Unusual Spindle on Schaublin 120 TO (plain 120)
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  1. #1
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    Default Unusual Spindle on Schaublin 120 TO (plain 120)

    This lathe as the thread chasing arrangement where by the chaser moves the whole spindle in and out. Does anyone have an understanding of how this works? What are the bearings - a plain bearing that both lets the shaft slide and rotate, or roller element moving inside a cylinder? I kind of like this lathe and was thinking of getting it, but there is over a thou TIR on the outside of the sliding spindle so something doesn't seem right. I thought it might less with the spindle locked but couldn't figure out how to lock it!

    The other is how do you lock the spindle in position? The grey knob on the inboard side of the headstock sort of engages the spindle a bit like a rack/gear,. except it only does so in a few spots so that''s either not its function or its messed up. Even if it was suppose to engage a rack on the bearing, it doesn't suggest how to lock the spindle form moving along the the Z axis.

    Finally the carriage lock doesn't work, shouldn't be a huge deal to fix, but I could not get a reliable inside runout reading as I can't lock either the carriage or the spindle.

    Can anyone explain what is going on and the spindle mechanism works and locks? What do you guys think of this arrangement? brilliant or run away?

    Thanks for any insight!






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    It has a sliding spindle.

    Its for chasing threads.

    They were used a lot in optical works to chase fine pitch threads of a short length.

    You lock the spindle in place buy lowering the block so that the half-moon brass piece drops in place to lock the spindle in place for plane turning.

    You raise it up for the thread follower to engage the screw to chase threads.

    As far as the run out the spindle either needs adjustment or is badly worn.

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    Quote Originally Posted by Mcgyver View Post
    What do you guys think of this arrangement? brilliant or run away?
    Depends on how bored you be, and how much "spare time" you wish to dedicate to f**king with it.

    Mess with it long enough, you'll figure it out, reduce the slack and error, come to understand some prior entity sought to solve a problem, perhaps even see and appreciate a measure of elegance IN that solution.

    Or not..

    I'm just as happy to take it as stipulated that the world is full to the brim with solutions I haven't yet seen, and go do what I can with what I have.

    Or not!

    Damned "round tuits" are STILL on backorder!

    You got any spare stock of those? Doubt I have the energy to manage a whole bar, but even "drops" would be an improvement...

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    Quote Originally Posted by SIP6A View Post
    It has a sliding spindle.

    Its for chasing threads.

    They were used a lot in optical works to chase fine pitch threads of a short length.

    You lock the spindle in place buy lowering the block so that the half-moon brass piece drops in place to lock the spindle in place for plane turning.

    You raise it up for the thread follower to engage the screw to chase threads.

    As far as the run out the spindle either needs adjustment or is badly worn.
    thanks, I thought maybe that curved upper bar might be to lock it because I could see what else it did, but it didn't seem very 'schaublin like', i.e. not much of a thrust bearing. I should clarify to that its not just run out, but you can actually physically move the spindle a little more than a thou so something is wrong, but I don't know whats inside. It would seem more complex the just replacing a couple of rolling element bearings to fix wear/runout

    My enthusiasms waning, with runout its a project and unless the bearing's a commercially available item, another tricky one. Don't need another of those at the moment, but I am curious what the spindle bearing arrangement is

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    Quote Originally Posted by Mcgyver View Post
    thanks, I thought maybe that curved upper bar might be to lock it because I could see what else it did, but it didn't seem very 'schaublin like', i.e. not much of a thrust bearing. I should clarify to that its not just run out, but you can actually physically move the spindle a little more than a thou so something is wrong, but I don't know what's inside. It would seem more complex the just replacing a couple of rolling element bearings to fix wear/runout
    When you think about the direction of thrust that half circle part isn't a thrust bearing, its to keep the spindle from sliding out. While I'm not familiar with this model of Schaublin lathe I would find it hard to believe that there isn't a way to take up the slack in the spindle bearings.

    I believe Screwmachine on here has a headstock like this that fits a Schaublin 102 perhaps he will chime in with some information on these headstock bearings.

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    Quote Originally Posted by Mcgyver View Post
    curious what the spindle bearing arrangement is
    Even "sight unseen" I'd bet on some form of conical, even "finger" or split-collet style Bronze or Babbitt that could be adjusted by applying pressure at the ends for the sliding sleeve, whether bearings were integral, or separate. And if separate, whether also sleeve or rolling-element.

    The forces are trivial. The need for adjusting to near-as-dammit zero runout paramount.

    One example for those short threads in high-volume could include "filters" that screwed onto the front of a lens. Production volume was a high multiple of the costlier lenses themselves.

    A "Skylight 1A" as sacrificial armour for an expensive lens was bog-standard for most photographers, "film" era. "Used up" rather a lot of those, Leica, Mamiya Sekor, and Gundlach view cameras. Saved some right expensive lenses, though.

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    Quote Originally Posted by SIP6A View Post
    When you think about the direction of thrust that half circle part isn't a thrust bearing, its to keep the spindle from sliding out. .
    I guess I was figuring it was taking a thrust, just in the opposite direction; toward the tailstock. Being Schaublin no doubt is excellent for the optics work intended but if one was to use it as a general lathe it does not seem as a secure as either the two cone arrangement or rolling bearings such as AC's. Its gone now so moot, but with lots of play in the spindle and perhaps a bit of a specialty use headstock I'm not bothered. Still curious how that moving spindle works, what the bearing arrangement is.

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    Quote Originally Posted by Mcgyver View Post
    I guess I was figuring it was taking a thrust, just in the opposite direction; toward the tailstock. Being Schaublin no doubt is excellent for the optics work intended but if one was to use it as a general lathe it does not seem as a secure as either the two cone arrangement or rolling bearings such as AC's. Its gone now so moot, but with lots of play in the spindle and perhaps a bit of a specialty use headstock I'm not bothered. Still curious how that moving spindle works, what the bearing arrangement is.
    Now... life had enough puzzles before you started this and now it is GONE??


    Still.. why would it need to be all that different from a mill or drillpress quill where the bearings for rotation were inside the carrier for long-axis sliding traverse?

    I've run a lathe with sliding quill.. 11 inch diameter and no through-bore IIRC. A late 1800's Niles Tool Works six-foot horizontal "boring lathe". Not optics. 100-ton crane body. Mount ring for the turntable bearing. But we traversed the spindle quill, as with a hor-bore. The massive "bed table" had no traverse, only elevation.

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    Default I have it.

    Hi Mcgyver; It's not gone! I have it. This is my first post here. After finding some pictures of a lathe similar to mine, then realizing it is mine, there became a need for an update. From what I understand the bearing design is much like a watch lathe in that they are conical in nature with the slack being taken up when the u shaped bushing is engaged. However the run out will still be there when the threading operation is working. The bearings are supposed to be plain bushings. Though I havn't laid eyes on them. The cross side lock was a simple adjustment. Everything became evident as full disassembly was required to get the lathe across town.It was wired incorrectly as well.
    It's a really nice piece a equipment to use. It shines best when used with the w20 collets making small detailed parts. The lathe it replaces was an ancient Korean unit that made me feel I was on the verge of an industrial incident. The 120 will be used as a hobby lathe and I'm sure it will serve me well. Cheers; Glenn
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