Threading die question

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sundown57

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Years ago i was at a machine shop and the guy was threading pieces of rod on a lathe. but he was using something other than a die in a tail stock holder, if i remember right it was like a 2piece die that he clamped around the stock. not sure what im talking about but is there another, better way to cut external threads then a tailstock die holder? if so what's it called? thanks
 
definitely better is a releasing automatic die heat that used interchangeable sets of chasers, such as a Geometric die head or other similar typed, but the Geometric is the most common and easy to set up.
 
Geometric die heads work great, but they are expensive, and generally have a small range. A New head alone usually runs between $1,200.00 and $2,500.00 each depending on size. To thread up to 1" you generally will need 2 different die heads. Then you need all the thread chasing dies for the size threads you want to cut. A new die set for each size usually runs between $200.00 and $400.00.

This setup is faster, and in most cases more precise than a standard hand die and therefore preferred in a production situation. However, unless you can find the size head and accompanying dies from a used machine dealer the system is all but cost prohibitive for a hobbyist.

As a side note one of the used equipment dealers, I visit has dozens of heads and thousands of die sets in stock. I doubt he sells more than a couple a year because of the cost, and the fact that dies don't interchange to different brand heads.
 
yeah I've been searching all morning and am learning lots of different brands and lots of cutters but no matches. at least not used.
 
It may well have been an "antique" still in use. There are/were "screw plates" that split down the middle that could be clamped around the work. I'm not sure of the name but, in theory, several sizes could be cut to some particular pitch. I recently acquired some taps that were odd sizes, large machine screw threads. Aming them was a 1/2-16 tap. Such a thread could be easily cut with a 3/8-16 screw plate described. I have seen such a device but don't have one and no intention to acquire one.

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Here is an interesting video on a Die Head

 
There are also "thread restoring tools" such as those pictured. It may have been one of those.
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The second photo is for small screws. I have seen adverts for a larger version that was hinged longitudinally, like a tube flaring tool, but could not find a photo. The largest of those I have seen had a "die" for 10 TPI. In theory, it could be used for different sized screws (bolts). The "die" forms were crescent shaped such that for 16TPI, one could dress from ~5/16 to ~1/2.

They quite possibly were devised when screws (bolts) were hand made, akin to making a bolt on a wood lathe. The OD might vary along the length +/- 10%. Or even forged round. . . Such fasteners, while not common, were used where appropriate.

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ok, now I need advice. been looking for like 2 days. I see a lot of die heads and a lot of inserts. never all together. Is there one brand that is most popular and that I can still get inserts for? im looking for one that will tap like 1/4-20 - 1/2-13 or so. thanks
 
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