Thread: My power hammer :p

I did. They then to jump open during the impact on the thing you are hitting full on with a sledgehammer.
I'm sure that can be solved somehow, but hold-downs are not really means for impact use

Sounds like the hole for the holdfast was a bit too large.
I use a 1/2" diameter hold fast in 9/16" hole. The hole is 3" deep through a steel bar. The steel bar is welded to a square tube on the bottom so that when I put the bar and pipe into the hardy hole it will sit flush with the anvil face. I've hit things with a 12 pound sledge and the holdfast didn't come loose until I knocked it loose.

Or maybe the smithy gods were smiling on me when I made it.

Yeah maybe I was just using the wrong kind or something.

I use the Roubo style holdfast of hand forged iron. The cast iron ones aren't "springy" enough to hold and often break.
It takes about 30 minutes to beat one out.