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Digital calipers for segmented turning...

Discussion in 'Jigs and Tools Forum' started by Brett Niland, Feb 23, 2018.

  1. Brett Niland

    Brett Niland PRO Member

    Hello all,

    I'm using a wedgie sled and "wedgies" to measure the cut angle for the sled. I'm quickly coming to the point that I need a more flexible solution for finding the angles on the sled reliably and repeatably.

    I see that a few of you are using digital protractors to set the angles for your sleds.

    Can I get you guys to chime in on pro's, con's and suggestions for make and model?


  2. mfisher

    mfisher Super Moderator Staff Member

    Some are using digital protractors in our club's shop to set angles. A couple of things they recommend is finding the longest ruler you can afford. One guy has an iGaging which he purchased from Amazon. He likes it. It has a 10" ruler.


    Another member found one at Harbor Freight that he likes.
  3. Brett Niland

    Brett Niland PRO Member

    Thanks for the quick response.

    In looking at these types of devices before I posted the question, I wondered at the accuracy. Several of them list .2 degree accuracy, so especially for closed rings with a good number of segments, that sounded a bit coarse. For instance, for a 32 segment ring with a .2 degree variance, that's 1.6 degrees off total. Since realistically that's distributed (albeit potentially unevenly) maybe it's OK. I'm too new to this to really know. I bet I get a different answer from everyone on the question of, "how accurate do I have to be". :)


  4. Frank Smith

    Frank Smith Member

    I have the one from Amazon and like it very much. I haven't had the need (yet) to setup my wedgie sled with it but I use it for all kinds of other stuff. Great tool to have in the shop.
  5. Bob Beaupre

    Bob Beaupre Super Moderator Staff Member

    Don't use a digital protractor. I draw up my wedgies in a AutoCad clone (draftsight) then I print them out and then cut them out and use the paper wedgie. I have done this up to a 96 segment ring.
  6. Brett Niland

    Brett Niland PRO Member

    Between your response and Lloyds post here (Title: Wedgie calculation) I think I'll just make custom wedgies when I need them. Using either of these methods seem likely to render much better accuracy and certainly better repeat-ability.

    Thanks Bob!

  7. peter white

    peter white PRO Member

    A mate of mine printed all the angles to the shape of a segment at the angles I need.He printed them on a 3d printer.
    I place them between fences of sled and don't have to test anymore.
  8. Halling51

    Halling51 Member

    I would lke to know who can make wedgie 3D?
  9. Lloyd Johnson

    Lloyd Johnson Administrator Staff Member

    Did you get a chance to read this post? Title: Wedgie calculation
    It is a good way to tell you how to make a wedge using Woodturner PRO and then test to see if it is the absolute correct angle. In my reply on that thread, I point out how to get three measurements that will tell you if the angle is correct. The angles are the width of the board from which the wedge was cut, the long S.E.L (segment edge length) and the short S.E.L. When your digital caliper says that all three of these angles are correct, the wedge will create perfect rings. It usually only takes me a couple tries to get it correct.
    I cut my wedges from 1/2" birch plywood. Once you know the board width, cut a piece of the birch plywood so that it is exactly that width. Then use the most accurate sled you've got to set the angle as if you were going to cut really big segments. Make sure that the segment you cut has the long S.E.L that is the exact measurement and then check to see if the short S.E.L. length is correct. If it is, the angle of the wedge is perfect. If the length isn't correct, make a slight adjustment to the angle and cut a new wedge and repeat the check.
  10. Brett Niland

    Brett Niland PRO Member

    Thanks Lloyd, Yes indeed. This is a great process. I may practice the angles on scrap and then cut using UHMW Polyethylene. Other than the materials, I will use your approach exactly!

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