AMC DC Servo drive adjustments explained

It sure is refreshing when the support people actually provide some support.

This is all very good news - that the adjustments appear so easy to accomplish. Not that I'm not interested in Karl & Tim's more scientific approach - I've designed a few controllers over the years and this is STILL interesting stuff, but it's nice to see that Gunner's more nuts & bolts method will get you close enough*. But what do the other pots do (there are five, if I remember correctly)?

• Wouldn't it be great if Gunner could just stick to what he knows?

Ha! That's what I figured.

Well....

It has nothing to do with the stability of the _drive_, but it affects the overall gain of the position servo. When you change the setting on that pot it'll change the gain that EMC 'sees'. Turning up the gain on that pot has the same effect as turning up all the gains in EMC.

So, set it such that the voltage range of the drive, without topping out in speed, matches the voltage range that EMC will send. Then don't ever touch it -- putting inspection paint on it to seal it would not be a bad idea, or even a drop of beeswax.

Did they tell you how to adjust Test Offsets? Very critical for proper and clean movements.

Gunner

One could not be a successful Leftwinger without realizing that, in contrast to the popular conception supported by newspapers and mothers of Leftwingers, a goodly number of Leftwingers are not only narrow-minded and dull, but also just stupid. Gunner Asch

Thats not really necessary..and he WILL need to retune it in about 2 yrs after the electronics have aged a smidge. Well..at least in less than 4 yrs.

And its very "voltage" responsive...IE..if the voltage you feed the electronics changes...so will the outputs. I see clients moving a machine from one side of the factory to the other..or to another site..one site may be 224volts..the other may be 245volts..and it does..does change things. Still runs fine..but may run slower, or with less accuracy.

Gunner

One could not be a successful Leftwinger without realizing that, in contrast to the popular conception supported by newspapers and mothers of Leftwingers, a goodly number of Leftwingers are not only narrow-minded and dull, but also just stupid. Gunner Asch

You seem very knowledgeable here. I've turned it till it drifts left, then turned it till it drifts right. Split the difference. Is this correct?

BTW, I have a Z servo that will vibrate on occasion. Used to be only once in a great while, now once out of ten jogs. I just give it a nudge to stop. But, I need to retune this, someday; when I get one of those round tuits.

Karl

They did not tell me that, but I would ilke to know!

i

Correct in theory. Put a volt meter on...hummm 3 and 4 (pins on the header connector) and set the last pot on the right... for IRRC...Zero Volts. As you jog in opposite directions...it will go +/-,,,,but it should go to the same voltage ..just plus/minus

The OmniTurn has a screen that shows both test offset and following error that allows one to tweak the amps while watching the screen.

Im so used to using that screen..Im having a stroke moment trying to remember the method without the screen.

Back off the far left gain pot a couple turns and see what it does.

Here is the owners manual for most of the early versions..

Download it and go to section 6 and check the data for the AMC amps and tuning. It may be of some assistance.

Gunner

One could not be a successful Leftwinger without realizing that, in contrast to the popular conception supported by newspapers and mothers of Leftwingers, a goodly number of Leftwingers are not only narrow-minded and dull, but also just stupid. Gunner Asch

...

Say, i scanned the gcode section trying to get to section 6. Omniturn has a great write up here. Much better than the fanuc yellow manual I go by. Of course, some Gcodes are different so i can't just copy it.

Karl

Ayup..each manufacture has different Gcodes, particularly canned cycles and whatnot, but some of the stuff is pretty much common. Mike did a very good job trying to make sure end users understood what was going on, and why.

I had a small hand in some of the manual as well..but very small.

I had a slightly larger hand in writing some of these....

Stuff like this....

And a fair number of the other stuff....shrug

One could not be a successful Leftwinger without realizing that, in contrast to the popular conception supported by newspapers and mothers of Leftwingers, a goodly number of Leftwingers are not only narrow-minded and dull, but also just stupid. Gunner Asch

Oh..and this one may be of some interest..while not directly applicable to a mill...there are some things one can do if something "isnt right"

Gunner

One could not be a successful Leftwinger without realizing that, in contrast to the popular conception supported by newspapers and mothers of Leftwingers, a goodly number of Leftwingers are not only narrow-minded and dull, but also just stupid. Gunner Asch

And I see they posted the new Generation 4 manual..which is mostly backwardly compatable with most of the older machines.

EXCEPT for older Servo Amps..it only covers the OmniTurn/Glentek servos. Damn..why the hell...never mind.....

Check out the G code listing on page...hummm 1.22 or somewhere about there.

Gunner

One could not be a successful Leftwinger without realizing that, in contrast to the popular conception supported by newspapers and mothers of Leftwingers, a goodly number of Leftwingers are not only narrow-minded and dull, but also just stupid. Gunner Asch