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Fadal VMC40 hi/low Speed Change "squeak"

Joined
Jan 22, 2019
Hey All,
Just had a new VFD installed in my 1992 Fadal VMC40.

While running through tests, the mechanic and I noticed that when the spindle is running at, say, 500 RPM and then is changed to 3000 RPM, the air system engages the high range belt before the spindle has fully stopped and the belts produce a very quick squeak as the two belts fight one another. This doesn't happen when going from Hi to Low. It also doesn't happen when I change speed range when the spindle is not spinning. It's definitely the belts.

Anybody have this issue before? Is there a way to set the speed change timing?

Thanks,
M
 
Two different belts for high and low? Does it have a clutch or a "belt tightener"? :confused:

I do get a kick out of your username seeing that machinists generally don't use fractions and especially not thirds........:D

:dopeslap:
 
One additional thought:

In the low range, the spindle is actually running about 30 RPM over. In high range, about 60 under. Is it possible that the controller thinks the spindle is stopped in the low range when in fact it's still spinning slowly?

Thanks,
M
 
Two different belts for high and low? Does it have a clutch or a "belt tightener"? :confused:

I do get a kick out of your username seeing that machinists generally don't use fractions and especially not thirds........:D

:dopeslap:

Yup, two belts. It has two air cylinders attached to idler pulleys that tension either belt in turn.

And yes. Nine and Two Thirds is both the name of my company and the number of fingers I have left...
 
On the machine side, you could try messing with the orientation factor in the parameters, but i don't think that will do it.

You are going to have to change some settings in the spindle drive. Ramp or a gain setting or something.
Shouldn't be that big of a deal to do. FINDING the parameter you need to change could be a pain in the ass.

What drive is it?
 
Hey All,
Just had a new VFD installed in my 1992 Fadal VMC40.

While running through tests, the mechanic and I noticed that when the spindle is running at, say, 500 RPM and then is changed to 3000 RPM, the air system engages the high range belt before the spindle has fully stopped and the belts produce a very quick squeak as the two belts fight one another. This doesn't happen when going from Hi to Low. It also doesn't happen when I change speed range when the spindle is not spinning. It's definitely the belts.

Anybody have this issue before? Is there a way to set the speed change timing?

Thanks,
M

one of your tensioners sounds loose. 1st make sure you have oil in the belt changing system. as thats mostly the cause no oil or low.
also make sure you have the proper tension on the tensioners, you might have to tweak them a turn or two if your belts are wearing or stretched.
 
Dude... We've got a 9 fingers, a 9 and Two Thirds fingers, and a 9fingers....

This forum cracks me up.

Keep your fleshy bits away from the spinny bits.
 
Dude... We've got a 9 fingers, a 9 and Two Thirds fingers, and a 9fingers....

This forum cracks me up.

Keep your fleshy bits away from the spinny bits.


And also that guy "D*cks4Fingers".........

I'll have to ask Don to change mine. I wanna keep up with the fads....:bawling:
 
is the actual mechanism fully releasing and maybe it is getting stuck as the other engages.

Oh its releasing fully if he didnt his title would be My Fadal sounds like a Jackhammer.
Thats a sound you will never forget is when the pulleys dont release.
 
one of your tensioners sounds loose. 1st make sure you have oil in the belt changing system. as thats mostly the cause no oil or low.
also make sure you have the proper tension on the tensioners, you might have to tweak them a turn or two if your belts are wearing or stretched.

I concur. IIRC, it's an airover oil system. If one side is low on oil it'll be less responsive.

As for the spindle RPM, sounds like a drive tuning issue. LO = 1/2 motor rpm, HI = 2x motor rpm. There's probably a relationship there, between the motor rpm, spindle rpm and drive arrangement. But I'm too tired to put it together.

Good luck, and please report your findings.

Sent from my SM-G930R4 using Tapatalk
 
I concur. IIRC, it's an airover oil system. If one side is low on oil it'll be less responsive.

As for the spindle RPM, sounds like a drive tuning issue. LO = 1/2 motor rpm, HI = 2x motor rpm. There's probably a relationship there, between the motor rpm, spindle rpm and drive arrangement. But I'm too tired to put it together.

Good luck, and please report your findings.

Sent from my SM-G930R4 using Tapatalk

Okay I'll check that out. Thanks! As for the RPM, the mechanic was having trouble getting it closer but I'll look into it and yeah maybe tweak the drive a bit.

Thanks all, I'll be back with results.
 








 
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