Need Help!- Fadal VMC 4020 - Spindle Load Problem

[phat]

Hi Everyone,

We've had a 1995 Fadal VMC 4020 (w/CNC 88HS) for nearly six months or so - bought at an auction - and have had intermittent issues with the spindle inconsistently losing RPM during operation making the machine unreliable. We contacted Fadal who sent out their "best guy" - he recommended an (expensive) encoder change - we did and it didn't help the issue. Whenever the spindle RPM starts to wander, the "Spindle Load" meter reports excessively high load.

This morning we turned on the machine and the "Spindle Load" meter shot up to ~90% without any spindle motion at all (see the attached photo.) I'm assuming the problem is related to our previous RPM issues.

One suggestion has been made internally (here) that perhaps we should clean up all the PCBs (ex. contacts to the back plane inside the control panel) to see if that helps resolve the problem.

Does anyone have another suggestion? Any help would be greatly appreciated.

BTW, we're located in Fremont (Bay Area.)

Thanks.

- Phat

[alex gitzel]

With the issue you are having the first thing i would change would be the encoder also,I read that you replaced it,my question is #1)did you replace it with a new sealed unit from fadal or old style one that comes in several pieces(us digital brand),and#2)if you used a new one from fadal did it come with the wiring diagram(there are a few changes when changing styles) the last few i got from fadal did not have the diagram included and that is why i am asking,if you need the changes i have the list.if you went wire for wire it may be the issue,also check the small gauge wires that go into the spindle drive(#'s 38(may be in slot 30 it is ok on some drives),31,32,33+34.see if they are loose or damaged also recheck the wires that the encoder plugs into for damage.it is also a good idea to reseat the control cards and make sure all the wires on the spindle card are tight and the bullet plugs lock in good.i did have a spinlde motor one time that had intermitent surges and the issue was in the wiring from the control card to the drive.if that is all ok you may want to swap drives with another machine to test it.

[Neal]

phat--
I would recommend that you MEG out the spindle motor to make sure that the motor is not causing the issue. You have already addressed the Encoder aspect. ALso make sure that there is no interference with the rotational binding of the belts.
I would also make sure that the spindle turns quite freely and ou are not having any spindle bearing issues. Lastly would be the Spindle drive itself having an internal issue. One far out possiblity would be the controller card.

Neal

[javibande]

Hi Everyone,
We've too a 1995 Fadal VMC 4020 (w/CNC 88HS) and we´re having now the same problem.
phat, could you tell me if you´ve solved the problem , and how did you do?

As I can understand, first I should replace the encoder.

Please, I hope anyone can answer me about it.
I ´ve contacted Fadal service here in Spain , but probably they should come 7-10 days later.

Thanks in advance

Kind regards

Javier

[carbidecraters]

We have the same issue on all our Fadal machines. Even the ones with new spindle motors. Even the ones with rebuild imverter drives. I believe its a load circuit issue and has little to do with any part of the machine after the pendant.

[denmar]

There are hundreds of Fadal machines out here with no load meter, (my is one of them), nevewr had aspindle problem (for 20 some years)