topless!

I have worked in machine shops for over twenty years. I have removed many broken taps in my days. A drill, whether it is carbide or high speed steel will not work as the top of the broken tap is never flat enough to allow a drill to center itself. Electro-Discharge Machining would be my first choice. There are specific machines referred to as "tap busters" which is a die sink EDM. Second choice is a carbide endmill and mill it out on a milling machine. That will only work if the taps are not too deep ( i.e. if tap is more than 1.5 to 2 times deeper than the diameter of the tap). Either case, the crank needs to be removed so it can be located on the machine. I have never had luck using a screw extractor. They are too soft. Good luck as either way it is a pain in the Ass. If you want to salvage it completely be prepared to use a heli-coil or equivalent screw thread insert.

SgtB

It's amazing how much a bit will dance around chucked up in a mill.

suspectchin

whoa ok guys, sorry it took me so long to get back on. I had some things going on, but the tap is out! thanks to all of you ( you know who you are ) for helping me and giving great ideas and awesome info on the different ways to take a tap out.

I tried something very very simple, just a plumbing trick and it work. I will go into detail about that soon because I have pictures. But I also tried the Nut Trick that was noted by Chris Barry (Thanks chris!) neat little trick that has many advantages. I wasn't able to take picks of the Nut Trick, Due to the fact that when my friend finally came back to town with the welder, the tap was already out and I was not going to put it back in. lol

So to see how good and creative this nut idea was; we tried it on a few things. I'm not a welder so I'm going by what my friend said and used. He used regular 70 wire? he said 70 wire, I don't know, but a bead was welded through the center of the nut as well as around to his satisfaction. Not only were we able to fit a cresant / adjustable wrench around the nut to unthread the broken nut, but we were able to use a drill through the middle of the welded nut so there was virtually no dancing with the bit.

Awesome idea Chris!, and both my friend and I learned something new. Point blank if you can weld this trick works great and is a cost alternative to EDM. Anyhow on to the impatient ppl like myself this is the trick I used(simple/effective). To my suprise it worked a little to easy, but the tap was not buried into the threads and I was lucky.

1) You will need a good pair of needle nosed pliers (short stubby one)and a adjustable wrench, along with some PB buster or any good nut loosing spray

2) After soaking the broken tap with PB several times in 2 minute intervals, I used the needle nose pliers to grab onto the broken tap, next I used the adjustable wrench to grab onto the needle nose pliers (grab onto the needle nose as close to the tap as you can for better leverage). wiggle the broken tap back and forth to see if it is loose enough to be unthreaded.



3)YAY!!! thats all it took. Now I know some taps are broken off real bad but I lucked out and it came out fairly easy! hopefully this will help for some, it is the cheapest and easiest way to remove a broken tap



Unfortunatlly the threads to the crank are boogered up a lttle bit, the damage is mostly done at the start of the threads so I'm pretty sure the crank will have to be re-threaded. Bahhh
again hope this info help and thanks to everyone that helped out

chris_barry

Glad you liked the welding trick. You can also use it to pull out ballbearings that they use to block off galleries in cranks, blocks or heads. Just weld a lug onto the ballbearing then pull out with side cutters.

The tap you pulled out looks to be too coarse a thread. I'm guessing some gorilla tried to retap to a different thread.

Good on you for persisting with this and not butchering it in the process.

Chris.

Slows2k

The tap is definitely the wrong size.

suspectchin

lol. gorilla probally so. yeah the tap was deff. the wrong size I don't know the person who put it in there or why he (the gorilla man) put a tap in there with such coarse threads as you can see on the tap. I couldn't get a good enough close up photo of the cranks threads but about three of the threads are damaged I don't think anything will thread into that part of the crank now. ahh maybe I'll re tap it myself. Slows2k can I use a 10x.8 tap like you mentioned earlier or do I need to go bigger now sense the threads are boogered?

Slows2k

I'd have to measure the flywheel bolts to verify the correct tap size. Drilling the hole oversize will pretty much destroy any value the crank has. I would only try retapping the hole the original size.

chris_barry

I would just try and use the correct size tape to clean up the threads. Hopefully the mongrel tap has only damaged the first 2-3 turns of thread. Once you clean it up you should hopefully have enough engagement with good threads to take the bolt load.

suspectchin

10-4 Slows2k and chris barry. correct the first few threads are the only ones that are boogered, I don't have the bolt to try and see if it will cacth on the threads. If you dont mind what size bolt is it? 10x.8? the threads sre very fine. lol. compared to the killer tap

chris_barry

I had a look at one and I think its a M12x1.0.