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View Full Version : BUILD LOG: My baby 15" x 15" machine



wilfy
14-09-2012, 12:59 AM
ok strictly it hasn't started yet, but i need to gather everything together and start planning this machine now as the mrs has all but given the green light due to a lovely PPI claim coming through unexpected.

so i'm trying to understand where to start and i suppose you start with what are you going to cut as this kind of sets the boundaries for what spindle you can use.

so.. i want to do some engraving in mdf, other nice woods, some acrylic so it can be lit up from the sides ect.. obviously there is some need for speed to keep the finnish up.. so before i try and cut corners here and say i want to use a dremel or something similar do i need to go all out and go for a water cooled spindle or is there something else out there that will suit my needs?

now once i figure out what spindle i am using i can then find out how big it's mount needs to be and from there i can work outwards and figure out rail sizes, screw sizes and then i can work on the frame to hold everything.


so with all the above in mind am i missing anything?

as a small note.. if i decided at a later date i wanted to cut alu with the machine would a need to design it differently than with the mdf and acrylic in mind

TrickyCNC
14-09-2012, 08:14 AM
Any reason you decided on 15x15 ?

and yes, cutting ally needs a very rigid build, and has to be designed in from the start.

Spindles ... it depends on your budget ? but a cheapish router will get you started. I've just bought a 25 one from Aldi.
ALDI - Sunday Special Buys 9th September 2012 (http://www.aldi.co.uk/uk/html/offers/special_buys3_26484.htm)
I'll be fitting it to my build soon, as my Bosch router is about 20 yrs old and needs the bearings replacing.

You can change the router mount to a spindle mount at any time if you make it as a 'bolt on' to the main carriage.
Design the carriage so it has no interference from the router/spindle at the end of the gantry, else you'll loose some working area if you put anything bigger on later.

wilfy
14-09-2012, 10:43 AM
15 x 15 was decided to cover off a 12" subwoofer ring if ever i felt the need to make one as this is what i used to do alot.. and i just thought 15" was a good size. if someone said well for very little extra you could go to 20 x 20 then i'd possibly go that far.. the idea with this machine is to keep the cost down, show the missus what it can do and for it to prove itself then i'll move on to a 4ft x 4ft so i can atleast cut half a sheet of material.

as for a cheap 25 router i'm willing to pay more for the spindle and i think from what i've read a router doesnt lend itself to variable speeds very well and from what i've seen of my own router it doesnt finnish plastic very well. also the standalone spindles are less bulky meaning machine design can be kept smaller and the collet extends alot further down than a router

so far i've seen these CNC 300W Spindle Motor & Mount bracket For Engraving Carving MILLING GRINDING | eBay (http://www.ebay.co.uk/itm/CNC-300W-Spindle-Motor-Mount-bracket-For-Engraving-Carving-MILLING-GRINDING-/251125000125?pt=UK_BOI_Building_Materials_Supplies _Carpentry_Woodwork_ET&hash=item3a783767bd#ht_3626wt_1163)

but i have no idea how good they are and what the limits would be.. also i suppose i need to consider psu for one? and how is the speed controlled?

or these 0.8KW MORE PRECISE WATER-COOL SPINDLE MOTOR ENGRAVING MILL&GRIND WATER-COOLED k5 | eBay (http://www.ebay.co.uk/itm/0-8KW-MORE-PRECISE-WATER-COOL-SPINDLE-MOTOR-ENGRAVING-MILL-GRIND-WATER-COOLED-k5-/200691892163?pt=UK_BOI_Industrial_Automation_Contr ol_ET&hash=item2eba2b3fc3#ht_11022wt_1397)

or to go as far as a 2.2kw, but again i just dont know.

i am hoping that as my machine is going to be small it wont need such a big motor, but again i'm open to ides if needs be and i need to spend 150 on a motor then so be it.

the plan is to get a list of all the parts i need and then go to one of the chinese guys and ask for a price for the lot which will hopefully save myself some money overall, but i cant get to this stage until i design the router

TrickyCNC
14-09-2012, 11:01 AM
when it comes to spindles, it doesn't matter that you have a small machine.
What matters is what you want to cut with it. Also, thinking of your woofer holes, you need to design in enough bed room for your sheet material, not just the cutting area.

I would say 300w is quite underpowered for anything except shallow engraving.

The larger spindles, and the water cooled ones are VERY heavy ! this will have to be considered into the design and motor/driver choice.

basicaly, lenght of screws/drive/r&P etc and length of rails/bearings determine the machine cost, (unles using extruded ally which is expensive). Most of the rest is the same cost regardles of machine size.

wilfy
17-09-2012, 09:15 AM
presuming i am going for the 2.2kw spindle, having a working area of 15" x 15" has anyone got any advice on the diameter of screw i should use?

Fivetide
17-09-2012, 07:44 PM
15 x 15 .. a baby like mine 8 x 12 :) I want aiming to do the same as you , and some PCB's perhaps , mine off the shelf though, although someone did suggest now I havea small CNC I could build a bigger one with it well some of the parts at least, when I can get it to run that is , and its been sat there for a month now all I'm missing is a bloody cable! lol good look with the build..

TrickyCNC
17-09-2012, 08:24 PM
As no one has answered yet .. I'll risk the wrath of posting a reply :)

For this size, I'd say 16 would be fine. 5 or 10 pitch depending on motors and drivers

are you going for ballscrews or acme (trapeziodal) ?

did you read the MicroCarve thread I linked you ?

wilfy
17-09-2012, 10:28 PM
i've been working 12 hour days for the past week and even working over the weekend.. what little time i've had i've spent with my family.. so no not read that thread yet... however i know how i want to make this machine i just need a few technical things ironing out.

16mm ballscrews is exactly what i had thought and it fits well with my budget so unless anyone has any good reason why i should go bigger then i'll likely go with them.

i'm on earlys this week with no call shift so i will be reading that thread at some point

TrickyCNC
17-09-2012, 10:37 PM
I didn't mean you should read it to change your mind ! just that it's about the same size as you are making, so it might be interesting reading :) screw size for instance .

Rich

Hobgoblin
11-10-2012, 10:57 PM
any updates wilfy?

wilfy
15-10-2012, 12:47 PM
nope i have all the welding gear now, but i'm still struggling getting my design down in goolge sketchup and until i do this i dont want to start, plus the money i thought we were getting got swallowed up by other things :/ life sucks atm

Hobgoblin
15-10-2012, 06:26 PM
cheer up cock. I agree with you wanting to get the design right before you start or buy things im in the same boat. Ive been desgining mine for months now, Ive just decided that i cant keep drawing ive just got to get on and try a bit lol. Im %90 there on design, the rest i can make up as i go along sucessfully im sure. Have you any sketches, plans etc to show, perhaps we could give you some input or a lift?

wilfy
27-10-2012, 12:35 AM
7212
finally getting somewhere with sketchup, i wanna run this past you lot before i progress this further

the 2 small piece of box section are 25 x 50mm steel box and i'm hoping to mount the router straight to them with a bracket i will design later down the line..

what i want to check is that the rails are not too far away from the router.. the box section the rails are mounted on is 50 x 50mm steel so that puts the base of the rails 75mm away from the base of the router support

and also the piece that the ball screw is mounted to is 10mm. firstly can i easily cut through 10mm steel with a holesaw? as thats the only way i'm going to be able to cut it? if not is 10mm thick ally enough considering how close the box section will be either side to support it?

audioandy
27-10-2012, 10:54 AM
Wilfy

Swap your rails and bearing blocks round, put your blocks where your rails are now and have the rails move up and down with your Z axis.

Andy

wilfy
27-10-2012, 12:00 PM
there are no bearing blocks in that picture yet...

let me show you where i got up to last night, i'm not 100% happy with it as i'm not sure what kind of bearing block i'm having for the ballscrew and the size of it

7214

audioandy
27-10-2012, 02:45 PM
Sorry thought the rails was on the front of the axis didn't realise is was the rear view.:stupid:

Put the blocks as low as possible and space them as wide in both ways as you can.

wilfy
27-10-2012, 08:50 PM
guys whats the difference between using BK or FK blocks for the ballscrew supports?

Hobgoblin
27-10-2012, 10:11 PM
IIRC BK blocks allow you two mount them in two planes, perpendicular AND paralell to the screw. FK only allow mounting in 1 plane, paralell to the screw.

wilfy
27-10-2012, 10:19 PM
hmm i only acctually want to mount parallel with the screw, i've seen some bk blocks though with no holes to mount parallel

Hobgoblin
27-10-2012, 10:32 PM
You've seen something like this:
https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcRmzwAQLy6XH0aDCSI8zfly9NJXY4MSx s8g-EMGzASIlIFuCNK-Xw

But I mean this type:
https://encrypted-tbn3.gstatic.com/images?q=tbn:ANd9GcTvEjAHq8dfyBasUdhG0vyLe8qqUUh6S yT5rZZ8-RTUSbeJz49z

wilfy
27-10-2012, 11:42 PM
so when i come to order my screws from chai.. if i ask for bk blocks they are 100% the ones i'm gonna get? the second ones u linked?

Hobgoblin
28-10-2012, 12:03 AM
Hmm before going to his shop I would of assumed so, but now looking at this: 3 SBR16 set+3 ballscrews RM1605+3 BK/BF12 +3 couplering | eBay (http://www.ebay.co.uk/itm/3-SBR16-set-3-ballscrews-RM1605-3-BK-BF12-3-couplering-/251172715947?pt=LH_DefaultDomain_0&hash=item3a7b0f7dab) Im not so sure.

Id suggest either wait for someone who has ordered from chai to post, or email chai direct and explain what you need. Im in this process at the moment and he is nothing but helpful.

wilfy
28-10-2012, 05:04 PM
ok i "think" i've finished designing the z? axis i've included a picture with 2 views, what i'm looking for is constructive ideas, so far everything is steel i think although some of the plated bits might end up being aluminium i would rather weld everything than tapping steel/alu.

the small rectangle box sections are 50mm x 25mm and there is acctually only 2 pieces of 50mm square in there but these could also end up being 2 pieces of 50x25 slapped together depending on cost. the plates are all 10mm steel although the mount for the BK bearing is drawn at 5mm i'll edit that later.

this has 100mm travel which i am hoping will be enough it is a 15" x 15" machine afterall so is intended to be small work pieces.

so questions to anyone who can help before i progress further. does it all look like it will function.. i.e have i connected all the right parts in the right ways? a simple question to ask but i did originally put the ballscrew blocks on the same side as the rails.

secondly as i am intending to make this out of steel is there going to be alot/too much weight on a 16mm screw and rails on either y or z axis?

i can provide sizes of everything so far and if someone can tell me the weight of a piece of 50 x 25 steel box section i could work out the weight of everything.

7221

also if you would like a better view of anything let me know

wilfy
28-10-2012, 05:31 PM
before anyone gets to pointing it out, i've just realised the bearing blocks on the rails are over hanging the 50 x 25mm box depending on what you guys think i might just replace the box section with 10-15mm alu as the next size up box section would have to be 80x40mm iirc and this will push the router further away from the y axis which is something i am concerned about

JAZZCNC
30-10-2012, 04:19 PM
Hi Wilfy,

Has requested cast my eye.!!

For an all steel structure it looks Ok thou I would replace the 50x50 with 50x25 to bring whole thing closer to Y axis plus gain 25mm travel.

The back plate which fastens to Y axis needs some cross bracing, just relying on the top bot plates won't be enough. Also Because your using steel this z axis will resonate quite a bit more than an Ali Z-axis would. So it would be wise to attach motor to ballscrew with a timing belt to eliminate any resonance problems, I would consider running that top plate back between the Y axis uprights so the motor is at the rear.
The 10mm plate is a bit OTT and 5/6mm would be fine strength wise and infact better if you take the route I've just suggested has 10mm is too thick because it shortens the motor shaft protrusion to much.

Regards weight then it won't be a problem for the screw it's the motor that you use that will take the stress but a 3nm will easily handle it.
3mm wall 50x25 weighs 3Kg/per Mtr

If you can use Alu then I would has it handles resonance better but what you have drawn will work fine.

wilfy
30-10-2012, 09:39 PM
the reason for using 50x50 was to allow spacing for the ballscrew and it's bearings but i'll re-think to try and bring it close.. plus using all 50x25 will be a bonus.

i had planned to use timing belts so i'm glad we are on the same page there.



the back plate which fastens to the y axis i am acctually considering using alu or steel plate in place of the box section as wont be able to use 50x25 box in the way i have in the drawings as the bearing blocks are 60mm wide with the holes at exactly 50mm spacing so i need to consider either 10mm alu or 6mm steel are both of these stiff enough if i'm using a piece of 370 x 170 plate?

and thank you for your input so far it's nice to have your mind put as ease especially considering i'm adapting other peoples ideas but realisticly drawing this blind

D.C.
31-10-2012, 12:57 AM
If you are buying steel, these guys seem to be having a sale on at the moment, they also list the weight per metre wilfy:

100mm x 50mm x 3mm Mild Steel Rectangular Box Section - 1051216-1m (http://www.metalineswroughtiron.co.uk/product/100mm_x_50mm_x_3mm_Mild_Steel_Rectangular_Box_Sect ion_1051216-1m)

martin54
31-10-2012, 02:11 AM
Wouldn't want to be paying their normal price, even their sale price seems expensive to me.

wilfy
31-10-2012, 02:13 AM
If you are buying steel, these guys seem to be having a sale on at the moment, they also list the weight per metre wilfy:

100mm x 50mm x 3mm Mild Steel Rectangular Box Section - 1051216-1m (http://www.metalineswroughtiron.co.uk/product/100mm_x_50mm_x_3mm_Mild_Steel_Rectangular_Box_Sect ion_1051216-1m)


you my friend are a star :D i've bookmarked them for future reference.



after the great advice from jazz earlier i've set about re-designing and i acctually feel much better about the one and it should bring everything close to rails aswell as giving me less work

7244


the green is the front where the router is bolted to, i aint had time to put that in but wanted to make this post before i go bed. it is just 50x25mm box with a 5mm steel plate on the front it's opaque so u can see the bearings underneath

the 2 rear views are my current options... due to the bearings being 60 and 62mm wide i need to either use 60x40mm box x 3 the total here is 900mm over the 3 pieces which using a rough math from jazz's earlier post i get them 3 piece at 4-5kg total or i could use a big 15?20? mm slab of alu as per the 3rd picture.. this will bring the design 20mm closer to the Y rails but more crucially it'll weigh a hell of alot less...

i would rather stick with steel as this is going to save me alot of money a rough guess see's the piece of the alu at 30 and the steel around 10 and thats before i go to a supplier with a full order with the hope of a price reduction... does anyone have any good reason why i should choose the alu over the steel?

D.C.
31-10-2012, 09:37 AM
Wouldn't want to be paying their normal price, even their sale price seems expensive to me.

Really? I thought that was a pretty decent price. :(

Where are you getting yours from?

martin54
31-10-2012, 11:45 AM
I got a price from a local company DC, was quoted 36 for a 7.5 mtr length of 50 x 50 3mm box. Downside was that they would only sell me a full length which I didn't really see being a problem with what I would need. Company is called GM Steel but not sure if they would ship or what shipping would be,
Point is that if you have someone local it is sometimes a good idea to pop in & speak to them, had other local suppliers for various things who have offered decent prices when you went to see them, especially if they knew you had been looking on the net. Face to face is always better than phoning from my own experiences.

JAZZCNC
31-10-2012, 05:39 PM
I got a price from a local company DC, was quoted 36 for a 7.5 mtr length of 50 x 50 3mm box. Downside was that they would only sell me a full length which I didn't really see being a problem with what I would need. Company is called GM Steel but not sure if they would ship or what shipping would be,
Point is that if you have someone local it is sometimes a good idea to pop in & speak to them, had other local suppliers for various things who have offered decent prices when you went to see them, especially if they knew you had been looking on the net. Face to face is always better than phoning from my own experiences.

Martins correct shop around at your local steel merchants. I pay between 24-28 for 50x50x3 at my local steel merchant. 7.5mtrs is standard lengths they come in so if they won't deliver or don't have transport suitable to move then Workout your rough lengths then take a grinder with cutting blades and rough chop to size or lengths that are more manageable. Most steel merchants will let you plug into wall before miss a sale.?

martin54
31-10-2012, 05:52 PM
Same applies if they know you can buy online at a much cheaper price, some places will stick to their guns but others will try to give a better price rather than lose a sale completely.
Never thought about asking if I could plug in to cut lengths Jazz as I thought they may want to charge me a cutting fee. Generator, chop saw & grinder go in the back of the car & away I go lol.

Jonathan
31-10-2012, 06:19 PM
It doesn't take long to cut through 50x50 3mm box section by hand with a hacksaw...just make the minimum number of cuts to get it in the car and do the rest at home.
The company I got my steel from cut it to length for me for no extra charge, but evidently they didn't know how to use a tape measure as some of the lengths were wrong! Luckily they were too long so I sorted it out. Not complaining though as they gave me some freebies to practice welding on which were very useful :)

martin54
31-10-2012, 06:40 PM
It doesn't take long to cut through 50x50 3mm box section by hand with a hacksaw............ The older you get the more difficult it becomes Jonathan lol
Think I have reached the age where I need all the help I can get !!!!!

wilfy
31-10-2012, 07:41 PM
i love how cutting box section is more interesting than my machine :(

one bit of input for anyone cutting steel, make sure you get nice thin steel cutting discs they slice through like butter, big thick grinding discs are no good for precision work.

i'll have an update 2nite.. it would have been nice for some input on wether i should use the 20mm alu plate or stick with steel and use 60x40mm box




you my friend are a star :D i've bookmarked them for future reference.



after the great advice from jazz earlier i've set about re-designing and i acctually feel much better about the one and it should bring everything close to rails aswell as giving me less work

7244


the green is the front where the router is bolted to, i aint had time to put that in but wanted to make this post before i go bed. it is just 50x25mm box with a 5mm steel plate on the front it's opaque so u can see the bearings underneath

the 2 rear views are my current options... due to the bearings being 60 and 62mm wide i need to either use 60x40mm box x 3 the total here is 900mm over the 3 pieces which using a rough math from jazz's earlier post i get them 3 piece at 4-5kg total or i could use a big 15?20? mm slab of alu as per the 3rd picture.. this will bring the design 20mm closer to the Y rails but more crucially it'll weigh a hell of alot less...

i would rather stick with steel as this is going to save me alot of money a rough guess see's the piece of the alu at 30 and the steel around 10 and thats before i go to a supplier with a full order with the hope of a price reduction... does anyone have any good reason why i should choose the alu over the steel?

wilfy
01-11-2012, 12:39 AM
ok i pushed ahead with the design with the thought of keeping the 60x40 in.

so this is 90% of the way there i just need to chuck the motors in.

7252

the colour coding is basicly for me so i know which parts form each axis... for the x axis i'm looking at twin screws driven by one motor from the centre with a timing belt, i would have liked to have used one screw to keep the cost down but i imagine you guys will tell me thats a big no?

can you guys see anything wrong with this design?

martin54
01-11-2012, 01:13 AM
Wilfy ok I'm new as well but do you really need 2 screws on a machine this small. I know why they say use 2 but that's normally on a much wider machine.

Oh and sorry about hijacking the thread, I would have comented on the build if I could have added anything constructive.

D.C.
01-11-2012, 02:47 AM
Sorry about that wilfy, my fault for asking non specific questions on your build thread. I'm so used to shopping online that I hadn't considered doing some actual real world shoppin, it seems so antiquated, like having CD's or a television...

wilfy
01-11-2012, 08:21 AM
haha it's ok i was only joking anyway.... if i need something answering i'll go straight to someone in a message, i just like to see the discussions round here as it helps me to understand why people recommend the things they do...

2 ballscrews on the X axis is me really covering my arse, if someone says its not needed then thats brill for me.. i just considered the extra screw as this thing is starting to look quite heavy.

the total width of the the whole machine is around 800mm which is double the cutting area i'm happy for this to be as it is, i know i have likely over engineered some parts but i'd rather spend a little bit extra to be sure.. also it might help should i want to machine alu further down the line.

if anyone can shed some light and let me know if i need 2 screws or not and also say if i need to strengthen anything else then that would be great. any information needed just say and i'll sort it out.

wilfy
03-11-2012, 02:18 PM
anyone willing to look this over and let me know if anything is drasticaly wrong?

total width of machine is 800mm so i'm wondering what the chances are of using a single screw??

and also is there any advice on what size motors to use on each axis? as everything is steel am i best just going for 3nm on all??

Jonathan
03-11-2012, 04:19 PM
It's hard to give a definitive answer as it depends on so many factors, what you need to cut and how often, how fast, required accuracy, personal preference... etc
It's borderline, you'd probably get away with one screw as the distance between the bearing blocks is fairly small, but if you're going to be cutting metals at all regularly or just generally want to be able to cut at a good material removal rate accurately then get two ball-screws. You certainly wont regret it.

wilfy
03-11-2012, 05:41 PM
brilliant thanks for the reply... is there anything else that looks out?? i did wonder if the gantry would need any triangle/cross bracing from top to bottom outer corner?

what i might do to start with is use one screw and then if i find myself cutting or want to start cutting metal on a regular basis i'll upgrade to a second screw.

the chances are if i get the bug i think i'm going to get from this machine i'll end up re-building and making a bigger machine anyway as i originally wanted a 4'x4' machine but cant justify the cost until i can get this machine to prove itself.

thanks again for the input i'll work on locating motors, mounting plates and anything else thats missing, i can also start to work out screw sizes so that i can get a price for my missus from chai

Jonathan
03-11-2012, 05:49 PM
I forgot to answer the motor question...

You could use less than 3Nm motors in places without reducing the performance, but 3Nm motors are by far the best price per Nm so it's hardly worth getting anything smaller, especially since the 3Nm motors would be good for the 4'x4' machine if you decide to make it. Currently the cheapest place I know of to get them is here:

Nema23 3.1Nm (http://www.cnc4you.co.uk/index.php?route=product/category&path=83_84)

Remember to ask Chai to make the end portion of the screw longer (25mm is good) to make it easier to fit and align the pulleys. This will of course mean adding a little to the length of the screws you buy.

The gantry is currently quite tall so it look like it could bend 'backwards' (parallel to X) relatively easily. It would be a good idea to add in some diagonal pieces as you said to combat that.

wilfy
03-11-2012, 09:07 PM
that site is now bookmarked than you for that.

i'm happy slapping some diagonal's in that wont be a problem...

i had already thought about the extra length on the end of the screws as i've seen u mention it a few times but thanks again for the reminder.

i'm quite surprised there's not much else to pick at tbh, now i just have to get prices and try get my missus to agree to part with some cash :D

wilfy
04-11-2012, 08:52 AM
electronics wise.. is this everything i am likely to need for my machine??
Upgraded Smooth CNC Standard 3 Axis TB6560 Driver +Box & 3Nm Nema 23 Motor & PSU | eBay (http://www.ebay.co.uk/itm/Upgraded-Smooth-CNC-Standard-3-Axis-TB6560-Driver-Box-3Nm-Nema-23-Motor-PSU-/271082801367?pt=UK_BOI_Industrial_Automation_Contr ol_ET&hash=item3f1dcb48d7&_uhb=1)

would it work out cheaper if i split them down and got the drivers from the place you recommended.. i'm not sue what size drivers to get and what size psu where as the above package seems to have it all included..

Jonathan
04-11-2012, 12:01 PM
Nooooo... those are terrible drivers and bad motors!
The TB6560 driver only reliably accepts up to about 24V and you want to drive the motors from a much higher voltage to get the best performance. Ideally around 75V, so three times as much. For example:

Best Selling! Wantai Stepper Motor Driver DQ860MA 80V 7.8A 256Micro CNC Router Mill Cut Laser Engraving Grind Foam-in Motor Driver from Industry & Business on Aliexpress.com (http://www.aliexpress.com/item/Stepper-Motoe-Driver-DQ860MA-80VDC-7-8A-256-replacing-MD882-Laser-Mill/560903752.html)

(But shop around, that may not be the cheapest.)

The motors in the listing you linked to have a significantly higher inductance than the CNC4You motors. This will limit the torque you get at higher speeds since a high inductance means the current takes longer to reach the rated value, so at high speeds the current doesn't reach the rated value and hence you get less torque. That is also the reason for using a higher voltage - the current rises faster when a higher voltage is applied.

Edit: Just remembered, I posted a much better explanation here (http://www.mycncuk.com/forums/general-discussion/3861-my-cnc-sessions-now-like-laundry-day.html#post25191).

wilfy
04-11-2012, 06:11 PM
ok without wanting to annoy you i need to ask this for my own peace of mind..

what is wrong with running the motors slower? why cant you cnc at the speeds your equipment can cope with if it ends up being that you buy the cheap crap stuff??

i understand you are looking out for us and dont want us to make mistakes and end up needing to buy the better stuff anyway, and for this i thank you... but i just wanna know why not if it's easy enough to explain it in simple terms.

just from a rough guess i'm looking at around 100 more than i expected to pay for the electronics, so i just basicly wanna be able to justify it..


also i will look in to finding a driver i presume aslong as i get any driver around 80v and 7.8A they will do the job?? any pointers on a PSU?? and is that all i need to buy.. motors,drivers & psu? the kit i linked seemed to have other stuff

Jonathan
04-11-2012, 06:46 PM
what is wrong with running the motors slower? why cant you cnc at the speeds your equipment can cope with if it ends up being that you buy the cheap crap stuff??

If it's sufficient to run your machine as efficiently as you need, then there's nothing wrong. It's just hard to know if it will be..
The motors from England and the drivers are cheaper than the kit you just linked to, so I see no reason not to get the better ones. The TB6560 is generally so unreliable I wouldn't even consider it an option as I guarantee you'll only end up getting better drivers a few months after buying that.

For the PSU a 500VA toroidal transformer, 25V(*2) or 50V is the best option, with a rectifier and capacitors.

JAZZCNC
04-11-2012, 07:36 PM
Wilfy I have spent many many hours talking and helping new people to DIYCNC on the phone and via email and THE MOST COMMON (by a long way) single mistake they make is buying the wrong drives and PSU. The TB based boards are one of THE easiest ways to waste money and more importantly time, mainly resulting in frustration and disappointment.

To answer the question regards speed and what's the correct drives PSU to buy then the Honest answer is CAN'T ANSWER.!! . . . . .Until more information is known about the machine and what materials your going to machine.?
I help loads of people either on here on via the phone etc and When I ask folks what they want to machine they generally say "Oh nothing too difficult just MDF, wood, plastic and the Occasional bit of Ali" . . ERmmmm is my reply.?
Whats wrong with that you may think.? . . . . Well it mostly boils down to cutting speeds.!

Given the TB based board and 24V has a crude example.!! . . Out of all those materials you'd think the hard ALi would be the challenge.? BUT in reality given the machine frame is strong enough it will be the most suited to the slow TB based board.? Ali only requires low feed rates and the 24V will probably be ok. This is also why lots of small milling machines and lathes use 24V.
But Wood, MDF, plastics etc require high cutting feed rates so in general require the motors spin faster for longer. There are other things that affect feed rate like screw pitch but in general in these softer materials the motors are working faster. To enable this speed you need voltage and 24V (Excuse the pun) just doesn't cut it and available speed is low and therefore feed rates. Too low feed rates wears tooling out very quickly and leaves a poor finish.
Then you have the workload of the drives.! They are constantly MAX'd out and eventually this takes it toll and in the case of the cheap TB based stuff results in either poor performance in form missed steps etc or has often happens they die quickly by frying themselves.

The extra 100 is worth every penny and will enable a very wide range of cutting capability with the least amount of stress.

wilfy
04-11-2012, 07:46 PM
your right acctually.. i didnt look at the prices correctly

so PSU - 480W High Power CNC Stepper/Servo Motor Driver Switching Power Supply 48V10A PSU | eBay (http://www.ebay.co.uk/itm/480W-High-Power-CNC-Stepper-Servo-Motor-Driver-Switching-Power-Supply-48V10A-PSU-/180998381443?pt=UK_Computing_Switch_Power_Supplies&hash=item2a24581f83&_uhb=1)
i cant find anything that relates to the 500va i'm guessing that is supposed to be 500w?? other alternative is 600W PSU 48V 12A CNC Power Supply Stepper Motor Milling (http://www.cnc4you.co.uk/index.php?route=product/product&path=81&product_id=33)

drivers - Best Selling! Wantai Stepper Motor Driver DQ860MA 80V 7.8A 256Micro CNC Router Mill Cut Laser Engraving Grind Foam-in Motor Driver from Industry & Business on Aliexpress.com (http://www.aliexpress.com/item/Stepper-Motoe-Driver-DQ860MA-80VDC-7-8A-256-replacing-MD882-Laser-Mill/560903752.html?cn=null&PID=5449378&tp1=skim20518X781349Xf12d616623e404a07c7e761e2a945 70d&tracelog=datafeeds&src=ale&URL=http%3A%2F%2Fwww.aliexpress.com%2Fitem%2FStepp er-Motoe-Driver-DQ860MA-80VDC-7-8A-256-replacing-MD882-Laser-Mill%2F560903752.html&cv=10887173&af=cj_5449378&vd=30)

motors - Nema23 Stepper Motor 3.1Nm x 3 (http://www.cnc4you.co.uk/index.php?route=product/product&path=83_84&product_id=66)

total around 255 is that everything i need or do i need a breakout board aswell for pc connectivity??

wilfy
04-11-2012, 07:50 PM
Wilfy I have spent many many hours talking and helping new people to DIYCNC on the phone and via email and THE MOST COMMON (by a long way) single mistake they make is buying the wrong drives and PSU. The TB based boards are one of THE easiest ways to waste money and more importantly time, mainly resulting in frustration and disappointment.

To answer the question regards speed and what's the correct drives PSU to buy then the Honest answer is CAN'T ANSWER.!! . . . . .Until more information is known about the machine and what materials your going to machine.?
I help loads of people either on here on via the phone etc and When I ask folks what they want to machine they generally say "Oh nothing too difficult just MDF, wood, plastic and the Occasional bit of Ali" . . ERmmmm is my reply.?
Whats wrong with that you may think.? . . . . Well it mostly boils down to cutting speeds.!

Given the TB based board and 24V has a crude example.!! . . Out of all those materials you'd think the hard ALi would be the challenge.? BUT in reality given the machine frame is strong enough it will be the most suited to the slow TB based board.? Ali only requires low feed rates and the 24V will probably be ok. This is also why lots of small milling machines and lathes use 24V.
But Wood, MDF, plastics etc require high cutting feed rates so in general require the motors spin faster for longer. There are other things that affect feed rate like screw pitch but in general in these softer materials the motors are working faster. To enable this speed you need voltage and 24V (Excuse the pun) just doesn't cut it and available speed is low and therefore feed rates. Too low feed rates wears tooling out very quickly and leaves a poor finish.
Then you have the workload of the drives.! They are constantly MAX'd out and eventually this takes it toll and in the case of the cheap TB based stuff results in either poor performance in form missed steps etc or has often happens they die quickly by frying themselves.

The extra 100 is worth every penny and will enable a very wide range of cutting capability with the least amount of stress.

thanks for that you replied while i was posting my previous post.. thats explains everything and kind of fills in the missing blanks that i couldnt get my head round.. as it happens using the info jonathan has given me i've pretty much match the earlier price but with the better components

martin54
06-11-2012, 09:13 PM
Wilfy, I've put this on your build log rather than hijack the other one. If your looking for a local steel supplier try doing a google search. I have just done a google search for "steel stockholders wigan" and up popped about 4 quite big companies. Probably more if I looked harder but there's a start for you. Guessing any one of them will offer you a better price if you actually go & see them rather than phone up.

wilfy
06-11-2012, 09:45 PM
yeah thats on my list of things to do, i did email one company to find no reply, but i'll work out how much steel i need over the next few days and then i know how much i need to order, the other problem is getting someone to deliver it

njhussey
06-11-2012, 10:26 PM
wilfy, I'd offer to get the steel for you but by the time you've either courriered it to you or come and collected it (5 hr round trip) you could probably buy it for the same price locally. Plus I can buy the odd thing through work but if they see my buying lots of steel then questions will be asked :concern: if you can wait until wobbly orders then I can tack it on, but still got the problem of getting it to you....

martin54
06-11-2012, 10:36 PM
You will get a better price if you actually go there rather than email, that's always been my experience so always try to speak to people face to face if I can.
If you can't get it in your own car do you not know someone with an estate or something like that? Just rough cut it on site if the supplier won't cut it for you.
I have a people carrier but all the seats bar the one I need have been removed so really it's small van size. Seats just clip in so if I do have to ferry anyone about I just stick them back in.

wilfy
06-11-2012, 11:11 PM
wilfy, I'd offer to get the steel for you but by the time you've either courriered it to you or come and collected it (5 hr round trip) you could probably buy it for the same price locally. Plus I can buy the odd thing through work but if they see my buying lots of steel then questions will be asked :concern: if you can wait until wobbly orders then I can tack it on, but still got the problem of getting it to you....

nah it's ok your right i'll find a cheap supplier near here, there is a few places around but i aint got a clue which one to approach.. i've never had to buy steel before :D

i have an estate so can fit 2.5m in one go seats folded down, but thats still 2 cuts needed

martin54
07-11-2012, 02:50 AM
Try them all lol, take a list of sizes you need & ask them nicely if they will cut it to length for you, they may charge you a cutting fee but it may be worth it. Even if they won't cut it all to length you may get a couple of bits cut so it fits in the motor.

wilfy
07-11-2012, 10:10 PM
hmm been doing some thinking tonight dangerous i know..

looking at the size of the moving parts it now feels when i look at it that everything i've designed i should have a bigger work space.. what i mean is the foot print of the machine is 792 x 700 and yet this produces a cutting area of 385x385 and i'm starting to wonder should i bump up the length of the rails and screws to gain some cutting area... the only down side in this is extra cost which i might be able to come to terms with.

i suppose the biggest decider is at what point do i need to move away from 16mm screws and rails as this will be the limits of the machine for me

7328

i've also added in the green bits for stability... with the above thoughts i'm also thinking of changing the 50 x 25 that supports the y rails to something wide enough so that the whole yellow section can slot in to the blue as at the moment it feels like wasted space that could be better used to shorten the ballscrew and the steel

wilfy
07-11-2012, 10:23 PM
infact just a quick look at getting the yellow section to tuck in to the blue i could gain 100mm workable width for the same size screw in just 100mm longer rails so i'm going to consider a slight redesign to make this happen


Edit: i've done it so it's the above with 100mm shorter rails or this one below with 100mm longer rails screw is the same length

7329

JoeHarris
09-11-2012, 01:33 AM
Looks like you are starting to get the hang of trusty old sketchup...nice one !

Nealieboyee
09-11-2012, 04:28 PM
How about 3Nm CNC Stepper driver Kit - 3 Axis for CNC. | eBay (http://www.ebay.co.uk/itm/3Nm-CNC-Stepper-driver-Kit-3-Axis-CNC-/220992304733?pt=UK_BOI_Industrial_Automation_Contr ol_ET&hash=item33742af65d) electronics kit from Zapp Automation?

martin54
09-11-2012, 05:14 PM
How about 3Nm CNC Stepper driver Kit - 3 Axis for CNC. | eBay (http://www.ebay.co.uk/itm/3Nm-CNC-Stepper-driver-Kit-3-Axis-CNC-/220992304733?pt=UK_BOI_Industrial_Automation_Contr ol_ET&hash=item33742af65d) electronics kit from Zapp Automation?

Power supply is only 36v so I believe you wouldn't get optimum performance from the drivers & motors if some of what I have learnt so far is correct lol

JAZZCNC
09-11-2012, 09:57 PM
Power supply is only 36v so I believe you wouldn't get optimum performance from the drivers & motors if some of what I have learnt so far is correct lol

Yep Martin your understanding is perfect.!!

These type of Kits are one of the worst Gotcha's I see new folks get stung with.!! Those drives are 50Vdc and the motors are easily capable of handling well above 50Vdc, 65-70Vdc is common. So the up shot is that any machine running this system with 36Vdc would be running motors working at nearly half the voltage they are capable handling. Speed of a stepper is proportional to voltage and very important for good performance so the system will be working minimum 48-50% less than motors are capable.
Also even if the correct voltage for these drives was used, 44-45Vdc then the motors are still working approx 35-40% less than capable.

wilfy
10-11-2012, 08:13 PM
How about 3Nm CNC Stepper driver Kit - 3 Axis for CNC. | eBay (http://www.ebay.co.uk/itm/3Nm-CNC-Stepper-driver-Kit-3-Axis-CNC-/220992304733?pt=UK_BOI_Industrial_Automation_Contr ol_ET&hash=item33742af65d) electronics kit from Zapp Automation?


while i appreciate you looking, i've found everything i need for 255 bar the breakout board and they are all recommended items by jonathan, so unless i find those items cheaper then i have no need to look at other things

oh and i got a sneak at the saw today.. its perfect for cutting the steel i need to create this build so that 50 really was a bargain

wilfy
24-11-2012, 11:25 PM
alright guys money for my project is here... i could order everything i need 2moro if i wanted to but i still dont feel condfident my design is 100% so i need to draw in the motors on my sketchup... is 5mm steel enough to mount a motor to the motor will be belt driving the screws on all axis

wilfy
30-11-2012, 03:58 PM
2 x SBR16 supported rails 700mm length with 4 SBR16UU bearing blocks
2 x SBR16 supported rails 754mm length with 4 SBR16UU bearing blocks
2 x SBR16 supported rails 260mm length with 4 SBR16UU bearing blocks

1 x RM1605-C7 ballscrew+ballnut 655mm threaded section add on end machining and extend dimension F to 30mm
1 x RM1605-C7 ballscrew+ballnut 754mm threaded section add on end machining and extend dimension F to 30mm
1 x RM1605-C7 ballscrew+ballnut 142mm threaded section add on end machining and extend dimension F to 30mm

3 SETS OF BK/BF12 blocks (with locknuts and cir-clips)

1 x 2.2kw water cooled spindle including VFD

order for that lot has gone to china, got a really good price from chai, there is nothing on any uk supplier or even any ebay supplier that comes close, have to say very happy, cant wait to order the other bits and get the thing built now

Jonathan
30-11-2012, 04:08 PM
1 x 2.2kw water cooled spindle including VFD

order for that lot has gone to china, got a really good price from chai, there is nothing on any uk supplier or even any ebay supplier that comes close, have to say very happy, cant wait to order the other bits and get the thing built now


Other sellers are significantly cheaper for the VFD and spindle. It's hard to know if there's any difference in quality, but I doubt it from what I've seen.

wilfy
30-11-2012, 06:35 PM
Other sellers are significantly cheaper for the VFD and spindle. It's hard to know if there's any difference in quality, but I doubt it from what I've seen.

whilst i agree as a single item it'll be cheaper i'd disgree that on a big order it works out cheaper.. chai has quoted me 389usd = 242 for the spindle, if you take in to account the postage is likely to be the same regardless of wether i get the spindle or not as the items i have ordered are big heavy and bulky (i think) then infact i'm getting the spindle cheaper than ordering it direct from ebay at around 252.

given the fact chai has given me a better price on the whole order than i could have got anywhere else i'm happy to pay him for the spindle aswell

Jonathan
30-11-2012, 07:34 PM
The spindle is still a significant proportion of the total weight of the things you have purchased, so the postage would have been a bit cheaper without it. Plus you can use best offer with some of the sellers on eBay to get the spindle for less than 252, so overall it's likely to work out cheaper. Even better, get the spindle on ali-express as there it is cheaper than any of the eBay sellers.

I'm not sure if Chai is still the cheapest for rails and ballscrews either since there are plenty of sellers on ali-express with them. Still, he's very easy to communicate with which does help.

What are you planning on using for the bed of the machine? In the drawing it looks like wood...which is fine if you're mainly machining wood and plastics.

wilfy
30-11-2012, 07:37 PM
The spindle is still a significant proportion of the total weight of the things you have bouht, so the postage would have been a bit cheaper without it. Plus you can use best offer with some of the sellers on eBay to get the spindle for less than 252, so overall it's likely to work out cheaper. Even better, get the spindle on ali-express as there it is cheaper than any of the eBay sellers.

I'm not sure if Chai is still the cheapest for rails and ballscrews either since there are plenty of sellers on ali-express with them. Still, he's very easy to communicate with which does help.

What are you planning on using for the bed of the machine? In the drawing it looks like wood...which is fine if you're mainly machining wood and plastics.

i'd rather order from someone i know is trusted by a few guys here, even if it means paying a little more, it's hard enough parting with my cash for the drivers on ali-express i couldnt bring myself to send the best part of 500 to a web site i have never heard of to a guy who no one has ever ordered off

bed of the machine isn't decided yet if i'm honest, it may start as mdf and progress to ali in future

JAZZCNC
01-12-2012, 03:10 PM
i'd rather order from someone i know is trusted by a few guys here, even if it means paying a little more, it's hard enough parting with my cash for the drivers on ali-express i couldnt bring myself to send the best part of 500 to a web site i have never heard of to a guy who no one has ever ordered off

Wise choice because the saving if any would be 10-20 and penny pinching can easily get you in trouble when things arrive broke,bent or faulty which can happen to vendor. Chai is very helpful when things arrive bust or wrong and to me this is worth paying him 20 more.!!

wilfy
10-12-2012, 09:05 PM
christmas come early for me today... too bloody early infact i didnt expect this lot to turn up till after crimbo.

7581

is it normal for stuff from chai.. or infact anyone in china to come in 2 deliveries? i'm missing the bk/bf blocks and also the spindle and vfd.

also i've noticed a stupidly huge cock up today whilst re-looking over my design, i've really done myself short on the rails for the x axis, looking at the size of the screw i've drawn and ordered i could have got at least another 100mm out of it.

i'm now tempted to re-order my x rails as thats the only thing i'd need and gain the extra length

JAZZCNC
10-12-2012, 09:28 PM
is it normal for stuff from chai.. or infact anyone in china to come in 2 deliveries? i'm missing the bk/bf blocks and also the spindle and vfd.

Yes normal to come in more than one package regards VFD but usually arrive at same time and usually the BK/BF will be in with the rails etc.? I'd email Chai and ask if sent in 2 packages and mention BK/BF blocks not in the package received.

wilfy
10-12-2012, 09:31 PM
it certainly says 1 of 2 on the package i have, but i too thought the bf/bk's would have come with the rails.. i was tempted to wait and see if the other package comes 2moro.

JAZZCNC
10-12-2012, 09:44 PM
it certainly says 1 of 2 on the package i have, but i too thought the bf/bk's would have come with the rails.. i was tempted to wait and see if the other package comes 2moro.

So what have you signed for.? The package may say 1 of 2 but did you sign for 2 packages.?

I'd still email Chai asking has it won't hurt and is unusual in my experience for the blocks not to be with the screws Etc.!!

wilfy
10-12-2012, 10:01 PM
i didnt sign for it my missus did, i didnt even know it was coming, it's only been 10 days since i ordered it

Fivetide
10-12-2012, 10:04 PM
I've bought stuff from China and there ahave arrived from 3 diffirent places on the same order, sometimes stuff is either wharehoused or built in different factories,, hopefully its wasnt those tards UPS .. they suck big style !

wilfy
10-12-2012, 10:39 PM
it was fedex that delivered it thats all i know, i've emailed chai see what he says.. have to say though 1st dec i paid which was a weekend.. and the rails and screws are here on the 10th.. thats some turn around if you think about the shipping involved

JAZZCNC
10-12-2012, 11:01 PM
I,ve had stuff in 7 days and been ordered on a weekend and 9-12 days is quite normal for Chai.. . . No matter how large or small the order.!! That's why I don't mess around trying to save 10 or 20 buying else where.

wilfy
11-12-2012, 09:17 AM
reply back from chai

Hello,
You should receive 2 parcels.
One parcel is packed with the spindle and VFD and also 3sets BK/BF.
The other parcel is packed with other items
Thanks
Chai

wilfy
11-12-2012, 09:19 AM
also just realised there is a tracking number on what they sent me

7585

wilfy
11-12-2012, 09:40 PM
i've added steppers to my drawing.
brackets are made up of 5mm steel welded in to shape and i think maybe bolted to the box section, the top of the stepper supports will have slots for tension of the belts.

i've also beefed up the underside of the bed.

7588

wilfy
13-12-2012, 03:23 PM
more goodies as expected the bf/bk blocks did come with the spindle and vfd

7630

and heres a shot with them all together

7631

wilfy
13-12-2012, 10:32 PM
just found a place that say they can deliver uk wide that sells some pretty reasonable priced box section..

for 2 x 7.6mtr lengths of 50 x 25 x 3 i'm getting it at 72 which all things considered doesnt sound too bad a price

http://www.fhbrundle.co.uk/groups/30SHS__RHS

JAZZCNC
13-12-2012, 10:54 PM
just found a place that say they can deliver uk wide that sells some pretty reasonable priced box section..

for 2 x 7.6mtr lengths of 50 x 25 x 3 i'm getting it at 72 which all things considered doesnt sound too bad a price

Rectangular Hollow Steel Sections - F H Brundle (http://www.fhbrundle.co.uk/groups/30SHS__RHS)

If thats delivered and inc Vat then it's an excellent price for a Web based company.?

Edit: Just had a look and the 50x50x3 is 11 per length more than I pay my local supplier who I've dealt with for years so all-in-all think that's not unacceptable difference if only buying small Qty 7.5mtr gets you a fair way with a average sized machine and more than enough for a small machine.

wilfy
13-12-2012, 11:56 PM
jazz.. you do know my design uses 13+ mtrs of 50 x 25 and another 2.5+ mtr of 60 x 40.... i've a feeling it's massively over engineered

wilfy
17-12-2012, 06:08 PM
going to be redesigning this now which is a pain considering i have the rails and screws here today.

the reason for the redesign is i have been using a drawing of the rail bearings from zapp i think. looked at my rails today and thought they aint 60mm wide.. turns out they are 45 mm wide which means they will fit on a 50mm box section which will help me a lot as i only needed 3m of 60 x 40 and it was proving to be a bigger cost than i wanted.

so take note guys, make sure you are using the right drawings for your designs before you order

kingcreaky
17-12-2012, 08:27 PM
i fell into that trap aswell.

wilfy
17-12-2012, 09:25 PM
you've made me feel so much better knowing it wasnt just me.. i'm acctually quite happy i noticed as i didnt really like having an odd size box section in my build, so now i get to pull the design apart and possibly even gain some cutting area now... the only limit is i need to restrict myself to 2 x 7.6mtr lengths of steel which i think will be a push

wilfy
25-12-2012, 11:51 PM
in re-designing i cant keep the shape of everything i want if i fully get away from the 60x40 box section across the top and bottom of the y axis bearings as i need the spacing of the 60x40 so that the y axis carriage doesnt bind against the y axis rails

a picture might help

7755

if i change the top and bottom yellow pieces to 50x25 i cant see any way it will work without wasting a whole load of 50x25 and i'll be honest since dropping the 60x40 i'm cutting corners to try and get all the cuts i need out of 2 lengths of 50x25 @ 7.6mtrs

D.C.
26-12-2012, 11:47 AM
Can you sub in some angle iron for some of the bits of box?

Angle Iron is 10-20 for 6m and I think there are parts where you could get away with, for example the green bits on your pic?

Equal Angle Steel Bars - F H Brundle (http://www.fhbrundle.co.uk/groups/3004E__Equal_Angle_Steel_Bars)

wilfy
27-12-2012, 03:01 PM
while i wont rule that out my mission is to make the whole machine bar a few bits of steel plate i might need from just the 2 lengths of 50x25.

i acctually had an idea last night, i've been struggling since realising that the bearings are only 45mm to only use 50x25 as this way there is no spacing between the y axis rails and y axis bearing mounts, basicly the machine would rub against itself, where as when i used the 60mm across the y axis bearing mountings it spaced enough away from the rails.

now my choice was to stick the the 60x40 just for this bit, but even ordering to pieces cut to length is a big jump in cost that i dont really want/need.

so my idea is i'm bound to have some scrap pieces of 50x25, and thinking about it i could quite easily cut one side off a section and leave myself with some 3mm shims that i could use to space out my problem

D.C.
27-12-2012, 03:13 PM
Or just add a length of flat bar to your steel order and use that to bulk it out.

50x10x3000mm 12 ex
MILD STEEL FLAT BAR 50x10MM 3M LONG - F H Brundle (http://www.fhbrundle.co.uk/products/300350103__MILD_STEEL_FLAT_BAR_50x10MM_3M_LONG)

wilfy
27-12-2012, 03:46 PM
tell ya what the stuff you linked upped my order by 15 but.. looking around i found some 25mmx5mm x 3M which is perfect i dont really need 10mm thick, my only concern with doing it this way is if the box section is uneven, then adding an uneven piece of flat bar to the top will make it worse possibly?

wilfy
27-12-2012, 11:45 PM
I've done it!!!

that is designed the whole machine using only 50x25x3mm box section..... oh and a little bit of 25x5mm flat bar as very helpfully recommended above... i had to give in somewhere as i needed 60mm spacing in a few places which using 50mmx25mm box section wouldn't allow... the fact is the flat bar adds on 4 to my total order so i cant grumble about that.

so the picture below is obviously missing a bed, but i have basically spent the last week or maybe longer re-designing this whole machine within the limits of the screws and rails I've already received. the reason for this was due to me using the drawings from another site for the rails and bearings making basically all measurements out.. but it actually worked in my favour as it reduced the need to have 60x40mm box section in my build.

the colouring is purely to make it easier to count the lengths and for me to picture which bits move together, so purple is the x axis and the bed when its done, blue is the gantry, yellow is the y axis carriage and green is the z axis carriage. i am also yet to design a spindle mount as i am planning to do this in another program so that i can export it to dxf and have some lucky member from here cut them pieces for me, the plan is to mount it to the 2 pieces of box section that the rails are mounted to.

7776

the biggest changes to this from my earlier designs are the x axis screw is now located a hell of a lot closer to the bearings which if i understand right should reduce any racking, my only concern here is do i need to add a length of box section on the outside of the screw bearing mounts to reduce flex here? in my mind they don't go under any stress when the screw turns but if someone tells me i'm wrong it'll be the next change.

I've also reduced the height of the machine which is one of the reasons there is no bed at present as the current z axis would smash straight through the previous design, the height now from x axis bearing center to y axis bearing center is 265mm.

all the bearing spacing's are as follows

z axis center of bearings on rails 120mm
z axis rail spacing 175mm ( should be 180mm actually)
y axis rail spacing 180mm
y axis center of bearings on rails 198mm
x axis rail spacing 804mm
x axis center of bearings on rails 255mm

this gives a total cutting area of x = 400mm, y = 529mm, z = 100mm which considering i originally said 15"x15" and its now more like 16"x20.5" i'm very happy.

the total length of steel up to here is around 8mtr's of 50x25x3mm and 1mtr of 25x5mm flat bar so i have around 7mtr's left to make the bed with which i know will take most of that 7mtrs. that brings the total cost of steel to 76.31 and the only other things i need to fabricate are the spindle mounts and stepper mounts which i have a feeling both will come from alu but i'm not sure yet.

so provided i dont need any more steel the total to date is 629.18 and thats for spindle, rails, bearings, screws, ball nuts, screw bearings plus all the steel to fabricate the frame

D.C.
28-12-2012, 08:43 AM
tell ya what the stuff you linked upped my order by 15 but.. looking around i found some 25mmx5mm x 3M which is perfect i dont really need 10mm thick, my only concern with doing it this way is if the box section is uneven, then adding an uneven piece of flat bar to the top will make it worse possibly?

True unless you make a way to level the box a bit. There is the self levelling epoxy method or the grind bits off method.

This wouldn't correct a seriously bent or twisted piece but it would level most stuff enough for mounting rails on:

homemade surface grinding machine - YouTube (http://www.youtube.com/watch?v=BrRewbhx8z8)

As long as you are starting out with a fairly straight piece this should sort out hot rolled steel, assuming you already have a variable speed drill press all you need is grinding head and a jig.

But if your steel looks like this abandon all hope now! :)

http://www.brindley-steel-forging.co.uk/acatalog/B-Rourke-Edge-Hammered-Box-Section.html


PS - Have you thought about how you are connecting all this together? (welding/bolts/brackets/epoxy etc) It might be worth putting in all of your bolts and brackets or you will have a nasty surprise when you can't tighten the bolts you have bought because another bolt is in the way.

wilfy
29-12-2012, 12:48 PM
most of it is going to be welded, i will be bolting certain bits to leave room for adjustment

7792

i am nearly there now, my main concerns are do i really need the turquoise bit?? would i get away with using a bit of flat bar instead? i have enough room in my steel for that piece but only just so i would rather use something else and keep that length spare incase i mess anything up.

also anything wrong with the bed? i dont know what i am going to cover it in yet, i would like to say alu but more than likely it will start out as mdf

wilfy
05-01-2013, 02:18 AM
re-designed again.. this time i've included a second ballscrew on the x axis, now due to my mis understanding of earlier comments i've kinda messed up a little bit in that i designed the machine to work around a single screw on one side. i've now been shown the errors of my ways and intend to fit a second screw. but i will go ahead and build the machine get it all wired and working to an extent before i order the second screw.

so here is what i hope to be my final design.

7870

i may change it a little as far as mounting the bearings for the x axis screws as it's come to my realisation that the spindle will hit the cross beam at the front before it gets to full extension thus cutting about 40mm off my workable area. i've also realised that had i not rushed in to buying the bits from chai i could have either reduced the size of the axis screws for the length of rails i have or better still ordered bigger rails as there is about 75mm of wasted travel along the x axis, but i'll have to live with that as long as i get my 15" mininmum cutting area i'm happy.

kingcreaky
06-01-2013, 08:22 AM
this kind of stuff hurts far less when you have not yet started building!. Your far better at sketchup than I!!!.. Im no expert but do you think the gantry beams (purple) may be a little thin? not that it matters I suppose because you can always add extra support if it does flex. As the two beams are on their side I should think they will be ok on the X plane, however applied pressure on Z while Y is in the middle may perhaps cause flex? Mind you it is only around 15" wide so it might be ok... what do you think?
when do you hope to start building?

wilfy
06-01-2013, 10:29 AM
i had thought about them being a little flimsy but then again it's a 15" piece of 50x25x3mm steel box section, not alu extrusion so i dont really know, i would like to think it wouldnt bend but who knows. and for the record it wont be a simple change to strengthen it without making the machine bigger as the ball screw running through the center of the y axis would prevent any support being added between the 2

jazz is currently looking over this for me as i bust my 2 length limit by about 2 meters which i didnt want to do, but it's not the end of the world it's only another 30. however i have a feeling it's all going to change

GEOFFREY
06-01-2013, 01:29 PM
Wilfy, its a good job you are such an expert with sketchup (wish I could hack it), but it looks like you are getting close to this build now Good luck, G.

wilfy
06-01-2013, 02:08 PM
i got all my help from this thread
http://www.mycncuk.com/forums/cad-cam-software/4819-google-sketchup-tips-discussion.html

D.C.
06-01-2013, 02:46 PM
i bust my 2 length limit by about 2 meters which i didnt want to do, but it's not the end of the world it's only another 30. however i have a feeling it's all going to change

In the corners of the machine you have a long vertical piece that the ballscrew mounts to and you also have a short vertical piece that doesn't seem to be doing anything, could you get rid of the short pieces to save your self some length?

If you have a load of flatbar left over you could also use that for the cross members of the bed instead of box section, that should get you back to your 2 length goal.

wilfy
06-01-2013, 05:21 PM
i cant see how 3mm flat bar can replace a 50x25mm piece of box section, the bed bending is the one thing i'd imagine u dont want. also the upright i could get rid of, but the little white spacers are all that the rails will be mounted to. i'd rather over spend and have solid for the sake of 30.. if it was another 100 i'd be more worried

JAZZCNC
06-01-2013, 07:00 PM
Hi Wilfy,

Had a play see what you think to this.? It's well within the 2 lengths but it does use 50x6mm (or5mm) flat instead of 25mm but you'll see why.

Although slightly taller this way strengthens and helps with squareness of quite few area's and allows the screws to be brought down and to the side which will help with crap hitting them.
Because your using twin screws you can get away with slightly less bearing spacing so gained you about 90-100mm extra in the X axis (twinscrews) by shortening the bearing spacing slightly and off setting the rails back.

Let me know what you think and I'll tidy up the model and send back.!

Edit: Blue is 50x25mm Red 50x6mm
Edit2: Oh and if you don't like it then don't be afraid to say so you won't offend me.!

wilfy
06-01-2013, 08:07 PM
looks awesome and very professional and its funny cuz i had the screws there on the x axis the first time. i feel happier about the rails not bending on the x and y axis with the supports and i didnt realise i wouldnt need to support the back of the y carriage. and if you gained me back some x axis length then thats even better.

brilliant thanks a lot dude.. if you gonna send me the drawing can u send it as a dwg, dxf, skp, 3ds, dem or ddf... strangely enough sketchup lets you export as an OBJ but wont let u import as one :S

JoeHarris
06-01-2013, 09:17 PM
Looks like you are getting the hang of skp. What travel are you getting on you x and y?

JoeHarris
06-01-2013, 09:20 PM
enough sketchup lets you export as an OBJ but wont let u import as one :S

that's google trying to annoy you into forking out for the full version!

wilfy
06-01-2013, 10:04 PM
it is the full version... erm travel i'm looking at 400+ on the x and 525ish on the y with 100 z in mm ofc

D.C.
06-01-2013, 10:21 PM
i cant see how 3mm flat bar can replace a 50x25mm piece of box section, the bed bending is the one thing i'd imagine u dont want.

Fair enough, if you do end up with a load of flat bar left over it is quite easy to weld two pieces together into a single piece of angle.

wilfy
07-01-2013, 12:45 AM
Fair enough, if you do end up with a load of flat bar left over it is quite easy to weld two pieces together into a single piece of angle.

never thought about that, but if you look back at the previous page, dean has kindly gone over my design and reduced it down and says that it should leave me with 3 meters now out of a full length and all i have to use is 50mm x 5mm instead. which outs the cost at 90 on the dot so i'm more than happy.. and it looks a damn sight better than mine lol

wilfy
07-01-2013, 11:16 PM
right, i've finally too jazz's drawing and re-drew it back in to sketchup. i couldnt get on with rhino, its possibly something i'll go back to as i'm aware sketchup isn't that great for actual cnc work.

any way here it is

7900

all colour coded as previous designs, the white flat bits are 50 x 5mm flat bar.

travel is around 450mm x axis, 578mm y axis and 100mm z axis.

i havn't worked out how much steel is used here, but i know already it's going to come in well under the 2 lengths now.. but as a trade off i've gained 50x5mm flat bar so that total cost of the steel as i said before will be 90. i'm happy with that and i still feel it's going to come in under my 1k budget.

i think it's time to start clearing the garage up a bit and think about ordering the steel :D

wilfy
08-01-2013, 04:49 PM
just added everything up total length of steel is 11.7mtrs before cuts which will probs be closer to 12mtrs leaving me a good 3mtrs spare..

now i've just done this rough but with 3 mtrs if i extend the legs down by 500mm shown in white here, i have enough flat bar to put support where the longer bits are pictured and that will be pretty much it, but i have a feeling that wont be enough :s

in this picture i have dropped the legs down 500mm, as shown by the white bits, i've also moved the rail supports down and put a piece of 50x25 in the middle of the rail support. the turquoise blue bits can be removed i've just left them in so i can revert back.

my question is will this extension of the legs work or will it be a bit wobbly? this is the maximum use of the extra steel left over but it would make it better for me to have it floor standing as i know the bench is no longer big enough to support it.

7906

Swarfing
08-01-2013, 05:21 PM
Wilfy sounds like you need to take a trip to the scrap yard? Go have a poke around and you never know what you may come up with. look for old metal cabinets or similar. this would work for your base, stick a wanted on Freecycle? save your money for the best bits :eagerness:

Wobblycogs
08-01-2013, 05:51 PM
Take this with a pinch of salt as my experience is with wood not metal but I'd say that your (white) bracing at either end is too long for that thickness of steel your using. I would shorten the bracing to roughly half way between old and new and then put stretchers between the legs (like a dining chair has). Grab a length of your 50x5 bar at the length you've drawn the brace and see if you can flex it by hand, if you can I don't think it'll be strong enough to act as a brace at that length.

wilfy
08-01-2013, 06:05 PM
it doesnt have to be done this way, it was just an idea i had to use the rest of the steel what you see in the picture is all the steel end of.. if it doesnt work, i'll just figure out a way to make it work as a desktop machine it might mean that 2 legs are secured to my worktops and with the left overs i will have enough to extend the other 2 legs down to the ground and do it that way and brace as you said like a chair.

is it likely i'll need any adjustment in the feet of the machine??

Jonathan
08-01-2013, 06:22 PM
I agree with the earlier post - those strips are too thin to be useful for bracing. Your problem is they need to be strong in tension (which they are) and compression. A strip is the worst cross section under compression as it'll just bend. Angle would be better, or better still more box section. Also using thin strip for bracing is asking for trouble with resonance as the strip can vibrate, just like a rubber band. If the resonant frequency of the strips is a long way from the frequencies induced due to the motors and cutter then you wont have a problem, however calculating that is not trivial. Shorter strips will have a higher resonant frequency, so are less likely to cause problems, but clearly to an extent offer less support so it is is a compromise.. There's some good information on this site, Mechanical Resonance - Factors that Affect Natural Frequency (http://www.update-intl.com/VibrationBook2e.htm).

wilfy
08-01-2013, 06:26 PM
I agree with the earlier post - those strips are too thin to be useful for bracing. Your problem is they need to be strong in tension (which they are) and compression. A strip is the worst cross section under compression as it'll just bend. Angle would be better, or better still more box section. Also using thin strip for bracing is asking for trouble with resonance as the strip can vibrate, just like a rubber band. If the resonant frequency of the strips is a long way from the frequencies induced due to the motors and cutter then you wont have a problem, however calculating that is not trivial. Shorter strips will have a higher resonant frequency, so are less likely to cause problems, but clearly to an extent offer less support so it is is a compromise.. There's some good information on this site, Mechanical Resonance - Factors that Affect Natural Frequency (http://www.update-intl.com/VibrationBook2e.htm).


sod it then i'll stick to the original plan above and find some other use for the spare metal.. i may cock bits up yet anyway so it's good to have back up i suppose.. plus i can use some scraps to set the welder up properly before i go at my good cuts

wilfy
08-01-2013, 08:39 PM
are these 100% the only steppers suitable for my machine??

Nema23 Stepper Motor 3.1Nm x 3 (http://www.cnc4you.co.uk/index.php?route=product/product&path=83_84&product_id=66)

and these the only option for drivers to suit them??

Best Selling! Wantai Stepper Motor Driver DQ860MA 80V 7.8A 256Micro CNC Router Mill Cut Laser Engraving Grind Foam-in Motor Driver from Industry & Business on Aliexpress.com (http://www.aliexpress.com/item/Stepper-Motoe-Driver-DQ860MA-80VDC-7-8A-256-replacing-MD882-Laser-Mill/560903752.html?PID=5449378&cv=10887173&cn=null&tp1=skim20518X781349Xa237e4cec45435b57e25b4bc17d33 01d&tracelog=datafeeds&src=ale&URL=http%3A%2F%2Fwww.aliexpress.com%2Fitem%2FStepp er-Motoe-Driver-DQ860MA-80VDC-7-8A-256-replacing-MD882-Laser-Mill%2F560903752.html&af=cj_5449378&vd=30)

i'm just asking so i can cost up the rest of the machine and them 2 seem to be the least popular models i'm coming across, seen plenty of 425oz steppers

Jonathan
08-01-2013, 08:55 PM
are these 100% the only steppers suitable for my machine??

and these the only option for drivers to suit them??


No, but they're the best value.

wilfy
08-01-2013, 08:58 PM
No, but they're the best value.

ok so why is it there are only a select few selling them if they are that good for the money?

D.C.
09-01-2013, 03:59 AM
There are zillions of people selling them, they just like to put their own number on so you have go to them for replacements.

Not 100% sure but I think these are the manufacturers:

Stepper motor|Stepping gearmotor wholesale|Stepping motor supplier (http://www.wantmotor.com/)

If you are thinking about buying one of their kits there are a few posts on cnczone moaning about how under powered the PSU is, might want to take that into consideration.

kingcreaky
09-01-2013, 12:05 PM
you ordered that metal yet wilfy?

patiently waiting for some more build threads to read ....

:eagerness:

wilfy
10-01-2013, 12:57 AM
believe me if i started this machine right now my mrs would lynch me.

i've got a bubble tube to finish which i am waiting on a pump to arrive from germany to finish off. i've also got to re-build the cabinet for the front room, now both of these HAVE to be done before i do anything else.

i also want to get my homebrew on the go which needs a circuit building for temperature control, which i have yet to even design, plus it then needs an enclosure. i would like to do this before i start work on the machine.

so as it stands i think i'm happy with my design but i need to clear some stuff out of the garage before i start it, gonna have a good push this weekend to get at least one thing done.

i should have got some of it done over christmas but being ill and one of my lads being ill didnt help and more importantly i had no money left over to buy stuff with :distress:

Lee Roberts
19-03-2013, 08:23 PM
Wilfy, give Ainscough a try for box section they are down on Warrington Road. In fact if you give me a list of what you want i can call in tomoz morning for you as i walk past everyday on the school run.

.Me

wilfy
19-03-2013, 08:35 PM
hey u bumped my thread lol... erm re: the steel i'm just holding back a bit at the moment, i'm going back to work full time in a few weeks so i'm hoping to get some pennies in the bank to pay for it.. the new van kinda ruined any chance of starting the cnc just now.

and with regards to ainscough, i thought they only did reclaimed stuff??

Lee Roberts
19-03-2013, 08:47 PM
Not sure mate there website says they do box section, they list it as "Std, Clean or s/rusty" so was going to give them a try for myself at some point.

.Me

wilfy
19-03-2013, 08:55 PM
Ok well when you speak to them let me know what you find out. I'm in no massive rush to buy mine just yet. There is a local company that I think I've linked earlier in the thread that I thought was quite cheap

Lee Roberts
19-03-2013, 09:16 PM
Ok will do, same here.