Saturday, March 29, 2014

Reversing Tap Attachment For MT2 Drill Press

A reversing tap attachment is something that replaces the drill press chuck on your drill press so that you can tap under power, but as soon as you release the handle, it reverses and backs out.  This is becoming a necessary attachment, because I am working on my first bulk order (five ScopeRoller sets) for a telescope dealer in Orange County.  Tapping in a drill press by hand is very slow compared to using a reversing tap device (and a bit hard on my left arm's tendons).  I have to tap 1/4"-20 holes in 1/8" aluminum (which is pretty quick) and 3/8"-16 or 1/2"-13 holes in 1" thick acetal (which is really slow).  I have tapped at 200 RPM in the drill press, but reversing the tap by hand turns out to wipe out nearly all the advantage of being able to power tap down. 

Harbor Freight used to sell a reversing tap attachment for the drill press that I have, which is an MT2 spindle, but no more.  Any suggestions on what I should be looking for when looking to buy such a reversing tap attachment?

Another possibility: hand tap the first few threads in the drill press, thus getting the starting threads exactly square, then use a reversing drill to tap the rest of the way.  It sounds so inelegant.

UPDATE: When I look at the costs of the various reversing tap attachments, and that I might need two different sizes to handle 1/4"-20, 3/8"-16, and 1/2"-13, the cheap alternative works pretty darn well.  Hand tap in the drill press for three to four threads to get the starting threads square to the surface, then use the tap in my reversing drill to finish the process.  The drill has enough power to finish cutting in acetal (which is the only material that requires the 1/2"-13 threads), and reverses out nicely.


  1. Based on an internet search, it looks like Grizzly tools has an MT2 tapping chuck:

    Best of luck!

  2. When I worked in a machine shop eons ago, we used one of these.

  3. They also make smaller, less expensive models.

  4. I STRONGLY recommend that for any precision work you not use a reversing tap attachment for a drill press. You're going to end up stripping holes and breaking taps a lot.

    My recommendation is a mill drill with a reversing function. I have one myself, from Grizzly... worth every penny.

  5. The Cadillac is the Procunier, next is the Tapmatic. Check Ebay, that's where I bought my Procunier. Just make sure the shank will fit your drill press, and use normal Ebay precautions.

  6. I had a nice tapping attachment, but had no use for it. Had a fella sell it on eBay, it brought <$10.00, IIRC. I was sick.

    I do my tapping in the Bridgeport, which as a VFD driving the motor.

  7. Jim: I am glad that SOMEONE made out like a bandit on that. You would not think it looking at eBay prices for such attachments today!