broken tap - Page 2

Teamfanok · #11 03-09-2012, 06:42 AM

Thanks for all of the suggestions

Jim Moore · #12 03-09-2012, 07:23 AM

Get a Granite drill bit from Lowes. It's the only bit I have found that will do this job.
Jim Moore

Mark Burns · #13 03-09-2012, 11:10 AM

My idea is the most cost effective and the quickest.
The hole would have been repaired last night.

I'll admit I don't even know what this screw is doing, but it is a 6/32.
Please let us know how you fix it and the cost plus your time spent.

Good luck with it.
Mark

35 years industrial maintenance experience.

380mxc · #14 03-09-2012, 11:58 AM

It is possible to drill out a broken tap with a carbide spade drill. It requires a rigid set up. Shattering the tap with a hammer and punch is done often with mixed results. EDM has the best results but is not economical in most cases.
After you remove the tap and for future holes I would recommend a two flute plug gun tap. The advantage of the gun tap is it pushes the chips forward of the tap requiring no reversal of the tap to break the chip also eliminating the possibility of work hardening the material on reversal. The gun tap is only to be used on thru holes.
My preferred tap brand is OSG they have taps for most materials. My preferred taping fluid for difficult materials, alloy steels and stainless steel is Moly Dee. Only a small amount of Moly Dee is required.
You can also put the tap drill hole in your favor. The 6-32 minor diameter for the 2B and 3B is .104 to .114 . The most common drill used for the 6-23 is the number 36 (.106) diameter but you can use the number 35 drill (.110) diameter making the hole larger requiring less torque on the tap with producing a thread to spec.
We should always check the tap drill hole diameter with a pin gage before tapping and the threads with the appropriate go/ nogo plug gage after tapping.

Teamfanok · #15 03-09-2012, 12:11 PM

to clarify what the tap was going into, is the roll bar for a RV-12 . This screw holds the rear lexan window. This along with many other screws holds the front edge of the rear window to the rollbar

Mich48041 · #16 03-09-2012, 01:50 PM

If the hole is unsuitable after removing the broken tap, a 6-32 nutplate could be installed. Jim Cone tells how to do that here:
http://www.vansairforce.com/communit...ad.php?t=47641
Another option is to abandon the broken tap in place and drill and tap one or two new holes to the side of the bad one. The disadvantage of doing that is that it will not look good.
Joe Gores

380mxc · #17 03-09-2012, 04:17 PM

Quote:

Originally Posted by Teamfanok

to clarify what the tap was going into, is the roll bar for a RV-12 . This screw holds the rear lexan window. This along with many other screws holds the front edge of the rear window to the rollbar

My apologies Jeff I was thinking of a steel roll bar. For aluminum if a tap extractor does not work I would use a grinding wheel in a Dremel and remove the exposed tap and then tap it out with a punch. The thread will most likely be damaged so I like the suggestion of the nut plate.
For tapping aluminum I would use a two flute gun tap in bright finish.
Aluminum likes to stick to black oxided drill and taps so they are not a good choice. Bolube would be a good cutting oil for aluminum.
Also helpful you can make a simple jig for hand tapping by drilling a hole the od of the tap in a small block of aluminum and use it to guide the tap straight.

gblwy · #18 03-10-2012, 01:24 PM

My commiserations. You seem to have some options to go at.

I managed to snap a tap in the nose gear leg while fitting the wheel fairings. Vans suggested leaving the remains of the tap in the hole and making another hole nearby. In my case, no one can see the error!

Cheers...Keith

rocketbob · #19 03-10-2012, 01:50 PM

This is quite an entertaining thread to read.

I'm with Mark, would have had this fixed in under 60 seconds.

Taps are hard and willl shatter when hit with a punch, and would only harm the areas that the threads are engaged in. The hole will still be usable with just a little cleanup.

Last night I was at my buddy's machine shop and was watching a sinker EDM boring a 0.030" starter hole thru a 5" thick piece of Inconel so that the wire of a wire EDM machine could cut the rest of it out. Pretty cool stuff. But a little overkill for getting out a 6/32 tap.

chaskuss · #20 03-10-2012, 06:57 PM

Quote:

Originally Posted by rocketbob

snipped

Taps are hard and willl shatter when hit with a punch, and would only harm the areas that the threads are engaged in. The hole will still be usable with just a little cleanup.
snipped

Bob,
Considering that the hole is tapped in aluminum, just how do you expect any of the female threads to still be "repairable" after driving a hardened steel tap through it? Those threads would be totally wiped out. I'm unfamiliar with how thick this roll over bar is, on the 12. Providing that it was at least 1/8" thick [approx. 1 diameter of the #6 screw], the ruined threads could simply be repaired using a #6-32 HeliCoil insert. Thinner than 1/8" would require re-tapping to #8 or installing a nut plate as was mentioned earlier [providing there is access to install one] If the roll over bar is made from 6061, you might consider simply welding the mangled hole shut, for a "do over".
Am I missing something? I've broken off my share to taps and gotten them out. I would consider trying to shatter one, if it was lodged in 1/4" [or thicker] steel, but not in aluminum.