Then remove the tool and move it over so the fork will roll the metal over the other side of the fork by twisting the metal the other direction.
How to shrink sheet metal with hammer and dolly.
Using hand tools and machines.
Then twist the handle of the tool to twist the metal around one side of the fork.
The idea was that if the hammered metal went up it was being stretched and if it went down it had shrunk.
You have to adjust your mind to the concept that when you hammer on sheet metal with a steel hammer onto a steel dolly or anvil that you will expand or increase the surface area by thinning the metal.
Start by inserting the fork into the edge of the sheet metal at the desired depth of the shrink you want to make.
The test was to hammer on dolly on one spot and measure what happened.
Very important do not let the dolly rebound onto the metal.
To shrink stretched metal you need a wood hammer a dolly a torch and a wet rag.
Use a permanent marker to mark the area you need to shrink this is critical as once you get going you can easily lose the spot.
First use your shrinking hammer and see what you can do to tighten up the metal with that.
This will tighten up that specific spot.
The metal worker finds the dent in the metal then places the dolly on the back side of the damaged area.
I have identified 14 distinct ways to shrink.
You are looking for a nipple to form in the center.
There are many ways to shrink.
Using care and finesse he then begins to tap the metal from the other side using the hard steel dolly as a backing plate for the hammer blows.