[lm6769]

I crashed my komo mach1 the other day. the spindle came down so hard the collet nut meet the table and it stopped the spindle from rotating. now when ever i use the machine it makes a weird noise when ever it rotates. at first it was pretty load. but as time went by it seemed to have calmed down. we have been running it like this for about 2 weeks now with no problems. i was worried i had broke a bearing inside, but if that was the case, wouldnt the noise get worse over time though. I called komo and they said the only way to fix it was to replace the entire spindle for 12,000$ there is no was i want to spend that much. and suggestions on what to do?

[HuFlungDung]

If a spindle bearing were damaged, then you have little choice but to overhaul the spindle yourself, or pay someone else to do it. The trick is to be sure of where the problem is.

Is there any kind of gear train involved? The shock load combined with spindle momentum can bend or break a gear tooth, bend a shaft, or damage a bearing in the gearbox.

If you have a low and high range, compare the sounds of the spindle in either range, and see if there is significant difference.

[Geof]

If the spindle is driven with a toothed belt the shock load can damage teeth on the belt. These can make a noise hitting the pulley but it gets less as they break of completely.

[mori_1]

yes a cog belt will make noise if it's missing "cogs". You're lucky if this is all it is. If it had ceramic bearimgs, goodbye spindle. Your best bet, look at the belt if it is belt drive, if it's a direct drive, look at the coupler between the motor and spindle. It could also be a drawbar issue on your pullstuds. Any problems with tools falling out at tool change or taperlock in the spindle? I don't know much about anything other than what I've seen, and all of the above could be potential noisemakers that are generally cheaper fixes

[ger21]

You should be able to get the spindle rebuilt for a lot less than $12K

[Geof]

I think if the bearings were damaged the noise would not have abated, it would most likely have increased.

When the spindle is spinning it is very difficult to cause bearing damage; large diameter spinning bearings have enormous load capacity and when it is spinning it stops 'gently' as the collet nut melts against the vise. In this kind of crash the machine is going to alarm out either with a spindle overload, spindle following error, Z axis overload or Z axis following error. If it hits under feed the forces involved are not going to be any greater than the maximum Z thrust which will only be a few thousand pounds.

[markn5660]

You might consider sending the spindle to Setco. They make and repair precision spindles.
We just had our spindle bearings replaced for $2800.00 and are very happy with the results

[NC Cams]

Spindle damage is hard to deduce/diagnose via discussion. YOU have to remove and inspect the bearings.

Yes a spinning spindle is harder to damage that a non rotation one but it is possible to damage one if you hit it hard enough. I"d suspect that one or more of the balls and/or raceways has become brinelled. I"ve seen guys hit them hard enough to shove the ball over the side of the raceway - "Gee, I didn't think we hit it THAT hard" sure.

IF you're lucky, the bearings in the spindle can be reverse engineered either by P/N or by having someone who KNOWS how to measure offset and preload measure them. Whoever you do have do the spindle, make sure they regrind the ID with the spindle fully reassemble and preloaded, Just replacing the bearing set is NOT an adequate and proper rebuild.