Is AC servo conversion really this easy?

[snoman70]

I purchased a Brother TC-211 drilling tapping center recently. It needs a new spindle motor, and all of the electronics are completely obsolete.

It currently has 3, 200w 100 V single phase AC servo motors for each of the axis. Should a granite driver really be compatible...even if I were to have to swap out the encoder. It would make my life so much easier!

From reading, the granite drives are compatible with PM AC servo motors, are there non-PM AC servo motors? I had never heard of an induction type servo motor.

So how do I find out for sure, prior to actually forking out the cash and purchasing a drive.

Also, I currently have a system set up for my CNC router with basically a breakout board for Mach3 and gecko 201's. I've never played with smart drives before, is it going to be basically the same setup? Breakout board to step/dir pins?

Has the open loop bridge been gapped yet for PC control, so that when I tell a drive to move 100 steps, it moves 100 steps, not just sends 100 signals and prays for the best.

[Spinnetti]

lots of questions there, but servo=feedback control. Stepper=send signal and pray, so by definition, both AC and DC servo have "solved" the feedback problem. I put DC servos on my mill, though 99% of the people here seem to use steppers (cheaper).. If you size steppers properly, there's no real issue with "lost" steps. Commercial stuff is pretty much AC servo as far as I know, but most people here aren't running 100,000's of parts a year.

[snoman70]

Individually, yes, a servo will not stop until it sees that it moved, but when multiple axes are interpolating, if a drive cannot keep up, you will have error involved. I believe on the more industrial type machines, if a drive cannot keep up, it will error out. I guess that's what I meant by missed pulses, even though it's not what I wrote.

Regardless, I'm mostly interested to see if my current motors will work with the granite drives!

[Al_The_Man]

Originally Posted by snoman70 It currently has 3, 200w 100 V single phase AC servo motors for each of the axis. Should a granite driver really be compatible...even if I were to have to swap out the encoder. It would make my life so much easier! From reading, the granite drives are compatible with PM AC servo motors, are there non-PM AC servo motors? I had never heard of an induction type servo motor. So how do I find out for sure, prior to actually forking out the cash and purchasing a drive. Has the open loop bridge been gapped yet for PC control, so that when I tell a drive to move 100 steps, it moves 100 steps, not just sends 100 signals and prays for the best.

Apart from 1ph AC stepper motors, I have never seen or heard of a 1 phase AC servo motor?
Do you mean the drive is supplied with 1ph? if so it is most likely a 3ph motor, check if there is 3 stator winding conductors.
There are 1ph AC synchronous motors, but these are not usually used in a servo set-up.
In a system like Mach, the drives close the servo PID loop, the motor position is still not known to Mach control itself, if you want true closed loop back to the controller there is EMC, Dynomotion also Galil motor cards that will do this.
If the motors have standard quadrature differential encoders, the Granite drives should work.
Al.

[snoman70]

The motors, according to the book are Toshiba RA 10M0100 assemblies.

As of yet, I'm unable to find anything on them.

Yes, the feed to the driver is 100 v single phase.

[Al_The_Man]

Toshiba AC servo's have traditionally been 3ph servo's, many recent ones have used a resolver for feedback, which if this is the case with the ones you have could limit their use on any other than the matched drives.
You may have to do some checking to see if the feedback device resembles a resolver, it typically would have 6 conductors and be an electromechanical device.
Do you know what type of input command the present ones use, if it is not step/dir?
Al.

[snoman70]

It's a resolver....and the motor is four wires labled U, V, W & E.

So the motors should work, I just need to fit them with new encoders?

[Al_The_Man]

Should do the trick.
Al.

[fusion_crank]

Snoman, any idea how much your mill weighs? If you disassembled it as far as possible, what do you think the heaviest part would weigh? I have a line in one a few hours away, but I want to set it up in the basement. Think it could be transported down a flight of stairs?
Thanks,
Mike

[ihavenofish]

Originally Posted by fusion_crank Snoman, any idea how much your mill weighs? If you disassembled it as far as possible, what do you think the heaviest part would weigh? I have a line in one a few hours away, but I want to set it up in the basement. Think it could be transported down a flight of stairs? Thanks, Mike

the specs say 2600lbs for the machine.

[fusion_crank]

Thanks for the info!