How to tell if the spindle bearings are bad?

[JMFabrications]

Hey Guys,

I have an '02 VF2 with pretty low hours on it for the model year. It has a 7500 rpm spindle, I mostly cut aluminum and very rarely run the machine over 75% spindle load, it never runs at max rpm for more then 30 min. The past few days at anything above 5K rpms I hear a strange rattling noise coming from high above the spindle, its more apparent when there isnt much load on the spindle at all. Im not sure if there is just something loose inside there or if im developing a serious issue. Is there any easy way to tell if the bearings are on the way out?

Thanks,
Jim

[JMFabrications]

If it helps any I posted a 40 sec video of the machine, about 24 seconds into it you can hear the rattle noise.

http://www.jmfabrications.com/videos/MOV01792.MPG

[Doug Tyler]

I have a mini-mill that does the same thing.
the spindle sounds fine at 4000 and above, but every now and then, at around 2000 to 3000 I hear the rattling sound. I've been told that it is normal. hard to believe though.

[Geof]

Before getting too worried take the covers off and look for loose setscrews on pulleys, or missing teeth on the belt. In general anything that may have shaken loose.

I have had several machines make funny noises that were due to loose cooling fan blades, vibrating sheetmetal hitting a small lump on the casting (this noise was fixed by grinding the lump off). I have a VF2 that makes a horrible noise at a specific speed and I am sure it is a harmonic vibration in the covers so we don't run it near that speed.

If you are worried about bearings you could get a vibration analysis done, I have had this on both mill and lathe to calm my worries. Your Haas tech should have all the equipment for this.

[Geof]

Originally Posted by Doug Tyler I have a mini-mill that does the same thing. the spindle sounds fine at 4000 and above, but every now and then, at around 2000 to 3000 I hear the rattling sound. I've been told that it is normal. hard to believe though.

I have two Minis that sometimes rattle. Strangely enough it seems to be temperature dependent, not the machine the shop temperature, it happens more in warmer weather.

[JROM]

put a streight round bar in a tool holder and put it in the spindle. Then put a .0001 indicator on the round bar and push the bar with your hand. If you can deflect the spindle more then a tenth or two with your hand you have a bearing problem. But not very likely. My next guess is there is something going on with the tool retention system.
That could be very dangerous so call the Haas doctor right away! Or you could be lucky and it's just a sheet metal issue or harmonics.

[axis]

STOP WHAT YOU ARE DOING CALL A TEC

[rlabonte18]

sounds maybe like the drive belts. you should also make sure your bearing lubricator is working correctly(clean the stone filter and check the regulator pressure and make sure you are using the recommended oil).

[JMFabrications]

Thanks for all the replies! I just spoke to my local haas tech and sent him the video. He was almost certain that its the transmission. He told me to drain the oil and check for debris. He also told me that there is a filter bowl in the head with a magnetic screen and I could check that. He pretty much said to run the machine until the trans takes a dump or starts effecting the finish, its a $3500 job to replace it!

Ill start by changing the oil now.

[vlmarshall]

I've had my VF-3 at work making the same noise, I think. It's equipped with the 10k spindle, and with no load, it would rattle a lot at a small speed range, and the spindle load meter would jump all over the place. I pulled off the head covers and found that the timing belt for the speed encoder was loose.
I've replaced that belt twice now, once avery two years or so... but this machine sees 8-hour days running at 10,000 RPM.