Precision Bearings

Ultradog MN

Ultradog MN

H-M Supporter - Gold Member
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Aug 2, 2020
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This pertains to the 1940s? Midway Millmaster that I bought recently.
I have the spindle apart on this thing and was thinking about replacing the bearings in it.
One of them fell apart when I bounced the quill on a board on the floor like I would a farm implement bearing.
These are a #20208 bearing.
I brought the good one in to my local bearing house and can get the 2 lower bearings for about $65 each.
See photos.
These are an open type "precision" bearing that need to be oiled all the time.
There is another open faced bearing on the top end of the spindle. It's just a simple #3208 open faced ball bearing and I thought I might replace it with a sealed type. Cheap enough at $33.
By the way, I could buy a pair of sealed type "precision" lower bearings but they cost $161 each and would break the bank.
Any advice - do/don't do from you guys on this?
Thanks20201117_140854.jpg20201117_065856.jpg
 
i think that that high quality will pay off in the long run with longer life and more accuracy just some thoughts
 
Plain commercial quality bearings are not suitable for machine spindles. Using an oil can is not so difficult that it would be good to go to sealed bearings.
 
Before shelling out any cash do a search on this site.

Search Results

From Textile machinery to vehicles, there is always a need for bearings. Let us locate the ball bearings you need from qualified and trusted manufacturers!
www.locateballbearings.com www.locateballbearings.com

I was able to find the bearings for the Worthington All Speed drive on my 1960 Sheldon lathe for less than $16.00 each. They ranged in price from over $120.00 at Motion Industries to a little over $50.00 from vendors on Amazon,
 
Those lower bearings look like they are angular contact bearings. I don't think they even come in a seal configuration (doesn't really make sense). They only take thrust in one direction - if you reverse load them, they come apart (as you discovered). They are commonly used in machine tool spindles. For a set of "precision" bearings, that have been set up to run together you can expect to pay easily 10x the amount you were saying would "break the bank".

I suggest you document exactly what you have and how it is set up. Then carefully put everything back together (cleaned and lubricated). Then use the machine for a while, see how it works, learn how the bearings and spindle perform - if there is an issue, then spend some time looking for the proper bearings, research how to install and adjust them (probably will need to make some tooling).

I too recently got a "new to me mill" and the spindle bearings are in poor condition (the spindle would not turn at all). I contacted the dealer, the last time the dealer had sold a set of bearings (these are a special bearing - the local bearing supply shop had never seen anything like them) was 6 years ago - they were $8000 USD back then!

The point being, spindle bearings are a big deal.
 
It appears that there is "DB" hand engraved on the bearing after the number. They are, most likely, a high-precision matched pair. $$$$$$! Clean, oil and reassemble the bearing, and be sure they are reinstalled in the same orientation they were in when you removed them. They may even have a "timing" mark on each bearing to indicate how they should be aligned with each other. I see an "S" on the outer race of the disassembled bearing, I may also see a ^ on the outer race of the other bearing (top of picture).
 
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Thanks fellas.
I did some more digging here and found what I was looking for.
Two of the precision bearings and the simple upper one.
A guy at one of the bearing houses I went to gave me a tip.
This place has bought out the stock from hundreds of places that built, used and sold bearings around the world. They don't have much of a search function but if you use your favorite search engine and type in the manufacturer and bearing number you may find what you are looking for.
I ordered the three of them and with shipping they cost me $58.74.

Locate Ball Bearings | USA & Worldwide Service

From textile machinery to vehicles, there is always a need for bearings. Let us locate the ball bearings you need from qualified and trusted manufacturers!
www.locateballbearings.com www.locateballbearings.com
 
That is a very good price for off brand, plain 'ol bearings. In power train elements (motors, gear units etc) one can certainly use regular class bearings and they will last a long time. I have little experience in all the reasons why spindle bearings are so fussy. My one comparison is on my surface grinder, a PO had installed regular 6200 series C3 clearance bearings (roughly 1.5" dia x 1/2" shaft) - cost would have been about $25CAD. I tracked down the proper bearings (one special ordered from the brg supply house, the other two as NOS of ebay) - all in $450CAD. The grind finish certainly improved (still it seems grinding is as much art as it is science - I'm still not getting results like professionally made parts).

Let us know how it all works out.
 
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