Myford ML7 mainshaft

[HopperParticipant @hopper]

Posted by Ben French on 13/01/2021 02:09:53:

Hi All,

Similar problem here, my ML7 has too much spindle play up and down, I've run out of shims to remove. I could buy a new spindle and bearing set from Myford for 300 quid which apparently also requires bearing-scraping to work well. I was thinking alternatively, seeing as there's plenty of thickness left in the bearing shells and both they and the spindle are in good condition, could i just skim of a very small depth from the mating surface on the top bearing shell where it meets the bottom bearing shell, so that it once again properly grips the spindle? I guess the bearing cap mating surface might also need the same amount removed. This could be done easily on my milling machine.

It might also be possible to place a very thin shim between the the upper shell and cap, so long as it has an oil passage…..

thanks

The traditional method is to do as you first suggest, machine (or file) a suitable amount off the flat mating surface of the bearing cap and bearing together  so they can come down further. Ideally machine enough off so another full stack of factory shims can be inserted (only about 20 or 30 thou I think from memory) so you have a full range of adjustment again as you peel off the 2 thou shim layers. Ideally you might need to do a little light scraping of the bearings too to get full contact. The bearing white metal is plenty thick enough to do this. Well over 100 thou thick from memory.

I would not try putting shim between the top of the bearing shell and the bearing cap. It will make the bearing a loose fit sideways, ie toward the mating faces of the bearing cap and thus allow movement of the spindle anyway. When fitting similar type bearings and even bushings to heavy machinery at work we used to scrape the outside of the bearing to a good all-over contact fit into the bearing housing before even starting to scrape the inner diameter to match the shaft. It is just as important if you want a top notch job done.

Edited By Hopper on 13/01/2021 11:33:44

[Ben FrenchParticipant @benfrench46909]

Thanks Hooper! I'll give this a crack. I was thinking of upgrading to the hardened spindle and PB bearings still available from myford some time down the track. I guess this would be still possible having machined down the bearing caps (and the old white bearings) by simply adding shims to the amount i had machined off, plus that standard shims that would go in with a new bearing set anyway? I'm told that going for the new bearing shell and spindle option also requires scraping. Thanks again for the advice

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