From: kimberln@crl.com (J. Kimberlin)
Newsgroups: rec.crafts.metalworking
Subject: Re: Broken tap-Help!
Date: 20 Sep 1995 16:46:52 -0700
Lines: 25

In article <43p2ct$57k@data.interserv.net>,
Reg Barron <BarronR@ncr.disa.mil> wrote:

>Last night, I broke off a 6-32 tap in a "U" shaped piece of aluminum

	[....]

This ought to be in the FAQ.  You put non-ferrous metal with broken taps 
into a saturated solution of Aluminum Sulfate at 120+ deg F.  Let it work 
a few hours.  Or you can just throw it in a room temperature for a few 
days and the iron will go away.  Only good for NON-FERROUS metals and 
make sure there are no other iron pieces on the workpiece.  Use a plastic 
tray too.  Tupperware works fine.

BTW - this has been a filler item in Coles' catalogue for eons.

JerryK

Newsgroups: rec.crafts.metalworking
Subject: Re: Broken tap-Help!
From: russ@bbxrbk.basis.com (Russ Kepler)
Date: Tue, 26 Sep 1995 23:19:04 GMT

In article <43t2vb$bhe$1@mhadg.production.compuserve.com>,
Tom Poulin  <74036.2507@CompuServe.COM> wrote:
>Hmmm...I've done this in the past by grinding the tap from the inside out with
>a Dremel tool.  Also the Home Shop Machinist magazine had an article awhile
>back describing a homemade EDM which is eminently suitable for removal of
>busted taps.

A tap in Aluminum is most easily removed using straight nitric acid.
If the part is small enough to cover with acid simply do so, leave for
12 hours and the tap will be gone.  If the hole isn't a through hole
and you can't immerse the part then build a dam with wax and cover,
pour out the used acid after an hour or so and repeat until it's
dissolved or falls out.

Sometimes the Al will sort of "glaze over" but it can be wiped off.
To make sure that you're dealing with Al you might check by running
some swarf or a spare chuck into the acid before trying it on
something you want to save.

-- Russ
--
Russ Kepler posting from home  russ@bbxrbk.basis.com

                      Please don't feed the Engineers

Newsgroups: rec.crafts.metalworking
Subject: Re: WHERE TO GET ETCHING ACID?
From: russ@bbxrbk.basis.com (Russ Kepler)
Date: Thu, 28 Sep 1995 01:46:06 GMT

In article <DFC89o.B1n@boss.cs.ohiou.edu>,
Mark Kinsler  <kinsler@bobcat.ent.ohiou.edu> wrote:
>I have an idea here that might be a lousy one, but I'll submit it for
>comment.  One possible place that you might be able to get small amounts
>of weird chemicals might be the chemistry department of your local
>college or university.  They sell stuff to the students for cash, so they
>might sell to you as well.  Just walk in like you own the place and ask
>for what you need.  Might work.

It's simpler than that - nitric acid can be obtained from radiator
shops, and sulphuric acid may be obtained from battery shops.  If
neither of these sources appeal or work then shool supply shops such
as Van Waters & Roger and Fisher Scientific can supply small amounts
at reasonable prices.  Note that all you really need is a tech grade
or less, don't buy CP or Reagent grade for something like this.

--
Russ Kepler posting from home  russ@bbxrbk.basis.com

                      Please don't feed the Engineers

From: Robert Bastow <Tubal_cain@hotmail.com>
Newsgroups: rec.crafts.metalworking
Subject: Re: Slick 50...LOOONG!
Date: Thu, 15 Oct 1998 01:05:53 GMT

Tom Holt wrote:

> [excellent post snipped]
>
> Thanks; now tell us what we *really* need to know - how to get the
> bits of broken tap out of the hole after you've snapped the ruddy
> thing off flush...

I dunno..never happened to ME!!  ;^)

I have never had much succes with tap extractors.

Sometimes, but not often, you can gently tap the gruesome remains
out in reverse with a small, flat pointed punch and a SMALL hammer

If the component is "not for pretty" I take a stout flat nose punch and a BIG
hammer and just belt the sucker right on through!! Itworks better than you might
imagine, as the tap threads/flutes being more brittle than the tappee, shear
right off and the threads, usually are not much damaged.

Best way is to find a local company that will EDM it out.

There was thread, recently about, this that came up with dome chemical solutions
that I have no experience of.

Robert Bastow

From: vantonova@aol.com (VAntonova)
Subject: Re: Broken Tap!!!#%$@
Date: 20 Apr 1997
Newsgroups: rec.crafts.metalworking

> When you know what chemicals you need (I think common lye might work,
> but the dialog box in my frontal lobe says "low on memory)

Lye will remove the tap... by dissolving the aluminum and leaving the tap
intact. I am sure you want to destroy the offending tap and not harm the
Al. I found that anodizing the aluminum removes the tap. Takes a couple of
hours and you get a nice thick anodized finish.

Alex.