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Reducing T-slot Bolt Shank (without a lathe)

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  • Reducing T-slot Bolt Shank (without a lathe)

    Hello all!

    I purchased some new 5/8" t-slot bolts to hold down my Kurt vise from Fastenal. I ordered the 5/8" bolt as I have 5/8" slots in my mill table. The problem I have with the bolts is evident below - the shank is 11/16 and the threaded area is 5/8"...



    If I owned a lathe I would reduce the shank diameter a bit, however I do not own one. So, I am left to reduce the shank size another way. I could file them I guess, but that seems to be a time consuming venture. What would you do?

    Thank you!

    Andy

  • #2
    If the thread diameter fits the slot (apparently does), I would mount the bolt in the mill collet (perhaps a soft collet) and a cutting tool and holder or clamp in a vise on the table (vis-a-vis a vertical lathe per se) - but I have little experience
    Last edited by Mr-Mike; 01-13-2016, 07:30 PM.

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    • #3
      Easy, use the mill itself.

      Hold the threaded portion of the bolt in a 5/8" collet (assuming you have such a thing) and mount a lathe tool to the mill table, using whatever blocks, clamps and baling wire you have on hand.

      Then it's just a vertical lathe. Move the table in and out for depth of cut, and crank the quill down to feed.

      You'll have to take light cuts, as the collet probably won't hold well on a the threads, but a few passes of .005"-.006" at a time shouldn't take too long.

      Doc.
      Doc's Machine. (Probably not what you expect.)

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      • #4
        You're not concerned with accuracy nor concentricity here. Haven't you got an angle grinder?
        Brian Rupnow

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        • #5
          If your T-slots measure 5/8", the bolt should be 1/2"-13:





          The throat for a 1/2" bolt actually should be 0.562" and not 0.625", but the next larger 5/8" bolt calls for a 0.688" throat. But if the square head of your T-bolt fits the slots, maybe the throats of your table slots are undersize. You should be able to clamp the bolt heads in a vise and mill flats on the sides of the bolt to fit the slots.
          http://pauleschoen.com/pix/PM08_P76_P54.png
          Paul , P S Technology, Inc. and MrTibbs
          USA Maryland 21030

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          • #6
            Gents,

            I must say that I greatly appreciate your patience with what seems like very simple questions. I just have an odd need for as much "right" information as I can get prior to doing something. I asked the same question on Practical Machinist and one man asked if I had a sign out front of my house that said, "Dumbass Lives Here"... I would like to loosen the man's teeth, but instead I forgave him and expressed my disappointment.

            Thank you all again.

            Andy

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            • #7
              I have 1/2" hardware already. I bought a swivel base for my Kurt vise and the Kurt swivel base came with 5/8" bots to connect the vise to the base. I was just upgrading the size of the bolts that will hold the base to the table. I figured if Kurt sells the base with 5/8" hardware, maybe it was OK to upgrade the 1/2" stuff... maybe not.

              Andy

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              • #8
                Originally posted by Guncraft View Post
                I asked the same question on Practical Machinist[...]
                -You have to remember these are two entirely different boards. This one, as the name and magazine implies, is for home shop machinists. On the other hand, the owner of PM wants to keep that site "professional", and attract professional machinists.

                Neither one is "better" than the other, it's simply two different sides of the same coin.

                However, a fair number of "professional" machinists, I've found, have little tolerance of the home-shop types. In some cases it's the annoyance they they did a seven-year apprenticeship and spent years in college to get a document that officially declares them to be a Machinist, and then they see some guy with a cheap import desktop machine in his basement who also calls himself a machinist.

                In other cases, it's simply the typical rivalry you'll see in any undertaking. Ford vs. Chevy, Mac vs. PC, F1 vs. NASCAR. The guy that runs a thirty-foot-long machine that has metal removal rates measured in tons per hour looks down on the guy that's just building a little brass steam engine. You see it everywhere.

                Don't let it bother you. PM has quite a few helpful people (I'm one of them ) but like any other board- even this one- it has a few loudmouths and jerks. Don't let the jerks spoil it for you. They don't speak for everyone.

                Doc.
                Doc's Machine. (Probably not what you expect.)

                Comment


                • #9
                  Originally posted by Guncraft View Post
                  I have 1/2" hardware already. I bought a swivel base for my Kurt vise and the Kurt swivel base came with 5/8" bots to connect the vise to the base. I was just upgrading the size of the bolts that will hold the base to the table. I figured if Kurt sells the base with 5/8" hardware, maybe it was OK to upgrade the 1/2" stuff... maybe not.

                  Andy
                  Just mill (hey, use the mill!) two opposing SIDES of the shank, you do not need to make it "circular" - just two loose flats. I have two Kurt's on my mill with t-bolts done this way, and I believe are "factory"

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                  • #10
                    How can one live in indiana and not own a lathe!

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                    • #11
                      Whats wrong with a file? All you need to do is file 2 flats on the plain section so its a free fit in the sides of the slot. Does the head fit? If not, same treatment. Its done in far less than the time to set up in the mill, indeed less time than you've spent asking the question and reading the answers. It doesn't need precision machine work. Personally, I'd have bought 1/2" bolts for a 5/8" slot.
                      'It may not always be the best policy to do what is best technically, but those responsible for policy can never form a right judgement without knowledge of what is right technically' - 'Dutch' Kindelberger

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                      • #12
                        I already have 1/2" bolts and t-nuts. The dissimilarity f 5/8 and 1/2 hardware together got to me... No other reason that a want and not a need.

                        Andy

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                        • #13
                          Originally posted by lakeside53 View Post
                          Just mill (hey, use the mill!) two opposing SIDES of the shank, you do not need to make it "circular" - just two loose flats. I have two Kurt's on my mill with t-bolts done this way, and I believe are "factory"
                          Originally posted by Richard P Wilson View Post
                          Whats wrong with a file? All you need to do is file 2 flats on the plain section so its a free fit in the sides of the slot. Does the head fit? If not, same treatment. Its done in far less than the time to set up in the mill, indeed less time than you've spent asking the question and reading the answers. It doesn't need precision machine work. Personally, I'd have bought 1/2" bolts for a 5/8" slot.
                          how would one tighten the bolt?

                          Comment


                          • #14
                            Originally posted by Doc Nickel View Post
                            Easy, use the mill itself.

                            Hold the threaded portion of the bolt in a 5/8" collet (assuming you have such a thing) and mount a lathe tool to the mill table, using whatever blocks, clamps and baling wire you have on hand.

                            Then it's just a vertical lathe. Move the table in and out for depth of cut, and crank the quill down to feed.

                            You'll have to take light cuts, as the collet probably won't hold well on a the threads, but a few passes of .005"-.006" at a time shouldn't take too long.

                            Doc.
                            is that not that exactly what I said? Not wanting to be offensive, nor do I care about recognition, but I feel like I am in the twilight zone... Am I missing something?

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                            • #15
                              Originally posted by Mr-Mike View Post
                              how would one tighten the bolt?
                              Nevermind LOL.

                              This is good, would also prevent driving the bolt into the table.

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