help with my cnc build

[long john]

hi guys
first of all im mainly using it for mdf,plastics and a bit of aluminium, so it will be mostly made of mdf, its based on the metalfusion design

http://i61.tinypic.com/2woc936.jpg

so im looking to use the following

supported linear rails SBR16-300/600/1400mm rails(6 supported rails+12SBR16UU bearing blocks)
3pcs of ballscrews RM1605-300/650/1400mm total length-C7(3screws+3ballnuts+3end-machinings)
3 SETS OF BK/BF12(with locknuts and cir-clips)
3pcs of flexible couplings (6.35mm for the motor shaft)


for the stepper motor drivers i was looking to use these the cnc4you cw5045 would these be ok and what motors and breakout board would you think i would need

thanks for all you help

john

[long john]

hi guys was hoping for some feedback, so i have spent sometime working on my cnc plans so here it is.

http://i61.tinypic.com/33lnvic.jpg

1st question is on my axis should i use 1610 or 1605 ballscrew ?

2nd what motors and drivers should i use ?

what my plans are is to make some money with the cnc then upgrade to steel or ali frames but atm i cant afford it, i have plenty of wood and mdf so that's why im doing it this way so it saves on money as im disabled and haven't got a lot, so i need to save my money for ballscrews, rails and motors and drivers.

i know i should spend more time researching but im running out of time due to my arms, so im looking for much help as possible or if someone lives local and willing to help me out i would be very grateful

thanks for you time

john

[njhussey]

OK I'll start the ball rolling with a quick reply.....I'll certainly not get into the debate about using MDF.........:whistle::cower:

The Y axis on the gantry needs moving to the back so the spindle is nearer the middle of the bearings, not hanging right out at the front. You'll also gain some more cutting space this way.

You need cross bracing on the legs to stop the machine twisting.

I'd beef up the gantry to X axis bearing mounts as a lot of force goes through them...

The X axis (long one) rail supports look a little flimsy, Ideally I'd put them on the torsion box as they'll be more supported that way and won't flex litle the sides you've currently drawn. That sort of design is great with a steel frame but not in wood.

The rails on the Z axis should be on the front plate as this will add to the strength, the bearing blocks should be on the back plate.

The SBR rails on the X axis should be 20mm ideally for strength.

Ballscrews should be 1610 for X & Y and 1605 for Z.

Motors and drivers, without knowing what sort of budget you've got.....

Motors: http://www.cnc4you.co.uk/Stepper-Motor/Nema23-3.1Nm/Nema23-Stepper-Motor-3.1Nm-x-3-60BYGH301B

Drivers: http://www.zappautomation.co.uk/electrical-products/stepper-drivers/em-high-performance-stepper-driver-step-direction/em806.html

These will be able to be used on your Mk2 machine, don't forget you'll also need a break out board, power supply (70V to get the best out of the drivers and steppers), Ball nut housings, E stop, limit switches, motor mounts, shielded 4 core cable (lots more than you think!) couplings (best to use pulleys and belts to lessen resonance) loads of nuts/bolts/screws/washers and lots of beer...sure there's more but that'll do for starters :D

[EddyCurrent]

OK I'll start the ball rolling with a quick reply.....I'll certainly not get into the debate about using MDF.........:whistle::cower:

The Y axis on the gantry needs moving to the back so the spindle is nearer the middle of the bearings, not hanging right out at the front. You'll also gain some more cutting space this way.
:D

This is the drawing I generally refer to; http://www.cncroutersource.com/do-it-yourself-CNC-router.html

[long john]

thanks njhussey

before i spend to much time doing my plan again, is this what you mean

http://i61.tinypic.com/2wp3qxi.jpg

[IanS1]

If you're happy to build the machine in MDF then why change the metalfusion design?
.
One thing that would improve it would be to use two motors/ballscrews on the X Axis and beef up the X Axis rail supports.
.
Have you seen his build log here? http://allthemods.com/project.php?id=386

[njhussey]

That design obviously works, but having the spindle hanging off the front seems to go against the grain when you ideally want it in the middle of the bearings?

[long john]

That design obviously works, but having the spindle hanging off the front seems to go against the grain when you ideally want it in the middle of the bearings?

hi havent finished the drawings just making sure i was doing the right things you said, will update with more pictures soon

[IanS1]

Agree with you completely Neil. Building a machine from MDF also goes against the grain. :devilish: :friendly_wink:

[long john]

well atm i cant afford making it in steel, as im disabled money is spare so, i will have to make in mdf then upgrade to steel when i make some more money

or unless someone can make me one cheap lol

[GEOFFREY]

Agree with you completely Neil. Building a machine from MDF also goes against the grain. :devilish: :friendly_wink:

I didn,t think that MDF had a grain plywood has, so that might be better. Good luck with whatever you decide - all cnc routers are grat, so have fun and enjoy making and using it. G.

[long john]

done a few more bits to my plans and just need to ask a couple of questions as to what way would it better to do my z axis, 1st or 2nd picture

http://i62.tinypic.com/2ekrg1t.jpg
this way i would upgrade the boxing on the z axis, just wanted to know what way would be better before i spent to much time on it

or this way
http://i62.tinypic.com/15dr9k.jpg

thanks for all your time