Announcement

Collapse
No announcement yet.

Holding screws for modifying the ends.

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

  • Holding screws for modifying the ends.

    So for some things I'm quite happy to hacksaw the screws shorter and dress the end with a file well enough that the nut goes on. But for other times I might want to dress the end a bit more fancy because it might be something that shows or I may want to put on a "Higby end" or something of the sort. Often that requires that I can hold the screw by the thread with the head back in the chuck jaws. To that end I've tried a few different options over the years with a mixture of success. Today I needed to hold a somewhat short 1/4" carriage bolt to add a Higby end to allow easy starting of a wing nut that will be removed and put on frequently. The picture below shows the bolt and the holder I made.

    And before you ask I learned about a Higby end for the screw from Guy Lautard's "Machinist's Bedside Reader" books. I tried the first one years back and it makes like really less fumble prone if you need to remove and replace a wing nut or threaded knob over a stud frequently on something. it's a reduce nose of the screw or stud that fits the minor diameter of the thread so the nut or knob slips on and sits there politely until you spin it on. And the partial thread left by this nose reduction is dressed back with a file about a half turn to where it's nearly a full thread. The second picture hopefully shows what I'm describing a little more clearly. And yes, I know that there's still a lot of the thread left. Blame it on the sloppy thread in the wing nut. As the screw is now the wing nut slips over that nose easily with probably .01" worth of play.

    I was worried that the single slit to the bend relief hole would not pinch tightly enough in a 3 jaw chuck. But when the open side slit is set between two of the jaws I was surprised at how little pressure on the chuck key it took to lock it against me moving it with my fingers. And when given a bit of a snap to the key it was no issue at all to hold the screw for machining.

    Size of the adapter is 3/4 diameter at the nose flange, a bit over 5/8" through the main part that gets grabbed in the chuck and it's threaded 1/4-20 with the bend relief hole being 7/64 with roughly .06 left to the outside of the relief hole. Slitting was courtesy of my band saw so sorry if it's not quite dead on straight. And it's just a whiff over 5/8" long overall.

    I'll need to counter bore it from the back to allow dressing the ends of shorter allen cap screws while still holding things well enough. But at just 5/8" long it won't need much of a counterbore to let a 1/2" screw stick through. And being the size it is I can also hold regular hex head screws without fouling the chuck jaws.

    This actually worked out so neatly that I think I'm going to slowly convert my other sizes over to a similar style with the slit and stress relief hole.

    Any of you out there do something similar? Pictures or descriptions of your holders? Or if you're not quite sure of how it works in the lathe let me know and I'll take a picture of the holder with a screw sitting in the chuck.


    Click image for larger version  Name:	P1030636.JPG Views:	0 Size:	105.9 KB ID:	1864737

    Click image for larger version  Name:	P1030637.JPG Views:	0 Size:	100.3 KB ID:	1864738
    Last edited by BCRider; 03-29-2020, 03:11 AM.
    Chilliwack BC, Canada

  • #2
    while thats nice, its a lot of work. the simplest way is to put a nut on the screw and clamp it, either in the chuck or the bandsaw. i also once made a thin plate with several threads lined up and slit through all of them, imagine a kind of pliers. its then easy to shorten a screw on the grinder and the thread gets corrected by screwing it out. i dont know where it ended up. i often put a nut on a screw, grip it in the pliers and grind off what is needed. i also have thin pliers with holes in the jaws.

    how concentric does a screw end up in your contraption?
    Last edited by dian; 03-29-2020, 03:28 AM.

    Comment


    • #3
      I use ER collets and ER chuck arbor if I'm picky about not marring the thread.
      Pretty fast as I just mount the ER chuck arbor in 3-jaw chuck.

      Comment


      • #4
        Not necessarily great precision but enough for this sort of job:
        https://www.ebay.com/itm/Hex-ER-25-C...YAAOSwE19d~en2

        Comment


        • #5
          To hold a thread in a lathe chuck I get one or better two, scrap nuts that fit the thread and hacksaw one side of each so that when threaded on and in the chuck it is easy clamp the nuts down on the thread.

          I always tell myself that I should keep the cut nuts for future jobs but can never find them when the time comes!

          Comment


          • #6
            i think bc wants to grab it from the other end.

            Comment


            • #7
              It would be a good idea to make a set of sizes and mark the outsides with the thread size. You never know when they will come in handy, but they could certainly be time savers.

              Comment


              • #8
                Originally posted by MattiJ View Post
                I use ER collets and ER chuck arbor if I'm picky about not marring the thread.
                ...
                Why doesn't the collet mar the threads?

                Comment


                • #9
                  This is what I use:
                  http://mikesworkshop.weebly.com/loose-chuck-jaws.html

                  Comment


                  • #10
                    Originally posted by dian View Post
                    i think bc wants to grab it from the other end.
                    Eggzactly. Apparently I should have included a picture of the setup in the lathe to make this clear. See below.

                    In the case of the first picture the head of the carriage screw used for a wood work project is bigger than the hex size of a nut. So the option shown in the second picture isn't possible.

                    The method in the second picture is one I've used for bigger sizes. But unless the nut is slit and then padded with a strap of shim stock around it to squeeze down it's not a great method. Side the play in the threads lets it rattle and shake around. Results are often messy unless the nut on the nose is slit and then padded with some shim stock wrapped around it to ensure it gets squeezed down.

                    The third method with an allen cap head and a slit nut DOES work fine. But, in smaller sizes can be fussy to achieve a nice centered grab. 1/4" or 6mm is about as small as we can go without a bunch of fussing such as holding the stub of the screw in a drill chuck while tightening the 3 jaw around the slit nut. And that's where these holding buttons come in handy since it's just spin in the screw and chuck it up. Plus small nuts I've found are not always all that axial. And they don't always squeeze down and then let go again.

                    And by now you must be recognizing that a collet won't work at all. The head on the shorter screws is obviously in the way.

                    Drmico, I'd never seen that setup. It's a brilliant design but a LOT more work than just making a set of holder buttons for the scew sizes needing it. And for the size of my chuck I'd need to find some1 1/2" hex bar at least. And really to ensure wide enough sides for the screws it should probably be 1 5/8 or 1 3/4". And something like that isn't all that common around here.

                    Click image for larger version

Name:	P1030638.JPG
Views:	672
Size:	92.6 KB
ID:	1864852


                    Click image for larger version

Name:	P1030639.JPG
Views:	618
Size:	92.2 KB
ID:	1864851


                    Click image for larger version

Name:	P1030640.JPG
Views:	621
Size:	93.9 KB
ID:	1864850


                    Attached Files
                    Chilliwack BC, Canada

                    Comment


                    • #11
                      When the shortened screw will be long enough , I use a threading die( the solid re-thread die won't work). Turn the screw into the die, chuck the die firmly but not tightly part way into the chuck.. Push the die into the chuck with the tail stock, then tighten the chuck. The screw will run as true as the chuck does. I do this also with a 7/8-14 die to shorten reloading dies. Dies are always at hand.
                      Mike

                      Comment


                      • #12
                        Originally posted by old mart View Post
                        It would be a good idea to make a set of sizes and mark the outsides with the thread size. You never know when they will come in handy, but they could certainly be time savers.
                        That's the plan. By the time I make up a set for all the sizes including some of the extra fine series for my home gunsmithing projects I'll likely have a set of around a dozen sizes. That'll cover me from #6 up to the 1/4" sizes and the two common smaller metric sizes of 5 and 6mm.

                        I may or may not do the same but in a bigger overall size for 5/16 and perhaps 3/8. And a couple of my fairly common metric sizes of 5 and 6mm. But after that I'll just use split nuts with a wrapped strip of shim stock. Or if I need to do enough screws to justify it I might make a split button for some project to suit whatever size.



                        Dian, you asked about how centered it holds them. I was curious too so I just checked.

                        Now my chuck is fairly badly bell mouthed at this point and I really need to rig up a tool post grinder and fix that. So I tried two different screws with smooth upper shanks screwed in from the front. This showed me that most cheap screws are not all that well made and run pretty wobbly to start with..... But I ran the thread in close to the end and indicated off the smooth portion right near the thread. I tried two different screws in all three possible positions for the button in the chuck. For each screw I saw a low end runout of .005 and .006". The other two positions were higher with both showing me a max of around .013 in one case and .016 in the other. So not great.

                        I should note that the button that started this was fully machined other than the front face in one grip. And that the thread was well started with the tap in the tail stock. So the threaded hole and the OD of the button are all coaxial.

                        I think I'll do a bit more testing and see if the .005'ish run out for a few different screws occurs in the same position. It may well just be swarf in the scroll at this point. It's been ages since I took the three jaw apart. But if I can nail down one position as being the most accurate with good consistency I'll make note of it and use it each time. And of course that's likely to change once I finally touch up the jaws to get rid of the bell mouthing.
                        Chilliwack BC, Canada

                        Comment


                        • #13
                          Originally posted by Der Ami View Post
                          When the shortened screw will be long enough , I use a threading die( the solid re-thread die won't work). Turn the screw into the die, chuck the die firmly but not tightly part way into the chuck.. Push the die into the chuck with the tail stock, then tighten the chuck. The screw will run as true as the chuck does. I do this also with a 7/8-14 die to shorten reloading dies. Dies are always at hand.
                          Mike
                          That's a slick idea Mike! It would be a valid use for some of the super cheap dies that come in a $20 tap and die set.

                          And I would not lose any sleep at all over slitting the solid dies with an angle grinder and thin cutoff disc then heating them to a nice electric blue temper to make them less "cutty" and more springy for this use.

                          You might just have changed the direction I'll go for the regular sizes.
                          Chilliwack BC, Canada

                          Comment


                          • #14
                            What I have been doing to shorten mainly the threaded end of small machine screws and most of these have had socket heads is -
                            I get a piece of round stock somewhat larger in diameter than the head of the screw and drill and tap down an inch or more for a setscrew that is the closest size to be larger than the diameter of the screw head. I then part it off about 1/8" past the bottom of this hole then drill and tap from the parted end to the size of the machine screw I want to shorten. Screw the machine screw in through the larger hole and lock it with the set screw. Put it in the chuck and machine away. Although I haven't done it, you could probably screw it in the other way if you needed to work on the head end. I have a selection of these now as I have been making them as the need arises .
                            Larry - west coast of Canada

                            Comment


                            • #15
                              Larry, that's a great idea for the cap screws and for the fillister head gun screws. In particular the smaller sizes. I measured and 1/4" cap screws would need to use a 3/8" set screw into an oversize hole that only has about a 40% thread depth. But I think it would work. The smaller number size machine screws would get by with smaller set screws.

                              The downside for doing fillister head slotted screws for the gunsmithing though would be the mark that the set screw would leave on the head. I'd have to put in a little button of brass or aluminium to avoid that. Not undoable by any means though.
                              Chilliwack BC, Canada

                              Comment

                              Working...
                              X