Announcement

Collapse
No announcement yet.

measuring across "open" dovetails?

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • measuring across "open" dovetails?

    not sure they're called "open" dovetails but I'm referring two
    the dovetails on a shaper ram. Just two long (male) dovetails
    running the length of the ram, front to back.

    any thoughts/suggestions on how to measure how parallel the
    two dovetail faces are along their length?

    There is obviously nowhere to lay dowel pins to mic over.

    Tony

  • #2
    I can't visualize what you mean, but when I was making quick-change lathe toolholders, I used two ground dowel pins and an adjustable parallel between them then measured the parallel with a micrometer.

    Comment


    • #3
      I think the only way you can do it is to have a device that registers on the three known surfaces to check the 4th.

      you scrape the two flat, then one angle. Connelly shows these things as wire diagrams; the indicator is held in a device that positively registers on the two flats and one angled such that the indicator point is on the second angled surface, read one end then the other. In the real world they are not wire diagrams but some structure you concoct or if you're lucky (or energetic to make) a Kingway

      http://www.metalworking.com/dropbox/...ealignment.pdf

      see the pic. The hollow cylinder with a chunk out of it registers on flat and the angled while the ball is on the other flat and the indicator is against the last surface. clear as mud?
      Last edited by Mcgyver; 02-23-2012, 12:54 PM.
      in Toronto Ontario - where are you?

      Comment


      • #4
        Yep, easy as anything that way.

        Incidentally, the "Kingway" tool is nothing new..... it really is simply a way to implement the various indicator setups shown in the Connoley book on machine reconditioning..... using a single "kit of parts".

        The setup you want is fairly elementary and a very good example of the proper use of the "Kingway" type tool.

        In fact, here is the setup you want.... I am measuring the degree of parallelism of two V-ways of the form you describe. They happen to be on a mill column, but the geometry is the same. (btw, the pic was actually an illustration, and the round "slider" was too hard to get in place on the vertical surface while taking the pic with the other hand......it WOULD be used)

        Last edited by J Tiers; 02-24-2012, 01:22 AM.
        CNC machines only go through the motions.

        Ideas expressed may be mine, or from anyone else in the universe.
        Not responsible for clerical errors. Or those made by lay people either.
        Number formats and units may be chosen at random depending on what day it is.
        I reserve the right to use a number system with any integer base without prior notice.
        Generalizations are understood to be "often" true, but not true in every case.

        Comment


        • #5
          One - the reference side - must be flat - ie correct angle with no "waves" etc.

          Use the reference to check the second side as described.

          If the reference surface is not flat and co-planar, neither will the second side be which is being set/checked against it.

          The second side "flat" must be flat as well as having the correct angle to the base surface.

          It should not be too hard to set up on a good surface plate.

          Comment


          • #6
            Originally posted by metalmagpie
            I can't visualize what you mean, but when I was making quick-change lathe toolholders, I used two ground dowel pins and an adjustable parallel between them then measured the parallel with a micrometer.
            Here's a pic of a shaper ram dovetail.

            Location: Saskatoon, Saskatchewan, Canada

            Comment

            Working...
            X