[gus]

if you watch the display the LSD[.0001] will change and the polarity + - will change. If iit is balanced 'perfectly' [not possible] the readout will read xxxx.0 and the polarity will slowly change from + to -.

The offset is ther to correct minor variances in the electronics either control or drive which cause it to try tomove in one direction or another IE the control puts out .05 volts instead fo zero

[machintek]

If the offset is set perfectly, in theory you could disable the position loop (unplug the encoder) and the motor will stay stationary. We used to set the offset on the BOSS 8 and 9 that way. If you unplug the encoder on this machine, you get a measuring system defective. I wonder if a gib is set too tight, and the motors are trying to schieve position? That is why you look at the lag screen (difference between commanded position and actual position0.

George

[gus]

Just a note, I fired up my Interact after it being unused for a few weeks. It hummed very nearly as much as the one here. It shut up after a bit of use. I wonder if it is just one of those oddities. My R2C3 has the same amps and similar motors and never a peep.....

[swarf_rat]

Normally motors hum because they don't know the words. Now that we have that old joke out of the way:

In testing the drives on mine, I noticed that the motors hum when the "drive release" relay for that drive is energized when the analog input is 0 (no motion called for). This is an input to the drive board, and I assumed would not be energized normally until motion is called for (but I don't know that for a fact, and can't check it till I get my control fixed). However this hum is not audible over the sounds of the motors while in motion.

[swarf_rat]

Be aware that in theory, the brushes on the SEM motors should be examined about every 4000 hours of operation. Attached are the Bridgeport service bulletins covering this.

George

Thanks for that bulletin. Do you happen to have a parts page or exploded view of the motors/tachs that are being referred to? That would be very helpful to us neophytes!

[rkdygert]

Maybe Gus is right...my machine has quieted up a little more with some use. After tuning the drives in according to what George posted, they quieted down alot...the remaining hum has lessened considerably since then...sounds pretty good to me now.

-Ryan