Clogged tap on the wrong side of aluminum

Inferno

Inferno

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Today I was making some clamps for the bed of my CNC Project.
I started all the threads on the mill and then finished them in the comfort of my living room using a power drill.

The tap is one that pushes the chips down and out. The thickness I'm tapping is about 3/4" Using M6X1 threads.

Well, I know better and did it anyhow, but I was tapping dry. On one of the pieces I got a chunk of aluminum stuck in the cutter on the back side of the piece. I've tried clearing it with all kinds of "digging it out" methods and it won't budge. Luckily I have a few of these taps so I was able to finish the rest but I'd like to free this tap. I don't really need this clamp as I made one extra just in case. But, it would be nice to have a spare.

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Had that once myself.

Ended up using my dremel on low speed with a slitting disc. It got enough of it out to back the tap out.

Sodium hydroxide, AKA lye, will dissolve the aluminum if you want to go that route, or Soak it in drain-o.
 
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I would think you could worry it out with an X-acto by picking away at it
 
If it's truly cold welded in there (Rare, hard to do, but it happens...), you might have lost the tap already.....

Take a nut that fits the tap, cut a pie slice out of it, removing one "flat" (hack saw would be just fine), thread it onto the tap, and using pliers (with a good squeeze) to turn it (Or maybe jam on a 3/8 socket or wrench, since it should be a a bit tight on a 10mm hex...) see if you can get it to rail that chip out. Kind of like a soft threading die.
If that won't budge the chip, I'd probably just cut the tap short and back it out, since even if it could be recovered by more extensive means, at that point you're into it for more than a new tap anyhow. Then you can inspect the aluminum threads to see how far in that chip came from, and how much damage it did on the way out of the hole.
 
well you know about cutting fluid.. I did this to a sabre saw blade. I tried cutting aluminum plate dry, and it welded the blade up. It's done.
so don't forget the lesson..
 
You needed a bottoming tap anyway, didn't you?

If you can't get that chip out, cut it off, back it out, then make a bottoming tap out of it...

-Bear
 
markba633csi said:
I would think you could worry it out with an X-acto by picking away at it
Click to expand...
Tried that. It didn't work.

I don't have any Lye anymore. I once had 25 pounds of the stuff but never had a use. Plus the entire part is aluminum and I'm notoriously sloppy.
I think I will try with a dentist cutting disk on my dremel.

Thanks for the ideas.
 
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