Garage CNC - A gantry style machine design

**fandango** · 17-03-2014

Hello everyone,

After working with CNC machining centres and grinders for most of my adult life I've decided to include my mid life crisis with work and build a home CNC.
Purchased the following from Ebay :-

Nema 34 1090oz motors, PSU's and drives
RM1605 1350mm X and Z, 300mm Z.
16mm linear bar rails and blocks
2.2kW water cooled spindle and VFD with ER20 toolholding.

Going to use 40mm box section for frame - going to get help from fitters in work who are excellent welders, so hoping to keep distortion to a minimum. Going for centre take off Y axis - single leadscrew, mounted underneath the table.

Kicking off tomorrow so will keep all posted on progress.

**irving2008** · 18-03-2014

Good luck, post lots of pics. Only thoughts are: you may regret those motors unless they are the more expensive 3.5mH ones, and single X screw might be an issue for heavy cuts off-centre due to racking.

**fandango** · 18-03-2014

Thanks for the replies - will see how much the extra ballscrew will cost. Already have an extra motor as I bought for a potential headstock upgrade in the future.

I'll re-design the gantry if I adopt the second X axis screw. Will keep you posted.

**dazza** · 18-03-2014

definitely go for two screws on the x fella if you can,you wont regret it ,my first router started out with a single 1200mm 1605 screw down the centre(x) and I bought in a second sharpish,

**routercnc** · 18-03-2014

If your machine really is 1350mm square (X & Y) then a single ballscrew is not up to it unless you are cutting foam/polystyrene or similar. I cut mainly wood on a ~700mm wide machine and upgraded to twin X.
600mm width is a rough transition point from single to twin X ballscrews.

40mm steel box section is also on the small side unless by 'frame' you mean just the bed, in which case it might be OK if you are using lots of them for crossmembers. If they are for the gantry etc then this is too small for anything other than foam or similar.
If that is all you have to hand then you could weld them back-to-back to create bigger pieces, but if you have a choice you need to go larger. Frame 60-80mm, gantry 80-160mm are better sizes, and at 1350mm machine size I would aim for the upper end of these numbers.

For a machine this size I assume you are cutting wood, acrylic, etc and not aluminium.

On the plus side the profile bearings and 2kW spindle are both good choices.

**irving2008** · 19-03-2014

Please don't hijack other people's threads, start your own. Suggest you do so and delete this then I'll answer your question.

Originally Posted by daniebjoubert

Hi there all CNC'rs,
Coming from a technical background due to my father, I was always interested in automatic/computer control for machines.
My interest is actually the electronic part of the projects.
I have semi-finished a table top cnc, to be used as an engraver in my friend's jewellery shop.
The driver boards were home made using a 4070 Ex-Or ic, 4027 Flip-Flop and L298 H-bridge driver
I have tested movements with 4 wire stepper motors running at 12 volt/0.3A, recovered from old plotters.
The results look ok but now I have to move on!
In South Africa I can get hold of Nema17-3.7V/1.68Amp stepper motors.
I am planning to use a beefed-up 5 volt supply but with current limit, set at approx 1.2 amp.
My question, if some-one can perhaps help is the following;
Will the L298 H-bridge be able to except a supply voltage of 5 volt/1.2Amp and drive the 3.7 volt stepper.

I don't want to buy the low voltage steppers and discover that it does not work.

Thank you forum group in advance

Danie

**AndyGuid** · 20-03-2014

Originally Posted by irving2008

Please don't hijack other people's threads, start your own. Suggest you do so and delete this then I'll answer your question.

Probably better still to start at the very beginning and not have an advanced build thread like this in the "New Member Introductions" section?

But really, this is nothing more than VERY New Members finding their way around........ Please give peace a chance .......

**Lee Roberts** · 20-03-2014

Originally Posted by AndyGuid

Probably better still to start at the very beginning and not have an advanced build thread like this in the "New Member Introductions" section?

But really, this is nothing more than VERY New Members finding their way around........ Please give peace a chance .......

On the money there Andy, not sure why Irving replied in such an abrasive way, must of been having a bad day or something?

Will do the moderating on this thread shortly and make any adjustments, will start you a fresh one Dan.

.Me

**fandango** · 19-03-2014

Hi all,

Had price for extra RM1605 leadscrew and ballnut, BK/BF12 blocks and end machining for 145USD - think it's worth the extra after listening to your advice.

Hoping to machine various materials, but engraving in slate would be my primary initial use as several people have asked if I can.

Honestly it's my mid-life crisis toy - better than a sport's car in my opinion

Thanks for the help.