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Broken tap..help?

Simon Hitchen

Simon Hitchen

Well Known Member
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
2yl2sev.jpg
 
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.
 
Tap

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.
 
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.
7140MKlnJ%2BL._SL1500_.jpg
 
Lessons Learned

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!
 
cjhammes said:
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!
Click to expand...

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....
 
good clarification point

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.
 
tapping thru holes

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.
 
Tap

How about a small flat blade screwdriver or punch. Lightly tap to turn the tap counterclockwise. I've backed out broken bolts that way.
 
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_tap_removal.htm#Armor Drill I might have to order a couple of them and see how well it works. At ~ $20/each they're not cheap, though.
 
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Those carbide armor drills look nice.

This is crude, but if you can not get to the back to remove it or heat to loosen, then just back it up, hammer it through and either use a plate nut or #8 screw.

If you want to spend several days getting materials, then get some nitric acid, make a pool around it with clay and dissolve it. It should take about 30 min. That is after all the trouble to procure the acid. Only nitric.

Edit: Link for Tap-X http://www.westtool.com/default.asp...stomerpages/prod_page_dgr_products_tap-x.html
 
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Walton Tap Extractor, Google it. I have used these with great success. it will cost $20.00 to 25.00 dollars.
 
I have had success in the past with beeswax, and heat.

Apply a dab of beeswax, heat with a heat gun, let cool. Repeat a couple times, and then use a tap extractor or other device to twist the tap out while the heat gun is still in use.

Dont rush things, just get the broken tap moving a little, then remove the extractor, and clean out any chips------then reinsert the extractor and repeat as needed. Keep it well lubricated.

Kahuna's idea of using snap ring pliers is a good one, probably cheaper than an tap extractor, and easier to find.

Just in case you are not familiar with tap extractors, see here. http://aviationmiscmanuals.tpub.com/TM-1-1500-204-23-9/css/TM-1-1500-204-23-9_100.htm

Good luck, just remember that sometimes it just simply will not come out--------dont waste too much time/effort/sanity on this, move the hole over a bit and redo.
 
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I know many will strongly disagree , but after 15 yrs of flying and maintenance, I'd use only #8 screws everywhere. #6's are pretty, but very easy to bugger, plus it's just something else to keep track of.
 
I haven't gotten to that part yet... why is a tapped hole called out? A nutplate would be much easier and less susceptible to complications...
 
rmartingt said:
.. why is a tapped hole called out?
.
Click to expand...

Typical Vans engineering ---------costs less, weighs less, quicker and easier than a nutplate, and (when done successfully) works just fine to do the job it is intended to do.
 
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Simon Hitchen said:
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
2yl2sev.jpg
Click to expand...





Happened to me too, probably everyone that has built an RV.

My solution was to simply tap it through using a drift punch, then installing a nut plate. Very simple, quick and easy

Peter
 
Avoid store bought taps like the plague. USA-made titanium nitride coated two flute taps are the way to go. I routinely do hard tapping on the milling machine and lathe, rarely if ever stopping on aluminum. Stanless, inconel, etc. different story. Tapmagic for aluminum or in a pinch kerosene is good for tapping.
 
Walton tap extractor took me 10 minutes to remove when I did the same thing. I was able to find one for sale locally, but I'm sure you can find online.

Aaron
 
tap

Sure you are drilling hole to correct size before using tap? That must be one cheap tap to break in aluminum.
I agree with previous poster, go with #8 screws.
 
Grip and turn

Hey Simon,

Looks like you should have room to grip and turn from behind. Mini Vice grips!!!

3 pages of people who have broken taps!!! We need a webinar:D
 
No good for now, but.....

For future reference, maybe some help. For me and my RV-7A build, #6-32 screws do not exist. Nothing smaller than #8-32 will be used, since not only are the #6 taps easier to break, so are the screws easier to shear. If the platenut is just a little tight, they can shear off before they even screw all the way in, and are a pain to get out. If you run a tap through the platenut, as some do, then it doesn't stay tight as reliably. No #6 for me.
 
rmartingt said:
I haven't gotten to that part yet... why is a tapped hole called out? A nutplate would be much easier and less susceptible to complications...
Click to expand...

++1. A nutplate is a heck of a lot easier to fix than an buggered up tapped hole in your longeron (not from tapping but from cross threading). That tapped hole has no thread locking feature. I figure a nutplate is lighter than the spare screws I would have to carry!
 
As a fire protection engineer, I would consider corrosion spotting to be the least of my concerns if dealing with electric sparking (arcing) in a cloud of aluminum dust. Aluminum dust in the right (wrong?) particle size and concentration in air is highly explosive if confined, and if not confined can still produce a pretty hot flash.
 
OLDSAM said:
As a fire protection engineer, I would consider corrosion spotting to be the least of my concerns if dealing with electric sparking (arcing) in a cloud of aluminum dust. Aluminum dust in the right (wrong?) particle size and concentration in air is highly explosive if confined, and if not confined can still produce a pretty hot flash.
Click to expand...

There's no dust produced into the air with EDM electric arc ablation. The work area is flooded with a stream of water to keep it all cooled so all the dust gets suspended into the water. Really messy and would be next to impossible to clean out all the contaminates from inside the tail end of a completed RV-10. It would be really bad news to end up with the steel dust, after the water dries away, imbedded into every nook and cranny and seam in the aluminum wherever the water carried it.
 
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