[Diy_efi] Tapping Metric Injector Threads

[Brian Michalk]

Thanks for the help.
No, the tap is definately not tapered, except where the threads are to be
started.
I did some experimenting with not running the tap too far in, and also using
a smaller bit, and using teflon tape.  I think that will do the trick.  If
not, I'll put a shoulder on it and use an o-ring.

 Brian Michalk  <http://www.michalk.com>
Life is what you make of it ... never wish you had done something.
Aviator, experimental aircraft builder, motorcyclist, SCUBA diver
musician, home-brewer, entrepreneur and mostly single


> -----Original Message-----
> From: diy_efi-bounces at diy-efi.org [mailto:diy_efi-bounces at diy-efi.org]On
> Behalf Of Martin, Sam
> Sent: Wednesday, January 08, 2003 11:17 AM
> To: 'diy_efi at diy-efi.org'
> Subject: RE: [Diy_efi] Tapping Metric Injector Threads
>
>
> Brian wrote:
> > I've got a Bosch CIS injector, 0 437 502 047
> > It has an M12x1.5 metric thread.  That's 12mm major diameter
> > with 1.5mm pitch.
> >
> > I bought a tap from MSC that I thought was supposed to be
> > tapered.  I tapped some scrap metal, and the injector screws
> > into it with a very loose sloppy fit.  I will try a smaller
> > drill bit size, but I don't think that's going to help.
> >
> > Does anyone know if there exists such a tapered tap, like for
> > NTP, except metric?
>
> Brian,
> 	Are you sure the tap you bought is for tapered threads? Looking at
> the MSC catalog, they refer to what is commonly known as a
> starting tap as a
> tapered tap. These are used to start threads in a drilled hole.
> If the hole
> is not blind, these can thread all the way through a piece of material. If
> the hole is blind you would start with this and finish with a plug tap and
> then a bottoming tap to cut threads to the bottom of the hole. The *taper*
> in the name only refers to the starting edge of the tap. The final cut
> treads will not be tapered as in NPT.
>
> BTW, when you cut tapered threads with a tap such as a NPT tap,
> you have to
> leave (I think) 5 or so of the taps threads exposed above the material.
>
> I would call these guys: http://www.newmantools.com/tapdie.htm#taps
> >From their website, it looks like they might be able to get what
> you need...
>
> TapMagic is the best cutting fluid I've ever used.
>
> Sam
>
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