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Thread: How to set an angle on lathe compound?

  1. #11
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    make one of the sine bar holders Weird just posted about. Or take a cut, adjust measure repeat., trial and error.... but check it with a sine bar and indicator, not a sprung collet. when doing trial and error, don't fully loosen the lock, and tap in the adjustments, put a piece AL on the side and tap the AL gently. this way you can make very small adjustments to it
    Last edited by Mcgyver; 08-17-2019 at 04:54 PM.
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  2. #12
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    Sine bar?

  3. #13
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    Quote Originally Posted by RB211 View Post
    Sine bar?
    How else do you check a taper if you don't have a solid one to to indicate to? Its not clear to me what it is you're asking.
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  4. #14
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    Quote Originally Posted by Mcgyver View Post
    How else do you check a taper if you don't have a solid one to to indicate to? Its not clear to me what it is you're asking.
    I am suggesting the use of a sine bar, not questioning it. Sorry I wasn't more clear.
    I didn't see your post.
    Last edited by RB211; 08-17-2019 at 05:06 PM.

  5. #15
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    ah i see, i thought you were referring to my post about using sine bar lol.
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  6. #16
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    Quote Originally Posted by Mcgyver View Post
    ah i see, i thought you were referring to my post about using sine bar lol.
    I thought he was too. Lol.

  7. #17
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    Looking at the pictures, I assume you wish to match the taper on the collet
    There is a 100 ways to skin a cat. I ground my tool-slide sides to be parallel to the tool-slide ways and use a protractor against the tailstock ram or the face of a chuck, but here is another method.
    First, if you are trying to match a collet's taper ...you may have a bad collet ? so (Good!) I see you put a dowel in the collet..excellent
    Now try another collet and see if the tapers match ?
    If so....good
    Then take the collet (with dowel) and chuck it in 3 or 4 jaw chuck, but clamp lightly on the rear half of the collet and leave the taper sticking out. now mount your mag base indicator on the tool-slide, but allow the indicator to rotate/swing up/down on the taper surface while the support rod on the mag base is rigid--this will let you swng up/down on the taper and the reading ON THE CENTERLINE will be the null . lock it there and now move your slide to get matched readings on the travel.

    Note: if you have runout of the collet of say +/- .002 , that is OK. just lock the chuck at "0" and you will be at the true center ( Middle of runout is always center.

    Rich
    No tools but a chuck and a indicator
    Last edited by Rich Carlstedt; 08-17-2019 at 05:49 PM.

  8. #18
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    All good suggestions, but the OP is in the middle of boring the taper NOW, so I don't see he has much option but the trial and error route.
    'It may not always be the best policy to do what is best technically, but those responsible for policy can never form a right judgement without knowledge of what is right technically' - 'Dutch' Kindelberger

  9. #19
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    If you know the taper angle you can calculate the amount of infeed for each turn on the compound. Set up a 1 inch travel indicator centered on a piece of ground stock in the chuck so it moves with the compound. Lock cross slide and take out back lash on compound and zero indicator. Crank in compound a convenient number of turns ( say 10) and check results against calculated value. Tap compound around until calculated value and indicator results agree. You will be closer than eyeballing scale on compound but will still need to use blueing and trial and error.

  10. #20
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    Quote Originally Posted by CalM View Post
    Use the travel indicator and trig out the angles. A piece of paper and a pencil is the correct tool for this prep work. After the first trial cut, make an evaluation as to which way the compound needs to go. Use the DTI to verify the changes you want to make. .001 over an inch is a lot of angle change, and you don't want to be chasing your tail bumping the compound back and forth.
    What CalM said. According to my calculator, sine of 10 deg is .173648.

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