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Thread: Mini-Lathe Improvements, A WIP Thread

  1. #11
    Join Date
    Nov 2008
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    SF East Bay.
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    6,172

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    Just to add a data point.

    I just checked my 7x12 lathe. First, a metal straightedge was laid across the plinth and a nice new Mitutoyo caliper was use to check the distance to the tops of the both ways. They measured exactly the same over that 4 inch space. Conclusion; the plinth is parallel with the ways.

    Second, I checked the thickness of the bottom part of the compound slide since it sits on the cross-slide. This was measured to the left and right of the male dovetail. The side with the the gib was .002 taller than the other side. Again, using a straightedge to magnify error. I measured 4 inches out from the end of the compound and found both matched the previous discrepancy. Conclusion; the surfaces are parallel but not on the same plane.

    Conclusion; It appears to me that they did grind these two pieces as matched sets. Maybe they just assembled them and then ran them through a surface grinder so that the relevant surfaces were parallel and flat??

    Suggestion; I would not try to make them coplanar since that would require grinding the top of the plinth to match.

    Dan
    There is a profound difference between spare parts and extra parts.

  2. #12
    Join Date
    Jul 2017
    Location
    Springfield Mo
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    483

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    Quote Originally Posted by danlb View Post
    Just to add a data point.

    I just checked my 7x12 lathe. First, a metal straightedge was laid across the plinth and a nice new Mitutoyo caliper was use to check the distance to the tops of the both ways. They measured exactly the same over that 4 inch space. Conclusion; the plinth is parallel with the ways.

    Second, I checked the thickness of the bottom part of the compound slide since it sits on the cross-slide. This was measured to the left and right of the male dovetail. The side with the the gib was .002 taller than the other side. Again, using a straightedge to magnify error. I measured 4 inches out from the end of the compound and found both matched the previous discrepancy. Conclusion; the surfaces are parallel but not on the same plane.

    Conclusion; It appears to me that they did grind these two pieces as matched sets. Maybe they just assembled them and then ran them through a surface grinder so that the relevant surfaces were parallel and flat??

    Suggestion; I would not try to make them coplanar since that would require grinding the top of the plinth to match.

    Dan
    Works for me! Thanks for the data points mate, I might still go through and do the same measurements on mine just to be sure, but if the same story holds true for mine it'll be nice to avoid the extra work

  3. #13
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    Nov 2008
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    SF East Bay.
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    BTW,

    If you want to check to see if your lathe is abnormal, I have access to 3 similar lathes, a 1990s HF 7x10, a 2004 SIEG 7x12 and a 1996ish HF 9x20 which can be used to see if a feature is deliberate VS a flaw.

    Since they are from different eras and models there is a good chance that any feature/flaw that is in more than one will be there for a reason. It may be a bad reason, but that's harder to divine.

    Dan
    There is a profound difference between spare parts and extra parts.

  4. #14
    Join Date
    Mar 2015
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    2,592

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    This is a lot like taking a crap in a toilet, then adding gold leaf and paint to your crap in the toilet, to some how polish it up.
    It's one thing to put work into a lathe that was properly built from the factory, and entirely another when nothing was machined correctly and made true. Typical Sieg quality. Go try to measure the tail stock, you'll probably take a sledgehammer to it afterwords in disgust.

  5. #15
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    Dec 2004
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    Quote Originally Posted by RB211 View Post
    This is a lot like taking a crap in a toilet, then adding gold leaf and paint to your crap in the toilet, to some how polish it up.
    Too many visuals.... Just say "polishing a turd" next time..
    Work hard play hard

  6. #16
    Join Date
    Jul 2017
    Location
    Springfield Mo
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    483

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    Quote Originally Posted by RB211 View Post
    This is a lot like taking a crap in a toilet, then adding gold leaf and paint to your crap in the toilet, to some how polish it up.
    It's one thing to put work into a lathe that was properly built from the factory, and entirely another when nothing was machined correctly and made true. Typical Sieg quality. Go try to measure the tail stock, you'll probably take a sledgehammer to it afterwords in disgust.
    Curious them, what would you suggest? Yeah, might be lipstick on a pig, butyou know what's worse than a crappy lathe with a lot of work in in?

    No lathe at all

  7. #17
    Join Date
    Dec 2004
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    East Coast, USA
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    7,442

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    Quote Originally Posted by epicfail48 View Post
    Curious them, what would you suggest? Yeah, might be lipstick on a pig, butyou know what's worse than a crappy lathe with a lot of work in in?

    No lathe at all
    I think fixing or re-working equipment to perform better is a skill few people have and fewer are acquiring. I tend to rather spend money instead of fix/upgrade and I'll have nicer tools, but at the cost of being less of a machinist as I'm just exercising my wallet and not improving my machinist skills in the process. Time is probably the most scarce so that and interest level are usually the deciding factors for me.
    Work hard play hard

  8. #18
    Join Date
    Jan 2014
    Location
    Long Island, N.Y.
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    2,560

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    Quote Originally Posted by epicfail48 View Post
    Quote Originally Posted by RB211 View Post
    This is a lot like taking a crap in a toilet, then adding gold leaf and paint to your crap in the toilet, to some how polish it up.
    It's one thing to put work into a lathe that was properly built from the factory, and entirely another when nothing was machined correctly and made true. Typical Sieg quality. Go try to measure the tail stock, you'll probably take a sledgehammer to it afterwords in disgust.
    Curious them, what would you suggest? Yeah, might be lipstick on a pig, butyou know what's worse than a crappy lathe with a lot of work in in?

    No lathe at all
    Pay no attention to RB211, his self loathing sometimes makes him behave like an ass. He's just trying to make himself feel superior by putting
    down your goals and abilities. By improving the fit and function you gain a skill set and wind up with a machine that operates more smoothly.
    I personally feel your quest is worthwhile and will be following along. Most of the other replies seem to be guiding you towards success, focus
    on them and ignore the noise.

  9. #19
    Join Date
    Jan 2004
    Location
    Missouri
    Posts
    30,085

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    The nay sayer(s?) are not thinking.

    How much worse were the castings for a Monarch 10EE when they came in from "seasoning"? Right.... they looked like funny shaped pig iron at first, but when finished and assembled, they were a fine machine.

    You have a lathe kit, which was pre-machined for you. Start with that idea. "It's a "lathe shaped object" that needs tuned up to be a real lathe. You can do that, given a little work and basic equipment.

    For dovetails, grind one edge on the scraper down at a slope until the business end is thin enough for the end to go into the space, so the remaining edge can scrape all the way into the clearance groove.

    As for the video.... that was painful to watch. At least the guy could have bolted down his "lathe shaped object".... it jumped every time he took a cut.
    1601

    Keep eye on ball.
    Hashim Khan

  10. #20
    Join Date
    Dec 2017
    Location
    Bemidji, MN
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    121

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    I'd like to applaud you people for even tolerating a discussion about a mini lathe. When I got mine and was starting to learn a little about using it and modifying it to do more of what I wanted, I bookmarked a number of machining sites and would visit them regularly. One of those I discarded when the owner blacklisted a bunch of contributors, most of which were answering questions accurately but the owner though were demeaning the novices. Some of you were in that list. The second site I discarded has a rule that small lathes and mills are never discussed because they aren't used by a practical machinist. I have used my mini lathe for a practical purpose more than once. Then as time went on I noticed that many of the answers given were either wrong or condescending to the person asking so I removed that bookmark too.

    I've learned a ton since I bought my mini lathe and mini mill, thanks to people like you. I'm nowhere near competent but I enjoy learning and doing projects.

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