Tuesday, August 30, 2016

The Tapmatic Reversing Tapping Head

A couple of minor struggles although with prompt, friendly, and helpful support from Tapmatic:

1. There's a retaining ring that holds the stop arm on the bottom of the head.  I could not figure out to install it, and the instructions gave no hint.  Retainer ring pliers: a tool completely unknown to me.  A neighbor used some very small end needle nose pliers instead to spread the ends enough to slip into place.

2. The collets that hold the taps seemed just a little too big.  I just needed to squeeze them manfully to get them into the housing.

I was able to run the tapping head sufficiently to power tap a 1/2"-13 x 1" deep hole in acetal.  When I released the handle, it reversed the tap.  It looks ugly to watch, but it works.

Not Tapmatic's fault, but the drill press chuck keeps falling out of the spindle.  This has been an intermittent problem for months, but the weight of the Tapmatic head combined with the rotational forces involved is aggravating the problem.  The proper solution is clean the arbor and spindle interior with acetone (or nail polish remover if only the local grocery store is open) and tap it back in with some vigor.  This isn't going very well so I am attempting to order a replacement arbor from Harbor Freight.  It appears the arbor is held into the chuck just by friction, and I should be able to tap it out through the open jaws.


  1. VERY carefully inspect all mating surfaces after cleaning.

    I just had a lesson on mounting a large drill chuck in my new-to-me T-586 Century drillpress. This thing is dated 1991, and appears new/unused. Turned out to be due to horrible runout in the original chuck, I suspect. A 1/2" drillbit had maybe .075" TIR.

    What I was shown was to get everything seated using a hardwood block and hammer. Then, spin it up with the motor (not too fast) and repeat the wood/heavy hammer (retract the jaws), smacking it firmly a number of times. Guy has a machineshop in his garage, and seems to know what he is doing. It now has a 3/4" chuck. Big, heavy sucker. Spindle had about .002 TIR. Arbor the same. New chuck about .003" TIR with long shaft.

  2. Yes, you can drive it out with a punch through the jaws. If it turns out to be a blind hole, you can drill it, usually. It's not held on with a screw in there, is it? Some of the smaller ones are.

    Btw, are you centering the tab on the end of the arbor in the slot at the top of the spindle? If not, that may keep it from moving deep enough into the taper when you tap on it. Theoretically, it shouldn't, but machining differences could.

    IIRC, you have the same drillpress. Have you checked the runout of that chuck? From what I've read about the oem chuck, most of them could be considered to be a simulated chuck (IOW, not for real use). If it has enough runout, that could be part of the reason for the arbor coming loose. Off-axis force, plus the g-forces of the off-center mass of the chuck and whatever you are holding in it (heavy Tapmatic!) could be your main problem. There wasn't anything wrong with my original arbor.

  3. Parallel jaw outside snapring pliers are not common, and about the most expensive non-powered tool you will find in a mechanic's toolbox. I bought one from the MAC tooltruck back in the early 70's, and it cost me over $40. Recently loaned it to my neighbor who was doing a brake job, and he lost it! Replacement cost is now about $70.

  4. Will: Thanks for the suggestion about tapping it in once turning. I have only been tapping it in with a rubber mallet when not turning.

  5. Will: You have a Harbor Freight drill press? This chuck seems to be a genuine Jacobs chuck.

  6. I have gone to the extent of warming the chuck before seating it on the arbor. In my case, it was an Albrect keyless chuck on an R8 arbor for my Bridgeport mill. That procedure finally kept it from falling off.

  7. I'm headed to imts in chicago next week. More than a million sq feet of machine tools and more.

    If there is anything you'd like me to look at for you drop me a note at Johnfajardohenry() Gmail. Com

  8. Central Machinery, #T-586, benchtop, 16spd, Taiwan, dated 1991, 3/4hp, 12amp. Coolant type rotating/tilting/crank elevating table. Originally had a -16L (5/8") chuck. Definitely NOT a Jacobs quality chuck!

    Looked like a good deal to start with, but after hours of swapping parts and measuring runout, and what I ended up swapping him for a good chuck, not so much. He got three oddball chucks and $30 to fix the problem. One was a small Spanish chuck, and the others were both 1/2", but neither could be mounted on this unit. I could have used them on my Bridgeport, since they had straight shanks, and I made the mistake of not checking them out before taking them with me. I was just hoping that one could be mounted on an arbor that would work, but he wanted them in exchange for his bigger chuck. He really wanted the Albrecht, but that was one I intended to keep for the mill, so he "settled" for all the rest.
    One had 4 jaws, and looked like a good one. Very nice condition.

    Just found it:
    1/32-1/2 Wahlstrom Automatic Chuck 1/2 Straight Shank # M1-94-SS0500 $310.44 (NEW) Cheaper on ebay, used.

    This allows you to change the bit while the machine is running!