Q re: 3/8 x 27 die

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I am attempting to make some parts for an old Craftsman scroll saw. In a couple of spots, the threads are 3/8 x 27 tpi (not 24). I have a die in this size, but it is tapered for pipe threads and won't work. No local store carries a die in this size, so I am force to purchase on-line. The link below appears to be what I need and is marked 'special thread'. Is this the correct die for these old threads (50's era?)

http://www.amazon.com/Special-Threa...TF8&qid=1340586655&sr=1-5&keywords=3/8+27+die

Thanks. Jim
 
The "special thread" just refers to the fact that it's not a standard pitch size. Here's a good description of the types of dies:

http://www.icscuttingtools.com/Dies.htm

So if you're certain that its 27 tpi you want, that die will cut it. And since it's adjustable you can tweak the diameter a bit over/under if need be.

And that price on Amazon seems pretty good - the same die on MSC is closer to $22.
 
I learn something new everyday. I didn't think it was possible to get a die in that oddball tpi. :thinking:
 
Sometimes seen in the threads mounting switches.
 
The story is that when houses 1st went electric they were already plumbed with 1/4" pipe so 3/8 x 27 was used to make fixtures compatible and it has stuck around as defacto lamp part thread.

Steve
 
I was going by memory but now that you mention it I think you are right.

Steve
 
I use 1/8" 27 bspp all the time and it is afull close to 3/8.
 
swatson144 said:
The story is that when houses 1st went electric they were already plumbed with 1/4" pipe so 3/8 x 27 was used to make fixtures compatible and it has stuck around as defacto lamp part thread.

Steve
Click to expand...

Actually, lamp threaded stock is 1/8-27 NPS and will measure around .388 or so--not a real precision part.

Regards
Bob
 
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