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Weldon tool holder

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  • Weldon tool holder

    Hi, I am looking to buy a cutter with a weldon shaft specified as 19mm, 3/4". In order to securely hold this on my ISO40 spindle, I am also looking to get an IS040/Weldon adapter. But the ones I can find are specified to be 18mm and 20mm. I haven't used a weldon holder so far, so if I get a 20mm holder, will it tighten up to hold the 19mm shaft? Or must I get an exact 19mm adapter?

  • #2
    The Weldon holders are a solid piece with a setscrew in the side. The setscrew goes in the flat on the shank of the end mill. The hole has to be an exact fit to the tool shank. You need to find out if the cutter shank is 3/4" or 19mm because they are .002 different. They are .748 (19mm) and .750 (3/4). For an ER collet they would be interchangeable. For a Weldon holder they are not interchangeable.


    • #3
      Thanks for the response. I can't find any local vendor that either has 19mm or 3/4" veldon holders. What's available is 18 or 20mm. I will call a few vendors tomorrow, but most are just sales clerks, clueless about the technical merits of the tools. But it looks like this cutter is a no go.


      • #4
        Lets back out a bit. Why exactly you need to buy a Weldon shanked cutting tool that is 19 mm in diameter? Correct me if I'm wrong, but that was the impression I got. If you actually need a cutting tool that is 19 mm in diameter, the shank is 18 mm with almost 100% certainty.

        If you however have the cutting tool already in your hands, it is most probably 3/4", which would mean that you need a 3/4" Weldon holder for it that has the 40 taper you need.
        Amount of experience is in direct proportion to the value of broken equipment.


        • #5
          Yesterday, I continued enlarging 36mm holes to 44mm using my boring bar. I used my go/nogo gage to test the first 4 holes (I need to enlarge 24 holes) and they were fine. Then I got lax and didn't check the holes afterwards. At the 8'th hole, I checked again and the gauge didn't go in. So the insert is wearing very fast. Now I have to go back a redo two tubes and I will rotate the insert every two holes.

          At this point I remembered in another thread, the guys recommended getting a rotabroach to do the job. So the tool in question is a 44mm rotabroach, but with a weldon shank that is specified as 19mm, 3/4". It is probably 3/4" then, as you are saying, cause otherwise the 19mm weldon would be one of the available sizes. I also found a 19mm cylindrical shank rotabroach, but when looking at that cutter, the shank seems awfully thin compared to the cutter. I was concerned that it would slip in the collet. Also, I was only able to find up to 55mm long cutters, but I need at least 60mm.

          So, gotta make the boring bar work and have some exercise swapping the tubes


          • #6
            I do this with a proper rotabroach adaptor/arbor with a Morse Taper 3 shank then use an ISO40 to Morse Taper 3 adaptor to hold that in the spindle.
            Here is a very expensive on as an example:-
            I have purchase mine at a better price off eBay but they are still not cheap.
            The advantage of using the dedicated arbor is that you clamp on both flats of the Rotabroach type cutter and you have the option to hold the centre pin which is spring loaded (spring and ball in the arbor).