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Posted by Don Young on April 28, 2008, 9:53 pm
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>> I have been using a Mastercraft 6-32 die to cut thread on a 1/8 welding
>> rod
>> to use (a small section of) as a gnomon for a miniature sundial. No
>> problems. Today I had the bright idea to use a diamond drill bit with the
>> round head worn out and a 1/8" shank in a similar fashion.
>>
>> Not only could I not make any impression on the drill bit with the die
>> but
>> when subsequently I tried the same die on the usual welding rod, it would
>> not cut at all. To all intents and purposes the die is dead.
>
> Out of curiosity -- is the die hexagonal in shape? If so, it is
> what is commonly called a "rethreading die" -- high carbon steel, not
> HSS (High Speed Steel), and make for cleaning up damaged threads on
> something which already has been threaded once.
>
> Not sure about what the shank of your diamond drill is made of.
> Some would be mild steel brazed or welded to harder steel, and then
> coated with the diamonds and a metal film to hold it in place. Others
> may have been started from HSS.
>
> But also, the diameter of the shank may be a bit larger than the
> welding rod. Hmm ... a 6-32 should fit a 0.138" clearance hole, and
> thus be just a little smaller -- not as small as 1/8".
>
> Anyway -- before you try your replacement (and hopefully HSS)
> round bodied die on it -- you should first see whether you can file the
> shank with a standard metal file. If it just skates over the shank, you
> can't thread it with your die. The only way to thread it would be to
> grind threads into it -- a rather expensive thing to set up to do.
>
> Good luck,
> DoN.
>
> --
> (too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
> --- Black Holes are where God is dividing by zero ---
I know that the re-threading dies I see for sale now are hex shaped. I don't
know if there is a later standard for die shapes but I have quite a few hex
and 12 pointed dies that are not rethreading dies, including a complete set
of HSS taps and split-adjustable dies bought from Snap-On. I think they were
made that way so you could use a box wrench or socket to turn them if
necessary.
Don Young
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>> rod
>> to use (a small section of) as a gnomon for a miniature sundial. No
>> problems. Today I had the bright idea to use a diamond drill bit with the
>> round head worn out and a 1/8" shank in a similar fashion.
>>
>> Not only could I not make any impression on the drill bit with the die
>> but
>> when subsequently I tried the same die on the usual welding rod, it would
>> not cut at all. To all intents and purposes the die is dead.