JMC 220V Servos with Acorn

[suntravel]

Glad that it runs now smooth.

Resonance is maybe from the belt, try to get a bit more tension.

Uwe

[RJS100]

I finished replacing the bearings and getting ready to make parts but ran into two issues:

One is that I am feeding the AC servo a 0-10 volt analog signal, but the servo motor does not run at its max of 3500 rpm with a 10 volt input. I verified that Acorn is indeed putting out 10.008 Volts. I used a tachometer and measured the max spindle speed of 5200 rpm. Since the pulleys are 1.8 to 1, the servo is then only turning (5200/1.8) or about 2900 rpm. I experimented with parameter P06-40 Speed analog instruction gain 1rpm/V and no matter what I entered, even 500 it made no difference. Not sure what to try next.

Secondly, I’m trying to educate myself with respect to fine tuning the servo (This is all new to me). The splined spindle is driven by a splined pulley. There is a bit of slop between the splines. I can actually hear the slop if I rotate the spindle back/forth by hand. I mention this because when I slow down the spindle, I hear a bit of a tapping sound. I think what I am hearing is the servo overcompensating as it decelerates due to incorrect tuning, and I believe the tapping sound is coming from the slop in the splines as the spindle jitters as it decelerates. I did run the AF_J-L and record the measured moment of inertia ratio and wrote it in P01-04. Not sure if there is a simpe fix for this as well.

Thanks... Richard

[RJS100]

I figured out how to stop the rattling sound be reducing the rigidity setting of the servo. Parameter 01-03 from defaul of 13 to 9. It is working fairly smoothly now, but I will revisit with tuning software in the future.

The JMC servo is rated for 2500 rpm normal and 3500 max. With a 10V analog input, it will not run faster than 2850 rpm. Here is the response from the distributor that I purchased the servo from:

Hi, I called JMC engineer and he confirmed the motor's max. speed can be 3500 rpm. But it's much higher than rated speed, please don't run it at 3500rpm long time. You can rise the frequency of input signal or set the Electronic gear reduction ratio to rise the speed . If still question, please write me detais ,I will try to ask JMC engineer give a solution.

Do you know what the easiest way to implement this. I would like to hit 3100 or 3300 rpm if possible.

Thanks... Richard

[cnckeith]

sounds like it would overheat and toast the bearings.

[RJS100]

Thanks... I will leave it as is. This will provide a spindle speed of about 5000. I'm good with that.

Best... Richard