stuck tap in aluminum housing

According to my intention Bernd, and the apparant message threading (at least on my newsreader) I was replying to and gently chiding Tim, not you. But I guess I ought to think about using names, huh?

Happy Holidays,

Jeff

I think it would be very instructive to those trying to assist you if you could reply to at least one or two of them, and give additional information about how this event happened, and what you were trying to accomplish when tapping into the housing.

Jim

Hehe, I just broke one last week, a 6-32. I have 16 little holes to tap radially in some short lenghts of 3/8" all thread (for set screws), and since it takes a longer time to do the "twist-in, twist-out", I decided that I would do it like the tapping machines do it, and do it in one fell swoop. This way I would save a lot of time.

Of course, I don't have a tapping machine, and at the time I didn't even have a proper handle (I was using an old set of Vise-Grips).

Guess what - I broke a tap!

I bought a proper handle and I'm doing all of my hand tapping now with the "twist-in, twist-out" technique. At least now I know why. :)

Jon

And -- more important, you probably did not have a "gun" tap -- a spiral point tap designed for the tapping machines. They are designed to chase the chips ahead of the tap. Normal taps (starting, plug, and bottoming) generate the chips in the flutes, and need to be backed up to break those chips free before they get big enough to totally wedge things.

And -- the 6-32 is probably the easiest tap to break. It is weaker than any other common tap, because the threads are deeper relative to the OD of the thread. I would much rather tap 2-56 or even

Get some "gun" taps, and use a proper tapping lube and you'll do a lot better without the periodic backup. But make sure that there is enough clearance on the other side for the chips to fall out. If you are dealing with a blind hole, I would suggest either a spiral flute tap, or even better (though more sensitive as to the size pilot hole) thread forming taps, which don't generate chips at all.

Good Luck, DoN.

Just the other day. And the next time I'm fixing to tap some 3xx stainless with an itty bitty 6-32 tap I'll ask here first.

But I never thought they were made of cast iron.

"Gene Kearns" wrote: (clip) I once ground a piece of 1018 to look just like a HSS lathe tool bit.... kinda funny watching the guy try to troubleshoot his set-up....(clip) ^^^^^^^^^^^^^^^ Kind of like the replica golf balls made of chalk.

Sorry. I hate to be such a jerk, but APINC... the body that has assigned your IP address has, collectively, been kicking my *ss! It seems like many asian IP addresses have nothing better to do than port sniff.... and worse.....

Anyway, let me know if it works... you *should* have access....

"Alum" is old term for Aluminum Potassium Sulfate, used in various manufacturing processes, not usually found in the house. "Ammonium Alum" is Aluminum Ammonium Sulfate, the common astringent, that is what I think the OP means.

Thanks Gene. Works just fine.

Now I'm off to surf...

Jeff R.

Yeah, and aren't most of us here to teach and learn? Randy

I have never successfully removed a seriously stuck tap in aluminium with any method other than Mig welding a nut onto what's left of the tap and turing it out. I have tried a lot of different ways, none of which worked even once. I guess that if I had a part that I could do the alum trick and dissolve it out I would try that, kind of hard to submerge a transmission housing (for example) still attached to a car in a solution of alum...:)

Brian

Hmm ... normal whois and jwhois only shows that many of these are registered with APNIC, and not the actual location.

Try:

whois -h whois.apnic.net ip.ad.dr.es

to find out where it is really located. This will help keep you from blocking Oz along with the others.

Good Luck, DoN.

My old shop teacher (hi, Tom!) made some 1/2" drill bits from mild steel for just such pranks. I still have a couple of them. Now I just have to figure out who to give one to... :-)

Alan

...and in aluminum, especially.

LOL trying to picture that. Sounds like a good cartoon. Happy Holidays, John

Hey, they might work pretty good for wood though.....

Jeff (Who's more than once clipped the head off a small nail and used it as an erzats drill for wood.)