PRT Advice wanted

[Gary Campbell]

Hey Guys...
I am donating my time to get a 2002 PRT at my local high school up and running. All is now well except for a very nasty sounding Z axis. Z motor is shown in pic below. All motion parts have been disassembled, lubed, reassembled and adjusted.

Very loud grinding sound when moved with keyboard, up or down
when off the machine, motor sounds resonant, but not bad
Z axis moves thru total length very well without motor (no binds)

Any ideas? TIA

[harold_weber]

Hey Gary, assuming the gear and rack are meshing OK, the driver may be bad. Try changing to the other one (the 2002 board comes with 5 of them). If you need, I can send the how-to.

[ken_rychlik]

Gary,

That same motor was used all the way up through the early prs model.

I am guessing it is not 4g with geckos??? Talk them into the 4g upgrade if it hasn't been done.

Also if that is the case, the motors are pretty loud and sound kind of like they are grinding. To verify the motor is ok, you can switch motors with another one.

Ken

[Gary Campbell]

Thanks Guys...
Another report tomorrow :rolleyes:

[gerryv]

Any chance they or the original owner might have put an incorrect pinion gear on it? That would be a lower cost fix than a new motor :(

[gc3]

agree with Harold...sounds like bad driver

[Brady Watson]

Very loud grinding sound when moved with keyboard, up or down
when off the machine, motor sounds resonant, but not bad
Z axis moves thru total length very well without motor (no binds)

Any ideas? TIA

Aside from the driver being bad, it may just be mid-band resonance. Have you tried increasing the move speed on the Z to like 2 IPS or so? How does it sound at that speed?

-B

[Gary Campbell]

Brady...
No, havent tried faster settings. I did try a [control] + [page up/down] which made noise unbearable.

Other motors have good amount of resonance that goes away at jog speed (4ips). Z, I forgot to mention, has visble chatter as it moves up or down.

I will swap driver & motor to isolate tomorrow. Any of these motors or drivers still available?

Gerry...
They are the original owner. There is little or no evidence of use on pinions, rails or rollers. How many teeth on the OEM pinion?

[ken_rychlik]

I upgraded an 02 this spring for a company in houston and it came with 18t pinions on the z. They only offer 20t replacements though.

Need to check and make sure the unit values line up with what you have.

Compared to the motors you are used to hearing, they will sound like you poured gravel in the gearbox with the oem board. :eek:

If they have the budget for the 4g that would be best. Maybe the school could get a better price too.

[srwtlc]

Gary,

I had one of them and had two drivers go bad in the time I had it. From what you describe, I concur with the others here that it sure sound like a driver.

[myxpykalix]

I'll make a suggestion to see if you can take the cover off this motor and see if the grinding and noise is as a result of either worn gears or the lack of any lubrication inside the gearbox?

per bradys suggestion of a bad driver, i'd like to ask how a bad driver would make the stepper make noise?:confused: (i'm not that technically proficient and i'd like to know this since occasionally i hear strange noises):eek:

[bob_reda]

I dont know scientificly how it makes the noise but I can assure you it does. I have an older prt that they don't have the drivers for but Frank gave me the address and number of a replacement driver, ran about $160 for the driver. Everything is nice and quiet now. Just did it last month. If you have the small gears with 1/2" shaft, they cost almost as much as the driver $84 apiece.

[Gary Campbell]

All is well. I swapped the Z over to channel 4 and life is good for the ol' girl. Thanks to all that got me pointed in the right direction.

[hh_woodworking]

Advise from an other teacher. Tell them to make sure that the student understand that you can not move any of the axis by hand with the rack and pinion engaged. As we all know the out come will not be good. From one who has experienced this problem:confused:

Ed