How to check for bad spindle bearings

I have a TM3 that has just started giving me some terrible problems with chatter when face milling. I have a decent Sandvik 590 cutter with adjustable pockets. The cutter is like new, all new inserts and screws and torqued to the insert spec with their special wrench.

I was cutting bronze bars 2.3" wide in Talon Grips and the finish was poor, could not really hear any chatter but could definitely tell the finish was not good. I flipped part over and machined aluminum jaws to hold. No difference.

The deeper cuts were not as bad as the .005" cuts. It looks like a zebra stripes down the length of the part.

I am now wondering if the spindle bearings could be the problem. I swithced from bronze to a piece of aluminum and they finish was the same.

I also tried different cutters and an new shell mill holder.

could be caused from the trailing end of the cutter. add a z move to your cut. make the endpoint a few thou higher than the start point. the part will be tapered, but it will rule out back strike marks. I hope its not the bearings!!!

Thanks, I have cut from both directions thinking that maybe the cutter was dragging, I assme that if you are dragging he back and change directions the back should have clearance.

I checked the spindle trammed to the table. At about a 12" swing I get a couple tenths. I only have a .0005" interapaid indicator but can sell less that one division of movement.

I put an indicator on the bottom of the cutter and can push it up about .001" by hand.

Is the spindle housing warm or hot to the touch? also you may have already done this but check the obvious. could the retention knob, inserts be loose? also check the cutter body to adapter screw and make sure that's tight, and if you have access to the right tools, check the drawbar retention force.

I have replaced all inserts and even purchased new screws for clamping.

Brand new parlec tool holder, brand new reteition knob. I did all of that trying to eliminate the problem.

I am pretty sure they are unrelated but having the same problem on 2 machines. TM3 and VF3.

Can't figure it out for anything. tried different face mill different material.(aluminum and bronze)

You have finish problems on 3 machines, how many machines do you have? Check a few other things:

Does the new holder have any fretting?
Is the machine level?
Can you move any of the leveling screws by hand?
Are all feet on the same slab of concrete?

Post some pictures of the parts.

What type of facemill are you using, positive rake or negative rake? Are the inserts plain flat sharp ones or chip breaker type?

Sounds more like the facemill to me. Also try touching each insert off of a know surface and see if one is sticking out more.

Mike

I also tried different cutters and an new shell mill holder.

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You mean it creates the same finish with endmills as well as facemills? Or are you saying that you tried other facemills that have worked for you ON THESE SAME MACHINES WITH THE SAME INSERTS in the past?

If you can push the cutter up .001, put the dial on the spindle face and try pushing that one up, same deal?

I know I slightly messed the bearings on my manual mill as a job I used to do with small endmills that never chattered, started to chatter quite bad after I had done the job that banged on the spindle pretty bad. Wasn't worth it

Finally got it figured out thanks for all of the advise.

It is a sandvik 590 cutter with adjustable pockets with positive inserts.

I checked the machines level and trammed. I was very skeptical that it was the machine since it did it on 2 of them but I just could not track down the problem.

Sandvik recommended new screws as they felt the inserts were moving. I purchased new screws, inserts, 3NM torque wrench. I installed the new screws in the cutter with old inserts, tried many cuts and different depths same pattern on the face. Not sure how to describe it but kind of like zebra strips running parallel to the direction of travel.

I moved the cutter over and recut and it was apparent the lines were tracking with the center of the cutter. I pulled one insert and ran the cutter and had the same issue. I then removed one more insert and ran the cutter, finish was very good. I put the first insert in the second insert pocket so I could tell if it was the insert or the pocket. It ran fine.

I moved the insert into 3 different pockets and it was leaving the poor finish everytime.

Removed it and problem went away. Called sandvik rep he said he would like to have insert sent in so they can check it.

We had tried what I thought was everything, new parlec holder, new J&M retintion knob, new screws/clamps. I blued the spindle taper to tool holder and it was also good. That was why I started looking at the spindle. I would never have guessed the insert was moving.

At least we are running.

Congrats-----Glad you are back in business.

Mike

machineit2 said:

Congrats-----Glad you are back in business.

Mike

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x2 and it wasn't an expensive fix