Tapping fixture

What if the upper handle included a protrusion to add a portable drill for backing them out? Bad idea? I am curious about making one.

joe
 
Awesome work! You "fixed" one of my biggest complaints about 99% of the commercial ones: you can move the "arm" up and down, or swing it side to side. I got spoiled at work, we had a couple old SPI tapping fixtures similar to your design (though much shorter) that allowed you to slide the arm up and down or swing it around as needed. I found that I almost never used it "square and true," frequently wound up swinging it 180* out and clamping the table on to a work piece to tap a hole that was in an odd location on a large part, or to tap holes in the end of plates that were too tall to stand up in a mill.

I've spent more hours than I care to admit searching the internet for more of those old SPI tappers, but all you can find are the ones with a C-style solid frame like an arbor press. To me, that eliminates 99% of the utility you've built into yours, whether intentional or not. Good work!

As SLK001 pointed out, you may want to consider a more 'secure' way to hold your taps. Taps are obviously pretty hard, they'll have a tendency to slip in a drill chuck. You can cheat a little by drilling slightly over nominal holes, and always always always keeping the tap wet. If you get a tap stuck, you're halfway to breaking it, and everybody loves a good broken tap mid-project.

I've used these and wouldn't hesitate to buy them again. They've got a square broached in the "socket" portion that the tap seats into to prevent them from rotating. The taps are held in place by an o-ring, which is my one major complaint. No issues yet, but I can't see the o-rings lasting forever.

I've got a pair of these in my "field kit." They make a small and large size, but I can't find the small at the moment. A little more universal than the above kit, so you only have to worry about losing two. I use them when I've got to run a tap in a tight corner where I can't get a normal tap wrench. Always fun trying to tap an #8-32 on the end of a 12" ratchet extension!
 
I ordered the casting kit for a Universal Pillar Tool, but have not yet started the build. It was going to be a spring project, until I read the George Thomas book on it (which, btw, is highly recommended). Now I'm worried I cannot meet his exacting standards :)

The simplified takeaway from the book is: use precision ground rod for the main shaft, bore all the holes that have to be aligned (e.g. on the shaft) at the same time, and make it modular so you can swap out the tapping fixtures for, say, a sensitive drill.
 
Joe, I suspect using a drill to remove the tap would probably slow down the process considerably. I thought about machining a square drive on top and using a commercial taping handle to turn, but decided the shaft the thru the knob was just as good. Also, quite often, I find turning the tap out of the work helps finish the threads. So generally like to hand feed in both directions.

CuriousRambler, thanks. Didn’t know about these style tap holders. Just ordered a set from Amazon- half off! BTW, your right about the chuck. Doesn’t hold the tap well at all. Without torquing the head down with channel locks. So will figure out how to change it out when the tap holders arrive.

Thinwoodsman,,, yes, my biggest problem was aligning the bore on the end of the arm to vertical, before I welded the pieces together. Got pretty close with a Machinist square. But making the whole arm, then boring both holes as one fixture on the mill likely would have been better than turning each piece on the lathe and welding afterwards.

Thanks all,
Glenn
 
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