South Bend 9A headstock shim problem
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  1. #1
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    Default South Bend 9A headstock shim problem

    Refurbishing a 9A, a UMD with bronze bearings in the headstock. The shims I found in the slots were not original and undersized. The spindle, inserted alone and with the shims and pinch bolts removed, is hard to turn - it does not spin freely. Expanders tight or loose makes no difference. I have been able to get a .054 shim stack in, with great difficulty, but no more and the spindle still won't spin - no change, too tight. I am afraid of any more prying on the casting to insert more shims. The bearing and spindle surfaces seem fine. Advice?

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    These are available for a 10l. There may be shims available for your 9A on ebay.
    These could be made only for the cast iron bearing. There was a member making shim packs. You may be able to cut the shims in the link below to fit. Other members will direct you better.
    SOUTH BEND CAST IRON BEARING UNDER MOUNT HEAVY 10L LAMINATED BRASS SHIMS | eBay

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    Are your expanders in correctly? I believe they are slightly tapered and only fit properly one way.

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    Quote Originally Posted by hsracer201 View Post
    Are your expanders in correctly? I believe they are slightly tapered and only fit properly one way.
    Thanks for your reply. Yes they are tapered and only go in one way. I now have a .056 shim stack left and right. Leaving the pinch bolts loose and doing them up good and snug makes no difference - either way the spindle will turn smoothly, but not freely - it still seems way too tight. Expanders then pulled up snug makes no difference either. Testing deflection on the spindle appears to show some play, but less than .001 (my indicator isn't as sensitive as would like). I have tried putting the spindle only in the small bearing (left end) to see if it seems any different - and it's the same. I'll give the spindle surfaces some Prussian Blue today to see if that tells me anything.
    Incidentally, I managed to remove and replace the shim stacks with the help of a 6" length of 3/8" brass rod placed in the pinch bolt hole as a lever, and leaned on. It pried up the bearing cap enough, and I don't think that much rod gives enough of a mechanical advantage to threaten the casting. A 'trick' with it seems to be to lift the rod up a little bit above the level of the shims before pushing on it.
    Last edited by ZeroGravid; 07-13-2019 at 07:17 PM.

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    Quote Originally Posted by ZeroGravid View Post
    either way the spindle will turn smoothly, but not freely - it still seems way too tight.
    If it turns smoothly by hand, it just might be correct. Spindles don't spin freely like skateboard wheels. I'd make sure you have your bearing surfaces lubricated, and make sure the spring loaded felt wicks aren't getting bound up during spindle installation. If everything seems okay I'd tighten everything up, check for spindle movement (order a more sensitive indicator) and run for a bit and check for heat.

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    Many thanks, that advice gives me some comfort. I did 'blueprint' the spindle and found a bit of a high spot on the lower front edge of the rear bearing (like someone had hammered on it)and I gave that a little scraping which helped some. But the big change I got was when I really tightened the screws in the bearing expanders. "Snug" was not adequate, apparently, and getting a screwdriver squarely into the slot-head screws was a non-starter that generally limited what I could do. I suppose that is why SB went to socket-head screws on later models. I got a proper-fitting hollow-ground bit in a small ratchet driver, and got a good torque on the screws with thumb and forefinger - like I'd use/flex an Allen key. Spindle now moves smoothly with much less effort. I'll do as you suggest.

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    OK, this sound like oil got between the bearing shells and the casting...the bearing should be installed dry in the bores,I suspect you are having to torque the expanders to squeeze the oil out.

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    Quote Originally Posted by mllud22 View Post
    These are available for a 10l. There may be shims available for your 9A on ebay.
    These could be made only for the cast iron bearing. There was a member making shim packs. You may be able to cut the shims in the link below to fit. Other members will direct you better.
    SOUTH BEND CAST IRON BEARING UNDER MOUNT HEAVY 10L LAMINATED BRASS SHIMS | eBay
    I ordered the shims - available for the 9A umd from the same source you list. I've been cutting my own shims mostly to get a feel for where my problem likes while I wait for the real deal to arrive. Thanks.

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    Quote Originally Posted by iwananew10K View Post
    OK, this sound like oil got between the bearing shells and the casting...the bearing should be installed dry in the bores,I suspect you are having to torque the expanders to squeeze the oil out.
    Is there anything to be said for removing and cleaning them ... or leave well enough alone now?

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    no harm, no foul.. if it works all good, if not then check it out.

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    more headstock shims:
    I am working through "A Guide to Renovating the South Bend Lathe" by Ilion Industrial Srevices, and I see on page 71 "if you are removing the headstock from the bed ... Sometimes there are thin shims between the headstock and the bed so note their position and save for later ...". On mine, sure enough, there are two shims between the headstock and the bed, left and right on the front surface of the rear v-way. The shims are .010 thick, so they lift/rotate the headstock over the ways by that much. Why would anyone do that? I found a very long thread on shimming the headstock in a "homeshopmachinist.net" bbs, talking about "shimming a few tenths", but the variety of opinion doesn't really help. Advice appreciated. Should I leave them, or remove them and try to figure out later why they were there?

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    I do not think they would do that at the factory.
    I have seen it before, usually from a questionable rebuild where they just "cleaned up" the ways and did not maintain the geometry.
    Also possible headstock swap.

    Blue and check contact to see if you need them.

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    Quote Originally Posted by iwananew10K View Post
    I do not think they would do that at the factory.
    I have seen it before, usually from a questionable rebuild where they just "cleaned up" the ways and did not maintain the geometry.
    Also possible headstock swap.

    Blue and check contact to see if you need them.
    Blue what? Contact with the ways? I don't think that there would have been a rebuild as the ways are not seriously worn, with original scraping still visible for much of the length and no perceptible change moving the saddle around. It was a high school machine retired/bought directly from the school - a headstock/parts swap is a possibility ...? The serial number on the bed is C54920NAR, which would indicate horizontal drive, but it is a UMD on a SB metal cabinet ... number on the gearbox CL344AD. Also, the shims have been in there for a very long time if that can be deduced from the staining shadow around them

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    yes, contact with the ways where the head sits...they don't have 100% contact but should be touching some everywhere it mates...each end of the flats and each end and both sides of the v's...

    Your serial number confuses me with the c prefix.

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    Quote Originally Posted by iwananew10K View Post
    yes, contact with the ways where the head sits...they don't have 100% contact but should be touching some everywhere it mates...each end of the flats and each end and both sides of the v's...

    Your serial number confuses me with the c prefix.
    may have something to do with the thousands provided to Canadian high schools in the late 50s and ear'y 60s
    I discover today that this machine has a Canadian GRYPHON 3-phase motor (but made in England, of course) fooey
    Last edited by ZeroGravid; 07-16-2019 at 06:51 PM.


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