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

Andy Glines andyglines at hotmail.com
Mon Mar 13 12:50:39 PST 2006


>    1. Tap & Die Set Help Needed--OT (Dave Rotigel)

>
>Message: 1
>Date: Sun, 12 Mar 2006 13:13:34 -0500
>From: Dave Rotigel <rotigel at alltel.net>
>Subject: [SEL] Tap & Die Set Help Needed--OT
>To: The SEL email discussion list <sel at lists.stationary-engine.com>
>Message-ID: <6.1.2.0.0.20060312125106.02659e90 at mail.alltel.net>
>Content-Type: text/plain; charset="us-ascii"; format=flowed
>
>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
I suspect that the 1/32 oversize set is exactly what Paul's friend used them 
for.  Before we had helicoils and arc welding the easiest way to fix a 
damaged threaded hole would be to put oversized threads in it.  If you tap a 
hole oversize you will need the dies to make a new bolt to match.  We do 
this on steam boilers sometimes.  If the threads go bad in a hole in the 
boiler sometimes we can simply thread in the tapered NPT tap farther to make 
deeper threads.  Since the hole/threads are now oversized a new fitting will 
be made to match.   12 pitch was popular on steam engines for several 
different diameter bolts.  1/2-12 is easily the most troublesome with 
today's standard of 1/2-13.  My Huber has some 1/2-12 and a friend told me 
that his Port Huron had quite a few 1/2-12 bolts.  Your tap could be handy 
when you go to work on a half-breed engine.





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