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What size dovetail cutter for making tool holders

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  • #31
    For those new to the Dorian style QCTP holders, there are two styles.

    One pushes a piston out aginst the bottom of that L1 surface, which forces the faces of the tool post and tool holder dovetails together. Once you cut the dovetail you can grind off 25% of the corner designated as L2 without impacting the fit.

    The style other uses an expanding wedge at the L1 corners to force the opposite end of the holder up against the tool post's dovetail. Again, the sharp edge at the corner L2 can be filed or ground off without impacting the action of the holder.

    At the end of the project, there is a profound difference between spare parts and left over parts.

    Location: SF East Bay.


    • #32
      Originally posted by danlb View Post

      That drawing and the listed specifications are geometrically correct, but impractical in real life. If you cut a dovetail to exact knife edges with the depth and width as listed it should work, but your next step should be to knock off the sharp edges and resharpen the dovetail cutter since the thin tips of the cutters will dull quickly and leave you with a rounded corner at the L1 measurement.

      The phase II holders you have appear to have the L2 knife edges ground down.

      All of this is why you usually can't measure the opening when duplicating a dovetail from a sample part. You instead use a couple of dowel pins to measure the distance between the surfaces of the dovetail, and then cut the new dovetail to match by using the same pins and cut to the same vertical height.

      This is true. The only reason they give a drawing with such sharp corners and the measurements between those sharp points is because you can then use those dimensions and the diameters of a couple of dowel pins to calculate the distance apart the dowel pins should be when the dovetails are correctly distanced apart, just in case you don't have one to take a direct measurement from.
      Location: Saskatoon, Saskatchewan, Canada


      • #33
        Originally posted by challenger View Post

        Who is "MF"?
        What type of tool post do these go to?
        I'll be needing to do the inside dovetails and will give the shaper a try on at least one. I haven't used it in years.
        I've read that the dovetails one the holders are a very critical operation to keep accurate and I don't want to ruin a part that's nearly done.
        In reality making one's own bxa holders is a colossal waste of time considering they cost less than 20.00 to buy. My only reason for doing these is that they will be usa made.
        MF is the name used over the phone to a character that escapes me in the movie Pulp fiction, said by Samuel L Jackson.
        The Toolpost is a Dickson clone made by Bison in Poland.
        Click image for larger version

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