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I've used it on countless occasions at school with the small Roland PNC2300 engraver.Quote:
Originally Posted by M250cnc
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.
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 dayQuote:
Originally Posted by M250cnc
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 :)Quote:
difficult to get it level
Edit: dont try this at home unless you have the magic spell off Gandalf !!!!
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...Quote:
Originally Posted by blackburn mark
I do like the look of your vacuum thingy. Where do you get the valves?
yep ! even by your crazy arsed standards :)Quote:
even by my 'accident waiting to happen standards' :lol:
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
nice one jonathan, i was starting to think i was on my own with this oneQuote:
I do like the look of your vacuum thingy. Where do you get the valves?
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
some developments :) another 4 pads to make and im ready to give them a try
Attachment 3607Attachment 3608Attachment 3609
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:
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?
iv considered it for long runs, might be a pain to get the holes routed to each o-ring if its a complex patternQuote:
You could stick a sheet of whatever plastic you're using down to the bed and mill slots/holes for the air
the problem with mixing diffrent size o-rings is the diffrent surface arias would compress the o-rings diffrent amounts
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 :)Quote:
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 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)
Oh, two valves ... you're using the syringe as a pump!Quote:
Originally Posted by blackburn mark
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?
dont worry about it man, work was scrapping old stock so i didnt pay anything myself :)Quote:
I can papal you something for it.
they dont like WD40 eitherQuote:
found out they don't like concentrated sulfuric acid
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 :)
ill try to get another the same as yoursQuote:
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?
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.Quote:
Originally Posted by blackburn mark
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.
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
great stuff, ill get on it as soon as i have time :)Quote:
Originally Posted by Jonathan
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
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 sectionQuote:
Originally Posted by ptjw7uk
Your right it is to good to be true, must have been asleeop when I did the calcs!!
Peter
Darn it ! never mind, it would have been nice :)Quote:
Your right it is to good to be true, must have been asleeop when I did the calcs!!
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
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
75mm oil filter seals, iv no idea why i save them when i service my car?
Attachment 3627
1mm outside diameter hypodermic needles, i drilled the seals with a .75mm drill (by hand)
Attachment 3626
squash for unusual shape
Attachment 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
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!
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 worksQuote:
I suggested cling film to mask off the unused holes
blu-tack might be an option for slighly larger holes, i think anything over 4 or 5mm would need a more sturdy plug
high on my list, my router is running inside the house (thank god im not trying to cut wood)Quote:
and best of all, QUIET!
Rubber test tube bung?Quote:
Originally Posted by blackburn mark
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...
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 :)
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. 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.
owch! that must have taken a bit of doing.... well done.Quote:
Mark, I've just skim read this thread in one turn,
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?)Quote:
750watt
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
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
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.
Love the vacuum pad idea Mark, will do something but a bit different, I am inspired though :) .. I went to school in Blackburn ...:surprise:
yea.. i sussed that one out in the end.. its kind of suprising that anodized aluminium is none conductiveQuote:
Originally Posted by Tenson
you poor sod... i went to boarding school in shropshire (not as posh as it sounds)Quote:
I went to school in Blackburn ...
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.Quote:
will do something but a bit different
...we want pictures :)
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 :)Quote:
Originally Posted by Fivetide
how long till it sets ?
or are you waiting double time just to make sure ?
done on my threadQuote:
Originally Posted by blackburn mark
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?Quote:
Originally Posted by Fivetide
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 :(Quote:
Originally Posted by m_c
You could try neoprene?Quote:
Originally Posted by Fivetide
neoprene sheet | eBay
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 lolQuote:
Originally Posted by Jonathan