Post-Crash Inspection / Spindle Noise

I have a RoboDrill D21MiA5 that I recently crashed. 2" face mill into a block of aluminum. The spindle is making a different noise (slightly louder) now under certain spindle speeds and loads. It doesn't sound that bad, and the bearings spin freely by hand. At 18k, it sounds perfect, but at 9k or 6k, you can hear a change. If I walked up to this machine, never using it before, I wouldn't think twice. Before I bring in a tech, is there anything easy to inspect? Motor/spindle coupling? Things like this?

Any issues with tool changes? If the dog alignment is still good then it's likely no slippage occurred at the coupling.

Get a automotive diagnostic stethoscope (they're cheap) and carefully listen to sections of the spindle while running up and down the RPM range. It's ideal if you have previous "readings", as then you can compare noises, but if something sounds out of expected levels of N or V then you likely will want to change out the spindle at some point.

But until then, just run it and as long as finish and tolerances are acceptable, go with it.

Thanks Milland. No issues with tool changes.

Good idea on the stethoscope. Do you use something digital that can take/log readings or is this more of a seat of your pants thing.

I'll keep an eye on surface finish and go from there. Thanks!

Stethescope = real big screwdriver/prybar or ??? up to the ear.


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Think Snow Eh!
Ox

Ox said:

Stethescope = real big screwdriver/prybar or ??? up to the ear.


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Think Snow Eh!
Ox

Click to expand...

Used to use a broomstick or any other wood dowel rod handy.
(don't want the spark plug wire to spark my head....)

Got one of those HF "auto mechanic stethoscopes"....Oooooh Much nicer.
S-T-E-R-E-O.
YouTube

werksmini said:

Thanks Milland. No issues with tool changes.

Good idea on the stethoscope. Do you use something digital that can take/log readings or is this more of a seat of your pants thing.

I'll keep an eye on surface finish and go from there. Thanks!

Click to expand...

Something like this: https://www.amazon.com/Lisle-52500-Mechanics-Stethoscope/dp/B0002SQYSM or the HF version that Digger mentioned. There's much fancier stuff out there based on accelerometers that can give you digital data and recordings, but it's not cheap.

Ox, I've done the big screwdriver trick too, but as Digger mentions the 'scope gives you improved listening and I think is safer too (no big metal thing to get bounced into your skull if you misplace the tip).

I am not sure there is a point to the listening. There is now noise in the spindle. Bearing damage seems pretty obvious. Check runout, taper, and finish, and start saving your dimes. I think I would be paying closer attention to heat because that is what is going to finish it off or start some other gremlins. If you know the machine well, you may know about how warm things get and you can assess from there. Typically operators couldn't care less so it makes troubleshooting harder.

Well, if he wants to check it out today, in stead of some time next week, there are other ways to skin that coyote.


Normally I would say that the drive belt just found a slightly new home, and will git to know it's new position soon, but I'm guessin' that an 18K spindle doesn't have a drive belt?



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"For 60 years (yesterday) we've been on our own..."
Ox

werksmini said:

I have a RoboDrill D21MiA5 that I recently crashed. 2" face mill into a block of aluminum. The spindle is making a different noise (slightly louder) now under certain spindle speeds and loads. It doesn't sound that bad, and the bearings spin freely by hand. At 18k, it sounds perfect, but at 9k or 6k, you can hear a change. If I walked up to this machine, never using it before, I wouldn't think twice. Before I bring in a tech, is there anything easy to inspect? Motor/spindle coupling? Things like this?

Click to expand...

I did that with a 3" face mill about 5 months ago kinda. I was running 6500 went to another fixture offset on a different height and kinda cut the part at full rapid. made it 4in 1.5" deep into the part before it faulted.

I had to reset the oriant on the spindle ran fine. however like you I have a funny noise at about 4500-6500rpms and only there. most people wouldnt notice it sounds just a like a spindle just a different pitch.
what I do is watch the heat. spindle never got warm. I check the heat on and off through out the day. I figure Im going to need a spindle replaced one of these days.
I am betting the coupler moved a tad between the motor and spindle and the harmonics are just that that certain rpm. reason I am thinking the coupler is because if I peck drill the noise will go away.
finish is just as good as it ever was and no heat so I'm not worried about it that much. Besides shit happens your allowed a screw up once every 10 years

buddy of mine who repairs machines said not to worry about it, said I just reset the preload on the spindle beaings back to factory spec as its ran 12k rpms for 10+ years.( thats a machine repair joke for those who dont know)