Awl --
or, 3/8-24 saga....
My buddy had a job that required two tapped holes, one a 3/8-16, the other a
3/8-24, through 6061, a 5/16 wall or so.The problem was, all his tapping heads were broke, and tapmatics are miserable-expensive to fix, so natcherly he comes over to my place, with everything done, except the tap.
Me: Fuuuuuck, you mean we gotta *line/indicate shit up*?????
Ackshooly, it turned out pretty good, the cut taps worked well, rigid-tapping these.
Until he mis-fixtured one part and broke the 3/8-24 tap.
A couple days later, with new 3/8-24 tapS, the job is running again, re-indicated, but the 3/8-24 tap is now leaving the threads ragged. WTF????
He solved the problem by bringing over a couple of aluminum tapping potions, slowing the job down rapid-wise, and applying the stuff by hand, whilst brushing off chips, which seemed to do the job. The tapping feed/speed remained the same.
Which seemed to indicate, to me, that the new taps were just different enough from the originals, that perhaps my 6-year old soluble oil was not quite, uh, cutting it. :) Can't really think of anything else.
BUT, my idea was this:
IF, for some reason, indication/hole alignment was also a part of the problem, I wanted to put each piece in a regular machinists vise, set this on top of the Kurt movable jaw, re-toolcal the tap, and just let the spindle/tap "find the hole", as you would on a drill press with a tapping head.
AND, you could still have the spindle "dip" the tap in the tapping fluid du jour.
The only real diff that I see is that there would be no reversing clutch. And yeah, a little bit of a safety issue, with no clutch, but any risk could be minimized by just not using too big of a tap in too deep of a hole.
Has anyone done this? Is it viable, in a pinch? Clearly, one limitation is volume, since now yer doin one'sies, which is why my buddy preferred the fixture, which was doing four'sies.
Also, the tapping preparation in fadal's rigid tapping is a fairly slow li'l dance, but the subsequent holes within that tap cycle go much much quicker, so as many holes as you can stick in one cycle, the better off you are, time-wise.
But it seems to me like this is a viable semi-manual option, esp. with perhaps cast pcs that can't be held with great repeat-ability, or other difficult-to-fixture stuff.
Esp. if you ain't got no working tapping heads around.