Mod A spindle clearance

Any tips on adjusting the spindle clearance?The splits on the bearing housings on my machine appear to be filled with babbit. Was this standard practice? Can I use shim stock or do I need to get correct clearance then rebabbit

Hi There,

In the slot under the "pinch" bolt, there should be shims. There will be an aluminum base shim and a laminated set of shims. The laminated shims are soft soldered together and probably are the shims you're thinking are babbit. The laminations are .002" thick. I need to use a pen knife to start peeling a layer off. Be careful, it is hard to just peel the top layer.

Before adjusting the bearings, it would be a good idea to get some .001" shim stock. This allows you to "fine tune" the adjustment. For example, your spindle may be just a little too loose; you peel a layer off and you check again. Now your spindle is too tight! Measure the thickness of the shim you peeled off and insert a shim .001" thinner (e.g. peel off .002" laminate, insert a .001" replacement). In the above example, this should get you within specs.

The aluminum base shims were used as a means for additional adjustment after the bearings had worn down enough that all the laminated shims had been removed. Then the aluminum base shim would be discarded and a new set of laminated shims inserted in its place and adjusted. This would extend the life of the spindle bearings and, in the case of integral cast iron spindle bearings, extend the life of the lathe.

I hope this helps. Good Luck!
-Blue Chips-
Webb

Because of the solder holding the layers
together, the sides of the peelable shim stacks
in the 9" SB machines do kinda look like babbit
metal.

There may already be a 0.001 shim in there
with the peel stack. They did come that way,
but sometimes the one shim gets thrown away
over the years.

Jim

Got the shims out and just as described there was the aluminum shim and the laminated shim,Looks like I should not have to many problems getting things put back together,Thanks for the advice I really appreciate the help


John

Are you aware of the standard procedure
for setting the bearing clearance on those
machines?

Jim

No I am not

OK, it's pretty straightforward.

1) remove all tooling from the spindle, be
sure the thrust bearing is not too tight (you
could slack it off a bit for testing the
clearances to be sure).

2) mount a sensitive (tenths reading) dial
gage to the headstock so it is pointing down
onto the register diameter as it emerges from
the headstock casting.

3) stick a broomstick, etc, into the
spindle hole, and pull upwards with about
75 lbs of force, and while doing so zero
out the indicator.

4) push downwards on the stick with the same
force, and read the TIR on the dial. That is
the bearing clearance.

The force on the spindle is to overcome the oil
film to get an accurate reading.

The total clearance should be more than about
0.0005 inch, and less than 0.0015 inch, more
or less. I think around 0.0007 is ideal from
the manual. A bit less than a thou.

Add/subtract shims from the stack to achieve
the numbers. Do both front and back bearings.

Jim

see if this will link...

http://f4.grp.yahoofs.com/v1/EO_rQf4Qmv-mBc7jbLotfsgvf-y3aqx2Wes3_REwXzZ229NHlECGtYKkUmZVM3TIQ3cFdp2t6Pv6QoKhRGEua87H6Sfj0g/Techinfo/Bearing_Adjustment/SBL_10H_Spindle4.jpg

this is the test for SB heavy 10" and larger. As Jim describes. The old link to the 9" and 10K has gone missing. It is similar. I can't remember if the force or clearances was less or not, but the above will get you a good running lathe well within the ballpark.

PS, looks like the link works. To read it, you may have to right click on the lower right corner of the page. then when the rollerball/expansion icon comes on, click on it and the page will blow up to readable size

smt

Excellent! thanks for the info I should be able to get to work on this in a day or two.I will let you know how I make out.


John