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5/16" Square Socket for Lathe Chuck Adjusting Screws

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  • 5/16" Square Socket for Lathe Chuck Adjusting Screws

    As part of my endless project of fixing my 6" four jaw independent chuck, I needed to make a 5/16" square socket, about 3/8" deep, in the end of the 3/4" round 4140 steel rod that will be threaded and turned as needed. I had prepared one piece for threading, and I decided to use that to attempt my proposed way to do it. Basically I would drill four holes 0.093" diameter on a 0.155" radius circle, and then drill through the center with a 5/16" drill. It would leave just about 0.02" of material to mill off with a 1/8" diameter end mill or diamond burr:


    The green square is the 5/16" size desired, and the green circle is the size of a 1/8" tool. I tried to drill the holes using my tool post rotary tool holder, but it was not very successful. So I rigged up a clamp and small vise and drilled them with the mill/drill, but they still did not come out very well:



    Then I put it in the lathe and tried to drill out the center with a 5/16" drill, but it jumped around a lot and did not stay on center. Finally I used a spotting drill to get a fairly good guide hole and followed with larger bits, actually up to 21/64" (0.328"). Then I went back to using my toolpost rotary tool holder and I was finally able to use it to mill the inner surfaces of the socket, but only after I filed a flat on the tool's spindle and used a tool that I made so I could tighten the collet (chuck) properly:



    Here is the result. It's not quite as deep as I would like, but the chuck key goes in at least 1/4" and it fits pretty well:



    The tool facing right is the homemade chuck key that came with the chuck. It is a bit undersize and fits sloppy, but well enough. I made some video and I'll put together a little project movie. It shows my continued difficulties with the collet on the rotary tool getting loose, and then the camera batteries pooped out, so it doesn't show the much greater success I had after properly securing the diamond burr.
    http://pauleschoen.com/pix/PM08_P76_P54.png
    Paul , P S Technology, Inc. and MrTibbs
    USA Maryland 21030

  • #2
    Here's the video:

    http://pauleschoen.com/pix/PM08_P76_P54.png
    Paul , P S Technology, Inc. and MrTibbs
    USA Maryland 21030

    Comment


    • #3
      I'm not exactly sure about you're trying to accomplish, but being one to take the quick & dirty way out, I would use an 8 point socket............ welded, brazed or soldered into an appropriately sized hole bored into the end of the bar stock. Something in 1/4" drive would
      likely do the deed.

      http://www.mcmaster.com/#drive-sockets/=smmbv2


      Rex
      Last edited by rode2rouen; 06-30-2014, 01:17 AM. Reason: speelage

      Comment


      • #4
        This calls for making a rotary broach tool. You need 4 square holes so it easily justifies making a specialized tool,even if it costs a little more. There are nice plans for a rotary broach on the HMEM site

        Comment


        • #5
          A rotary broach would be best, and I found one on eBay for $40:
          http://www.ebay.com/itm/5-16-Square-Rotary-Broach-Punch-Fits-1-2-Shank-Holders-Made-in-USA-S0315B-/121141005958?



          However, the holders are $375, although I think it may not be too difficult to make one:
          http://www.ebay.com/itm/NEW-Basic-Ro...-/121372163309

          I considered making one, using a 5/16" lathe tool. I even ground a broken 5/16" brazed carbide tip tool to try something like this but with a round starter point and notches to form cutting edges, but the shank is not hardened. It might be possible to make something like this with one cutting corner and press it into the hole four times at 90 degrees each. But it might not work well in 4140 steel.

          Mostly (other than getting the job done) I wanted to see how this process might work, and I think now that I've fixed the loose collet problem and know how to drill the corner holes accurately, I think this could be a viable option. It is also able to make sockets of almost any size and shape, but especially the common square and hex.

          Another option is to use a 1/4" or 3/8" square socket and then use standard square drive socket wrenches. In that case I could get a cheap 3/8 drive socket set or individual sockets. It should be easy enough to drill a hole for the OD and a deeper hole for the tip and then use a roll pin to hold it (or a force fit and Loctite, perhaps).
          http://pauleschoen.com/pix/PM08_P76_P54.png
          Paul , P S Technology, Inc. and MrTibbs
          USA Maryland 21030

          Comment


          • #6
            Some good ideas: http://rick.sparber.org/msh.pdf

            Comment


            • #7
              That's an excellent article. Lots of good ideas. Thanks!

              I like the idea of square holed sleeves, as available from:
              http://sturdybroachingservice.liveon...roducts.nxg/#1

              Not sure how expensive they are. I saw a couple on eBay for about $15:
              http://www.ebay.com/itm/Sturdy-62-Sq...-/251177745053

              They are also available from Stock Drive Products:
              http://www.sdp-si.com/web/html/newprdrsleeves1.htm

              I didn't see square hole sleeves in stock, but a 5/16" hex sleeve is about $11 for a 2.25" length.

              I was able to clean up and deepen the hole in the steel rod I worked on, using my B&D "Wizard" hand-held rotary tool, with a new NiMH battery to replace the original NiCad that had died as they usually do after twenty years or so - I've probably had it that long. I paid $13 including shipping for this, whereas the B&D replacement is about twice that. I got the last one:
              http://www.ebay.com/itm/221326024022
              http://pauleschoen.com/pix/PM08_P76_P54.png
              Paul , P S Technology, Inc. and MrTibbs
              USA Maryland 21030

              Comment


              • #8
                A stub drill might give more rigidity. Old machining texts suggest supporting the drill bit with a hss tool bit reversed in the toolholder and pressed lightly against the drill bit.

                Comment


                • #9
                  I would have purchased a bushing with a 5/6" square hole broached in it and silver brazed it into the tool.

                  Comment


                  • #10
                    Many excellent suggestions here, including Rick Sparber's great article. One that was missed is the way my wrench was made:



                    It shows no signs of any problems after years of use.

                    I take no credit for this as it came with the used chuck when I purchased it. The braze line is so fine and nice that I had to use a magnifier to see it. I was very curious as to how it was made. I suspect the design would work even without adding the insert if you used a better grade of steel.
                    Paul A.
                    SE Texas

                    Make it fit.
                    You can't win and there IS a penalty for trying!

                    Comment


                    • #11
                      That's another pretty good method, although making the insert seems a bit difficult. Of course, you could just use a piece of 5/16" square steel and then turn it to dimension after brazing/welding. Here is a similar idea that does not require any extra material except for welding rod or braze:



                      I have not taken into account the thickness of the kerf from the saw, but it can be filled in, or taken care of when turning down from 0.75" to 0.728" as needed. There can be a small extension before the threads begin, as can be seen in this picture:

                      http://pauleschoen.com/pix/PM08_P76_P54.png
                      Paul , P S Technology, Inc. and MrTibbs
                      USA Maryland 21030

                      Comment


                      • #12
                        Paul, Looks like that would work too. If you do not mill quite so far, you will not have the half moon opening on the side.

                        And it would need a final, cleanup cut on the OD in any case if you want it to look nice.

                        Whoever made mine did such a nice job on the insert that you have to look close to see the braze joint. I imagine square or rectangular stock and file/sand the matching radius on the end. Then braze it in and turn it down as you say. But, as I said, I did not do it so I can't say for sure.
                        Last edited by Paul Alciatore; 06-30-2014, 05:31 PM.
                        Paul A.
                        SE Texas

                        Make it fit.
                        You can't win and there IS a penalty for trying!

                        Comment


                        • #13
                          I'm trying to avoid welding or brazing. I have a small arc welder, but I've never used it. I don't have an oxy-acetylene setup (or any oxygen gas equipment). I do have a regular propane torch which I have used for sweating copper pipe, but I don't know if it is suitable for brazing. The videos I have watched all seem to use a welding torch with oxygen, and the one I found using a simple plumber's torch was actually silver soldering with SSF-6 "Muggy Weld".
                          https://www.youtube.com/watch?v=-oifC7fbQfY
                          https://www.youtube.com/watch?v=T2wYgQtPg4g

                          Similar product:
                          https://www.youtube.com/watch?v=I8zsBKvFfFs
                          $28 for 1 ounce kit:
                          http://www.ebay.com/itm/35-Silver-Br...-/301218935938

                          Oxy-Acetylene:
                          https://www.youtube.com/watch?v=ZojIpKCo4TQ

                          Brazing rods are cheap and easily available:
                          http://www.homedepot.com/p/Lincoln-E...H515/202715833

                          An Oxy-MAP torch kit is $60:
                          http://www.homedepot.com/p/Bernzomat...1673/203391033

                          56% silver brazing kit (1 oz) for $80 at Home Depot:
                          http://www.homedepot.com/p/Lincoln-E...KPOP/100672839
                          http://pauleschoen.com/pix/PM08_P76_P54.png
                          Paul , P S Technology, Inc. and MrTibbs
                          USA Maryland 21030

                          Comment


                          • #14
                            I have made some similar holes by first making a male pattern, drilling an undersize hole, heating the work red hot, and then driving the male pattern into the hole. Don't know how this would work with the material you used.
                            Don Young

                            Comment


                            • #15
                              As I said, I believe the technique I showed would work even without closing the fourth side. The milled slot would function much like a standard, "C" shaped wrench, which has an open side. If you want to close it without welding or brazing, just cut it flat as your drawing shows and bolt a rectangular cap on it. Four 4-40 or 6-32 SHCS would hold it quite nicely. Round the edges a bit with a file.



                              Originally posted by PStechPaul View Post
                              I'm trying to avoid welding or brazing. I have a small arc welder, but I've never used it. I don't have an oxy-acetylene setup (or any oxygen gas equipment). I do have a regular propane torch which I have used for sweating copper pipe, but I don't know if it is suitable for brazing. The videos I have watched all seem to use a welding torch with oxygen, and the one I found using a simple plumber's torch was actually silver soldering with SSF-6 "Muggy Weld".
                              https://www.youtube.com/watch?v=-oifC7fbQfY
                              https://www.youtube.com/watch?v=T2wYgQtPg4g

                              Similar product:
                              https://www.youtube.com/watch?v=I8zsBKvFfFs
                              $28 for 1 ounce kit:
                              http://www.ebay.com/itm/35-Silver-Br...-/301218935938

                              Oxy-Acetylene:
                              https://www.youtube.com/watch?v=ZojIpKCo4TQ

                              Brazing rods are cheap and easily available:
                              http://www.homedepot.com/p/Lincoln-E...H515/202715833

                              An Oxy-MAP torch kit is $60:
                              http://www.homedepot.com/p/Bernzomat...1673/203391033

                              56% silver brazing kit (1 oz) for $80 at Home Depot:
                              http://www.homedepot.com/p/Lincoln-E...KPOP/100672839
                              Paul A.
                              SE Texas

                              Make it fit.
                              You can't win and there IS a penalty for trying!

                              Comment

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