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#7-30 Threading Die

thestelster

Ultra Member
Premium Member
HELP!!

I am hoping that someone might be able to lend me a #7-30 threading die.

A little while ago I purchased a Starrett No.995 planer gauge. It's missing a couple of accessories which I would like to make. Starrett uses odd size screws, and my lathe doesn't cut 30tpi. (I plan on making gears for it in the future.)

I found a die online, but they discontinued making it.
 

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Bizarre, hate when they do crap like that. Working on a Record plane and threads on it (holding the handles on) are 7/32 20. Grrrr.

So you actually found a use for a planer guage? Do tell! Semi-joking, I've got one but can't remember when I last touched it. I think it has the accessories if you need anything measured/photographed
 
I was planing on using it to hold an indicator while on the surface plate.

I have a Starrett height gauge that I use but its 18" tall, so I wanted something smaller, more portable.
 
See if you can find a #6-30 adjustable die:

20240426 6-30 Die.webp


My guy at Starrett once explained to me that legacy tools (and many of the current versions where they haven't made any changes) have "odd-ball" threads because they didn't standardize parts when they were first developed. The topic came up when I was trying to figure out what the threads were on a PT13820 (called out as "380"); part of a 196A1Z Kit:

20240426 Starrett PT13820 no380.webp

The threads are 28 TPI, but larger than 12-28, and I wanted to make a longer rod. The Starrett specification is 0.231"-28, so I turned the end of a rod to 0.231", got a 12-28 adjustable die and opened it up until it produced full threads on the new diameter.
 
My guy at Starrett once explained to me that legacy tools (and many of the current versions where they haven't made any changes) have "odd-ball" threads because they didn't standardize parts when they were first developed.

Believable, but if the only reason for doing something is "we've always done it that way", well, it's not good.
 
Believable, but if the only reason for doing something is "we've always done it that way", well, it's not good.
Maybe, but seeing as how Starrett instruments last a really long time, it’s good to know that repair parts will fit the old and new ones.
 
More info: ASME screw threads.
 

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Any chance that old book can be found as a pdf?

And what's with that dumb title? I bet there are more machinists than machinist's apprentices who have and use the book.
I was thinking the same thing.

Here is the link to the 1st Edition.

 
Yeah I looked through like 100 small dies and I don't have a single 7. I have dozen of 8s and dozen of 6 and 5s etc. but not a single 7. This is very rare indeed.

30 is also not a very common number, this is why maybe lathe is not set to even cut this.
 
Yeah I looked through like 100 small dies and I don't have a single 7. I have dozen of 8s and dozen of 6 and 5s etc. but not a single 7. This is very rare indeed.

30 is also not a very common number, this is why maybe lathe is not set to even cut this.
Thanks @Tom Kitta , I really appreciate you looking. Apparently, they stopped using #7, #9, #11 in the 1920's. I think I'll order a #6-30 split die and open it up to #7 like @ChazzC mentioned.
 
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