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A Little Success

Well I finished up a tool today that I've been wanting for some time. It's a basic tap starting alignment tool that can be clamped in a drill chuck, etc. A 1/2" diameter rod clamps into the drill chuck and a hollow cylinder with a tap wrench mounted on the end slides and rotates on the rod. This doo-dad could also double as a "sensitive drill chuck" in a lathe's tailstock.

The design difficulty I had was that I have two sizes of tap wrench and I wanted them both to mount onto the end of the cylinder. The large wrench has an O.D. of .75" and the small one has an O.D. of .375", so I bored out a .755" diameter socket in the end of the cylinder deep enough to hold the wrench. I then milled a slot through the socket wide and deep enough to accept the t-handle of the wrench, so that when seated in the cylinder, the butt of the wrench bottoms out in the socket while the t-handle bottoms out in the slot. For the smaller wrench I turned a collar .75" O.D., .380" I.D. and about .25" longer than the socket is deep. Next I milled a slot similar to the one in the socket, only for the snaller diameter t-handle. To use the smaller wrench I just slip the collar onto its end and then slip it into the cylinder. (I might cross drill and tap a small hole for a set screw in the collar and attach it permanently to the small wrench).

I got my first chance to try it out tonight on a chunk of steel that I'm temporarily using as a toolpost on my lathe. This chunk of steel is just bolted to the topslide and has a 1/2" wide and deep slot milled into its side to take 1/2" toolbits. Three 7/16" set screws clamp the bit from the top. I got tired of removing the thing each time I wanted to mount a boring bar (1/2" shank HSS) so I drilled a 1/2" hole in the side of this chunk of steel, rotated it

90 deg. and cross drilled a tap hole for 7/16-14. All of this was done with the work mounted in position on the topslide and the drill bits clamped in the 3-jaw chuck. Next was tapping the hole of the clamp screw. I chucked my new tap alignment tool in the 3-jaw and went to tapping the hole. It worked bee-uuu-tif-ully!! No muss, no fuss, no sidewinding threads! The t-handle cleared the ways nicely, even when extended to increase leverage.

There is a bit of slop where the cylinder slides on the rod, and that's because I could only drill the .5" hole and it's not completely straight, forcing me to turn the rod undersized. I should be able to ream the hole oversize a bit and make a new rod with a true slip fit. Once I get a reamer....

Now I'll have to dig out my knurling tool and make it pretty!

Reply to
Artemia Salina
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If you drill undersized and then single-point bore you get closer. If you use a piece of drill rod for the rod, then try to match it as close as you can get in machining the sleeve--that may be the way to get a good slip fit.

Half inch, etc. reamers should be common on the used market locally in CT.

Frank Morrison

Reply to
Fdmorrison

This was my first plan, but I realized that I didn't have a boring bar in my set that was long enough. I would've had to have bored half way in and then flipped the sleeve and finished from the other end. It seemed too error prone and I have very little spare stock for the sleeve.

I'm not sure what the steel is, some sort of high carbon stuff I think. It was in my junk collection. But although it is harder than mild steel the finish produced when truing up the OD was excellent.

The rod I'm using is an old grinding wheel arbor shaft that I bought from Sears hardware. Very inexpensive IIRC but the finish is outstanding when turned. I had a little left over so today I was practicing single pointing threads with it, and I remain impressed with it. The threads were smooth as silk with no tearing, even when viewed under a strong magnifying glass. The stuff is about 5/8" in diameter and about 8 or 10" long, overall. I mention this in case anyone is in a bind and needs short lengths of steel rod that has to give a good finish in a hurry.

I wonder if Al Babin is still in CT? :-)

Reply to
Artemia Salina

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