Bring 32A Alpha crank back from the dead

Crank broken at drive shaft keyway. Keyway far too deep, and shaft far to hard IMHO
Tub ready to take red-hot crank. It will sit on two steel bars and be covered in *dry* sand. This, I am told, will allow it to cool slowly enough to be properly tempered. Crank shaft around keyway and half way down shaft brought to bright red heat using a welding torch. Kept there for 30 seconds and then covered in sand before if looses its redness.
I have filled in the hole and built up the crank all round. Next step is to grind it all back and see what the penetration is like and whether any impurities have been bound in.
Job in lathe with toolpost grinder in place
Looking hopeful
Well, not as claggy as I feared, but not perfect either. Still a few thou' to take off to finish. I will think on it for a day or two to decide if it can be used, or whether I have to melt it all again.
I did infact melt it all again, and added quite a bit of metal. May not have been such a good idea, First, the heat distortion was rather more than I expected, the outer nose of the crank is now some 20 to 25 thou out of true, so the crank cannot be ground between centres any more. Second, the crank actually shrank. The crank in the picture did clean up just about, but the other one was about 1 to 2 thou undersize. This I was not expecting. With all the heat treatment and hardening that it went through at the factory I imagined that it would be stable. I have a lot to learn.
This is a close up of the first crank I recovered, OK, useable, not first class, some impurities have burned down into the original metal.
Close up of the second crank. I haven't got down below the new metal on the parallel portion of the crank and already I am undersize, the bearing is already loose on the shaft. This is scrap. I propose to soften and drill out the shaft, then make a new shaft to push in, just to see if I can. I intend to make a shaft to hold a sprocket on a taper. Watch this space!
More to come

		Crank broken at drive shaft keyway. Keyway far too deep, and shaft far to hard IMHO
		Tub ready to take red-hot crank. It will sit on two steel bars and be covered in dry sand. This, I am told, will allow it to cool slowly enough to be properly tempered. Crank shaft around keyway and half way down shaft brought to bright red heat using a welding torch. Kept there for 30 seconds and then covered in sand before if looses its redness.
		I have filled in the hole and built up the crank all round. Next step is to grind it all back and see what the penetration is like and whether any impurities have been bound in.
	Job in lathe with toolpost grinder in place
		Looking hopeful
		Well, not as claggy as I feared, but not perfect either. Still a few thou' to take off to finish. I will think on it for a day or two to decide if it can be used, or whether I have to melt it all again.
		I did infact melt it all again, and added quite a bit of metal. May not have been such a good idea, First, the heat distortion was rather more than I expected, the outer nose of the crank is now some 20 to 25 thou out of true, so the crank cannot be ground between centres any more. Second, the crank actually shrank. The crank in the picture did clean up just about, but the other one was about 1 to 2 thou undersize. This I was not expecting. With all the heat treatment and hardening that it went through at the factory I imagined that it would be stable. I have a lot to learn.
		This is a close up of the first crank I recovered, OK, useable, not first class, some impurities have burned down into the original metal.
		Close up of the second crank. I haven't got down below the new metal on the parallel portion of the crank and already I am undersize, the bearing is already loose on the shaft. This is scrap. I propose to soften and drill out the shaft, then make a new shaft to push in, just to see if I can. I intend to make a shaft to hold a sprocket on a taper. Watch this space!
More to come