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  • Ttmttmttmt

    Tools to make tools to make tools, etc.

    Got back on my tapping stand project again. This is a converted shoe sewing machine, which now is basically a horizontal table with a vertical spindle. The spindle doesn't rotate, but it can be raised or lowered and fixed in position. Surrounding the spindle is a rotating tube which will hold the tap head. This part can slide up and down freely and can be rotated by hand easily. It's held in the uppermost position by magnets, so you can mount a tap, then the workpiece, then slide the post down to bring the tap into contact with the workpiece. Turning it by hand it will easily follow the threads up or down. The fixed spindle keeps the alignment. A movable vise sits on the table and can be clamped down in any position. I'll use some kind of x-y system for this, probably not screw-driven but push by hand to align the hole under the tap, then clamp down. Not very critical in these slideways.

    I see that I have the makings of a tap holder partly fleshed out- four swiveling jaws that remain in contact while being rotated. The end result of this is a square hole that gets large enough to hold a 1/2 inch tap tang and small enough to hold a 4-40 tang. This all looks good, but it seems like a weak point. I have several tap holders, but my favorite is the two bars with an angled notch near one end. These get clamped around the tap for a very solid grip, and the length of the bars becomes the handles. The depth of the notches is made to suit the tang square end, so that basically means a full contact area on all sides of the tang.

    Now I want to make some shorter bars, with notches depthed to suit, and these would be bolted to the tap being used. Then this assembly gets bolted to what might be called the faceplate on the movable tube. I could make a few of these clamping bar sets and probably leave them attached to some taps that I often use. The faceplate would have arms that you rotate the tap with.

    I see that most taps have either a point on the end, or a divot to define the rotational axis of the tap. One way or another, I'd like to be able to center a tap with ease before bolting the holder up. This is my current snag. Because there are different tang sizes and styles, I can't see any easy way to do this each time. Perhaps I should make the holders first, clamp them to a tap, center the tap in the lathe, then turn the holder round. Each holder would be turned to the same diameter, then a recess on the tap head would automatically center the tap as it's mounted. That would work, but it would be a bit dicey turning the holders when the tap is a small one, like a 4-40 for instance.

    Just trying to come up with an elegant solution here.
    I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

  • #2
    So many words and no pictures. Tsktsktsk.
    Cheers,
    Gary

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    • #3
      My little Cedarberg tapping frame holds hex collets, which have a round hole with square end to hold the taps. Works well.

      I made the collets from hex stock, drilling through with a small drill, almost through with a drill to fit the shank of the size, and filing the squares. There are 6 collets to hold sizes 2 to 5/16".

      Having a guide section on the shank is far superior to only holding by the square end.



      Last edited by J Tiers; 02-08-2015, 08:07 PM.
      1601

      Keep eye on ball.
      Hashim Khan

      Comment


      • #4
        'Having a guide section on the shank is far superior to only holding by the square end.' Hmm, good idea. This gives me other ideas for the holders too-
        I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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        • #5
          You can hold the square top end by drilling and tapping through the hex where you want the top of the tap to be and put in 2 setscrews to hold the square part. Just slide the tap into the hole until the ss can tighten down on the square.

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          • #6
            That's what I was thinking, though I'd probably use square stock to start with- fours nice sides to give stability to the holder for the drilling and tapping operations. Center in four jaw to drill and bore for the shank. Probable drill and tap for four holders in one length of material before cutting it into individual holders. I'd be inclined to use four set screws, making the ends flat and chamfering them to give maximum area of contact to the sides of the square on the end of the tap- in other words making sure the four setscrews can come close enough together to grip the tap on all sides.

            If I'm lucky, the tube I used is large enough inside diameter to take a one inch square inside it- then I can clamp four pieces of flat bar to a piece of this square bar, machine the outside round to fit the tube, then fasten the resulting arc-shaped pieces inside the tube to make a square home for the tap holders.

            I'm kind of liking this idea.
            I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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            • #7
              No reason to go crazy with setscrews. The ONLY function of the square is to drive the tap. All the alignment is via the shank hole. In my case, careful drilling, and use of a set-tru Buck 3 jaw got it good enough for my purposes.

              So the square does not need to have any special super accuracy. Filing will be entirely suitable, and works quite well.
              1601

              Keep eye on ball.
              Hashim Khan

              Comment


              • #8
                JT, how do you hold the taps in the holders- or do you at all?
                I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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                • #9
                  Ok, I have settled on a design and am partway through it. Instead of a holder with set screws for each one, it will be one holder with set screws. There will be two sets of set screws, one set having smaller faces to suit the smaller taps. The holder will become a permanent part of the guide tube, with the handle permanently mounted to it. The holder is bored to .618, and individual guide bushings will be made to fit that. Each bushing will be bored to suit a tap shank size. A bushing will be slipped onto a tap, then pushed into the holder- set screws are then run in to lightly contact the flats on the tap, then fully tightened.

                  The holder bore size is arrived at using two criteria- one is that the largest tap I'd ever be using has a shank size of .598, meaning that I can use 10 thou material rolled into a tube as a bushing for that one. The second criteria is that 5/8 diameter stock can be used to make the bushings, with little material needing removal to make it fit. I'll bore the ones meant for taps larger than 1/4 inch, and carefully drill the ones for smaller taps.

                  Because there will be just one head, I took the time to very carefully machine and bore it, then drill and tap for the set screws. Part of the length is turned down for a press fit into the guide tube, and I'll probably use JB weld as a lube for the pressing. Once the JB cures, I'll drill through the guide tube and into the head, tap for bolts. These bolts will attach the handle and will ensure that the head must rotate with the handle and can't come out.

                  I'll post some pics when it's something to look at.
                  I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

                  Comment


                  • #10
                    Originally posted by J Tiers View Post
                    My little Cedarberg tapping frame holds hex collets, which have a round hole with square end to hold the taps. Works well.

                    I made the collets from hex stock, drilling through with a small drill, almost through with a drill to fit the shank of the size, and filing the squares. There are 6 collets to hold sizes 2 to 5/16".

                    Having a guide section on the shank is far superior to only holding by the square end.



                    That is how I made mine up except I used a old hand drill press converter for my base. I drilled my rod out to fit the collets and use a set screw to hold them

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                    • #11
                      About the handiest things I ever made for tapping ( I do most of my tapping on the mill ).



                      ...lew...

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                      • #12
                        Originally posted by darryl View Post
                        JT, how do you hold the taps in the holders- or do you at all?
                        Most fit well enough not to need anything but a smear of grease. I had a plan to put in a rubber plug friction holding system, but have not bothered. The holders are held in the device by a spring ring.
                        1601

                        Keep eye on ball.
                        Hashim Khan

                        Comment


                        • #13
                          I have this set: http://www.amazon.com/Lisle-LI70500-.../dp/B0002SRFOE. Simple not too expensive. Standard 3/8" drive.

                          bob

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                          • #14
                            Originally posted by rowbare View Post
                            I have this set: http://www.amazon.com/Lisle-LI70500-.../dp/B0002SRFOE. Simple not too expensive. Standard 3/8" drive.
                            Great link Bob, thanks. Got a set on the way!
                            Milton

                            "Accuracy is the sum total of your compensating mistakes."

                            "The thing I hate about an argument is that it always interrupts a discussion." G. K. Chesterton

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