broken tap

[Teamfanok]

on page 25-05 step 5. Tapping #36 hole with tap 6-32. I broke the tap in the rollbar. What is the best way to remove broken tap. I tried drilling out the tap, but the tap seems to hard for the bit

[DMFenster]

I would take it to a machine shop.

[Mark Burns]

Broken taps are very difficult to remove.
Since the roll bar is not that thick I would suggest using a small punch and driving it on through. The taps will sometimes break into smaller pieces and fall through. The remaining hole might still be able to be tapped for 6/32. Can you go to 8/32 in that location? I'm not familiar with the RV-12.

Mark

[Andy J]

A friend showed me a cool gadget last time I broke a tap. Its called a "Tap Extractor". Worked for me. Google it and you will see what they look like - They come in 3 and 4 flute.

Also, I learned there are specific lubricants for thread cutting. Next time I have a few to do I will get recurrent training - Always best to not break it in the first place.

[N941WR]

Find someone local with an EDM machine. They can burn it right out without harming the surrounding material.

PS. I see you are in NJ. Contact Claudio T. He will be able to help you.

[jlfernan]

I've heard of people using needle nose pliers in the flutes and being able to turn them out.

[Teamfanok]

I will first try a Walton tap extractor or then I will try to
contact claudio t

[Bob Kuykendall]

There's an important takeaway here:

The 6-32 tap is the weakest one in the standard size range of aircraft hardware. It is the one for which the thread depth is the greatest percentage of the outside diameter. So it is the 6-32 tap that is the most likely to break while tapping a hole, and the 6-32 screw you are most likely to twist the head off of.

I am pretty cavalier when tapping 1/4-28 holes; for rough work I will often go at it with a cordless drill that has a clutch. I am almost as easygoing with the 10-24. With the 8-32 I am kind of careful.

But with the 6-32, especially in expensive parts, I use only fresh sharp taps (none of that Hanson junk from Ace Hardware), good tapping oil, and reversals every quarter-turn to clear the chips. I hold my tongue just so, and think good thoughts with every half-turn of new thread.

Thanks, Bob K.

[Dgamble]

Originally Posted by Bob Kuykendall

I hold my tongue just so, and think good thoughts with every half-turn of new thread.

I think that's the secret to a good many of the things we have to do.

[chaskuss]

Andy, Bob & Bill give you good advice. I would only use Mark's suggestion as a last resort and ONLY if you used a 4 flute tap. Taps [and tap extractors] come in 2, 3 & 4 flute models. Each has strengths and weaknesses. The 4 flute model centers in the hole the best, will clear the most chip, BUT is the weakest of the 3 styles and breaks the most easily. The 2 flute tap is the strongest, needs to be reversed more often to clear chips, but more care must be taken when starting it. The 3 flute version is a compromise of the other two. My choice for tapping into tough alloys [4130 of the weldment] would be a 2 flute tap.
An EDM machine will definitely be able to remove the broken tap. That said, unless you live in an urban area, you are unlikely to find a shop which owns one [$$$ piece of equipment]. Using a hammer to drive the broken tap through will surely destroy the threads, requiring re-drilling the hole for a #8 screw [considerably stronger than a #6] It may also leave you with a permanent "rattle", if you can not get the broken tap out of the weldment.
Using a tap extractor is something of an art. I would suggest if you can still remove the weldment, that you take it to a god machinist and have him/her remove the broken tap.
Charlie
PS If you own a "made in China" tap set, run, [do not walk] to your garbage can, and insert said tap set inside.