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Now what. Vevor 7x14 mini lathe

F

Feeop

Member
So I decided to do the spindle bearing upgrade to tapered roller bearings. I purchased the recommended bearings (30206) and now that it's stripped down, the races don't fit properly. One I pressed in by hand (snug but won't come back out or turn), The other one just slides in and out. It seems snug but spins. Can they be fixed with loctite 660 as recommended or do I need to source new ones.

Thanks in advance.
 
BaitMaster

BaitMaster

Super User
That is definitely a bit of a pickle. Hopefully someone with some experience chimes in on this one…..

If you have accurate measuring tools you could start by measuring the OD of the bearing that doesn’t fit, the OD of the bearing that used to be in there, and the ID of the spot where it’s supposed to fit, using your most accurate method.

You could also make sure that the new and old bearings have the same size numbers on them. Basically look for a manufacturing defect or a mistakenly specified bearing….
 
P

PeterT

Ultra Member
Premium Member
Strangely I have been running into a few machining / machine rebuild preojects where the new (offshore) bearings were completely out of whack on the basic dimensions. Like all ground nice & shiny but a thou out +/- 0.001" I dont think there is any bearing class with tolerance like that is there? One guy bought 6 angular contact bearings, supposedly matched sets. Some were sloppy & some were just not going to go into the hole - within the same set!

Not sure what to say about the one in there already but maybe good practice for all of us is take nothing for granted & sanity check mic on the races before going any further.
 
slow-poke

slow-poke

Ultra Member
Agreed measuring would be a good place to start. I recently ordered a matched pair of NSK angular contact bearings from China. After ordering but before they were shipped I Googled counterfeit NSK bearings and sure enough counterfeit bearings are being produced with perfect looking packaging. NSK has gone to the trouble of providing a unique QR code with each bearing and a decoder on their website to let you know if what you receive is genuine. After reading this I contacted the seller and requested a cancellation of the order, my request was ignored and the bearings were shipped a couple of days later. Fortunately eBay has stepped in.

Previously I found a genuine NOS set of NSK (old blue box, not new gold box) at centralsurplusny for a fraction of retail price and $11 shipping. They only had one set of the NSKs at the time but after searching there again I found a matched NOS set of RHP brand so ordered those. Assuming the second set are also good this appears to be a good source for NOS bearings. Fingers crossed.
 
Tom Kitta

Tom Kitta

Ultra Member
As someone that just fit 16 bearings, they do have tolerances - and it is hard to actually find how tight the fit should be for a bearing type.

Ideally there should be no play and there should not be any need for Loctite. I would try another bearing.

Certainly thou out is not possible even with automotive stuff as my tight fit was over 0.01 mm per side.

You could pin instead of Loctite as well, but for precision stuff I would go with pressure fit.

Ah and I had out of 16, 6 bearings that were mixed metric / imperial. Outside was 52mm but inside was 1in not 25mm... Numbers the same!
 
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