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DIY 5" sine bar

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  • #16
    I have a real nice 10" sine bar that I made 30+ years ago 10" so you didn't need to spend a lot of time figuring what size JO blocks to use,you know just move the decimal in the sine table by the angle you need. What I was getting at is in all those years I can count on my fingers the number of times I have really needed it and have fingers left over. There are too many "field expedient"ways of getting where you want to go.
    Lumpsmith

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    • #17
      i understand the concept of what you guys are posting, but just to be sure, you don't actually clamp the work to the sine bar, right? you are just using it for setup?

      thanks,

      andy b.
      The danger is not that computers will come to think like men - but that men will come to think like computers. - some guy on another forum not dedicated to machining

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      • #18
        Great thread. And while we are discussing sine bars and such, I thought someone should mention the method described by Marv Klotz. If you go to his website and grab the little utility called "SINE.ZIP" it describes a clever way to make accurate angles using two cylinders joined by a link, and provides a small program that does all the math for you. Quoted from his description:

        "A simple and accurate way to make sine bars for machining precise angles is to use two cylinders of unequal diameter held at a fixed distance. This program provides all the machinery to make the needed computations and estimate the error in the resulting angle. A second program removes the need for making the separating link in favor of an approach that uses two butted cylinders of differing diameters."

        I have used this method a number of times. Quick, handy and works great!
        (THANKS MARV!!)

        Al A.

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        • #19
          Reviving this from the distant past. Can you please repost the photos/drawings of your sine bar implementation? I tried visualizing from the description but didn't get to a solution.

          Thanks

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          • #20
            And if anyone knows what HTRN's "gizmo" referred to that would be nice too. The link is to some long dead product and MSC's website comes back with a 404 error.
            Chilliwack BC, Canada

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            • #21
              Originally posted by BCRider View Post
              And if anyone knows what HTRN's "gizmo" referred to that would be nice too. The link is to some long dead product and MSC's website comes back with a 404 error.
              Don't know for certain, but I'd guess it's one of those "stair step" looking blocks, with the step heights equaling the height required for setting standard angles on a 5" sine bar. I've seen them before, along with shop made versions.
              George
              Traverse City, MI

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              • #22
                I did a quick calculation, and found that a 5" sine bar which was 0.01" too long would only have an error of 0.0202 degrees with a nominal 10 degrees angle.

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                • #23
                  Originally posted by George Bulliss View Post
                  Don't know for certain, but I'd guess it's one of those "stair step" looking blocks, with the step heights equaling the height required for setting standard angles on a 5" sine bar. I've seen them before, along with shop made versions.
                  That's what came to mind for me too. But the word "gizmo" opens up a lot of other options...
                  Chilliwack BC, Canada

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                  • #24
                    Originally posted by tony ennis View Post
                    This is a great thread.
                    It's CRAPPY thread because half of the picture are no longer there. A result of not having them on this site. :-(
                    ...lew...

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                    • #25
                      The reason the pics of mine referred to as regards the "shop made" sine bar are no longer here - or in existence so far as I am aware - is that there was so much adverse comment regarding some/most/many pics that I posted that I just "called it quits" and removed them from PhotoBucket and my computer.

                      Too many of the adverse comments were directed to/at me personally and I wanted to remove that post and pics and some others so as to avoid the "pile on" and to get things "back to topic".

                      I thought that some one else may have stored those "sine bar" pics away - but it seems not thus far.

                      Sorry.

                      (Edit).

                      I had another (better) "close(er?) look" - and lo and behold:





                      Last edited by oldtiffie; 10-06-2016, 02:55 AM.

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                      • #26
                        And:





                        I hope it helps.

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                        • #27
                          Back in the Jan-Feb 2009 issue of Home Shop Machinist I had an article on an inexpensive method of generating accurate angles. It describes a method for using a set of angle gauges, which are less expensive than Jo blocks, and combining them with the sine method but without an actual sine bar, so that any in between angles could be accurately generated.

                          It also discusses sine bar theory.

                          I have placed it in my LockBox folder so it can be downloaded.

                          Caution: It contains math but only addition and subtraction is needed to actually use the method in the shop.

                          https://www.dropbox.com/s/6hx2gq491h...Gauge.doc?dl=0

                          If you have any questions just post them here.
                          Last edited by Paul Alciatore; 10-06-2016, 03:35 AM.
                          Paul A.
                          SE Texas

                          And if you look REAL close at an analog signal,
                          You will find that it has discrete steps.

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                          • #28
                            I shudder when some one wants "Jo Block" and "True Sine Bar" measurement - and "tolerance" where all to often they are neither wanted nor needed within what ever the real tolerance/limits needed for a job really is in fact.

                            Same applies to "surface finish".

                            If they really are justified - then by all means use them - otherwise don't.

                            I rarely use some quite accurate and sophisticated tools that I have as I always start at "basics" and "fundamentals".

                            They have stood me in very good stead over any years and are often "on show" (used) where as the "better/precision" stuff rarely gets used or sees the light of day - but they are there for when they really are needed.

                            Same applies to choosing which machines to use.

                            One of these days I will start a thread about "limits and fits" and "tolerances" and "surface finish" all of which are inter-related/dependent/reliant to some degree - and how to take advantage of them for the optimum result.
                            Last edited by oldtiffie; 10-06-2016, 04:01 AM.

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                            • #29
                              Originally posted by George Bulliss View Post
                              Don't know for certain, but I'd guess it's one of those "stair step" looking blocks, with the step heights equaling the height required for setting standard angles on a 5" sine bar. I've seen them before, along with shop made versions.
                              I asked him, and it was. HereĀ“s one:

                              https://www.google.com/search?q=sine...lE1lQgKfkLM%3A

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                              • #30
                                A couple of decades ago, when we were still measuring angular errors in degrees, arcminutes, and arcseconds -- then using custom-machined wedge shims to reduce them to less than one arcminute -- I designed a shim machining fixture using three balls (arranged as in Les A W Harris's picture in Posting 7, above) to generate the required compound of angles. To simplify the calculation of the required under-ball spacing shims, the distances between the ball centers was set to 3.441 inch along the ball-triangle base and height, square-root-of-2 times 3.441 inch = 4.866 inch along the triangle hypotenuse, so that each 0.001 inch of under-ball spacer tilted the plate 1 arcminute.

                                The 0.001 inch per arcminute is, of course, a linear approximation of a non-linear function . . . but for angles of five degrees or less (and we hardly ever needed to correct more than a half degree of angle error), the error of the approximation is less than arcseconds magnitude.

                                Worked really well, but updating our measurement equipment resulted in angular-measurement units expressed in decimally-subdivided degrees. I revised the fixture design, enlarging it so that two of the ball-center distances were 5.735 inch, with the third being square-root-of-two x 5.735 inch = 8.111 inch. This reduced tilt angle generated by 0.001 inch of under-ball spacer to 0.01 degree, with very nearly the same maximum error over a range of 0 +/- 5 degree.

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