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Thread: Lathe upgrade

  1. #1
    Join Date
    Nov 2007
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    Caboolture, QLD, Aust
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    Default Lathe upgrade

    So, I've got a fairly popular midi sized lathe which I find does just about everything I need at the moment and given the finances will have to continue doing this for a long time. It does have a flaw which causes some problems and that is there's quite a bit of sideways movement in the tailstock. For bowls and bigger spindles it can be accommodated but for smaller things it causes problems.

    This is the second one of these lathes I've had, the first was replaced under warranty with electrical problems and the first was also afflicted this way so I don't see returning it as a fix.

    The "tenon" under the tailstock which runs between the beds is not wide enough to hold it straight, and nor is it deep enough to have enough room to get shims fitting properly.

    I have access to a fairly well setup workshop and was thinking about cutting a steel plate to mount under the tailstock to fit better between the bedways.

    My question (yep, I've got a question) is what sort of fit is required to hold the tailstock straight yet allow easy movement? The bedway gap measures a constant 32.30mm. Assuming I can make a parallel block of steel (remains to be seen) how wide should it be? Or am I oversimplifying the possible solution?

    Thanks

    Sent from my SM-N975F using Tapatalk

    Cheers
    Redbeard

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  3. #2
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    Default

    How accurately machined are the inside edges of the bedway? That 32.3mm gap needs to be constant all the way along.

    If it is accurate then you could simply make up a steel plate of the correct width and temporarily bond it with CA to the existing tenon. Once satisfied that the tailstock is correctly centred then you drill and pin the plate so it is more permanently locked in place.
    Nothing succeeds like a budgie without a beak.

  4. #3
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    Default

    Chief, that's pretty much my exact plan, except I hadn't thought of temporarily gluing it.

    The bed gap seems pretty consistently spot on was far as I can measure with my digital verniers.

    Sent from my SM-N975F using Tapatalk

    Cheers
    Redbeard

  5. #4
    Join Date
    Oct 2008
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    Leopold, Victoria
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    Default

    If you were able to machine the width to 32.2mm it would certainly be adequate for aligning the tailstock on that particular lathe. If you can make it a neater fit it will be even better.
    How thick will the piece be that still contacts the bed? ie. how far is it from the bottom of the existing key to the bottom of the bed?
    Dallas

  6. #5
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    Default

    That's something I haven't considered at this stage. From top to underside of the beds is "probably" in the order of about 12mm. I'm thinking of grinding/milling the existing tenon flat to the same level as where the trail stock bears on the beds and then use something like a piece of 6mm plate as the replacement.

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    Cheers
    Redbeard

  7. #6
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    Might be best not to remove the exiting tenon as it will give you a good starting point for the alignment with the headstock. Providing the bottom of the tenon has been machined flat and not a rough casting that will also help with alignment. If leaving it there and adding 6mm to it doesn't protrude past the bottom to the bed rails it will work fine
    Dallas

  8. #7
    Join Date
    Feb 2006
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    Perth
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    Default

    Quote Originally Posted by Chief Tiff View Post
    How accurately machined are the inside edges of the bedway? That 32.3mm gap needs to be constant all the way along.

    If it is accurate then you could simply make up a steel plate of the correct width and temporarily bond it with CA to the existing tenon. Once satisfied that the tailstock is correctly centred then you drill and pin the plate so it is more permanently locked in place.
    I would use double sided tape to hold the steel plate in the approximate place and then drill two pilot holes through the plate into underside of the tail stock.
    Remove the plate and tape, and open up the holes in the plate to take an M6 socket screw.
    Machine/file the holes into short slots perpendicular to the lathe bed.
    Drill out and tap the holes in the underside of the tail stock to M6.
    Screw down the plate semi-firmly and place the tail stock onto the bed.
    It should now be possible, by tapping with a wooden or nylon mallet to move tailstock into place - then screw the M6 sockets tightly.
    Then pin the plate as CT says above.

  9. #8
    Join Date
    Nov 2007
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    Default

    Quote Originally Posted by Treecycle View Post
    Might be best not to remove the exiting tenon as it will give you a good starting point for the alignment with the headstock. Providing the bottom of the tenon has been machined flat and not a rough casting that will also help with alignment. If leaving it there and adding 6mm to it doesn't protrude past the bottom to the bed rails it will work fine
    Unfortunately the underside of the headstock tenon is a rough casting, I'm going to have to mill or grind that flat before I can start fitting pieces together but you're right, it will give me a good starting point to work from.

    Sent from my SM-N975F using Tapatalk

    Cheers
    Redbeard

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