What do you want them for?

Could you not use a length of o-ring material?
You can buy kits for making o-rings, which are essentially a length of round rubber in rubber/viton/whatever spec, and some glue/bonding/vulcanising stuff.
I'm sure you can probably get lengths of square material aswell, which would be far better than oil soaked seals.

I bought a set of o-rings but because they are round and the rubbers fairley hard you dont get enough surface area for the vaccum, it tends to role across the rubber, my larger rubber ring is flat and compresses under the force, the o-rings dont :(

Jonathan
18-10-2012, 08:08 PM
I bought a set of o-rings but because they are round and the rubbers fairley hard you dont get enough surface area for the vaccum, it tends to role across the rubber, my larger rubber ring is flat and compresses under the force, the o-rings dont :(

You could try neoprene?

neoprene sheet | eBay (http://www.ebay.co.uk/sch/i.html?_nkw=neoprene+sheet&_frs=1)

I can send you a bit if you want to try it...

Fivetide
18-10-2012, 09:15 PM
You could try neoprene?

neoprene sheet | eBay (http://www.ebay.co.uk/sch/i.html?_nkw=neoprene+sheet&_frs=1)

I can send you a bit if you want to try it...

What a fantasic idea ! never thought of that .. many thanks for the offer Jonathan :) but i have an old hud I didnt get around to selling with my dry suite its in the attic I'll dig it out I think its a 4mm .. not sure ..god it must be 20 years old by now lol

m_c
18-10-2012, 09:19 PM
Oil filter seals aren't any softer than o-rings, and by the time they get changed, they've usually hardened up even more.

You do get o-rings made from softer material, but they're not common place.
I wonder what the proper name for the seal strip type stuff that comes in strips and used for sealing junction box covers is called. I've worked on various junction boxes, where the seal is just a press fit into a machined groove. It's usually a round or rectangular shape, and is normally very soft so you get a good seal with minimal pressure.

Fivetide
18-10-2012, 09:28 PM
Oil filter seals aren't any softer than o-rings, and by the time they get changed, they've usually hardened up even more.

You do get o-rings made from softer material, but they're not common place.
I wonder what the proper name for the seal strip type stuff that comes in strips and used for sealing junction box covers is called. I've worked on various junction boxes, where the seal is just a press fit into a machined groove. It's usually a round or rectangular shape, and is normally very soft so you get a good seal with minimal pressure.

I know what you mean M_C old tobacco tins use to have an orange'ish rubber seal but now it looks like some kind of bonding ..and comes away in bits.The other thing of course is jam making jars .. u can get replacement seals in all sorts of sizes.. they are flat an i think quite soft, I shall borrow one off my mum on Sunday :)

Jar Seals (http://www.ebay.co.uk/itm/10-x-Spare-Rubber-Kilner-Parfait-Jar-Seals-Sealing-Rings-/360492832831?pt=UK_HomeGarden_Kitchen_FoodStorage_ GL&hash=item53ef0c183f)

m_c
18-10-2012, 11:18 PM
A quick google for "enclosure sealing gasket" turned up this (http://www.ebay.co.uk/itm/BOSS-ENCLOSURES-33070041-SEALING-GASKET-IP65-/130682944964#vi-content) on ebay.

m.marino
22-04-2013, 02:27 PM
Mark,

I have an idea of setting up jigs for cutting parts and using your idea of a syringe, with a valve to create the vacuum to hold them down. Where do you get your syringes from? I would be hooking the tubing into a block of HDPE that would be shaped so that flat surface on the bottom would have vacuum draw against them to help hold the piece in place. If you could let me know where you got those from and/or what you consider good pricing I will post some pictures of the pieces once they are assembled and working.

The other idea I am looking at in a vacuum bed made out of a solid surface (Hi-MACS or Corian). Which since they are non porous could be a very useful option instead of steel or aluminium. Also a good bit easier to machine and assemble.

Michael

blackburn mark
22-04-2013, 05:18 PM
PM me your address and I'll send you a slack handful (work was binning old stock so they didn’t cost me anything)

the idea works quite well for specific tasks like engraving lots of the same item but for a larger bed/pads it would take quite a bit of effort to draw out the static volume.
Remember to put the one way valves close to your syringe to get maximum draw

The way I had mine set up it worked like a by bicycle pump but in reverse

birchy
22-04-2013, 06:55 PM
If it were me, I'd be looking at suction cups of some sort. Maybe some of these: 2 Acupuncture Massage Suction Cup Heat back Pain Relief | eBay (http://www.ebay.co.uk/itm/370530223089) but it might be difficult to remove the work piece once it was under vacuum.

The other option might be to use dent pullers like these: Mini Dent Puller Bodywork Panel Remover Removal Tool Car Van Suction Cup Glass | eBay (http://www.ebay.co.uk/itm/300894394259) but attach them to the machine and activate them with an air cylinder or some other mechanical actuator.

On the syringe theme, you could use air cylinders to create a vacuum. You could either use one air cylinder and actuate it manually or use 2+ with one as the actuator (i.e. you feed one with compressed air and it then pulls the other(s) to create a vacuum). Air cylinders are not cheap to buy new but can be manufactured at home if you have a decent lathe. Hydraulic cylinders are another option (minus the oil!). Or the scrap yard...

Ross77
23-04-2013, 01:55 AM
Might have the wrong end of the stick as I haven't read all posts from the beginning but if you are looking for a vacuum pumps then most compressors can used the other way around, especially the diaphragm pumps.

Clarke Mini Air Compressor - Wiz - Machine Mart (http://www.machinemart.co.uk/shop/product/details/wiz-mini-air-compressor) Bit pricey but easy to mod, just fix a tube to the intake filter plate and keep the output open. depending on the amount of vacuum you need you could use the smaller 12v tyre inflates or even a fish tank aerator.

GEOFFREY
23-04-2013, 12:59 PM
Mark,

I have an idea of setting up jigs for cutting parts and using your idea of a syringe, with a valve to create the vacuum to hold them down. Where do you get your syringes from? I would be hooking the tubing into a block of HDPE that would be shaped so that flat surface on the bottom would have vacuum draw against them to help hold the piece in place. If you could let me know where you got those from and/or what you consider good pricing I will post some pictures of the pieces once they are assembled and working.

The other idea I am looking at in a vacuum bed made out of a solid surface (Hi-MACS or Corian). Which since they are non porous could be a very useful option instead of steel or aluminium. Also a good bit easier to machine and assemble.

Michael
Michael, I made a vac bed using grey pvc. Bottom sheet 20mm, top sheet 6mm with 5mm round gasket/o ring seals. this works very well. I can send you dxf (if I can find it!) of my vac table if you wish to give an idea of what I did if you wish. G.

m.marino
23-04-2013, 03:13 PM
Geoffrey,

If you can find it that would be great. What kind of pump are you using to get the vacuum pressure with?

Michael

GEOFFREY
23-04-2013, 09:26 PM
Michael, send me your email address and I'll send the dxf file. I use two small GAST pumps, table divided in 2 halves. G.

Bazzer
23-04-2013, 10:01 PM
Geoffrey, any chance of having a look at your dxf, and what size are your gast pumps?
Many thanks in advance
Simon

JAZZCNC
23-04-2013, 10:28 PM
Geoffrey, any chance of having a look at your dxf, and what size are your gast pumps?
Many thanks in advance
Simon

Simon you'll have fun trying to suck sponge down. .. :hysterical:

Got the perfect stuff for you to make Vac bed with. It's a man made resin board that machines great is super flat and hard has nails. It's Called Trespa Athlon look it up.
Got some that's 20mm and some that's around 12-15mm but would need to check that.?

Let me know if you want some and size and I'll chop you piece and take to work for next time your over our way.

Bazzer
23-04-2013, 11:04 PM
Simon you'll have fun trying to suck sponge down. .. :hysterical:

My favourite hobby sucking sponge !!! :hysterical:

Would love FREE trespa, you can take the boy out of Yorkshire, but you can't take the Yorkshire out of the boy!

:hysterical:

GEOFFREY
24-04-2013, 12:15 AM
Michael, Simon, I would post the dxf here, but don't seem to be able to do so. That is why I asked for email. Will check on my pump sizes tomorrow and post. Obviously my drawing is to suit my machine and will need modding. I have made 2 circuits, one for each pump. Each pump is simply plugged into a double socket and switched on and off as necessary, no valves, reservoirs or vac controllers etc. very simple,but effective.
JAZZ's offer of the free trespa sounds unbelieveable - Almost makes me wish I was a "northerner". G.

Any help on how to add an attachment on here would be very useful. thanks. G.

birchy
24-04-2013, 12:27 AM
Geoffrey, if you click "Go Advanced" in the bottom right corner of the "Quick Reply" box, you get some extra options, one of which is "Add Attachment". the icon looks like a sheet of paper with a paper clip on it.

GEOFFREY
24-04-2013, 01:21 AM
Thanks Birchy, trying that now8817





I have tried to open it here, but the grooves (channels) seem a bit incomplete. My dxf output was set to six decimal places, maybe I should have reduced that. Any way let me know if it is readable, if not I'll try again. G.

birchy
24-04-2013, 01:31 AM
Looks OK in DraftSight on my Linux machine.

GEOFFREY
24-04-2013, 09:55 PM
Geoffrey, any chance of having a look at your dxf, and what size are your gast pumps?
Many thanks in advance
Simon

My GAST pumps are model nos. 0523 702 q er 32x and 0522 v734 r 32x. Both are 240v single phase motors with a current rating of 2.9A. sorry for hi-jacking this thead. G.