1024 CPR Encoder G320

[Raba]

Hello. Im currently using an 250 CPR encoder with my Gecko G320. It works good, but due to my 1:1 drive ratio I need something with more resolution. Has anyone ran those drives with 1024 CPR encoders?

[Mariss Freimanis]

A 1,024 CPR encoder will work OK, just make sure it doesn't consume more than 50mA at 5VDC. I'm a little concerned; what are you driving 1:1 from your servo motor?

Mariss

[Raba]

The rack and pinion drive from the cncrouterparts. One revolution of the motor equates to 1 inch of movement.

[Mariss Freimanis]

Normally you don't do that with a servomotor. Servomotors are high RPM, low torque motors; typical is:
NEMA-23 50 in-oz, 6,000 RPM 200W (1/4 ~ 1/3 HP)
NEMA-34 150 in-oz, 4,500 RPM 500W (2/3 HP)

You trade in unneeded RPM for badly needed torque by gearing the motor down. Say you have a NEMA-23 motor with the above specs:

Router thrust = Pinion torque / Pinion radius = 50 / 0.16 = 314 oz = 20lbs. The router's "push" is only 20lbs continuous. You apply more load than that and you will burn the motor down.

Router Speed = Motor RPM * Pinion Circumference = 6,000 * 1 = 6,000 IPM. 6,000 inches per minute is kinda fast, maybe 1,200 IPM is more practical. You get that by gearing the motor down 5:1 which now gives you 5 times more push, 100 lbs instead of 20 lbs.

Mariss

[Raba]

"Router thrust = Pinion torque / Pinion radius = 50 / 0.16 = 314 oz = 20lbs."

Are you calculating this when pinion is directly conected to the motor?
Because there is an 1:3 reduction from motor to pinion.


Actually I checked twice and you already included it? 0.16 is .5/3.
Sorry for that.