How to set up a oscilloscope to tune Gecko 320's not X's
I have a small 5'x5'x16" router I built. Has all THK slides. Ball screws on the X and Z axis. dual belt drive on the Y axis.
Motors are 850 oz/in Nema 34 servos from Home Shop CNC. All drives are Gecko 320's from 2005. I put building this off for a while. I am using a Candcnc PSC 1500 power supply with his differential encoder pigtails and servo cards.
Final reduction on X and Y axis is about 4:1.
Computer is a Dell 3ghz. Mach3 running at 45hz.
I have a Tectonics 2236YA scope with 1/10x probes.
I have tuned X and Y drives by ear as good as I can get. I can get both axis running at 280 ipm back and forth with no faults. I set up a small program to run one axis and bounce it back and forth for 10 min. Acc is 0.05G's. Each one works fine. Now if I try and jog both the X and Y at the same time Both drives will fault. Every time I try it at 280 ipm both will fault. If I back it down to 150 ipm then they only fault some of the time. Is this a limitation of the power supply or lack of tuning?
Second problem. Now if I shut down and go to lunch. When I come back fire everything up. When I try and run I get faults at almost any speed mainly in the X axis. This has a 1:1 screw and a 4:1 reduction belt from the motor to the screw. It takes no effort to turn the screw let alone the large pulley on it. I have changed drives, motors, encoders and differential pigtails. I have hooked this motor to the Y axis and it still faults at all speeds. After hooking it back up to the right drive and spend a while retuning I can get it back to 280 ipm stable. But if I shut it down and turn it back on it looses tuning and faults. The Y axis will do the same thing but not as bad as the X axis.
Any suggestions. I am on my second controller from CandCNC I have gone through 3 Servos drives from Gecko and several motors. The motors and Drives were bought in 2005 the PSC 1500 was replaced new in May this year minus the Torrid. None of the electronics were used till this project.
Third problem: I hooked the Scope up to the drive via the instructions in the Gecko Manual. By the way the test points are different than the diagram. They are located in different positions. I used a meter to figure out witch one was ground. Channel 1 test point ground to ground. Channel 2 Direction pin leaving drive. Dc couple Trigger Channel 2. Norm Slope Positive. 2v on input and 1ms on horizontal. I cannot get a trace that looks anything like the diagram. All I get is a flat line that jumps every other direction change. No matter where I tune the drive. I have had 2 other people that supposedly know how to run scopes come over and they cannot get a trace that looks similar to the one in the gecko manual either. Any suggestions. This is making more grey.
Donny
Re: How to set up a oscilloscope to tune Gecko 320's not X's
Thats not exactly the case, you just need a two channel scope, you can trigger the trace off of the second channel every time it changes direction. It will show at 1ms time and 2v voltage just fine. The instructions are sort spewed throughout the gecko manual but it is there,
Quote:
Originally Posted by
Runner4404spd
In order to tune with scope you need one that can record the trace. the trace shoots by the window of the scope so fast that you never see it and then its gone. most scopes as far as i know are not setup to record their traces. other than that you have it setup correctly.
the faults i'm guessing are from noise in the lines. put the scope on the encoder wires that feedback to the drives and move the machine around. see what you get. i would try and put some capacitors on the encoder wires at the encoder. that does a pretty good job in eliminating or at least minimizing noise. when i first setup my system i didn't used shield twisted pair wire for the encoders and what a mistake. at 5 volts output, the wires had about 4.8 volts of oscilating noise on them. with the shielded wire it was much better. also make sure to only ground the shield wire at one end. you want it to act like an antenna and pull the emi to ground. make sure this ground is the not the computer ground by earth ground, so connect to the chassis.