Subject: Re: Going Nuts looking for 1-20 Nut

From: [email-masked] (David Jenkins)
Date: 10 Aug 1994 07:52:32 GMT

In article <[email-masked]>, [email-masked] (Bob Neidorff) writes:
|> 
|> 
|> Rather than make one myself (last resort), I am looking for
|> a 1" Nut with 20 threads per inch. I only need one. Any ideas?
|> 
|> Well, I may have to make my own after all.  It isn't a standard
|> thread on either side of the Atlantic.
|> 
|> What do people think about using a real tap (such as a 1/4"-20)
|> as a thread-cutting boring tool?  I don't happen to own something
|> appropriate for this job in my box of lathe cutters.  Probably
|> stupid.  I may have to buy another lathe tool...
|> 

What's wrong with a standard single-point boring tool, driven by the
screw-cutting gears?  It's not too difficult, easier with practice,
and you can easily get a good result in quite a short time.

For a once-off job you could use carbon steel for the tool, suitably
tempered.

-- 
David Jenkins

My motto is to forgive and, er... the other thing.

---

From: [email-masked] (ron a ginger)
Date: Fri, 12 Aug 1994 00:22:54 GMT

In article <[email-masked]>, Bob Neidorff <[email-masked]> wrote:
>
>
>
>What do people think about using a real tap (such as a 1/4"-20)
>as a thread-cutting boring tool?  I don't happen to own something
>appropriate for this job in my box of lathe cutters.  Probably
>stupid.  I may have to buy another lathe tool...
>
>-- 
Ive done this several times. Use an old tap, grind away one half and
use it like a boring bar. Gives you a nice thread form much eaiser
than totaly grinding a tool

ron ginger

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From: [email-masked] (Russ Kepler)
Date: Thu, 11 Aug 1994 23:24:25 GMT

>stupid.  I may have to buy another lathe tool...

You have a lathe and no inside thread cutting tools?  That's pretty 
easy to correct, and a 1"-20 thread is a good thread to learn on for
inside threading, plenty big to work with

I'm also not clear about your mention of using a 1/4"-20 as a boring
tool.  If you mean using a tap for inside threads on a lathe then it's
nothing new or unusual - any time I have to do a standard thread in a
lathe I'll always use a tap before inside threading - it's a whole lot
easier.  Something this size is a bit bigger than I'd use a tap on,
though.

-- 
Russ Kepler posting from home  [email-masked]

                      Please don't feed the Engineers

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From: [email-masked] (gary preckshot)
Date: 12 Aug 1994 19:46:44 GMT

In article <[email-masked]>, [email-masked] (Daryl Bender)
> > In article <[email-masked]>, Bob Neidorff <[email-masked]> wrote:

[....stuff...]

> > Use an old tap, grind away one half and
> I have,
> however, never heard of using a tap in this manner (boring). How do you
> hold the tap? How does it compare with "my" method? Just curious.

You just grind away all but one segment of one thread, leaving a relieved,
HSS thread form.  However, I think I'd start with 1/2-20 as opposed to
1/4-20.  1/2-20 is standard in the US, being the fine pitch version of 1/2"
threads.  However, most people use this trick with an old, wornout tap,
rather than a brand new one.  It's probably cheaper just to buy a
thread-form 1/2" shank boring bar from Enco if you're going to buy a new
tap and destroy it.

G.

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From: [email-masked] (Daryl Bender)
Date: Fri, 12 Aug 1994 10:18:55 -0500

> than totaly grinding a tool

When I do internal threading I use a boring bar with a cutter ground to a
60¡ point. The cutter is mounted in the 90¡ position on the boring bar. I
find threading in this manner very easy and straight forward. I have,
however, never heard of using a tap in this manner (boring). How do you
hold the tap? How does it compare with "my" method? Just curious.
-- 
Working, but not speaking for BNR.

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From: [email-masked] (John Wishneusky)
Date: Fri, 12 Aug 1994 21:33:16 GMT

>For a once-off job you could use carbon steel for the tool, suitably

I'll second David's recommendation and add a couple of comments.
First, boring a thread this size is about as easy as boring a thread
gets, there's plenty of room for most any boring tool, yet the
thread's not going to require a real heavy cut.  Make sure there's
adequate room behind the nut for the cut to run out without
interference with the chuck.

Re the boring tool itself, I've had good luck with a simple one using
insert cutters I make myself.  The tools's just a steel bar with a
hole bored across the diameter and a small setscrew to hold a round
cutter insert.  The other end of the bar has a co-axial hole and
radial setscrew.  That end serves to hold the small cutter insert for
freehand grinding.

I make the inserts from the shanks of solid carbide printed circuit
board drills.  The shanks are 1/8" and I bought a small handfull of
used drills at a flea market for about a buck.  I've had occasion to
use this boring bar on semi-hard steel that I couldn't or wouldn't
temper.  The carbide handles these jobs that HSS won't.  If you use
carbide, you'll need a green wheel for your bench grinder, but they're
not very expensive and will be handy for touching up carbide tools.

John

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From: [email-masked] (Bruce Holder)
Date: Mon, 15 Aug 1994 15:52:57 GMT

Bob Neidorff ([email-masked]) wrote:
: What do people think about using a real tap (such as a 1/4"-20)
: as a thread-cutting boring tool?  I don't happen to own something

I saw a letter to the editor in HSM one time that described grinding
excess teeth off a broken tap and using it as a threading tool.  Makes
a lot of sense to me -- you know the tooth form is right, and you
already have the broken tap. :(
--
Bruce Holder		[email-masked]
			(303)530-8739