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Thread: Mini-Lathe Improvements, A WIP Thread

  1. #101
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    get the alignment right with the headstock's own weight on the bed.

    then epoxy it on, then tighten the bolts a little bit.

  2. #102
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    You might want to find the end of that crack, and drill a hole through there, to stop it from progressing.

    Another idea would be to instead, drill a cross-hole from the side, and put in a screw to hold the pieces together. That will probably stabilize it as well as prevent iit extending.
    1601

    Keep eye on ball.
    Hashim Khan

  3. #103
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    Quote Originally Posted by johansen View Post
    get the alignment right with the headstock's own weight on the bed.

    then epoxy it on, then tighten the bolts a little bit.
    Think that'd just leave me where I am now, the epoxy wouldn't stop the crack from opening up when any force is applied, and I'm 90% certain that includes cutting forces. Explains my rigidity issues
    Quote Originally Posted by J Tiers View Post
    You might want to find the end of that crack, and drill a hole through there, to stop it from progressing.

    Another idea would be to instead, drill a cross-hole from the side, and put in a screw to hold the pieces together. That will probably stabilize it as well as prevent iit extending.
    I actually considered this, problem is there's nowhere to put a screw. There's next to nothing in the casting in that area, with the exception of the bolt hole, and if I put a screw there I couldn't also bolt the headstock down. I considered brazing and welding, struck both those off as more likely to cause other problems. Just going to have to bite the bullet and replace it

  4. #104
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    Quote Originally Posted by epicfail48 View Post
    Explains my rigidity issuesit
    maybe, partially. A lathe should have all components of the pancake stack with adequate bearing over their surfaces. Low cost lathes don't usually have that unless you scrape them

    You made a comment about getting a grinder....how big a grinder and how long is the lathe bed? The correct procedure even if you grind the bed is to scrape the headstock, carriage and tailstock into the bed so it both fits the new grind and for alignment.
    .

  5. #105
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    The headstock appears possible to repair but may be impractical so you would have nothing to loose by trying a bit of a bodge.

    First of all ensure that everything is perfectly clean where it meets the prism and determine where the pressure is that opens the crack then gently scrape or grind that area until the crack no longer opens under pressure. Apply epoxy and position the headstock as accurately as possible. Tighten the bolts when the epoxy is cured.

  6. #106
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    Quote Originally Posted by Mcgyver View Post
    maybe, partially. A lathe should have all components of the pancake stack with adequate bearing over their surfaces. Low cost lathes don't usually have that unless you scrape them

    You made a comment about getting a grinder....how big a grinder and how long is the lathe bed? The correct procedure even if you grind the bed is to scrape the headstock, carriage and tailstock into the bed so it both fits the new grind and for alignment.
    6x12 Grizzly, assuming i can find one. Nothing fancy, just something to learn on. Touching the bed itself was never part of the plan for this project, maybe scraping the headstock, tailstock and carriage to the bed but not the bed itself. Funnily enough thats the one movement axis i havent had trouble with, minus those blasted gibs. Tapered saddle gibs might make the project list...

    My biggest concern for this project is the dovetail ways, its more self-training than it is making a perfect tool anyway. Least thats what im telling myself to justify cutting a few of the weirder corners.

    Quote Originally Posted by The Artful Bodger View Post
    The headstock appears possible to repair but may be impractical so you would have nothing to loose by trying a bit of a bodge.

    First of all ensure that everything is perfectly clean where it meets the prism and determine where the pressure is that opens the crack then gently scrape or grind that area until the crack no longer opens under pressure. Apply epoxy and position the headstock as accurately as possible. Tighten the bolts when the epoxy is cured.
    I might try that, but i have very low hopes for any repair actually working. Crack pretty deep already, maybe 3/16-1/4", right at the relieve groove corner, and it heads straight up the line of the bolt hole. Add that to the prisms shape naturally trying to wedge things apart and i dont imagine anything short of a weld would hold, and that sounds like more worth than the headstocks worth. Its working for now at least, so its low on the list of shop priorities.

    Appreciate the advise everybody!

  7. #107
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    Quote Originally Posted by epicfail48 View Post
    Think that'd just leave me where I am now, the epoxy wouldn't stop the crack from opening up when any force is applied, and I'm 90% certain that includes cutting forces. Explains my rigidity issues
    you don't just epoxy the sides of the V, you put enough in there to fill up the whole cavity.

  8. #108
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    or you just spend the 20 bucks for a new casting...

  9. #109
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    If you can get a new casting, go for it.

    I was thinking that a screw in from the side would go into the thickness of material in the wall of the headstock that has the spindle bearing in it. If the hold down bolt interferes, well that could be a problem. And if you can get a new casting that is machined, maybe you can just transfer the stuff over to it. Or get another headstock complete. There must be folks parting these things.
    1601

    Keep eye on ball.
    Hashim Khan

  10. #110
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    Quote Originally Posted by J Tiers View Post
    If you can get a new casting, go for it.

    I was thinking that a screw in from the side would go into the thickness of material in the wall of the headstock that has the spindle bearing in it. If the hold down bolt interferes, well that could be a problem. And if you can get a new casting that is machined, maybe you can just transfer the stuff over to it. Or get another headstock complete. There must be folks parting these things.
    Little Machine Shop actually sells both options for replacement. I can either get a bare casting for $50 and transfer all the old parts to the new casting, pay $150 for a complete headstock with all the bits n pieces pre-installed, or pay $50 for the casting, plus order the 'upgrade' parts, namely angular contact bearings, metal speed gears and a spindle with a 4 inch flange. Im leaning towards the last option, given its all stuff id wanted to do anyway. Make hay while the sun shines and all that

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