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  • Sine vice setting angle

    How do you set the angle using a sine angle vice. Do you use gage blocks stacked up. If so how do you keep the blocks from slipping I got a sine vise from little machine shop Part # 1756 ( really good deal) but I too much of a newbe to know how to set it right.

    Thanks
    Better to be silent and thought a fool, than to open ones mouth and remove all doubt.

  • #2
    Yeah, or you can machine a block and make your own. You're probably not going to need sec. of a degree anyway.

    Comment


    • #3
      Here's a little writeup I did for our club that may help you.

      SINE BAR ERRORS

      In the metalworking books, when you see a picture of a sinebar in use, the
      stack used to form the angles is generally composed of gage blocks, the
      accuracy of which is measured in millionths of an inch. Are gage blocks, a
      moderately expensive item for the amateur, really needed? Or is it possible to
      get by with a homeshop-made stack that's only accurate to a thou?

      The equation for a sinebar is:

      sin(A) = S/L

      where:

      A = desired angle
      S = stack height
      L = sinebar length (i.e., roller center-to-center distance)

      With a little bit of differential calculus, it's possible to write the error
      equation for the angle due to errors in the stack height.

      dA = (1/cos(A)) * dS/L

      where:

      dA = the error in the angle due to an error of 'dS' in the stack height.
      (For purposes of this discussion, we'll ignore the effect of any error in 'L'.)

      Let's plug in some numbers...

      A = 10 deg
      L = 5 in
      dS = 0.005 in

      Then:

      dA = 1.01543 * 0.005 / 5 = 1.01543E-3 rad = 0.0582 deg

      or about one milliradian error. That's pretty small. Think about it this
      way...If I make a one milliradian error pointing my rifle at a target 100 yards
      away, I'll miss the bullseye by 3.6 in.

      If I'm any kind of machinist, I should be able to machine the block I'm using
      for the stack to within 0.001 in, which would reduce the error to 0.2
      milliradian, or a target miss of 0.72 in at 100 yards.

      The error depends on the angle for which the sinebar is set. For:

      L = 5 in
      ds = 0.001 in

      it looks like this:

      5 0.0115029
      10 0.0116359
      15 0.0118634
      20 0.0121946
      25 0.0126438
      30 0.0132319
      35 0.013989
      40 0.0149589
      45 0.0162057
      50 0.0178273
      55 0.0199784
      60 0.0229183
      65 0.0271147
      70 0.0335043
      75 0.0442748
      80 0.0659906
      85 0.131479

      where the first column is the angle, A, in degrees and the second column is
      the error in A, dA, in degrees.

      Since a sinebar is seldom used for angles greater than 40 degrees, we can
      count on an angle error of less than 0.015 deg (0.25 mrad) if we can machine
      the stack block to an accuracy of one thou. Unless you're making highly
      critical components, don't be afraid to machine your own blocks for setting
      the sine bar. Setting an adjustable parallel with a mike is another option.
      Regards, Marv

      Home Shop Freeware - Tools for People Who Build Things
      http://www.myvirtualnetwork.com/mklotz

      Location: LA, CA, USA

      Comment


      • #4
        You have to set the height up with a gauge block set, and use trig to work out the height you need. If you know the angle you want to set it to then you would multiply the distance between the sine bar centres (4” in this case) by the sine of the angle to give you the height of the gauge block stack.

        For example if you wanted to set an angle of 38 degrees it would be 4” x 0.61566 (sine 38 deg) = 2.46264”, then use this figure to set your stack to the closest you can get.

        I don’t know why they didn’t use 5” centres (keeping the overall size down perhaps?) as if they had then you could just use the table of sine bar constants from Machinerys Handbook.

        A word of caution here – these vices are meant more for light machining operations like grinding where you are only removing a few thou’ at most – rather than for a heavy milling operation.

        Peter

        Edit - Oops! I see you've already been cautioned about the application of this vice in another thread. Still good advice though.
        Last edited by Peter N; 07-17-2006, 02:37 PM.

        Comment


        • #5
          Wring your blocks well, clean and lube before storing. Hell, you knew that already.

          Comment


          • #6
            Thanks I don't need any close tolorances, i'm making custom parts for motorcycles and small steam engines and the like. I am also using a HF mini so the cuts are light. Nice write up Mklotz I copied that down as well as the other formulas or equations (if that's what you call them) I got from you guys. I think I will make my own blocks because money is an object (one I don't have). I need another angle vise for a machine, do any of you know of a good small angle vise designed for milling?

            Thanks
            Better to be silent and thought a fool, than to open ones mouth and remove all doubt.

            Comment


            • #7
              Just go by the weight, mass. The heavier, the better.

              Comment


              • #8
                Originally posted by Peter Neill

                I don’t know why they didn’t use 5â€‌ centres (keeping the overall size down perhaps?) as if they had then you could just use the table of sine bar constants from Machinerys Handbook.
                The numbers in MH are 5 * sin(angle). He can still use them by multiplying them by 0.8:

                4 * sin (angle) = (4/5) * [ 5 * sin (angle)]

                But what a waste of time. Scientific calculators can be had for < $5 these days. Punch in angle, hit 'sin', multiply by 4...done. Beats fussing around with a gigantic book.
                Regards, Marv

                Home Shop Freeware - Tools for People Who Build Things
                http://www.myvirtualnetwork.com/mklotz

                Location: LA, CA, USA

                Comment


                • #9
                  You do'nt need to make different blocks,just use your set of adjustable parallels and set them with a micrometer.
                  Lumpsmith

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