[wolfman1]

We have a Monarch 5024T mill and we are getting a lot of spindle noise at high RPM's. The spindle is a 12,000 RPM but we never run it that fast, about 8,000 max. Anyway, the higher the speed the louder it gets. Also, when we mill using x-axis it gives a rough cut, y-axis is not bad.
We replaced the x-axis ballscrew about a year ago and worked great so I don't think it's that.
We replaced the spindle bearings about 5 months ago and spindle stays cool.
We checked the play in the z-axis and if we use a lot of pressure we can move it about .002'' from side to side.
We checked the play in the spindle and with a lot of pressure we got about .005'' of play from side to side. We adjusted the spindle nut (could only move it a tiny bit until it was very tight) and then we had .003'' of play using a lot pressure. Checked the spindle play on our Chevalier 2040 VMC-L mill and we got .001'' play.
Could it be the bearings again? Any info or suggestions would be greatly appreciated. Thanks

[firekoe]

have you checked the drive motor for heat? is that setup a derct drive or belt setup?
also for the x slide i would check the trust in the ball screw bearings

[wolfman1]

It is a belt drive.
I made a mistake on the play on z-axis, we don't have the side to side play, its the up and down play that we have.
When I say "play" I'm meaning that's how much "give" I have when I use leverage on it.
I will check the motor for heat.
Thanks for responding.

[wolfman1]

I checked the motor and it gets a little warm but not hot.
I was informed by one of my guys and he was telling me that the spindle bearings were installed with the "V" markings on the outer ring of bearings as follows = from top to bottom - v - ^ - v - v. Does anyone know if this is right? We talked to a Monarch tech and he didn't know.

[ifixcnc]

It looks like your TAC bearings may be out of order based on your -v-^-v-v check your prints. They also need to be lined up in order.
.005 is alot of radial play. When you say alot of pressure what do you mean? Are you pushing it by hand or with an axis?

[wolfman1]

Thanks for responding. I will try and clarify a bit on what we did to get the measurement. We only have .003'' of "play" or "give" from side to side on the spindle cartridge using a 5' tubing prying from the side by hand and using a magnetic based dial on the table.
One of the threads on cnczone mentioned that the spindle bearings need to be pressure side up on the bottom and pressure side down on the top so when you tighten them they will come toward each other and snug up. This makes sense to me but not sure if all spindles would work like that.
I think because of the way the bearings were installed we can't load the bearings correctly because 1 bearing on top is facing the wrong way. I am probably going to take the spindle apart and install new bearings but it is a bit of work and and I need to be more sure that it is the bearings before I do that.
Again, thanks for responding. Any suggestions REALLY are appreciated.

[zavateandu]

as far as i know the order should be :^-^-v-v and should be no axial movement and radial must be under 0.01 mm,normally on new bearing is around 0.005mm
if is axial movement on spindle than the bearings are not tight enough and when u mil your spindle will go up and down and make traces on workpiece.

ps:i never met this :-v-^-v-v kind of line up---strange.

[jjautomation]

hi
Just a previous experience. I have seen problem in which spindle noise becomes high with the increase in RPM.
We checked everything as you mentioned.
You didn't mentioned that sound comes in cutting time or in idle also.
The problem in our case was spindle belt. We sprayed belt spray and the noise was gone.
Check for that also.

[wolfman1]

We checked the belts and they are good.
I checked the web for spindle rebuilders and found one that was really helpful. They are called Specialized Spindle Services from Ontario, Canada. The guy I talked to was Brent and he told me that he thinks the noise is bearings and that they are too loose, and the reason I can't tighten them more with the top nut is because of the bearing placement "v-^-v-v" which should be "v-^-v-^". We are waiting for bearings now and will report our conclusions after we put them in.
Thanks again for you responses.