The Stovebolt Site Forums The Shop Area General Truck Talk Machinists Alert -- Advice needed for a broken set bolt/screw

I especially enjoyed Grigg's unbridled scolding of 'Da Boss' about staying away from the not-so-easy outs.
I do, however believe that cletis is losing his sharp edge by allowing this clearly off-topic discussion to remain in this forum. (Special note regarding the two 'smiley faces')
Carl

Yes it is kind of off topic but there really isn't a proper place to put it. And it is a truck part. So I cut a little slack for the boss. Maybe I'll get a raise.

The way I figure it, if Grigg can't do it, You are just screwed. John knows this from experience, so that is why the outcome was totally expected.

The other day I was dealing with one of Griggs inventions, and had a SEVERE problem. I wanted to call Grigg, but didn't have his number. (Grigg is happy that I do not have his number, trust me). So it was the 1/2" thick oil adapter bracket that he did for Cosmo. Someone wanted one, so I made one for them. This is where it gets interesting...

While tapping the #7 hole for the 1/4-20 tapped hole, I broke the tap off about half way through the 1/2" and flush with the top, so no way of grabbing it to turn it out. That was about a one hour ordeal I really hope to never repeat!

In a case like that, there is no amount of heat, reverse drill bits, easy outs, nothing I know of that even starts to fix the problem. None of the regular ideas worked. In the end, since it was only tapped half way, a very long very sturdy punch and a very big ball peen hammer were the only hope. My 20 ton shop press just bent my very solid punch, so out of ideas, and a little bit mental by this point, I just beat that sucker out of there! Once I pushed it out the way it came, I had enough threads to feel good about its holding ability.

But MAN!!! What would Grigg have done? He doesn't realize that there are people out there that ask that question. After Grigg, the same question could be asked of Jesus. I think Jesus would have called Grigg!

I can't see the pic of what your dealing with,but the best way is to disassemble it, put it in a mill and get dead centered on the bolt. Then you can drill it out with carbide if necessary. And Heil coil it if the threads are damaged (If your burning up drill bits,sharpen them at the first sign of heat,slow the rpm down and use lots of cutting oil)

Deve
I have done that before with a punch.
But the punch will not last long against a broken tap.
Save old taps and tool bits, to sharpen up and break the teeth out of the stuck/broken tap.
There are even more tricks out there, but once a piece of tool steel is broke off deep, it will take tool steel and patients to get it out.
Punches are just surface hardened and after a few wacks, you will be using mild steel.

Don
Edit: I forgot to add, Grigg is a very talented metal worker and I have seen his shop.
He also makes great homemade ice cream.
Black berries are in the freezer and will be ready for the Stovebolt Homecoming.

Don

Seems like somewhere I remember a tool for removing broken taps that has steel fingers to insert in the flutes of a tap to remove a broken tap, anyone seen one?

Remember when drilling and tapping, drill the correct size hole and run the tap in with your Bridgeport before moving the table. Use back gear for the tap, of course. If the tap gets tight, it will spin in the chuck before breaking.

I routinely do this and never had a problem, however, on pure Al, unknown at the time, the tap started galling and I shut it down, got some Al alloy instead.

Ed

Ed
I have tried those finger tap removers.
They do not work unless the broken tap is loose in the hole.
May even have a set somewhere in an old tool box.

http://www.newmantools.com/walton/extrtap.htm

Don

The only thing that's going to remove a jammed broken piece of high speed steel (a tap) is bolting your part down to a mill and go threw the center of it with carbide tooling. All the other ways are hit and miss, mostly miss!

There are always other ways...
There is an EDM machine made solely for burning out broken taps. In my experience this is often the best way, least likely to harm the part. It is certainly not the only way.

Has everybody lost sight of the original problem in all this theoretical discussion? The setscrew is at an oddball angle in a difficult location on a big piece of equipment that would be impossible to set up in a mill, an EDM, or any other sophisticated piece of equipment. This one is going to end up as a very tedious operation with hand tools with two possibilities of success- - - -slim and none. I would choose a diamond-dust burr in a variable-speed tool like a Foredom flex-shaft device, the same way I deal with broken-off #6 screws in rifle receivers. Now, to really increase the pucker factor, try removing a broken scope mount screw on a $15,000.00 custom engraved Mauser, made before WW II by a German master gunsmith!
Jerry

The original mission was accomplished. It is time to shut this one down.