[DaOne]

Well I was surfacing some aluminum stock last night taking a .2 cut with a 3 insert face cutter. Done it a million times before in the past. Well for some reason it grabbed the stock and crashed the machine pulling the stock from the vice jaws. I was running at 7500 RPM at 60 IPM when this occurred. Anyways is stopped the spindle instantly with a nice load bang. Now I am hearing a couple new noises that concern me a bit. When I spin the spindle up to say 7500 and stop it (applying the break) I get a noise that sounds kinda like a bad backlash problem on a gear when its decelerating the spindle. Also when cutting I am getting a resonant frequency almost like a zinging around 2200 rpm. I was told to check the belts but since I haven't been into the spindle I am not even sure where to look. Any help would be appreciated.

Specs are:

1995 Haas VF-2
7500 RPM Mitsubishi Spindle

[tobyaxis]

Sorry to hear this happened.

If you look in your manual you will see a Machine Diagram that shows where the belt is. Usually these are easy to get to by removing the top cover and then the front cover on the Head.

You may just need a new belt or a tension adjustment.
I hope your problem isn't too severe.

Maybe Greg, Geof, Hu, or the Haas Apps guy will see this Thread.

Good luck with this.

[Geof]

Very likely you have stripped some teeth off the belt.

The belt is located at the top of course but to get at it you have to take off all the sheet metal on the head; get help because it can slide down when the last bolt is taken out and trap fingers.

Cross your fingers; because the spindle hit spinning and it is only a 7500rpm unit your bearings probably survived.

Once the belt is replaced run it through its speed range and check for new noises. Even if you think you hear something my suggestions is to keep running it because if the bearings are damaged you will find out pretty soon when the noise starts to increase but you will not damage anything else.


EDIT: It just occurred to me. Is this a gearbox machine? If the answer is yes you may have problems there but I cannot help on that aspect not having any machines with gearboxes.

[wms]

If it is a gear box machine..You could have knock a tooth or two off a gear..Been there, done that..An instant stop has that effect..

[DaOne]

Yes it is a gear box unit. The weird part is that the noise is on the ccw motion.Also I can tap just fine. Surface finish hasn't changed. I feel the bearings are ok. I think the noise is either a belt or a gear. I guess its time to tear it apart.

[DaOne]

If it is a gear box machine..You could have knock a tooth or two off a gear..Been there, done that..An instant stop has that effect..

If that is the case. Can a gear by itself be replaced or is it the whole gearbox? Also any idea on cost for parts to fix it if it is?

[Donkey Hotey]

I don't know if anybody has a secret source of gears but--generally speaking--if the gears are damaged, you'll need a whole new gearbox (about $4500 I think). I'm with Geof: I'd check the belts, make sure nothing came loose and just run it. You might consider changing the gearbox oil after a few hours to see if you have any flakes or chunks in it.

If it's going to frag itself, the damage has already been done and there's little you can do now. If not, you'll get used to the new noise.

[Geof]

Keep crossing your fingers.

The belt can protect the gearbox because it fails and in doing so absorbs some of the shock loading coming from a rapidly deccelerating motor.

[Cory]

I don't know if anybody has a secret source of gears but--generally speaking--if the gears are damaged, you'll need a whole new gearbox (about $4500 I think). I'm with Geof: I'd check the belts, make sure nothing came loose and just run it. You might consider changing the gearbox oil after a few hours to see if you have any flakes or chunks in it.

If it's going to frag itself, the damage has already been done and there's little you can do now. If not, you'll get used to the new noise.

It's $4400-4500, minus 50% of the cost when the tech takes the old one with him.