Bad surface finish 6x12 surface grinder spindle disassembly questions

[metric_taper]

I would not buy any "used" bearings for a grinder spindle, without a money back guarantee.
And then, only if I was willing to waste the time to receive, check and return the bearings.
Why would someone be selling a used, matched pair of angular contact bearings?
Easier to find a full set of hens teeth.

Not sure how to proceed until reviewing the results of a survey.

I would not buy used bearings either. I'm seeing only new ones on eBay. Semi affordable. But they don't have dust shields on either side. Probably because they may get installed back to back or face to face. It's an enclosed motor, but FOD is most likely circulated from day one of manufacture.
I'll work more on this tomorrow, I need to pull the 6303 bearing off and check that bearing land.
That's a good idea to do quadrants and runout tests on the various critical features.
It's evident to me they didn't do this spindle as one setup.

 

[extropic]

I would not buy used bearings either. I'm seeing only new ones on eBay. Semi affordable. But they don't have dust shields on either side. Probably because they may get installed back to back or face to face. It's an enclosed motor, but FOD is most likely circulated from day one of manufacture.
I'll work more on this tomorrow, I need to pull the 6303 bearing off and check that bearing land.
That's a good idea to do quadrants and runout tests on the various critical features.
It's evident to me they didn't do this spindle as one setup.

My suggestion was to survey the entire shaft/armature. Maybe take readings at every .5" of length. Certainly every inch. Not just the "various critical areas".

I apologize for my comment about buying used bearings. Apparently, I read eBay but understood used. My bad.

 

[Liljoebrshooter]

Not sure they make angular contact bearings with seals. The race is a lot different on one side than a common ball bearing.
Joe

 

[Lo-Fi]

Yes, I don't recall seeing any shielded angular contact 72 series during my research for spindle bearings.

 

[metric_taper]

Yes, I don't recall seeing any shielded angular contact 72 series during my research for spindle bearings.

I've come down with some bug, that has shut me down for the past 3 days.
Yes, I can't find them either. So I need to see about installing seals in the motor houseing. There is a ring that can preload the bearings, that has another ring that spins inside this, I'm going to install an O-ring by machining a groove in one of them. That will protect the hub side from grinding dust. On the motor rotor side, there is some material next to the bearing I can machine for a yet to be found lip seal. That I don't know about or have I measured the size range to do a search.
I'm not a bearing expert, so if there was something available in a matched pair with a seal on one side, I don't know what that is.
I believe the original intent was for a pair of angular contact bearings. But they wanted a much lower price point.
I know this machine is a bottom end piece of junk, but that has never before stopped me from putting lipstick on the pig. Or trying.
It's the hobby of trying to fix broken stuff, or badly designed stuff. I really can't make is worse. Unless I mess with one of the bearing fits, and permanently machine its surface.

 

[DavidR8]

Have you talked to a bearing supply house?

 

[metric_taper]

Have you talked to a bearing supply house?

No, I don't want to spend $800 (or more) on bearings, as that's what I'm seeing for online prices, for the ones I can find on eBay. I need to settle for what I'm willing to spend, and fix the seal problem. I found ABEC7 bearings for $90 with tax and shipping $110. But they do not have a seal.
I did not see a 30mm ID, 62mmOD, 14mm width, pair (28mm) with seals on one side.

 

[extropic]

No, I don't want to spend $800 (or more) on bearings, as that's what I'm seeing for online prices, for the ones I can find on eBay. I need to settle for what I'm willing to spend, and fix the seal problem. I found ABEC7 bearings for $90 with tax and shipping $110. But they do not have a seal.
I did not see a 30mm ID, 62mmOD, 14mm width, pair (28mm) with seals on one side.

Previously you wrote that you were looking for bearings with "shields". Now you're referring to "seals".
If you will use sealed 7206 bearings, they are definitely available. McMaster-Carr sells individual 7206-2RS (ABEC1) for more than you want to pay, but none-the-less, they are available. You are missing out by not calling bearing distributors.
If I were in your shoes, I would start a new thread titled "Want reasonably priced spindle bearings", describe your requirements and ask the community for recommendations on bearing houses to call. I know I've read posts about members finding spindle bearings at very reasonable prices. Good luck.

 

[metric_taper]

I could not find a matched set of bearings with 30mm bore, 62mm OD, and 16mm width (32mm for the pair) that have integral seals. They may be available as custom made.
I did find SKF 7206 matched pair. These are 15 degree contact angle, ABEC7/class4 dimensional accuracy and running accuracy (5 micron=0.0002"). I got them from eBay for $90 plus $10 shipping, and I had to pay 7% tax.
I see they raised the price for the other one they had to $319.
I spent the last two days making a fixture to hold the spindle motor cast iron housing, so I can machine an internal boss for the pressed in seal. This is on the motor side, which is totally enclosed sealed. But you never know what FOD is in the motor for original manufacture, or that I put there.


Attached some photos of the fixture plate.
The motor has a 80mm pilot standing proud on it's mount to the surface grinder. So I just copied that in this fixture plate.
I used my automatic boring head to machine that recessed feature. Took many hours to do, as I could only remove .5mm per pass, and need it to be 8mm deep.
My finger is pointing at the boss that needs to be made to fit the 52mm OD of the seal. I assume the bore should be this for proper fit. That boss currently is 52.7mm, so not much to remove.

 

[extropic]

Congratulations on getting those bearings at such a great price.