Re: [CAD_CAM_EDM_DRO] Z axis servo reduction gear

A direct drive would not be very efficient. Power in HP is ~760 watts=1 hp. Watts is torque times the speed times .00074. So if you were to direct drive it and you wanted 30 IPM on the spindle you would need to run the motor at 300 RPM. so 300X50X.00074=11.1watts
You always want to get the RPM up on a servo motor so I would go with at least a 3/1 ratio timing belt drive and 5 or 6 to one would be much better.

Dan Mauch
economical 3D scanner software and kits
low cost stepper and servo motors.
cases for Gecko drives
kits and assembled 3-4 axis drives
www.camtronics-cnc.com
www.seanet.com/~dmauch

----- Original Message -----
From: dcassyc1
To: CAD_CAM_EDM_DRO@yahoogroups.com
Sent: Thursday, March 26, 2009 8:49 PM
Subject: [CAD_CAM_EDM_DRO] Z axis servo reduction gear


Hello,
I'm trying to decide whether I need a speed reduction on my Z axis router carriage design. The Z axis is powered by a nema23 servo motor from homeshopcnc,
http://www.homeshopcnc.com/servo2.html
and is rated 50 oz in continuous and 350 oz in peak torque. The acme lead screw is 10 tpi V thread and the nut is Delrin AF, the bearings are IGUS dry lin on 3/4 inch shafts. I plan on using the homeshopcnc 3 hp spindle at 21 pounds, so I think the carriage weight will come in at around 30 pounds total by the time the spindle is mounted in a clamp.
Is it possible to drive the lead screw directly off the motor with no reduction or would I be better off coupling the servo to the screw through a timing belt reduction setup to increase the torque and reduce the load on the motor somewhat? If it's obvious that I need a reduction what sort of ratio should I aim for?
Thanks
Denis




[Non-text portions of this message have been removed]