After a good many years of using and verbally abusing my Craftsman post hole diggers, I believe I stumbled onto a "cure" for the bent tips that invariably happened every time I hit a rock or large root. On my farm, that means every other hole I dug for my wife's shrubs, my trees, and various posts for fences, etc. Extremely frustrating, to say the least. Use it, bend it, haul it to the shop, take it apart, bang the tip straight, reassemble, return to work site, repeat often....

Step 1: First Things First...

I used tools that have in my shop, but other tools could be substituted pretty easily as the operation is simple.

To begin, I disassembled the diggers again, cleaned them a bit, and pounded the tips as straight as I could on my large vise/anvil with a heavy mallet. Once I was satisfied they were basically straight, I took two pieces of heavy, galvanized strap that I had on hand and laid them out vertically on the blade of the digger. I oriented them to best use the existing holes in the strap for attaching to the blades and marked the tip profile on the straps.

Step 2: Shaping and Drilling the Holes...

Sorry, no pictures here, but I cut the straps with a grinder as close as I could to the curve I had marked. After completing the cuts, I clamped the straps on the digger blades and marked and drilled the holes through the blade to line up with the holes in the straps. Once done, I bolted the straps to the blades using some appropriately sized screws I also had on hand.

Step 3: Ready for Final Shaping...

Once mounted on the blades, I moved to my bench grinder and put a rough bevel on the tips of the galvanized straps to help them cut the ground a bit easier. I used the shortest bolts possible to have as little projecting out of the back of the blades to reduce drag when hitting the sides of the hole. After a few test holes (still not an easy job on my place), I can say that I haven't bent the tips even when connecting on a buried rock. My cost was more or less zilch since I had the straps and bolts from a cleanup of my dad's shop.