Welding Tips and Tricks

My neighbor brought me a post driver to be repaired. It has a single acting cylinder that raises the weight. The end of the cylinder shaft (hardened) broke were the threads start. Can this be welded back with any success? If so, what process? I have stick welder and a mig. My gut feeling is to replace the cylinder shaft. Any thoughts?
Thanks,
Kevin

In most applications, I'd say no, replace it.

In a post-driver, though, it may be worth a try. The tensile stress is no more than the weight divided by the cross-section area of the shaft, and the impact will tend to work-harden the weld. As for stick vs. MIG, it's a coin-toss. The important thing will be to keep the HAZ small -- One pass at a time, thorough cooling. (You don't want the HAZ to approach where the seal sits at the top of the stroke... If this softens enough to "mushroom" during the impact, It'll ruin the seal, and re-hardening the shaft is not practical in anything but a specialty shop.

Good luck.

Steve S.

Thanks, I am going to give it a try.