[Tom488]

Hi all - relatively new Patriot CNC owner here. I was fighting an oil leak coming from the oil seal around the retainer for the lathe spindle. When I disassembled the spindle and pressed off the bearing to get to retainer off, I saw the worn/damaged felt seal. Replacing that with a new piece of felt wasn't working for me - couldn't get the right size felt, and trying to fashion a new piece of the proper thickness/length just wasn't working.

Instead, I found it pretty easy to machine the retainer to accept an automotive-style oil seal. A quick look through the Timken catalog found a seal with the proper dimensions. The 47X62X8 seal (also made by Precision Automotive) worked nicely. Timken p/n 710320 would also work. I simply machined the retainer plate to match the OD of this seal (62mm, or 2.440"), and lightly polished the journal on the spindle itself (journal diameter was 1.855" - seal ID was 1.850". Taking off a couple of thousandths via polishing was all that was required). Fortunately, I had another small lathe to do this work (who says Harbor Freight isn't good for anything?). I suppose you could also mill this out - I just didn't have the guts to try that

Now, finally - no more oil leak from the lathe spindle.

[julian wilson]

That's a nice fix.
I want to do something very similar, but I've only got the one machine so I have to make the part before I take the machine apart to fit it.

How did you pre-load the bearings when you put the spindle back in?

When I did mine, I did it by feel, but there must be a more professional way of doing it.
I think I need to make myself a new puller for the front bearing too- when I did it last time it was at the limit of my bearing puller and made the job a struggle.

[Tom488]

That's a nice fix.
I want to do something very similar, but I've only got the one machine so I have to make the part before I take the machine apart to fit it.

Well, like I said - you could use your mill, and cut a circle pocket with an end mill. I just didn't trust myself to perfectly center the piece in the mill. The nice part about lathes - concentricity is a lot easier to achieve.

How did you pre-load the bearings when you put the spindle back in?

30 ft. lbs. on the inner spindle nut. The spindle nuts take a 4-prong, 54mm spindle socket - which I couldn't find anywhere. However, a 2-1/8" spindle socket from the auto parts store works close enough - especially if you put a little tack weld with a MIG welder on each prong, then grind it to fit with a Dremel.

I think I need to make myself a new puller for the front bearing too- when I did it last time it was at the limit of my bearing puller and made the job a struggle.

I used an OTC 1130 bearing separator - 9" capacity, in my Harbor Freight 20 ton press, with the press blocks standing on edge to support the separator, and allow enough room for the spindle to drop free. To press the hearing back on, a 1-1/2" piece of PVC pipe (no kidding... plain ol' sch 40) JUST fits over the spindle, and matches up perfectly with the bearing's inner race. It could probably stand about .010" off of the ID of the pipe... I had to beat it off the spindle afterwards.

[smallblock]

Here's a modification I did on my machine. I found some double sealed angular contact ball bearings on E-Bay that had the proper ID and OD for the lathe and mill spindles. I just removed the tapered roller bearings and replaced them with the angular contact units. Voila- no more need for seals, oil etc. It's been a few years now and still running smooth. The only modification necessary was to machine some spacers for the lathe head casting and the quill, as the roller bearings are a little thinner in cross section that the tapered rollers.
I took a couple of pics- sorry, quality was not so good.