replacing angular contact bearings in a surface grinder

Hello,

I have a boyar schultz 612 with a noisy spindle. I turned it on the other day and it was even noisier than usual. I turned it off and it the spindle stopped immediately. I took it apart, cleaned and inspected it. Couldn't find any obvious damage but it seemed like the bearing at the wheel's end had a very loose cage. Regreased, reassembled, and found it to be even noisier, but with no resistance in the spindle when stopping, like before.

It has an oscillating sort of vibration pattern to it now that is enough so that you can just barely feel it in the concrete.

Do you think replacing the bearings could bring this thing back to normal? I don't mean "will it" but rather could it? Are there special precautions that I need to take? What bearing rating do I need for a good chance at a successful repair?

Seems like I can get any kind I want up to an abec-7, hybrid ceramic for about 200ish each. Not an expense I want, but the next best option seems to be to buy a grizzly to replace it

Good info here if you can find a copy - the maintenance section includes scraping lock nut faces for actual squareness

I would be 7's but not ceramic. You do not have that kind of speed.
What? scraping locknuts, who of thought that changes with a new bearing pair. That seems like a lot of work.
You have already torn apart once? Be very nice to the housing and shaft. All should get a very, very light stone and a work on any high spots from disassembly.
This fairly simple spindle will put up with a lot of abuse in rebuild.
Loose cage should not have been a problem. Something else.
Clean, clean and clean again. If the races have spun on the shat or housing ,,,more problems but can be ignored "sometimes".
Use spindle grease not auto grease but this more just a lifetime deal.
Do not overfill the bearings and jog and check temp during runin.

A spindle rebuild on this machine not hard to do but you do have to be careful, gentle and nice to the parts involved.
Bob

Make sure the Belleville washer preload is working correctly and the bearing can move easily in the bore. My bearings were ancient but with a cleaning and new grease they work just fine. They don't even look that good, with substantial swirling on the balls.

Make sure you have the bearings facing the right direction. http://vintagemachinery.org/pubs/2682/4155.pdf

I found this one on Vintage machinery and it looks like they are back to back...or fat sides of outer races facing each other. Also buy some good grease Mobil red aviation # 28 or 32 grease and only fill by volume 30%. If you buy new bearings don't wash them out, just squirt in the grease with a syringe you can buy at a vet supply store. Bob is so correct, be super careful and keep things clean. Don't use a punch and hammer to push the bearings on the spindle. Press them on or use a bearing heater. I would suggest looking on You Tube and find a movie on installing precision bearings. Also if you did not mark the * TIR inner race when you took it apart, you should rotate the spindle on a V block using a .0001" indicator to find the high spot on the spindle and mount the * mark on the # 7 bearings 180 degree's from TIR on shaft bearing mounts.

Do a search and check out this post.

https://www.practicalmachinist.com/...ndle-rebuild-327379/?highlight=boyar+bearings

I used it as a guide when I cleaned and re-lubed my B/S. I had a similar problem with bearing noise about 1/3 of the time, and a quick coast down.
Reusing the bearings worked out fine for me.
John

Well, assuming belleville washers are a standard part in a bs612, that may be why there's a problem. There's nothing of the sort in my spindle. Not the biggest surprise based on the condition of the nuts retaining the bearings - it looks like it's been taken apart half a dozen times before me.

Ok that makes me happy to hear that I didn't waste my time haha - I chilled the bearings and spindle to get things in place without force. I didn't mark that, no. Based on my other reply I think it's safe to say that that alignment may not have been there when I bought it. Looks like I have some studying to do. Thanks all. I'll update if anything other than a machine replacement happens

I've been installing spindle bearings for 45+ years. I have never heated bearings to 400 F. I was taught to never heat them over 250 F. I have a cone shape bearing heater and I used to use a wax heat pen years ago and over the past 10 years I heat them to 140 to 180 F and they fall on. I also took a bearing class at SKF in King of Prussia PA and we also used magnetic bearing heaters and they warned us not to go hotter then 250. So if I were an installer I would not heat bearings that hot or I predict premature failure. I found this PDF about installing Barden Bearings that is pretty interesting. You can also google the high operating temp of bearing heaters and you can read what I just said. https://www.schaeffler.com/remoteme...andling_mounting_precision_bearings_us_en.pdf

Richard King said:

I've been installing spindle bearings for 45+ years. I have never heated bearings to 400 F. I was taught to never heat them over 250 F. I have a cone shape bearing heater and I used to use a wax heat pen years ago and over the past 10 years I heat them to 140 to 180 F and they fall on. I also took a bearing class at SKF in King of Prussia PA and we also used magnetic bearing heaters and they warned us not to go hotter then 250. So if I were an installer I would not heat bearings that hot or I predict premature failure. I found this PDF about installing Barden Bearings that is pretty interesting. You can also google the high operating temp of bearing heaters and you can read what I just said. https://www.schaeffler.com/remoteme...andling_mounting_precision_bearings_us_en.pdf

Click to expand...

Yeah 400 is too close to tempering range in my mind - I wouldn't go that far.

great document, thank you!

Regarding the Belleville washers, angular contact bearings are not going to work without a preload. That's also the reason they caution against grinding anything on the back side of the wheel- it unloads the bearings. If you pull the wheel towards you, you should feel a slight motion or softness. If the bearing can't move in the bore it won't preload correctly.

I talked to a spindle repair company that listed boyar schultz as a specialty and when I mentioned the missing belleville washers, they reacted like they've never heard of such a thing. It's a good sign that I need to know more

By grinding on the back side of the wheel does that apply to just grinding on the flat face or does that include feeding positive in Y?