Repairing a small cast iron gib key

Hey guys, I am working on restoring an old hit and miss engine and in the process of trying to remove the gib key that holds the pulley to the shaft....it broke.

Now the question is how to weld the broken piece back on or do I weld a tab on the end of the gib key so I can use a slide hammer to remove it?

The question is how would I weld something that small? Do I have to preheat it and slowly cool down?
I did order some aluminum bronze tig rod and see if that works. I have AC/DC Tig, stick and mig capability at home.
Any ideas or suggestions?

here is a link to a video showing the problem and how small the piece that I am working with.

http://www.youtube.com/watch?v=As6tyNdPXOE

Cheers

Richard

I would just hear the area up with a torch and try to pull it out with vise grips. Heating on that end shouldn't have any impact on the rest of the crankshaft. If you concentrate the head on the outer hub rather than the shaft, it will likely be a little better.

I agree with heating things up to get some expansion. If that key is cast iron, I doubt any weld is going to be good enough to use impacts to get it out. Brazing might be ok, but I would just plan on making a new key out of steel after you remove the old one. The problem is that welding will make the cast iron even more brittle, and it will break again right next to your weld. Here is a trick I used to use all the time to pull stubborn dowel pins. Take a slide hammer and fit it with a bolt with the same thread as the adjusting screw in the handle of a pair of vise grips. Use a pair with real sharp serrations on the jaws. Grip the key with them, and use the slide hammer to pull, while you heat up the hub. If worst comes to worst, you can probably drill out most of the key and brake out the corners with a small punch.

Looks like the rust is also around the shaft not just the key ,I don't think the key will be the main problem, I am with Rambozo , Heat will help , I have removed many keys like that on farm machinery and old fertilzer equipment in the past. A rosebud torch and applying heat ( you must just get it red not orange white hot )to the hub of the flat belt pulley will help loosen up the rust around the shaft. You might have to do it a couple of times the expansion will fracture the rust and let the penetrating oil move further into the hub.

I was thinking the same thing, vice grips (and the kind with the fresh, sharp serrations on the jaws) to grab the remnants and either pry or slide-hammer the key out of there. If needbe you could use TIG to build a glob of aluminum brone and grab onto that with your slide hammer instead. Just my thoughts.

I'd try heating it and placing a parrafin bar up to it, to try and draw lubricating wax into the rusted crevices.

And yeah worst case scenario, drill it out while trying to save as much of the flat surfaces as possible. Cast iron drills nicely. :) You might need to set up a three jaw puller to pull that pulley off the shaft, with it set up to press on the end of the shaft. I could see you loading it up with a good bit of force, a then suddenly "tink" it's free. Best of luck.

The paraffin wax is good on things that you can heat. I have heard (although not tried myself) that a 50/50 mix of acetone and ATF works really well as a penetrating oil .

Great ideas guys.
I'm going to give it a try tomorrow and see where it gets me. I will post my results, good or bad.

Cheers

Richard

Well guys I was able to remove the gib key by tig welding a bolt onto the end of the gib key and then using a home made slide hammer. I used silicon bronze as a filler. I did not preheat or let the key cool down. Once it was welded, I screwed on the slide hammer and gave it a couple of good hits and it just came out.

The video tells all: http://www.youtube.com/watch?v=0vLLZJ1cnI8

Thanks for the ideas and help guys.

Cheers

Richard

Congrats! Thanks for the follow-up report.