Quote Originally Posted by Soyb View Post
Hi Clive, why larger pitch ballscrews? from a newbie I assumed that 5 mm would give better control, less backlash etc
The pitch has nothing to do with how much backlash you get and everything to do with the speed and resolution. Clive is correct that for a router that will cut a range of materials you are better with 10mm pitch on X & Y as it covers a much wider range of feed rates for the various materials correctly. Also, like Clive says it allows you to keep the rpm down which gives higher torque where you need it, which is when cutting.

If you are planning on cutting mostly Aluminium then a 5mm pitch would be better as it allows higher resolution, that said 10mm pitch still gives a decent resolution. However, if you are mostly cutting aluminium then you'll need a stronger machine than what you are planning now.
The design you have now is ok for an all-around machine, though it could use a little beefier gantry sides, it would also benefit from using my "L" shape gantry design which will be much stronger than what you have shown. If you do stay with your gantry design I would drop the plate at the rear on the x-axis carriage as you will find it a pain to set up and doesn't add very much strength.

I have built lots of machines using a similar design with higher sides and the design is stronger than people realise, so don't let the naysayers put you off because as an all-round material cutting machine they work very well. I also have customers who run very very successful businesses with my machines which are very similar in design.

Some advice would be to use 20mm rails rather than 15mm as the bearing size is easier to work with and just suits a machine like this better, the cost difference isn't much more and worth the extra. 15mm bearings are fiddly little things.

Use 15mm plate as a minimum for gantry sides and Z-axis. Remember the Z-axis is the most important area as it holds the cutting tool so if it's weak and vibrates then doesn't matter how strong the rest of the machine is you'll get rubbish finish and excess tool wear.

DUMP the KRESS, they are toys compared to water-cooled spindles.

DUMP the KK01 Bob and buy a decent Ethernet motion controller like the AXBB-E and run it using UCCNC, this will be the best investment you'll make.

Lastly but not as important as the controller but still does make a big difference, I would use higher power drives than 50Vdc and if you can afford it go with closed-loop steppers as they are SOOOO much better than standard steppers.

Building a good machine is all about the balance of electronics and components along with a strong design, if anyone is weak the machine will suffer.

Good luck.