I saw a demo at a cba event spring conference in Exeter, CA Tom Clark and Tsur Sadan and others they slit and drifted a piece of 2'' round with a 2'' drift and place a piece of the same material through this and creates a joint when cooled that is very solid. I know the drift has to be just a little bit smaller than the parent metal this drift is hammered all the way through from one side then another heat is taken and then you insert the other member. Does any one know the formula for the drift size? I tried this with 1/32'' smaller drift and it came out too loose i was using 1/2'' stock and my drift is 15/32. I will try to take another heat and resize the drift but its like spitting hairs the belt sander is another option (too slow)

I saw a demo at a cba event spring conference in Exeter, CA Tom Clark and Tsur Sadan and others they slit and drifted a piece of 2'' round with a 2'' drift and place a piece of the same material through this and creates a joint when cooled that is very solid. I know the drift has to be just a little bit smaller than the parent metal this drift is hammered all the way through from one side then another heat is taken and then you insert the other member. Does any one know the formula for the drift size? I tried this with 1/32'' smaller drift and it came out too loose i was using 1/2'' stock and my drift is 15/32. I will try to take another heat and resize the drift but its like spitting hairs the belt sander is another option (too slow)

Clinton,

Take a look at Hofi's Blueprint 1051. He goes through how to calculate drift and chisel size. here is a link

I Forge Iron - BP1051 Punch Calculations

Brian

Keep in mind: metal shrinks as it cools. If you drift a hole in a hot piece of steel to exactly 2.000" the hole will be less than 2" when cool.

Right on look at the effort required to drive the second piece in.
Ken