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Messages - smurph

Galil / Re: Galil + Mach3 slowly losing position
« on: January 19, 2014, 02:13:28 PM »
Glad to see you got it sorted!!


Galil / Re: DMC-4080 on-board amp hardware questions
« on: January 15, 2014, 11:22:48 PM »

I have not actually seen a 4000 series controller with the amps built in.  All I can say is read the Galil docs a couple of times and then re-read them.  The last thing you want to do is brick it.  But I feel like the integral amp boards can be used.  If not, I'm sure Galil will reconfigure it for a reasonable price.  I was just reading the docs and I thing it is certainly possible to use the controller though.  The only thing is the amp enable outputs are a bit different on the amp controllers.  It may require removing the cover to configure them.  An the voltage ranges may not be available.  Regardless of if it has amps, you will need to provide power to that plug.  The amps are powered by a different power source I believe.

I can tell you for certain that the 4000 series controllers are really sweet. 


Galil / Galil plugin version 4.6 available.
« on: January 08, 2014, 05:54:30 PM »
There is a new Galil plugin available on the plugin download section of http://www.machsupport.com.

Two plugins...  One for Smart Term and one that will work with Galil Tools (and possibly Galil Suite) PCI drivers and Ethernet controllers.  Pick the one you want.  You don't want both plugins in the plugin directory at the same time! 


Galil / Re: Galil Connector
« on: December 10, 2013, 05:47:33 PM »
Yes, exactly like that.

Drive enable is a function of the Mach enables.  I believe you can stagger the enable delay in Mach 3, but I do not know how.  You may want to pose that question in the General section.


Galil / Re: Ethernet communication drops with RealTek card
« on: December 10, 2013, 01:48:39 PM »
I have seen a fair amount of computers come with these RealTek Ethernet controllers on-board.  And another issue with them is that the transmit buffers are woefully inadequate for streaming data TO something.  They work fine when the PC is streaming data FROM something, like a video from the web, etc...  But streaming data to the Galil was problematic.  So you have to go fiddling with the Ethernet card driver settings.  Find the transmit buffers and max them out.  Then it seems to work fine.


Galil / Re: Galil Connector
« on: December 10, 2013, 01:38:44 PM »
Ilia, you can limit the output voltage with the TL command.  I use it on my Matsuura because the amplifiers actually take a -6 to +6 voltage range.  Galil is VERY handy when running obscure stuff.  :)


Galil / Re: Galil Connector
« on: December 10, 2013, 12:40:16 AM »
Nice!  Thanks Ilia!


Galil / Re: Mitsubishi J2S-40A and Galil DMC-2183 with ICM-20105
« on: December 02, 2013, 02:19:48 PM »
The DMC-2260 is a good controller.  It has 100 Mb Ethernet and can probably do 2ms in LI mode pretty well.  Tweaking the VA, VD, and VT params via the plugin will smooth things out even more.  I have never tried the position control (step/dir) input servo drives, as there is really no reason to use a Galil with them.  So for your machine, I would suggest 200w analog command servos.  A bit overkill, but you can soften them up with the PID parameters.  You will most likely want to drive the screw with a reduction belt drive to the servo.  No direct drive as often used with steppers.  Most servos will do 3K RPM so gear reduction is the norm. The more encoder counts per unit you can get is going to help all things out.  The Galil will handle 50,000 counts per inch easily.  So use 5:1/4:1 reduction or so on the servo to the screw and then calc in the screw pitch to get in the 30,000 to 50,000 counts per inch ball park, assuming 1024 counts per rev or more encoders on the servos.  Adjust accordingly for metric.

I like the little Yaskawa SDG/A servo drives and the matching SGM motors.  Bullet proof.  And you can find them pretty cheap on eBay.  SDGA-02BS is the 100v (110v mains) drive and the SDGA-02AS is the 200v (220v mains) drive.  The motors have to match the drive voltage.  For smaller 100 watt system, SDGA-01BS or SDGA-01AS.  Big thing here is getting the cables control cables with the drives.  Or at least the stubs.  Otherwise, you will have to order some expensive cables!

The 200 watt motors are not much bigger than NEMA 23 steppers.  The 100 watt motors are even smaller.

Tuning the servo system is a royal pain.  But once done, it is well worth it, IMHO.  Quiet and smooth.  Less stress while operating the machine.  The sound is rather nice on the ears.

Be careful though...  Once you go servo, you never go back!  :)

Galil / Re: Galil + Mach3 slowly losing position
« on: December 02, 2013, 03:13:40 AM »
I guess it is possible.  But I was talking about noise sources such as switch mode power supplies or VFDs that use switching transistors.  They are terrible!  

Try this test that will take Mach and the Galil plugin out of the equation.

What happens in the Galil terminal if you do this:
1.  ACX=5000 ' set accel to something your machine can deal with.  5000 is just a number I thought up.
2.  DCX=5000 ' set deccel to something your machine can deal with.
3.  SHX  'servo here to turn on drive.
4.  DPX=0 ' set the X axis encoder count to zero.
5.  PAX=10000  'move the X axis pos 10000 counts (or something that makes you machine move about an inch or two)
6.  PAX=0 ' Move X back to pos 0.

Do you get back to 0?  If not, PID or mechanical.  

Also, the motor should hold position at zero after the last test step.  If it does not, then there is something really wrong somewhere.  It should really not ever creep after SH has been issued.  If you try and turn the screw by hand, the servo should fight you and try to keep the encoder at zero.  This is really a good test because you will see if you PID values are good.  If it fights back and tries to return to zero and it just never makes it back after you let your hand off, there is a sign that the PID values need tweaking.  It should go back to 0 and stay there.  It may dither back and forth a couple of counts, but not much!

After MO (motor off), the servo loop is disabled and the motor can creep if there is a bias on the analog command input of the servo drive.  In this case, you can adjust the voltage bias with OF (offset) to get a no creep setting.  Use BN to burn the OF value to the controller.  

Oh, and it goes without saying but I will say it anyway...  Be careful!  :)


Galil / Re: Galil + Mach3 slowly losing position
« on: December 01, 2013, 07:02:22 PM »
At best, it sounds like your PID may need a bit of tweaking.  IF there are no mechanical issues.  

The encoder is on the motor, right?  Well what if the shaft is slipping in the gear/coupler a bit?  That will lead to a table/position mismatch.  So the first thing I would do is verify the mechanical parts.  I took apart a machine (not a mill, but a second op special purpose machine) from work that was having position problems that no one seemed to be able to find.  Every time they started the machine up, they would have to change an offset value in the program to make it work.  They just accepted it as that was the way it is and dealt with it.  Eventually, they decommissioned the machine and I bought it for scrap price.  I wanted the servos and ball screws for my mill project at home.  As I took the machine apart, I found the problem.  Way deep inside the guts in a location that was very inaccessible, there was a shaft coupler that was designed to be used with a key way.  Well...  someone neglected to put the key in!  So all that was holding the shaft was the friction of the coupler.  It would slip just a bit every now and then and this caused the offset issue.  It was insidious because just looking at the shaft coupler, you would never find it.  Lesson learned!

Your rounding "lip" problem smells distinctly like the stench of mechanical problems.  :(  It is very possible to slip in only one direction.  I would advise taking the X axis apart and looking at everything.  Just turning things by hand measuring might not immediately show where the problem lies.  

If all is well mechanically, tighten up the PID so that commanding the servo to a position makes it hit the numbers.  If you get into a situation where you say G01 X1 and your encoders don't read 1.0000 (assuming your encoder resolution will actually let you read to the tenth), then you need a bit more gain (or less dampening) in the PID.  This sounds like the problem you described in your first paragraph.  If you find yourself over shooting, then you need more dampening/less gain.  There is also sticktion.  If the gain and dampening are generally good but on very slow moves to the target you find yourself not hitting the numbers, you may want to throw just a tiny bit of KI in there.  Be careful with adding too much I because it will cause the system to get unstable!  Your KP and KD parameters need to be pretty much on target before you go messing with KI.

Also, check for noise issues.  This might make the encoder "count" even if it is not moving!  It is best if the encoder signals are differential and not single ended.  And it is also best if the encoder cables are not run along a path that take them near any noise sources.  VFDs, power supplies, etc...