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Posted by Roger Shoaf on April 29, 2008, 11:21 am
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Tapping cast iron is not too difficult, especially if you are using sharp
tools. One thing you might want to consider is to do it on the vehicle,
cold with the engine off. You can rig compressed air to flow in to the tail
pipe and that way the air pressure will blow the swarf out.
You can loosen something along the way to allow a little pressure to escape.
I think about 10 to 15 PSI should do the trick without blowing anything.
--
Roger Shoaf
About the time I had mastered getting the toothpaste back in the tube, then
they come up with this striped stuff.
> Good to have verification on #1.
> Haven't done any pipe taper tapping yet. So how deep to tap is a
> concern for me. I'm not sure how tight the fit should be until
> the shoulder hits. I'll practice with some scrap AL first.
> I don't think I have any cast iron around (old water pump or whatever).
>
> Wayne D.
>
> wrote:
>
> > Just 2 comments:
> > 1. In my experience, cast iron DOES "powder" when cut.
> >
> > 2. If you haven't tapped with a pipe tap before, just be sure to test
> > the hole as you tap it, so you don't tap too deep. I don't know the
> > exact specs on the holes, but some fittings vary in actual size. If you
> > tap too deep, the fitting can bottom out before it seals well.
> >
> > Pete Stanaitis
> > --------------------
> >
> > Wayne wrote:
> >
> >> Since I'm going to be tapping into a big buck part and don't
> >> really have any experience tapping cast iron, I figure I'll
> >> just ask a few stupid questions.
> >> I'm tapping a 1/4 NPT hole into the exhaust section of a
> >> turbocharger. An EGT sensor will be put in there. The part
> >> is cast iron, about 1/4 thick. The directions are to remove
> >> the turbocharger, drill a 7/16 hole, then tap. The part
> >> that screws into the hole has a shoulder which is
> >> supposed to rest against the turbocharger.
> >> Alternately they say I can drill and tap the hole
> >> with the engine running. Once the drill bit goes
> >> goes through, the exhaust pressure is supposed to
> >> push any particles out. When drilling cast iron
> >> they say it is supposed to turn to dust. I'd
> >> be drilling from the top down.
> >> I have to get a tap since I don't have one that size.
> >> I assume HSS will be ok?
> >> It's supposed to be a pain to get the turbocharger out.
> >> But if it was out, I could finish the hole with a
> >> 7/16 HSS end mill. That I think, would give me a more
> >> round hole than drilling by hand under the hood.
> >> So I would think it would seal better that way.
> >> Any thoughts?
> >> Wayne D.
>
>
>
> --
> Wayne D.
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> 1. In my experience, cast iron DOES "powder" when cut.
>
> 2. If you haven't tapped with a pipe tap before, just be sure to test
> the hole as you tap it, so you don't tap too deep. I don't know the
> exact specs on the holes, but some fittings vary in actual size. If you
> tap too deep, the fitting can bottom out before it seals well.
>
> Pete Stanaitis
> --------------------
>
> Wayne wrote:
>