Piercing Punches

[quickcut]

I had to replace some round punches(10mm) in a press tool. I was thinking is their a reason why the front end(piercing part ) is not hollow ground. Surely this would help with a better rake angle while punching. I am punching .7mm stainless 430. Thanks

 

[kd4gij]

Hollow ground would load up and dull to quickly.

 

[quickcut]

Thought as much. I am going to try it just to see how long they take to dull and what effect it has on the strip.

 

[JimDawson]

I have hollow ground punches. Normally use about a 4 inch wheel and put about a 1 inch radius on it. This puts about the right shape on the punch. Have had good luck doing that. I have also hollow ground the cutoff tool in progressive dies with good success.