Re: [CAD_CAM_EDM_DRO] Encoder count selection for G320

You must have made a mistake when you said that you wanted 30 IPM I think you meant 300 ipm. With a 4200 RPM motor and a 3/1 reduction with a .891 pitch diameter of the 14xl pulley you would have
4200/3X(piX.891)=3918 IPM negating other factors. That is a tad too fast.
You should look to increase the reduction to at least 6/1 . You can also lower the top runaway speed by using a lower voltage power supply.
With your current setup and the encoder on the motor shaft I would say that the resolution using a 250 line encoder would adequate and give you plenty of speed and not a high number os steps per in that the programs you mention would be fine with.
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: Monday, February 09, 2009 9:15 PM
Subject: [CAD_CAM_EDM_DRO] Encoder count selection for G320


Hello all,
I want to use homeshopCNC servo motors on a router. The motor is rated
72VDC and 4200 rpm no load speed, 850 in oz peak torque, 170 oz in
continuous torque. My plan for the gantry drive is to go from the
motor through a 1:3 reduction and drive a jackshaft with 14 tooth XL
gears on each end, which rack over stationary belts fixed to the
frame. I calculated the gantry mass at 175lbs aprox. I'd like to
achieve 30 ipm traverse speeds for the gantry and carriage. Is that an
unrealistic speed?
I don't know how to make the choice between 250 or 500 line quadrature
encoders. The 'files' sections servo motor files were empty. From what
I remember, top speed depends on pulse throughput from the PC. The
control software is CNCPRO, Turbocnc, and EMC. Would the 500 line
encoder provide greater precision?
Would anyone care to show me how to make the line count selection for
the Gecko G320 and advise on the PC speed/performance requirements?
TIA
Denis




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