[skmetal7]

Ok so I decided to install new spindle bearings in my X2 minimill. I bought the upper and lower from littlemachineshop. Seem like high quality bearings... but the top one is making a baaaad noise. IDK if they just need breaking in; but I did run them for an hour or so at different speeds.

The noise started as soon as I turned on the spindle, kind of goes away after a long time of running. The sound is like crunching. It is dependent on how much force the belt has on the spindle; it's super quiet and smooth when the belt has about .25" of play, and louuuud when I tighten up the belt.

I was really careful installing the bearings. I sanded the spindle down so it isn't such a tight press fit on both bearings. When I pressed them into the housing, I only applied force to the outside race. These bearings can't be that delicate, right?

[ame=http://www.youtube.com/watch?v=bi9KtYDqr4Q]Bad spindle bearing? - YouTube[/ame]

[nolage]

Sounds almost like an unpacked race or trapped ball inside the bearing... That's not good obviously.

[wildwestpat]

Hi Shaun

Curious as to bearing type you have used. Is it the standard radial ball race with integral rubber seals or the tapper roller? Hence these questions.

If the suffix is 2RS then the ball bearing is probably shot possibly due to applying to much force in fitting or being supplied a duff one. Did you check the new bearing? IMHO it is worth paying that bit extra for a bearing from one of the big names and making sure it is in the original sealed box / wrap. There are lots of low quality ones about and these find their way into the dealers who might not be aware that bearings they are buying in bulk are inferior. (To help ensure the bearing is clean the bearings are individually wrapped or supplied in sealed tubes or other containers for quantity users.)

With ball bearings applying the pre load might have brinelled (dented) the race bearing surface or flatten one or more balls particularly if the race outers are not fully bottomed in their respective bores (or not aligned - has this spindle been OK prior to fitting the new bearings?) . Pulling a pre load will then apply all the load to just one or two balls. If this is the case the noise will get worse until it fails big time. (The noise sounds a bit like a cage problem or a coasting bearing with large clearances. You would need to apply axial loads to see if this eliminates the noise.)

For example the 6206 bearing is good for 11K newtons static radial and the axial force is probably only one tenth of that ie 200 pounds force and that is easily applied via the fine screw thread. These bearings have nine balls to share the 200 lbs force of axial load - if the race is tilting the load will not be equally shared - hence my question.

Have you tried pressing the shaft up and down whilst it is running?

Or have you fitted rollers????

Regards - Pat

[mrcodewiz]

How tight did you set the preload? Did the bearings feel smooth before you pressed them in?

[TXFred]

My X2 did that. I used a mechanic's stethoscope and determined that it was the motor making the noise, not the spindle.

Frederic

[skmetal7]

THis is the bearing that I used: LittleMachineShop.com - Bearing, Spindle

I don't think I over preloaded them, I only tightened the spindle till there was no axial play. (The spindle now just slips into the bearings)

It might be the motor bearings, I'm installing a new motor soon, after I build my new controller. I'll see if that clears the noise. It's strange that it would start making the noise after I install new bearings in the spindle. Bad luck or coincidence?

[LUCKY13]

I think you either got a bad bearing, or maybe even hurt it during the install. It really doesnt take much sometimes. Even a tiny place in a bearing race can make noises like this and just simply dropping a bearing can cause a bad place.

With bearing alignment the smallest little ding in a housing where a bearing fits can cause alignment problems. The finicky nature of bearing is why high quality spindles cost so much, and why hobby level machines dont have very high quality bearing setups.



One thing you might be able to do is take a hand drill and try to run the spindle with the belt on the drill. It would be alittle hard to hold in possition but it may help tell if its the spindle or the motor making the noise. To me it does sound like a bearing, but noise will travel in a system a fool you so seperating the two parts ( spindle & motor) will be worth goign through the trouble.


Jess

[skmetal7]

I'm going to see if I can find a low priced SKF or similar on ebay.