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measuretwice

Boley Leinen WW-83 bearing replacement

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Wanting to do a bearing replacement on a nice Boley Leinen ww-83 I picked up recently, nicklesilver gave me the idea of using angular contact bearings instead of deep groove bearings.  AC's need a way of preloading them and need to be installed adjacent to one another or with precision spacers between them.  I splurged for the expensive p4's and while they are the right diameters, they're thicker than the OEM deep groove bearing so I had to make both spacers.  I bought universal matches AC's so if I ground the spacers exactly the same, it should be the right preload.  So far so good, but it did seem like the preload was almost a tad heavy.  The groove in the outer spacer is for a felt oil wick

Drive.  As nice as this lathe is, the drive was terrible.  Basically a universal motor with a great big rheostat, yuck.  I had a consew motor (variable speed servo) that I moved from below the bench to the back and connecting it to a jack shaft bolted to the bench.  I took the brushes out of the motor so its also just a jackshaft, er, flywheel.  I made a control box so I can switch between rheostat control of the motor and foot control - you want both for different ops.  Its actually a better arrangement as the Consew is mounted on an adjacent bench so zero vibration reaches the lathe.  I'm stuck with the hole in the bench....have to 3d print some tool tray thing and make it look intentional.  I've 1/2 a dozen watchmakers lathes, each one has something unique, so the idea is they're out of the way in a cupboard but can be placed in front of the jackshaft and set to running in seconds....keeps the bench less crowded and I only have to have one drive.

This one has the rare thread cutting attachment, which even has tumbler!   To use it though, I'll have to rig up a toggle reverse switch (the consew is a bit of a pita to reverse)
 I replaced the bearings in the motor and counter shafts as well, stripped and repainted and installed the new p4 spindle bearings.     Not shown is a full set of change gears, milling spindle and second 3 way slide rest.  I think I'm having too much fun :)

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big headstock.....little headstock

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Edited by measuretwice

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Why spacers have to be ground? Isn't there some type of steel available to make them strong enough and face turned?

That nostalgic-50's-kitchen-green make half the beauty. 

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The spacers are just regular steel easily machined.  They are ground not because they are hardened but rather that grinding is just a convenient way to get them the same length to a high level of accuracy.  As a general statement, grinding is a level up from turning and milling insofar as accuracy and finish go.  With a good grinder set up properly those parts should be the same length with less than a tenth (1/10,000", or a couple of microns) difference as was a have flat and parallel faced (again to a tenth) which is the sort of accuracy you're shooting with bearing spacers and not that easy to otherwise accomplish.   I've not heard tale of a spacers done for any other way for those reasons

Edited by measuretwice

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The spacers are then possibly more precise than the bearings. Have you measured the spindle runout compared to before?

I have the dial to measure on my humble one but not the correct base and arm yet. 

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14 hours ago, jdm said:

The spacers are then possibly more precise than the bearings. Have you measured the spindle runout compared to before?

I have the dial to measure on my humble one but not the correct base and arm yet. 

The bearings are very high precision, while specced as P4 as I understand SKF actually provides them at more like P2 class, and FAG (what I have)have their own designation "P4S"which is similar. The faces of the races are ground in a way that when the two sets of faces are the same distance apart there is a predetermined preload on the bearings. This is really important to get right, which is why these types of bearings generally come with it "built in". All you need is to get them equally spaced, very precisely.

I don't have a grinder suitable for the spacers, so I hand lapped the faces, checking them on a surface plate with a very sensitive dial test indicator. On my Leinen the measured runout at the collet taper, outside of the spingle nose, and spindle nose face were all for all practical purposes zero. Checked with an Interapid 0.002mm indicator and Compac 0.002mm indicator, there was no needle movement. There is of course some runout, but if those indicators won't show it for watchmaking purposes they are "perfect". That was true with the original bearings and new.

I really like ball bearing headstocks but still have a soft spot for plain bearings. In theory they can be made to be even more precise than ball bearings. But if searching for microns in work, with a well adjusted plain bearing setup, one would need to run the machine for some length of time to get everything up to temperature and have the right oil in for the right speed to the oil film works right and and and. It doesn't always really matter, but ball bearings sure are easier. And- you don't get an oil stripe down your face and shirt after making a stem!

BTW that paint job came out great!

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