I broke a tap, now what?

[adamjr]

I drilled a couple of holes in my step bumper in order to bolt up a trailer wiring jack. My first mistake was probably buying the Kawasaki (as in the motorcycle) branded tap and drill set from the local Pep Boys instead of a really good Irwin tap from the hardware store. I was at Pep Boys getting something else so I thought "what the heck?" It is a 1/4 20 tap and I've tapped plenty of holes in my day.

It started off easy enough and I got about half way through it. It's a thick piece of metal, I'd estimate 3/8" steel. My usual method is a liberal shot of wd 40 on the tap. Once I get a bite I turn it about 3/4 and back out about 1/2 turn to clear chips. Without warninh the darned thing snapped off. Of course it snapped off flush with the bumper on both sides of the hole so there's no getting a vice grips on it.

No what?

 

[Mntom]

Re: I broke a tap, now what?

Is it possible to get to it from the back side? IF (I know) you can get to the back then take a punch and tap on the tap itself. That just might loosen it up enough to be able to work it out. You can also try the punch to the other side and just keep trying to back it out.

 

[45Auto]

Re: I broke a tap, now what?

If you have a Dremel tool, the 1/8" diameter carbide Dremel bits are harder than the tap. You can bore a hole through the tap with the carbide bit in the Dremel then use it to cut the tap apart so you can pick it out of the hole. They've saved my ***** several times.

Home Depot sells the one similar to this but with the rounded nose that will bore through the tap:

http://www.amazon.com/Dremel-8-Inch-Carbide-Grout-Removal/dp/B00004UDID

 

[tx1961whaler]

Re: I broke a tap, now what?

Would it be easier to just leave it in there and drill some new holes slightly offset from the original?

 

[adamjr]

Re: I broke a tap, now what?

Good ideas and thanks for the fast replies. No Dremel, I burned it up and haven't fixed it yet. I have the old school Dremel from the 80's that was before they went direct drive. There was a splined shaft coming out of the motor and a splined shaft that went to the arbor. They were coupled with something as durable as aquarium tubing that was molded to fit the splines.

I may pick up the 1/8" bit and chuck it in my drill and do that. It seems much easier then the pin punch method. If the drill can't get fast enough to cut it then I'll try the punch out.

Thanks again.

 

[45Auto]

Re: I broke a tap, now what?

Your drill isn't going to turn any where near fast enough for the Dremel bit to do you any good. Don't waste your money on it if you don't have a Dremel.

 

[DECK SWABBER 58]

Re: I broke a tap, now what?

The only thing worse then a broken off tap is a broken off "easy out".

Well.... hitting your knuckles with a sledge hammer does rank up there too.

 

[windsors03cobra]

Re: I broke a tap, now what?

In the metal shop I work in on of the many things I do is broken tap removal mostly in cast iron. My first attempt will be to use a punch or other tool and attempt to turn the tap back out the way it went in, nice when it works.
Another method depending on how much tap is broke off and or where it is in the hole you can sometimes bust the tap up into little pieces and get it out.
The last method for me is to use a tap burner which uses electric discharged through coolant to disintegrate the tap.

Bust it into pieces or move the trailer plug bracket over an inch, err over the broken tap hole/s.

 

[adamjr]

Re: I broke a tap, now what?

The only thing worse then a broken off tap is a broken off "easy out".

Well.... hitting your knuckles with a sledge hammer does rank up there too.

Yeah, I have one about as bad. I have an F-150 which pretty much assures my tools won't rust. While replacing the rear leaf spring cradles I had just bolted the shackle to the rear eye of the leaf spring. I was holding the spring while trying to line up the top bushing of the shackle with the cradle. As I was holding the spring and pushing up the shackle (which weighs about 2 pounds pivoted forward and guillotined my first and second fingers leaving a gash about an eighth inch deep in my first and second finger. My hand was covered in grease and anti-seize and using the scrub brush to clean the grime out was oh so pleasureable.

I just thank my lucky stars that my doc has me on a tetanus booster schedule every 5 years instead of the traditional ten.

 

[fdmsiv]

Re: I broke a tap, now what?

Use the old dremel with a cut off wheel and cut a slot across the top of the broken tap and use a flat head screwdriver to turn it out or cut an X and use the intersection of the lines for a drill bit, maybe a 3/16 bit

 

[dwco5051]

Re: I broke a tap, now what?

All the above methods I have used at one time or another. Which one will work the best seems to depend on the phases of the moon, how the gods of broken taps are looking at you that day, or how much of your good luck you have already used up this year

Cheap taps are usually very hard and very brittle. Smashing it up may be your best bet in this case. WD40 is not a good substitute for actual thread cutting oil but I think you already know that.

 

[Tim Frank]

Re: I broke a tap, now what?

Out of curiousity, what drill size did you use for the hole?

You could get a punch smaller than the tap, or a small cold chisel, hit the tap with a goooood shot of freeze spray and quickly give it a rap with a hammer and chisel/punch.

Obviously wear wrap around safety glasses!

 

[j_martin]

Re: I broke a tap, now what?

Somebody handy with an aircraft size cutting torch could blow that tap out of the hole and not even mess up the threads you've made.

Another thought would be to use a 3/16" starter punch and just punch the tap through the hole. Then drill it out and use a bolt and nut. Safety glasses, or better yet a full face shield is a must.

 

[Tim Frank]

Re: I broke a tap, now what?

As above, my post and j_martin....since it is a through-hole, you are in WAY better shape than a blind hole.

You should be able to drive the tap stub out the way it came....or just shatter it.

Remember Fudd's First Law...."If you put enough force on anything, it will either break....or fall over."

 

[rbh]

Re: I broke a tap, now what?

As above, my post and j_martin....since it is a through-hole, you are in WAY better shape than a blind hole.

You should be able to drive the tap stub out the way it came....or just shatter it.

Remember Fudd's First Law...."If you put enough force on anything, it will either break....or fall over."

YUP, drive it through and drill and tap it to the next size up.

 

[Pascal]

Re: I broke a tap, now what?

if you can find a machine shop with this tool they might get it out for you IF you haven't gibbled it up with a torch or a large beatin tool.....

you might even opt to purchase one yourself if you are or have been prone to breaking these brittle babies........

http://www.waltontools.com/products/extractr.htm

There are bound to be other brands out there as well. This is just an example......

 

[Jeff-in-PA]

Re: I broke a tap, now what?

Your first mistake was using WD-40 as a lubricant. Engine oil is way better than WD-40.

Was the tap straight or were you crooked? If you were crooked, it started centered in the hole and as you went down, one side of the hole got all the cutting pressure and it broke off the tap.

Did you have a tap handle or were you using some other mickey mouse method? A tap handle allows even pressure on tap ( it's not forced to one side like if you used an adjustable wrench to turn the tap )

The home hobbiest should use a 13/64 ( .203 ) drill for 1/4-20 UNC. If you have a drill press, drill a hole using a "F" drill ( .2570 ) in a piece of metal at least a 1/2" thick. This will help keep the tap straight.

Also, look at the cutting edges in bright light. If they look dull or chipped, get a different tap. You no longer have sharp cutting edges and you are flirting with disaster.

Jeff
Machinist since 1978

 

[dwco5051]

Re: I broke a tap, now what?

Agree that the 13/64"is a good substitute for a #7 bit but even the home hobbiest should have a few of the right size bits in his drill box.

 

[Jeff-in-PA]

Re: I broke a tap, now what?

Agree that the 13/64"is a good substitute for a #7 bit but even the home hobbiest should have a few of the right size bits in his drill box.

Those few thousandths of bigger drill size plus drilling with a hand drill should make for a slightly larger hole but still more than 70% thread. The larger hole will make for easier tapping which reduces the chance of breakage.

 

[a70eliminator]

Re: I broke a tap, now what?

If your steel bumper had two layers of steel (double walled) than thats why your tap broke, it cuts threads in the first layer then begins to bind as it digs into the second layer, that's the best I can do at explaining what I've experienced with taps, shattering the brittle steel of the tap and working the broken pieces out has worked for me.