Broken tap..help?

Simon Hitchen · #1 07-22-2014, 06:20 AM

Well, surprises still happen this far into the build. I managed to snap a 6-32 tap this morning while tapping a hole in the longeron for the rear inspection plate.

A quick attempt to drill into the tap failed and wandered, so that was quickly abandoned.

Any thoughts on the best way to remove this would be greatly appreciated. Once out I can enlarge to 8-32 if needed.

Many thanks

apkp777 · #2 07-22-2014, 06:50 AM

Tap extractor!, you probably don't have one (I don't either), An "engraving" tool also work very well. Try it and you will be surprised.

Vern · #3 07-22-2014, 07:52 AM

If any of the tap is exposed on the back side, you can grip the stub with small pliers or vise grips and back it out. I have a tiny pair of channel locks that I use for this.

If it is broken off flush, then you can sometimes insert two sharp picks on either side of the relief channels, spray some lube into the hole, and possibly back it out.

Kahuna · #4 07-22-2014, 08:03 AM

I have used a pair of these. Blow out filings. oil, and give it a try. Cheap tool at your local store. Tool may take customization prodding on a #6 tap. Have done this on a #8. Sorry for the giant image.

cjhammes · #5 07-22-2014, 08:08 AM

Apparently I am a slow learner as I broke two of these darn 6-32 taps before I changed my tapping process. Thought I'd pass on to you.

-Take it slow
-Use your favorite lube on tap
-Don't tap all at once, back all the way out every turn or so and clear shavings
-Be even more careful if tapping a 6-32 in steel

This will take more time, but far less time than removing a broken tap.

Good luck!

JonJay · #6 07-22-2014, 08:29 AM

Quote:

Originally Posted by cjhammes

Apparently I am a slow learner as I broke two of these darn 6-32 taps before I changed my tapping process. Thought I'd pass on to you.

-Take it slow
-Use your favorite lube on tap
-Don't tap all at once, back all the way out every turn or so and clear shavings
-Be even more careful if tapping a 6-32 in steel

This will take more time, but far less time than removing a broken tap.

Good luck!

Your setting yourself up to break another. If you have gone a full turn, you have gone too far.
You need to break the chip as it reaches the next flute. You can feel the flute catch the chip, then stop, go backwards to break the chip, then proceed. This can be as little as a 1/4 turn, depending on the type of tap, size, and material.
As you get further into the tapping process, you can start to feel the chips get smaller and they start to break off as you turn allowing you to be more aggressive. Once you are into the finishing thread, you can typically freely turn the tap and not worry about chip breaking at that point.
Small taps break easily from side load too, so be careful with your touch....

cjhammes · #7 07-22-2014, 08:52 AM

Good point of clarification. The "turn or so" statement did not mean always 1 full turn +. There is definitely a "feel" you learn after doing a few correctly. Sometimes is less than a turn, 1/2 or less, maybe only a 1/4, or sometimes it can be greater depending on material type, thickness, tap type, # of flutes, etc. For sure #6 taps are real easy to break.

380mxc · #8 07-22-2014, 08:55 AM

Use a two flute gun tap and make a guide block to keep tap straight.
No need to reverse the tap until the thread is complete. The gun tap shoots the chips forward. The 6-32 tap is inherently week because of the coarse pitch and small diameter. Use a copious amount of Boelube.

wirejock · #9 07-22-2014, 08:56 AM

How about a small flat blade screwdriver or punch. Lightly tap to turn the tap counterclockwise. I've backed out broken bolts that way.

Neal@F14 · #10 07-22-2014, 08:59 AM

A broke-off 6-32 tap is hard to remove. My friends' RV-10 still has one broke off in the longeron below the horizontal stabilizer where an empenage fairing screw is supposed to go. We tried almost everything to get it out without success. Even broke the brand new Walton tap extractor purchased especially for this job. The tap just would not move.

Didn't think to try an electric engraving tool, might be worth re-visting the problem with that.

Also, would attempting to use EDM (electro discharge machining) be safe to use on a tap broken off in aluminum? .... provided that you could find a portable EDM machine that can go down small enough diameter? I would have fears of the electric sparking plus a bunch of steel and aluminum dust mixed together might promote a corrosion spot to develop later on.

EDIT: Just found these special drill bits... http://www.2linc.com/tools_broken_ta...or%20Drill I might have to order a couple of them and see how well it works. At ~ $20/each they're not cheap, though.