Heavy 10 Rear Spindle Bearing Cap Gets Warm Quick

Due to life's obligations, getting my SB10 up and running had to wait. It sat for two years in my hangar, but now it's getting attention.

I bought a TEMco VFD, and after some head scratching got it to work. Now I'm 220, single phase.

One odd thing was the "stiction" of the spindle. Once you get it to spin, it's fine, but you have to "break it loose". On the higher speeds, the belt will slip until you spin the chuck by hand to get it going.

The machine was neglected before I got it, and who knows what kinds of oils were used...but as we all know, the wrong oil is better than no oil. I have purchased the correct oils.

My (current) problem is that starting with the second highest speed, the rear spindle cap will get warm quick, and if you keep it running, it will get too hot to leave your hand on...I'd say two minutes.

Pull the rear cap and have a look, and what about draining the old spindle oil?

Thank you,

Arnie

Offhand, it sounds like there are several possibilities:

1. The rear spin dle bearing has insufficient clearance - doubtful, since the machine was neglected and probably had no repairs. If anything, it should have additional clearance due to wear.

2. Too heavy oil - possible, but why isn't the front bearing also running hot?

3. Insufficient oil - possible. Could an oil ring be broken, a wick missing/plugged, or an oil passage plugged?

I would definitely pull the rear cap and see what's what. And definitely clean things out and change the spindle oil

Don't pull the rear cap until you know how to do it. You must remove the pipe plugs and the tiny screws which are under them first. Also- you need to check the take-up nut and the ball thrust bearing. If the end-play is too tight, the bearing will also get warm.

allan

Well I removed the pipe plugs, the small allen head cap screws, the bearing cap allen head cap screws and seeing the cap was pinned, decided to leave it on. I dripped spindle oil down the pipe plug holes and saw oil seeping out the spindle bearing and overflowing out of the rear oil cup. So no blockage, right?

It is better, I can now run it on the second highest speed forever, it'll get warm, but not hot. The highest speed is still temperature limited. The front bearing cap stays cool.

Maybe the old girl just needs to loosen up a bit...

Thanks Bob and Alan for taking the time to help.

Arnie

Sounds like the spindle needs to come out and clean up the oil wicks and passages.

Replacing wicks if worn or springs broken.

Bill

1) slack the thrust bearing adjustment.

2) measure the beaing clearance for the rear bearing (and
front while you're at it) according to the SB instructions. If
incorrect, set it to the spec.

Be sure you are using correct spindle oil in the cups.

If those things fail to solve the heating problem, open things
up and look into it.