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Taphead ?'s

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  • Taphead ?'s

    I've a got job coming up that needs 320 4-40 holes drilled and tapped in aluminum. More than likely 6061, but we shall see. I've done some hand tapping in the past and I'm willing to hand tap all of these if necessary, I'll just call it payin' my dues, but in rooting around the shop I found this stuff ....

    The part on the left threads in the top of the taphead and there is a J-Head BP in the shop. Maybe it went up the snout of that? In any event that part's actually 2 pieces that I have yet to separate, but I'd like to mount up on my drill press here at home anyway. Call that a "just curious" question.

    My DP is an old Craftsman with a Jacob's 633C chuck on it and I know for a fact it has a taper. Nothing at Sears or Jacob's I've found yet tells me what taper tho. Meanwhile the taphead has a 5/8-16 hole ..... Some kind of adapter?

    Now I know any number of you guys would fire up your lathe and just whup one out, but it's a little early in my career for that!

    As a matter of fact I'm having trouble getting the chuck OFF the DP. I put it on a new quill 20 some years ago, hasn't been off since, and it ain't wanting to leave now. Most of my experience with tapers is automotive related but I don't think my favorite BFH is gonna help me on this one. Any tips?

    Like most of the objects in this shop the taphead has no ID on it. The word Procunier got nothing but blank looks. Tapmatic rang a faint bell with someone tho so I suppose that's possible. No clue on a Model # but I'd like to know.

    There's what I believe is called a Tap Cap on the bottom of the head. The rubber collet deal I found there accepts 1/2". To the right are the associated 1/2" holders for taps with 1/2 or 3/8 shanks.

    I also found the Jacobs Tap Cap on the far right laying loose. It claims to accept 5/16 to 5/8 holders. Has a 5/16 rubber in it now.

    None of which will be useful for 4-40 work tho ..... and that's all there is.

    Sorry to be so helpless guys but I'm far from hopeless. Any advice on where and what to buy to get these holes done would be real useful.

    Thanx in advance.


  • #2
    You can get rubber flex collets that will accept smaller taps for that tapping head. Sometimes that style of tapping head has a torque limiter on it which helps from breaking taps.
    Are these holes through holes? Use lots of cutting fluid.


    • #3
      The tapping head is a Tapmatic. Information here;

      The current model number may differ from what you have, but applications are the same.

      The collets are available from most tool houses, although I believe Jacobs no longer makes them. You will probably need a smaller collet for the #4 taps.

      You should also be able to get a straight shank for the head to permit use in the drill chuck. For the smaller tap sizes, this will work without slipping and may be simpler than going to the trouble of removing the existing chuck. Unless there is a MT mount in the drill spindle, removing the chuck for installation of the tapping head is not worth the problems involved.
      Jim H.


      • #4
        Hand tapper

        4-40 is pretty tiny to machine tap with a head that large. Used to be able to buy a small head that is ideal for your part for about $200. I'm guessing that the job won't have much profit with an expense like that. I have used the small hand tapping machines in the past (maybe a Black Diamond? it was much larger than the cheap ones that Wholesale Tool or Travers sell), I don't have one yet, but if I come across another set of 8-32's in A-2 tool steel I will! They have the advantage of being very square and giving a good feel for what the tap is doing. They consist of a base plate and arm with a sliding spindle and tap holder driven by a tee handle manually. This makes them much faster and less likely to break a tap than free hand. Buy a bag of taps, keep a sharp one, the most frustrating thing is going to be breaking one off in the last hole and scrapping a part (I guess you don't have a tap disintegrator? Neither do I).


        • #5
          You guys are right on all counts.

          It is a Tapmatic Model SPD7 and yes, it's too damn big for #4's! It's rated and collets are supplied for #10 to 3/4". In 1010 steel even.

          What I need is an SPD3 with a JT33 taper mount, but I'm probably gonna wind up twistin' my wrist.

          We'll see. Thanx again.



          • #6
            You didn't say if that was aluminum plate and these are thru holes. If they are, with that many holes to tap I'd definitly try a hand drill and a scaled down version of this:

            If those aren't thru holes it looks like you're going to have some sore wrist from a hand job
            - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
            Thank you to our families of soldiers, many of whom have given so much more then the rest of us for the Freedom we enjoy.

            It is true, there is nothing free about freedom, don't be so quick to give it away.


            • #7

              I'd not be tapping that many holes by hand !

              3 suggestions:

              1. Use an old drill press minus the motor with a spoked round where the drive pulley went. This is provided you can fit the work on it. If not a spoked round, use an old gearhead servo motor and run it off a 12 volt wall wart. The weak motor will act like a clutch.

              2. Get a cheap ass 14 volt cordless drill with a clutch. HF has some that will do the job. Pretend the tap is a drill bit. Use some sort of a guide block too. Depends on the material thickness, shape, size etc. etc. Make something to guide the drill.

              3. Use a roll form tap and the appropriate drill bit. Those things work great ! No little chips to get out of the little threaded holes either !



              • #8
                Never did get specific about the materials did I? These parts are rails to assemble a circuit board onto and form a simple box type chassis. 1/4" sq bar stock that comes in 6' pieces. 1st I gotta cut to length. 80 pcs @ 8.43". Both ends have blind holes. Gonna use the lathe with a square 5C collet to drill those puppies straight. .250 min. threaded depth, and that will account for half.

                The other 160 are thru holes and I'll bet I can find some way to power those thru. Thanx for the ideas. Just about cut that job in half already didn't we?

                I am checking on a price for a suitable sized taphead but I'll bet it winds up being a hand job on them blind holes. I'm a painter by trade so I have absolutely no fear of repetitive motions. I can swing these arms all day. It's all in the wrist and having the ability to disconnect your brain .....

                SP aka "The Skinny Painter"