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  1. #21
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    Quote Originally Posted by 220swift View Post
    Thermite

    Why is it that you have to start trouble with Donie?
    I do not. Lie harder.
    I like to hear what Donie has to say.
    Why? it is the same filthy language most days? Where'd you pick up a fetish for filth?
    He has years of experience from running his own shop and working on his 10EE's.

    Hal
    Oh really?

    Who told you that?

    A string of failures makes an expert?

    "Expert"... at WHICH failure?

    Building atom bomb cores?

    Ask him WHO SAID he was a "professional machinist"?
    At what level, where, for how long, and why did he leave?

    Running "Big Twinn Motor and Electric"?
    What happened to it, then? That's in the record, BTW.

    How about the mythical hydraulic shop that makes him so rich?

    That's a RECENT invention, BTW. Check the archives. Came up long after the "Bad Ass" "Biker Dude" myth was debunked.

    Ask him about the SILVER project!

    Ask him about his pro photography

    Ask him about monkeys and masons.

    Ask him how it is he can say his Mother died of COVID when there has been no such obit?

    Better yet? Ring his Mum and ask HER what sort of Son with a sick attention hunger she has? Number is published. So is her email, even her career.

    Does "donie" forget the real world still exists and the internet works BOTH directions?

    Could was? Which year is it again?
    Recycling "drama" can get confusing?

    And why are you STILL (hardly your first go at it..) pretending to be so dense as to think anyone is left on-planet that is NOT aware that..

    .. HE is the initiator!

    .. not just with ME,

    .. not just with the site founder OF PM

    .. not just with several Moderators

    .. not just on PM, not hardly!

    .. and not just in the last many years, either?

    Go to his profile. Look at the locked threads. Dig deeper. Keep in mind the Moderators have already SANITIZED the worst of the insane filth!

    It's what he does. Everywhere. Everywhen. Many websites and forums.

    Off-line records kept by more than one agency. more than one continent.

    PM moderators clean out his worst filth? Too late. It is already preserved.

    In the record.

    "Big Bang " to .. probably several more years into the future?
    I'm impartial. May he live long and suffer chronic exposure to himself. And "oh, by the way?" with the most childish of invective, the most hyperbolic of lies?

    Seems to WANT to be the center of digust more than approval? Pretty pictures - some decades OLD already - and used a hundred times as "bait"? Any current newspapers in those many, many photos?

    Then, audience assembled, click on the emcee's mic, start the head games.. all over again?

    He THINKS he is whom? Weird-Adolf Hitler? Lionel Shriver's "Kevin"? Ming the Merciless? Nils Bjurman?

    ANY character BUT himself?

    Can't help it. Not new. Unfortunate genetic dice-roll.

    See "wound collector".

    ....all for love of attention?

    From you?

    So GIVE it!

    His address and such are easily found online. No "for fee" detective service needed. He PUBLISHED the starting point HIMSELF!

    "Drama queen" left a trail as bait so as to claim persecution and death threats for sympathic attention!

    So GIVE it!

    Go move in with him!

    You could enjoy all that machinery and expertise close-up! And LEARN STUFF!

    400 odd square foot home?

    Plenty of space for all those machines he has owned by the dozens .. plus space to keyboard.

    Well? Maybe ONLY the space to keyboard?

    Go for it! Still more of a free country than not.

    Might be AMAZED what you can learn!

    Might not have a damned thing to do with machine-tools, though?

    Last edited by thermite; 04-12-2021 at 12:14 AM.

  2. #22
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    Quote Originally Posted by Hothead View Post
    I have a Vextrax Lathe. it's a good machine. Has all the bells and whistles. The lathe is
    extremely accurate . I have a 6 jaw adjust tru, Bison chuck on it. I would like to grind
    the jaws on this chuck. Reason is with a ground shaft , after indicating in , has about .004
    -.005 run out at 12 " . I did all the instalation of the chuck corectly, took cut on backplate before installing chuck.
    ...................
    Grinding is the wrong answer for ordinary runout. Scroll chucks tend to have runout, and 4 or 5 thou is not out of the question.

    Grinding is an "OK" answer for bell-mouthed jaws, or maybe for jaws that hold the stock pointed off-axis.

    So, if the chuck lets stock slop around, or if it is significantly "out" at the end of a short piece, but Ok at the end of the jaws, then maybe.

    What happens out 12" from a chuck is not generally of interest because as has been said, you have no business letting that much hang out anyhow.

    Do something differently if your setup calls for that. Steady rest, between centers, anything other than a huge "stickout".

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  4. #23
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    Quote Originally Posted by JST View Post
    Grinding is the wrong answer for ordinary runout. Scroll chucks tend to have runout, and 4 or 5 thou is not out of the question.

    Grinding is an "OK" answer for bell-mouthed jaws, or maybe for jaws that hold the stock pointed off-axis.

    So, if the chuck lets stock slop around, or if it is significantly "out" at the end of a short piece, but Ok at the end of the jaws, then maybe.

    What happens out 12" from a chuck is not generally of interest because as has been said, you have no business letting that much hang out anyhow.

    Do something differently if your setup calls for that. Steady rest, between centers, anything other than a huge "stickout".
    To be fair.. pretty sure he meant that bar as a test indicator ONLY, had no plans to run cuts out on it?

    "PM" general quasi-consensus stands that a mass-market, medium-priced chuck - 6-jaw even more than 3 - is not likely to have jaw guidance, jaw fit, nor final touches to do any better than what is actually a right-decent figure at that length away from the jaws.

    Schunk and brand-new I WOULD expect better. Even so, one certainly does NOT do typical single-point work unsupported out there!

    Last two times I've seen it, one in aluminium, one in stainless, the work bent off the cutting tool digging-in, then REALLY "got BENT" as it climbed over TOP of the tool-holder, laid itself sorta exaggerated-banana-shape across the top of the compound, operator in panic mode getting powered OFF!

    FORTUNATELY.. with the work now sort of "Ell" shaped, leverage according, both times it spun in the jaws of the chuck. So not a lot of force involved and no dmae to the lathe atall.

    Don't recall the shiney-wood diameter. That one was another guy.

    The stainless was half-inch. And I had learnt a valuable lesson for a cocky youngster as thought if he was but careful enough, he could beat the odds. And failed to do.

    If you cannot be perfect - and who can be? Make your mistakes early, fast, and often ... so as to learn better, more firmly, more widely, wisely, and sooner!

    Helps to SURVIVE them, of course! And not repeat!

    DAMHIKT!

  5. #24
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    Quote Originally Posted by thermite View Post
    To be fair.. pretty sure he meant that bar as a test indicator ONLY, had no plans to run cuts out on it?

    ...........
    Sure and he did.

    But if, as it could be (in a perfect world!), the runout near the jaws is 1/12 of that, or about 4 tenths, almost anyone would think that was fine for a chuck.

    A few thou out at 12" is not that surprising even for "a ground shaft". You might have that much chucking error, jaw error, or bend in the "ground shaft", etc. (that would be an error of 0.02 degrees). And how serious is that really, when there are other ways to hold the parts?

    All things to be considered and eliminated before getting out the abrasives to "fix it".

  6. #25
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    A simple test would be to indicate the chuck Od and face to see if that matches (somewhat) the part error.
    an error like that might be the trueness of the back plate

    A 6" chuck face running .006 out would make .012 at 12" out. Yes, just a rough test. inspecting the jaws for nicks/bugs.

    blue-up a part and see how it contacts the jaws, or look at jaw markings.

    Quote somebody: [you have no business letting that much hang out anyhow.] very good point...

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    It seems that many are shy to go to between centers.'
    I used to just bump a straight part with my tool bit and have near-perfect straight in less than a couple of minutes, with not even using an indicator. Just using the dial numbers...and then to move the tail half the difference.
    you don't even have to take a cut to get .001 or .0005

    That is so easy, and the same with using an indicator...Every (want to be) lathe guy should master this task.

    A good condition lathe and the tail often does not need to be changed.

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    BEFORE YOU GRIND ANYTHING, a proper survey should be done to determine if the spindle/headstock is properly aligned with the bed. this is usually done with a test bar matching the spindle taper, and the taper of course must be inspected carefully for damage or wear first.
    the spindle face, external taper, internal taper must be checked for concentricity and runout at operating temp and with loading/noload, etc, etc ....

    you simply can't assume that it is aligned, it could have had a bad crash that tweeked it, been damaged in a move, or even been bad from the factory, yes, it happens.

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  10. #28
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    If its a one time thing just tighten the gib. If youre deadset to not tighten the gib, just use a C clamp

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  12. #29
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    .004 to .005 12 inches out seems a small amount.
    You might make a few test tries with turning the test bar 180* to see the error is constant to the same relation to the chuck.
    You might even try tightening different T-wrench screws to see to the error is constant.
    Check to see the backplate is as true as it might be.
    To grind the chuck it has to be clean and the jaws loaded/having outward pressure.
    The infeed has to small perhaps .0005 or .0002
    It is not uncommon to lock the cross and use the compound for in feed with the compound angle at 20* or 30* long ways to be able to control a very fine in-feed. At 20* compound long-ways each .001 on the dial is only a couple tenths.

    Good to in-feed inside the chuck and make a few spark-out passes before the next infeed, A spray bottle of pink liquid soap with water a good coolant. Od dress the wheel so it runs smooth.

    For dead true far out turning I have tickled a mild center in the headstock with the part close end on the hesadstock center, the out end in a steady, a dog turning the part, and a stack of rubber bands holding the part head end tight to the center.

    A live center at the tail can some times pull a few thousandths back to center at the out end.

    Chucks and even colletes are rarley perfect.

  13. #30
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    Here is one method of loading jaws:
    Chuck Jaw Truing Fixture

    Some chucks have an internal step.
    Some guys use jaw screws with making a ring washer.
    One could even make jaw clamps and stack rubber bands.

  14. #31
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    Here a good trick perhaps for a production part and using a .015 run out chuck-> getting the part to run .001 TIR (.0005 a side)

    Get your parts to run true in a non adjustable chuck. YOU MUST WATCH THIS! - YouTube

    This is good even with using a 4 jaw because a 4jaw may have wobble.

  15. #32
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    If you turn your test bar and check a few times and get different readings then griding of the jaws may not do any good.
    Figure there is .002 or so clearance around the scroll and .001 or .002 sideways...that you can't do much about.
    Getting .001 or .002 on a 2' or 4" out test is not bad for a scroll chick.

  16. #33
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    Sometimes When I'm in a hurry to bore a hole in a short part true to the axis I find a chunk of aluminum round bar that is just oversized, chuck it and drill/bore it to just slip the part in, then tighten the chuck which will normally clamp the part without throwing it off center.
    Years ago I used to slip shimstock between the "outer" jaw and the part, but that means the other two jaws have to move out some tiny amount and that makes it hard to figure, if you've calculated the exact amount of runout at a certain diameter chucking that will change after installing the shim obviously.
    On a four jaw independent however runout at a distance from the front of the chuck can use that method in my limited experience.

    A proper test bar would have the headstock's ID taper on the end so it would show if the lathe's spindle had somehow gotten bent.

  17. #34
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    These 6 jaw chucks can get used hard, and because they are weaker then a 3 jaw, they need to be replaced more frequently, or serviced by re grinding the jaws.
    Another observation from my deranged , but focused on successful machine operations mind,,,
    the 6 jaw chuck has a lot of flex! So, if you chuck a long piece, and it runs true near the jaws, the end will sag!
    With the jaws not absolutely tight, but pretty tight, you should be able to push the bar true at the outer end.
    If you cant push the bar true, then the jaws, or the chuck mounting is the problem.
    I have a few photos of a 6" Buck that may help.

    This really needs to be pointed out out regarding 6 jaw chucks, the front half is largely cut away for 3 extra jaws!
    In fact the 6 jaw chuck is a great study in "you cant gain in one area, without losing in another" but, knowing the weakness allows intelligent compromise, to make this tool function better.

    This chuck was pulled from scrap and re tightened up successfully, with a few simple operations, and the jaws re ground.
    I took these photos when I was last cleaning the chuck, I use it for dusting out bronze bushings, and it gets fouled from that.
    The chuck is an older Buck 6" made of cast semi steel instead of forged, I use this on a Monarch ee, but not over 2500rmps, because the weaker body allows enough stretch that it will release a part at high speed!
    I tend to look at the 6 jaw as a compromise for collets. That is, with my twisted and warped mind, of course..
    Last edited by donie; 04-25-2021 at 03:44 PM.

  18. #35
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    Quote Originally Posted by partsproduction View Post
    A proper test bar would have the headstock's ID taper on the end so it would show if the lathe's spindle had somehow gotten bent.
    Spindles hardly EVER get bent.

    Spindle tapers hardly EVER fail to pick up a ding or two that raises even at least a TINY burr..

    soo.. getting the spindle taper stoned.... a PITA because they are not exactly a "spacious" place to work in, is crucial to bluing-up and mounting a good taper-mount test bar.

    THEN ... one can ascertain if the HS is even accurately aligned with the bed! Check the bearings, "sweep" a TS for mis-alignment (it WILL exist!) "etc".

    But few actually doo this. Time consuming. Expensive for a GOOD bar and really good metrology.

    And what can most folk actually DO about it even if a fault is confirmed?
    Nothing fast nor cheap, trust that much anyway!

    Gunsmiths are "usually" too much into "git 'er DONE" practical to be overly fussed about "perfect" lathes in any case.

    No need. MOST of the other stuff they do is far more about "understanding what actually matters", then applying personal skills to make the good-stuff happen, the bad-stuff, NOT..... than ever it was about perfection in the machine-tools.

    Understand the limitations of whatever it is you have. Sharpen-up your ways to compensate, then:

    "Run what you got!"

  19. #36
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    the termite is active today! and why is this clown allowed to post such crap about me me!
    I now have to put current news papers in my photos?


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