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  • Reducing a diameter

    I need to reduce the diameter of a 3/16" steel rod to .0860" (#44 drill size). Prolly won't work in the 10" lathe. Any ideas on doing this without investing in a 15 ton extruding machine? I thought about making a die similar to a threading die but without the threads and using it as a cutting tool. Never been tried, tho. Any ideas? Thanks!

  • #2
    What you need is a box tool. See post #2 here: http://www.homemodelenginemachinist....ing-tool-2773/

    It mounts on the tool post, it moves with the carriage, and it holds the rod and a tool for reducing the diameter.
    Any products mentioned in my posts have been endorsed by their manufacturer.

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    • #3
      Fun part here will be keeping it from bending/snapping. You may have to start with a thicker rod and turn it down in small segments from the tip inward to maintain rigidity... Its likely a lot easier just to buy a #44 drill rod however...
      Play Brutal Nature, Black Moons free to play highly realistic voxel sandbox game.

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      • #4
        Here's how I turned down a bit of brass to make an oval head machine screw:

        http://metalworkingathome.com/?p=40

        Can you use a drill chuck in your spindle taper to hold the work?

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        • #5
          Tried the drill rod idea, but I can't seem to get silver solder to stick to it. Attaching it to a hole in a larger diameter piece. I suppose JB Weld would do it, but solder is better.

          Thanks for the input, dp. That might work.
          Last edited by bdarin; 05-06-2014, 05:08 PM.

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          • #6
            I guess im not understanding the question - unless the piece is long and you forgot to mention?

            toss it in a collet on the mill and have at it? flip if needed and match it up?

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            • #7
              Putting a small round piece (2" long) into the end of a 2" long x 1/2" dia. round piece. All steel. I like the box tool idea. Never seen that before! Learn something new every day.

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              • #8
                Drill rod is a steel, so it can be soldered with a silver bearing solder or silver brazed. But you have to use the right flux. I'd use Harris Stay Clean flux for a silver bearing soft solder, you can soft solder SS with that.

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                • #9
                  Here is a part made with a home made box tool I made that takes 3/8 dia ss down to 1/8 in one pass. I used rollers on the od
                  see the shine on od where the rollers were ahead of the cutting tool.






                  jimsehr

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                  • #10
                    Originally posted by bdarin View Post
                    I need to reduce the diameter of a 3/32" steel rod to .0860" (#44 drill size). Prolly won't work in the 10" lathe. Any ideas on doing this without investing in a 15 ton extruding machine? I thought about making a die similar to a threading die but without the threads and using it as a cutting tool. Never been tried, tho. Any ideas? Thanks!
                    I make 3/8 inch drill rod stylus' (styli?) with a variety of end diameters, from 3/32 to 1/4 inch.
                    Using the lathe, it is easy to drill the end of the 3/8" rod with whatever size drill is needed and push in a piece of smaller drill rod.
                    I drill in about 1/2 inch and use liquid flux and lead free solder to fix the smaller drill rod into the larger one.
                    I usually use a long piece of smaller drill rod and then just cut it to length with a handheld abrasive wheel while the stylus is still held in the chuck.
                    Takes about 2 minutes each and the diameters are always perfect.
                    Your work is smaller, but the idea should work.

                    Hope this helps,
                    Dennis

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                    • #11
                      Originally posted by bdarin View Post
                      I need to reduce the diameter of a 3/16" steel rod to .0860" (#44 drill size). Prolly won't work in the 10" lathe. Any ideas on doing this without investing in a 15 ton extruding machine? I thought about making a die similar to a threading die but without the threads and using it as a cutting tool. Never been tried, tho. Any ideas? Thanks!
                      I had the inside out drill bit epiphany once too, till i tried to make the thing, i gave up, it worked on plastic but generated so much torque on the slim diameter that it twisted it up, ended up grinding it on a brierly drill grinder, slowly, wonder why drill grinders are never fitted with coolant systems? Seems sensible
                      How about a tig tungsten electrode, not sure of the sizes available
                      Mark
                      Last edited by boslab; 05-06-2014, 08:41 PM.

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                      • #12
                        Feed the work stock through a drill bushing with the cutting bit just at the exit of the drill bushing. Don't have a drawing of the set-up, but with the bushing and tool held within the same assembly and the tool bit adjusted by an adjusting screw, you can effectively create your own box tool for small diameter work.
                        Hope my vague explanation is good enough for your "minds eye" to envision it.
                        Krutch


                        Mentally confused and prone to wandering!

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                        • #13
                          whats actually wrong with a follow rest?

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                          • #14
                            Thanks for all the help, guys. I've been doing this HSM thing for 15 years and this is the first I've heard of a box tool. Never too late to learn something new! I captured some pix and will be making myself one real soon. Will also be joining the cnc crowd (finally) this fall with some courses at ECC in Buffalo.

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                            • #15
                              How long is it? I'd put the 3/16" rod in a collet with about 1/4" sticking out, turn that down, extend another 1/4" and turn that down, etc.
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