Some of you may recall about two years ago I designed a tension/compression tapping head, and built one prototype. The prototype was mostly ok, but had a runout problem, due to the way I made one of the parts on my crappy lathe. I ran out of time, and haven't gotten back to it until now. A few days ago, I made some design changes, and updated the prototype, resolving the problem. I am now in the process of making 6 more, so I can have all of my commonly used taps permanently mounted in ATC-friendly TC heads.
Here is a Fusion360 rendering of what it looks like:
And the on-line viewer for the design: A360
And the Fusion360 design file is below, in case anyone wants to make their own. Just remove the .zip extension, and import into Fusion.
I sacrified some cheap Chinese knock-off TTS ER20 chucks to make these. I first cut then in half, at the top of the ATC groove, then bored precision 0.495" holes in the center of the two halves. The 303 stainless "top cap" of the tapping head presses into the hole in the TTS shank, and has the remainder of the ATC groove machined into it. This cap has a 0.500" dia. x 0.500" high boss on top, making it a VERY tight press fit into the hole in the TTS shank. The ER20 chuck is attached in exactly the same manner to the 303 stainless 1/2" Hex shaft that provides the required sliding motion. The "housing" is just a short section of 1.5" thin-wall tube, and houses a set of springs that provide the tension and compression force, with +/-1/4" of travel from the rest position.
I should have all 6 heads up and running in a few days, once the springs show up...
Regards,
Ray L.