[Diy_efi] Tapping Metric Injector Threads

[Greg Hermann]

At 6:25 PM 1/10/03, Patrick Cahill wrote:
>It sounds like you've bought a tapered lead tap which is different to a tap
>that creates a tapered thread. A tapered lead tap's purpose is to provide an
>easy lead in to tapping a hole that goes right through something.
>
>I made the same mistake once.

There are three tyypes of tap for straight threaded holes. Taper, plug, and
bottoming. For a "through" hole, one only needs a "taper" tap, you simply
run it through the hole far enough to get a straight thread all the way
through.

For a blind hole, one taps FIRST with a taper tap, until the end of the tap
hits the bottom of the hole--then the threads are chased first with a plug
tap, and finally with a bottoming tap so as to get full depth threads clear
to the bottom of the hole.

Greg
>
>
>
>>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
>>
>> _______________________________________________
>> Diy_efi mailing list
>> Diy_efi at diy-efi.org
>> http://www.diy-efi.org/mailman/listinfo/diy_efi
>>
>
>
>
>
>_______________________________________________
>Diy_efi mailing list
>Diy_efi at diy-efi.org
>http://www.diy-efi.org/mailman/listinfo/diy_efi



_______________________________________________
Diy_efi mailing list
Diy_efi at diy-efi.org
http://www.diy-efi.org/mailman/listinfo/diy_efi