[Danny1978]

Hello all I'm currently in the process of designing myself a heavy router the problem I have is I'm unsure of what size motors and reduction I need for a rack and pinion. I have myself a 20amp servo system from low cost cnc retrofits. They came with the ametek 600oz servo motors max 1000rpm, I'm not that confident in all he calculations needed to achieve what I'm wanting out of this machine, hopefully some one can help with these bits of info I can give. I have estimated the gantry ( y axis ) to weigh around the 200/250 pound mark ,it will run on 25 mm hiwin rails as will the x and z axis. I plan to run module 2 rack and pinion on the y and x axis and a 20 mm 5 mm pitch ballscrew on the z axis. I'm not looking at a lightening fast machine I want something that is reasonably quick around the 10,000 to 20,000mm a minute rapids but really want something with reasonable accuracy and plenty of grunt as i want to cut a fair bit of aluminium,I just don't think these motors are up to the task,especially when I want to run the gantry from only one motor through a reduction to a drive shaft which connects to the racks on either side. This problem has stopped me in my tracks,I'm looking for some advise on this from someone with experience ,I have searched cnczone for the answers I need but a lot of it doesn't make sense to me. I'm very keen to get this build underway but don't want to pump money into guessing motors and reductions. Any help would be greatly appreciated,I am quite new to this as you could probably tell with the lack of knowledge .thanks Danny

[beachcnc]

Use a motor and reduction on each side.....Check out CNC Router parts nema 34 low induction steppers and 3.2to1 pro reduction drives they can output over 600 pounds push!! ..

I have never been able to stall them..the pinion will jump out of the rack first...in my 48x96 build the gantry weighs about 160+ pounds...

It is plug and play....and proven on dozens of working machines....


Dale
Myrtle Beach SC

[Danny1978]

Thanks for the reply Dale. The issue I have is I already have the controller and want to put it to use . I did some calculations but don't no if they are right,I worked out the motors spin 1000rpm and 600oz torque if I did a 4:1 ratio this would give me 2400oz torque and 250rpm and using a 20 tooth mod2 pinion which is approximately 125mm travel per rotation would give me a max speed of 31250 mm minute. Now that is quick for what I need and that is also the motors running flat out. I don't no what speed I should run the motors for continuos use . I'd be happy with 20000mm a minute but I need it to pack some punch is there any way these motors would be capable of moving around a 200 pound gantry without them choking up. Danny

[ger21]

I've always heard to run servos at about 80% of their rated speed.
Is the 600oz the continuous rating, or peak rating? I think with the 600oz of torque, you'll be looking at around 180lbs of force, minus frictional losses.