Unstable Encoders

[bill south]

Hey Guys.
Any encoder experts out there???? I have my lathemaster mill controls set up with mach 3, g320s and reliance motors. The encoders are HP 250 count on the x and z axis with USDig 500 count on the y. I'm useing .2 pitch screws so my mach 3 counts are 1000 for the x and z and 2000 for the y. Also installed is a rogers encoder interface board for error checking. That is where the problem is. In the instructions for the EI, you must set up the encoder inputs for the display on the settings screen. It's my guess that the board looks for an error from the settings screen as compared to the machine actual. Anyway, my encoders are bouncing .0001 to .001 with the motors stable. Any ideas where I should look or is there any way to add stability to the system.
Thanks in advance for all the help! Getting close to firing up this puppy and making some chips!!!!
billyjack

[bill south]

Bump

[HuFlungDung]

If your screws really are 5 tpi, then I think you have not got the correct number of counts per inch.

Other than that, the motors will hunt for position. Since the resolution is only 250 counts per turn, and each turn is .2" then, the error range that the motor must bounce between is going to be near a thousandth of an inch.

More counts = higher resolution = more accuracy for the PID parameters for each motor.

[mlaws1172]

the encoder count you show is that cpr
mike

[bill south]

Hey Mike,
Where ya been????
HuFlung is correct is that I think I'm inaccurate with the steps per unit.

Situation is, .2 pitch screws, 250 count encoders on the x and z, 500 count on the y (yeah I know, but I'm going to upgrade encoders later if I need to), and 2 to 1 gears on the x and y and 3 to 1 on the z. (X&Y) = 48 tooth screw and 24 tooth motor, z = 72 tooth screw and 24 tooth motor.

Example calculations are as follows (I think), X = 250 * 4 (quad) * 5 (turns per inch) * 2 (pully ratio) = 10000 (is this the number for mach step per unit???).
Damn, I've confused myself!!!
Bill

[mlaws1172]

looks like you can do math. I got what you need to solve your servo reset.
sent me address again and i will send you a "kit".
mike
got to go am having a new grandbaby

[bill south]

Thanks Mike and congrats on the young-un!
Bill