Quote Originally Posted by Boyan Silyavski View Post
ball nut is 10mm per revolution. Only z is 5mm
Figure out what you want your max velocity to be, and gear it so it reaches that at 80% of the servos rated speed.
Gerry thats just the problem, dont know what I want or need my max velocity to be...

Boyan, so you are taking the gear ratio the other way then? i.e. screw speed (or ballnut speed) * 1.5 to give motor speed. If I take the same equation from before your 20,000 mm/min with a 10mm/rev screw gives a motor speed of 3000rpm?

What would be the disadvantage to doing a 5mm screw? I know the torque issue with gearing the motors the other way. However I ended up ordering 1.8kw 6Nm 3000rpm motors since they ended up being cheaper than the 1kw motors so I think I can sacrifice some torque to a gear ratio. Are there other issues with 5mm? I havent ordered the long screws so I can go either way just asking the question.

I am thinking about implementing brake resistors, I do this on my VFD's (to run 3 phase woodworking equipment) for quick motor braking. Im just trying to decide if the inertia of the gantry being so high warrants braking resistors or not. Has anyone needed to add them to their setup?

My motor order was as follows (in case anyone is interested)
Qty: 3 - 6Nm 1.8kW 3000 rpm servo motors - these will be for 2 for X axis and 1 for Y axis
http://www.aliexpress.com/store/prod...761095604.html

Qty:1 - 2.4Nm 0.75kW 3000 rpm servo motor - this one is for the Z axis
http://www.aliexpress.com/store/prod...760999511.html