[SEL] Tap & Die Set Help Needed--OT

[John Hall]

A little late chiming in but here are my thoughts.
Are both oversize or is one over and the other under. My thought is someone 
was trying to make patterns/castings already threaded and possibly hoping to 
just clean the parts up with an on size tool after casting. I also thought 
if the tap is undersize and the die is oversize then maybe they were used 
for roughing with standard taps and dies used for finishing?

For what it is worth, all taps are oversize, at least real ones not made in 
China. They are designated with an H limit.  An H3 tap is .0015 oversize, an 
H6 is .003 oversize--for every number the H value increases, the tap 
increases .0005 in size.

Can't say I ever heard of an oversize die other than adjustable dies.

Oversized taps, as was stated earlier, are used often where shrinkage from 
heat treat, hard-coat anodize, or nickel plating comes into play. But we are 
normally talking just a few thousandths--not 31.

Someone also mentioned 12 pitch threads and yes they are still widely used 
on hydraulic cylinders.

John Hall




----- Original Message ----- 
From: "Dave Rotigel" <rotigel at alltel.net>
To: "The SEL email discussion list" <sel at lists.stationary-engine.com>
Sent: Sunday, March 12, 2006 1:13 PM
Subject: [SEL] Tap & Die Set Help Needed--OT


> Hi All,
> While at the Zolfo Show a week or so ago I picked up a nice old tap and 
> die set made by Wiley & Russell (Greenfield, Mass.) (It's got to be rather 
> old because the 1/2 " die indicated 12 threads per inch!) The set goes 
> from 1/4" to 3/4" and each die (while removable) has it's own handle! The 
> set is in a nice old wooden box measuring  37 1/4" X 10 3/4" X 3".
> Now my question. Each die has 1/32 stamped (or perhaps engraved) into it. 
> What does this 1/32 stand for/mean? Any help on this will be appreciated!
> Dave
>
>