Steel Router 610 x 1220 x 200

[Stickio]

Thanks Johnathan

My current power supply is 40V so it looks like upgrading those should help out alot with regards to the steppers being able to cope.

I suppose I should of been a bit more specific with my pretty fast comment :) my current machine rapids at 10000mm/min and I am pretty happy with that so if i go for 20mm dia at 10mm pitch on the X and 16mm dia also at 10mm pitch on the X and Z I should be able to achive those speeds.

At first I will be direct driving the screws as it will be alot easier to mount the steppers. Once the machine is built I will be able to make brackets and motor mounts for a timing belt/pullys with the machine.

I did consider 2 screws on the X and I do agree with you, the only reason I went with the single was so I didnt have to buy another driver, stepper and ballscrew, the cost is mounting up as it is, if there is any way to get arround using 2 screws would be a big help. I have seen some pretty good ideas on ways to help prevent racking which I may try out, one that sticks in my mind is a system using pullys and cable similar to those used on sliding patio doors I will see if I can find the link. Failing that I guess I will have to let some more moths out my wallet and buy the extras.

[Jonathan]

Yes, more than 40V will be much better - so long as your drivers are rated for more?

You can't get 10mm pitch 20mm diameter screws from eBay (or at least that was the case next time I checked) so it looks like you'll have to use 16mm pitch. I wouldn't go for 25mm as the moment of inertia of the screw will be significantly greater which will affect the acceleration.

Remember that a 10mm pitch screw on the Z-axis will backdrive very easily, so you will almost certainly have to prop up the axis before switching off. I used 5mm pitch on the Z-axis, but with a pulley and gravity does cause the axis to drop when I switch off.

If you don't want go spend a lot on another stepper/driver (fair enough) then why not link the two ballscrews with a pulley on each and a timing belt. Ideally 3 or 4 pulleys with the motor in between so that belt stretch is even... easer than the cable method I think.