If you're going to use my technique for centering work in the 4jaw...
it's a good idea to have what I'll call an "elephant foot" tip on the dial indicator. This way you don't need to worry about having the DI axis exactly in the plane of the lathe axis.
I had been using the baby elephant foot from a set of points I bought, something like these...
but it was required in another application so I had to make an adult foot to replace it.
Normally I would turn a 0.112" stub on a piece of steel and use my 4-48 die to thread it. However, my die seems hopelessly dull so, until I can sharpen it or buy a replacement, a different approach is required.
I turned a 3/16 stub 1/4" long on a bit of 1/2" steel. Then I drilled the stub #42 (0.0935") and tapped it 4-48 with a good tap, followed by a bottoming tap I'd made from another 4-48 tap. I then threaded a 4-48 screw with some Loctite 609 on it into this threaded hole. Cut the screw to length with a jeweler's saw and deburred with a Dremel sanding disk. Voila, an elephant foot for my DI.
Two remarks here...
This approach to creating the threaded stub actually has two advantages over using a die. The threads automatically extend right up to the end of the foot so it can seat flat against the end of the DI probe; there's no need to undercut the thread next to the foot. Also, it's a more economical approach for folks on a budget who might not want to spend the money for a die they'll only use rarely.
The elephant foot can serve in lieu of my flapper, shown here with my older DI mount...
when working with small diameter polygonal stock.
Last edited by mklotz; 07-05-2017 at 03:50 PM.
Great add-on to the kit Marv, Thank You! However you got me with "However, my die seems hopelessly dull so, until I can sharpen it..." I've often wondered if this was possible and here you are saying it can be done. I wouldn't know where to begin such a task on a hard die. Could you please explain how to do this. I am sure this would be a great topic here for all of us cheap and cheerful DIY'er, especially in lieu of tossing it and buying another.
Thanks Much, ~PJ
Paul Jones (09-23-2016)
Well, I'm something of a Neanderthal when it comes to sharpening so the "real" machinists may take me to task...
I mount a small cylindrical stone in the Foredom and insert it in the swarf clearance holes in the die, carefully grinding the leading edge of the teeth that can be reached. Doing this for each hole improves performance enough to satisfy me.
Thanks Marv! Unfortunately I'm not a real machinist but do love sharpening and pretty good with it most of the time all the way up to my 27" Katana and pretty much anything else...but gouge angles . Just made a shallow hollowing tool for a wood working guru friend and he's way happy...now the hard compound bend ones and why the interest in your bender.
Never really thought about the cutting geometry of a threading die but your method makes good sense to me. If I can get a couple more runs out of them it would be great. I'll give it a try on some to see if I can do it. Thanks Much! ~PJ
To Marv & PJ's, and any other interested economical types, or anybody at 2:30 in the morning.
It's exactly how we'd accomplish that. On larger dies perhaps a jig grinder, or by hand, over an inverted spindle and table; like a router. Only the leading edge guys, and in small increments! Usually first tooth is chipped at side or top - warrants close examination. Stay away from perimeter where hole and OD are close. Those puppies are brittle.
...we'll learn more by wandering than searching...
Thanks TM, Good to know and a good tip about the chips...I've found that too looking closely. ~PJOnly the leading edge guys, and in small increments! Usually first tooth is chipped at side or top - warrants close examination.
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