[Public-List] Manifold petcock Atomic 4

Sun May 20 09:22:49 PDT 2012

Ok, if you've got enough of a thread that the normal tap doesn't cut
before it's bottomed out, then it's time for the bottoming tap. As long
as the bottoming tap doesn't get used before/without trying the normal
tap you should be fine. (Starting with bottoming taps is a road that
leads to weekends squandered chasing tools out of the holes they were
supposed to fix, damaging said holes in the process and having to fix
them with helicoils or epoxy, and--of course--madness.)

Cheers,
Kris

On Sun, May 20, 2012 at 05:00:20AM -0700, Ronald Walker wrote:
> Thanks Kris
> Problem is that the hole is so shallow (maybe 1/2inch) that the tappered tap bottoms out before it can begin to cut. I started the engine yesterday and held my finger over the hole. Almost no pressure so it wouldn't take much to plug it. 
> Ron #292
> 
> --- On Sat, 5/19/12, Kris Coward <kris at melon.org> wrote:
> 
> > From: Kris Coward <kris at melon.org>
> > Subject: Re: [Public-List] Manifold petcock Atomic 4
> > To: "Alberg 30 Public List -- open to all" <public-list at lists.alberg30.org>
> > Date: Saturday, May 19, 2012, 11:30 AM
> > 
> > A bottoming tap is intended to be used _after_ a regular
> > tapered tap;
> > going straight to a bottoming tap can lead to uneven threads
> > (because
> > the bottoming tap doesn't have enough of a thread to bite on
> > at the
> > beginning of the hole), or even shards of broken tap left in
> > the hole
> > (taps are hard and therefore brittle; if one has to cut too
> > much
> > thread at once, the stress can crack it, and then it'll need
> > to be
> > ground out). It may be less of a concern when cutting a
> > softer metal
> > like brass out of an existing thread, but I've damaged
> > enough threaded
> > holes (and ground out enough tool shards) that I wouldn't
> > hesitate to
> > get and use both taps just to be on the safe side.
> > 
> > Cheers,
> > Kris
> > 
> > On Sat, May 19, 2012 at 09:40:37AM -0400, Don Campbell
> > wrote:
> > > If you can find a bottoming tap of the correct size, it
> > has far less
> > > taper than the normal tapered tap. You might want to
> > compare it with
> > > a plug tap to see which might suit you best. I imagine
> > you will have
> > > to go to an industrial supplier who carries an open
> > line of tools to
> > > find them.
> > > Don #528
> > > 
> > > On 5/19/2012 8:27 AM, Ronald Walker wrote:
> > > >The engine is the old Atomic-4.Its my understanding
> > that all Albergs were originally powered by them.I believe
> > the petcock is brass and the manifold is some type of steel.
> > As I said the threads are there, just flattened out. I'm
> > going to try some J.B.Weld. Don't know what else to do.
> > > >
> > > >--- On Sat, 5/19/12, Glennb<brooks.glenn at comcast.net> 
> > wrote:
> > > >
> > > >>From: Glennb<brooks.glenn at comcast.net>
> > > >>Subject: Re: [Public-List] Manifold petcock
> > Atomic 4
> > > >>To: "Alberg 30 Public List -- open to
> > all"<public-list at lists.alberg30.org>
> > > >>Date: Saturday, May 19, 2012, 1:18 AM
> > > >>What kind of engine/manifold do you
> > > >>have, and what material is the petcock made
> > of?  sounds
> > > >>like the petcock corroded off, leaving part of
> > the threaded
> > > >>portion in the manifold.
> > > >>
> > > >>If so, try going in with a very small drill
> > bit, maybe
> > > >>slightly larger than the ID of the hole, then
> > run a series
> > > >>of increasingly larger taps to ream out the old
> > material to
> > > >>match the original ID and thread.
> > > >>
> > > >>just did this on my steam engine, took about an
> > hour to
> > > >>replace the broken nipple. But it was brass and
> > the boiler
> > > >>is steel.
> > > >>
> > > >>Glenn p
> > > >>dolce 318
> > > >>
> > > >>
> > > >>Sent from my iPad
> > > >>
> > > >>On May 18, 2012, at 12:47 PM, Ronald
> > Walker<rwpsw at sbcglobal.net>
> > > >>wrote:
> > > >>
> > > >>>Maybe someone can help me with a small
> > problem I
> > > >>discovered during the spring start-up
> > procedure.On the aft
> > > >>part of the manifold there is a petcock. Its is
> > for draining
> > > >>the manifold water jacket. As I began to close
> > the petcock I
> > > >>noticed it was loose. I tried to tighten it but
> > it ended up
> > > >>falling off in my hand. After a good close look
> > I saw that
> > > >>the threads were all buggered up.On the petcock
> > as well as
> > > >>the hole. I thought about running a tap in to
> > maybe sweeten
> > > >>up the threads but the recess is way to
> > shallow. Any advise
> > > >>would be appreciated.
> > >
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> > -- 
> > Kris Coward       
> >             http://unripe.melon.org/
> > GPG Fingerprint: 2BF3 957D 310A FEEC 4733  830E 21A4
> > 05C7 1FEB 12B3
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-- 
Kris Coward					http://unripe.melon.org/
GPG Fingerprint: 2BF3 957D 310A FEEC 4733  830E 21A4 05C7 1FEB 12B3

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