Introduction: Sheet Metal Counter Sinker Tool
I like to use sheet metal for the sides and bottom of drawers. So to attach them I like to use screws, but to drill a counter sunk hole in sheet metal doesn't work well. So I would drill a hole a bit smaller than the screw and use a BIG center punch to bend the metal into a cone. It was a bit messy and took some time.
Step 1: Stock Hand Hole Punch
So I had found this Hand Operated Hole Punch at an auction house. It was cool, but it only came with one punch and die set, so it could only punch one size of hole. I thought of making more punches and dies from scratch, but then Harbor Freight started selling a knock-off copy and now they are easy to find on Ebay:
( I have no commercial interest in where you find your punch. )
The really nice surprise was the punches and dies also fit my older punch. So now I had two punches and could punch two different size holes without changing the tool. One could punch a clearance hole and the second punch could cut the "tap" hole for a sheet metal screw.
These hand punches are also great for "Pop Rivet" holes.
Step 2: New Die
The dies are all threaded 7/16" x 20 tpi ( threads per inch ) and a common bolt will work. So I put a 1.5" long bolt in my lathe and center drilled the end to make an opening for the sheet metal to sink into. You could hand drill this or use a drill press, but it is much easier with a lathe.
Step 3: Punch
The punch needs to be 0.275" diameter, I found a bolt in my junk bin the right size. One end needs a 90° cone cut on it. The other end needs a shank cut to match the levers of the hand punch.
Here are the dimensions:
Over all length = 1.4"
Cone on end = 90°
Groove on other end:
Diameter = 0.18"
Head thickness = 0.1"
Groove width = 0.25"
Sorry I didn't make a fancy drawing, I hope this works for you.
Step 4: Finished Tool
So you can screw in the die and install the punch and you are all set.
Step 5: Give It a Try!
So adjust the die until you get the metal to form just the way you want it. You will know when the punch / metal / die are clamped solid, so don't force it farther. Something will break if you push hard enough!
I hope this helps you make a tool that I have certainly found useful.
Be Safe and Good luck.