Broken fastener removal

[Sberry]

I wish i would have tossed them all in a coffee can over the years.

 

[Sberry]

I can do it any way but prefer mig. I had to fish for this one.

 

[mmranch]

Thanks very much for the detailed step-by-step... great stuff!

I am currently working on a broken off metal screw. I have a TIG setup but am very new to welding and have only done stick and MIG (currently I'm not very good... I'm the Salvidor Dali of welding). The screw is very tiny and you with your TIG abilities, you could get it out but I can't at this point. I have some tiny easy-outs coming and the screw is soaking in penetrating oil. We'll see what happens but I may have already broken rule #1.

Thanks again for the inspiration!

 

[jwmorris]

If you don’t feel comfortable so you didn’t, you are on the right track already.

 

[Smokeydog]

I have done the weld on a nut on a broken stud a few times with success. Prefer using stainless steel nuts and steel mig wire or stick. The SS nuts have no coating, zinc or cadmium to blow a hole. The little nickel helps bond dissimilar metals.

Also use welded stainless nuts for threaded holes.

 

[jwmorris]

This is my least favorite method because it is quite time consuming; however, it does seem to always work, when you can’t use other methods.

This one is an 8740 chromemoly fastener that broke off in a crankshaft and the threads are several inches deep in the crankshaft before they start. Welding is out and the chances of a decent drilling are slim, without some help.

This help comes from a piece of 3/4” cold rolled that is turned to fit the ID of the bore on the crank shaft. It runs all the way down to the edge of the broken bolt.

I started out with just a 1/4” hole in the sleeve because the center of bolts is generally softer than the edges. Then drill out the sleeve with the next size drill bit in a lathe, then go back and open up the broken bolt and repeat.

I generally like to use left hand twist drills because if it’s not galled like this one was, they often will come out while going up in hole size. If they don’t just keep going up to the correct drill size to tap the hole. This was a 16mm-2, and the correct drill size is 14mm.

Once the core is drilled out of the broken bolt, what is left are just the threads that you can pick out like a mangled helicoil, leaving the original internal threads untouched.

This makes it easy to see why absolutely perfect alignment is necessary for this to be an effective technique.

After that I run a tap in to clean up the galled spot where the fastener seized.

Then it’s ready for the new bolt.

 

[Gator6x4]

This is my least favorite method because it is quite time consuming; however, it does seem to always work, when you can’t use other methods.

This one is an 8740 chromemoly fastener that broke off in a crankshaft and the threads are several inches deep in the crankshaft before they start. Welding is out and the chances of a decent drilling are slim, without some help.

View attachment 786113

This help comes from a piece of 3/4” cold rolled that is turned to fit the ID of the bore on the crank shaft. It runs all the way down to the edge of the broken bolt.

View attachment 786112

I started out with just a 1/4” hole in the sleeve because the center of bolts is generally softer than the edges. Then drill out the sleeve with the next size drill bit in a lathe, then go back and open up the broken bolt and repeat.

View attachment 786114

I generally like to use left hand twist drills because if it’s not galled like this one was, they often will come out while going up in hole size. If they don’t just keep going up to the correct drill size to tap the hole. This was a 16mm-2, and the correct drill size is 14mm.

View attachment 786115

Once the core is drilled out of the broken bolt, what is left are just the threads that you can pick out like a mangled helicoil, leaving the original internal threads untouched.

View attachment 786116

This makes it easy to see why absolutely perfect alignment is necessary for this to be an effective technique.

After that I run a tap in to clean up the galled spot where the fastener seized.

View attachment 786117View attachment 786118

Then it’s ready for the new bolt.

View attachment 786119

As i was looking at that a thought came to mind. The thought was I wonder how long it took to remove the parts to provide such a clean and open work area.

 

[jwmorris]

It was a brand new engine intended to go into a vehicle. I was confident enough on success work carried on getting it ready and made my life easier because of work height.

Some vehicles the engine/transmission and front subframes are faster to drop than pulling just the engine. Such is the case with this car too, I imagine.

 

[GeneV]

Beautiful, patient work, but I don't understand how you weld your "false" stud to the broken AND BELOW the surface stud?
I'm going back to read it again to see what I missed, but my hats off to you.

Yeh, same thing I'm impressed with, he go right in there! I've done this before with a stick welder, but in my case the screw was partially exposed, although only slightly. I fit a washer over it, and then I dab dab dabbed the exposed screw with 6013 rod until I had enough buildup to grab with vise grips. With the broken screw inside like that, I don't even know. I guess I'd find an aluminum spacer that fits just in there, and weld inside of it.

Oh, I just read, the head is aluminum!

 

[oldtimer 66]

I don't have any pictures of this method you will just need to visualize how this is done. To the machinist in house I think most of you can remember Ingersoll cutters, face mills end mills etc. The cutting inserts were generally held in place with a single Torx screw in the 10-32 range. The insert pocket was just a milled relief in the cutter that captured 2 sides of the insert plus the mounting face. If you had an accident with the cutter and broke out the insert and screw the cutter was repairable if you dressed the insert pocket with a file and removed the broken screw. To remove the broken screw we would use a air scribe aka pneumatic pencil, vibropeen etc. It was just hand work. You would get a small divot started on the radius of the screw and the walk the screw leftie loosie direction to remove it. The vibration basically walked the screw out with very little effort. Now this did not work all of the time maybe 75% successful. Then it was either to the tap burner or back to the manufacturer.