Author Topic: LOST on setting up a servo motor in Mach 3  (Read 8730 times)

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Offline archerks

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LOST on setting up a servo motor in Mach 3
« on: January 17, 2009, 12:14:05 AM »
Got my first servo motor in for testing and really don't understand the setup for it in Mach 3 ( my steppers work fine ). I can get the servo to turn real slow in one direction but it will not move in the opposite direction (mach screen is showing moverment). In the motor tuning section I have no idea where to set the "Steps Per" "Velocity" "Acceleration" "Step Pulse" and "Dir Pulse".

Would appreciate some pointers in getting me going the right direction.
Thanks
Dave

Here is the specs on things.

I am using a Gecko G320 with a Cand CNC EZservo board, UBOB and related electronics. The G320 is set as follows.
DAMP and GAIN at the 10 'clock position (8 'oclock = fully CCW, 4 'oclock = fully CW). LIMIT fully CW.

Here are the specs on the motor.
-Skewed Rotor Design
-constant torque: 1.2 N.m ( 170 oz-in)
-peak torque: 6.0 N.m (850 oz-in)
-max. speed at voltage constant: 4200 rpm
-terminal voltage: 72 VDC
-continuous current: 8.8A
-peak current: 40 A
-torque constant (KT): 0.14 Nm/am
-voltage constant(KE): 15 V/100rpm
-resistance: 0.52 ohm
-inductance: 1.8 mh
-inertia: 3.39 kg/cm^2

The Encoder as follows.
US Digital: E5S-500-250-EG-PKG2
Shaft-Mount Optical Encoder with latching connector, 500 CPR

Here is the specs on the ball screw.
RM2505 - 25mm diameter, 5 lead, turn circuits 2.5*2
« Last Edit: January 17, 2009, 01:06:50 AM by archerks »

Offline Chip

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Re: LOST on setting up a servo motor in Mach 3
« Reply #1 on: January 17, 2009, 03:02:16 AM »
Hi, Archerks

Change the Step & Dir. Low-Actives to Opposite State in Ports & Pins, Motor Outputs, The Steps Per should be 2000 X Turns per inch on your Ball Screw.

Start at a vel of 20 or so and Accel. of 5 and work your way up from there,

Make sure you have the Gecko's on a Good Heat Sink's / Fan cooled, You Should be able to turn the Limit up all the way up as your servo's are rated at 8.8 Amp's Cont.

Gain & Dampening can be tricky, Adjust the gain up till the motor start's to vibrate then adjust the Dampening up till it stops, Repeat this and run the servo's some, The Gain set's the Power/Torque  of the servo.

It's All a Balancing Act, Take it Slow. If you feel the geckos or motor's are getting to Hot, Turn the Gain down some.

Hope this Helps, Chip


Offline archerks

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Re: LOST on setting up a servo motor in Mach 3
« Reply #2 on: January 17, 2009, 03:31:31 AM »

Change the Step & Dir. Low-Actives to Opposite State in Ports & Pins, Motor Outputs, The Steps Per should be 2000 X Turns per inch on your Ball Screw.


I can only get the motor to turn one direction, clockwise. By changing the Low-Actives in the Ports & Pins, Motor Outputs, I can make if go the other direction, counter clockwise. Any idea what to look for the make it run either direction?
Dave

Offline Chip

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Re: LOST on setting up a servo motor in Mach 3
« Reply #3 on: January 17, 2009, 04:10:26 AM »
Hi, Archerks

This may be an issue with your BOB, I've always run my Gecko's direct to the P-Port, The Gecko's are internally OPTO Isolated so a BOB just adds double OPTO Isolation and complications to the setup in My opinion.

Are you running +5 volt's to the common terminal on your Gecko's as outlined in the Gecko Manual. ?

Theirs a note somewhere on the Common pin 13 and it saying +5 volt, The drives having "Common" are bi-direction OPTO's, With these you can Gnd or use +5 volt's the common pin 13 on the others you can't.

I think that's where the BOB issue Start's getting strange, Some BOB don't allow holding/floating, Hi or Low option.

Try wiring it Direct

Chip
« Last Edit: January 17, 2009, 04:56:51 AM by Chip »