I'd like to find an easy way to punch small (1/4 to 1/2") D-shaped holes in sheet metal up to 1/16" thick.
I'm thinking of doing this in a small hand or hydraulic press, as follows:
The movable die is a piece of drill rod with a flat milled on one end, hardened and tempered.
The fixed die has a hole bored in it, intersected by a milled channel. It is also hardened and tempered.
The female d-shaped hole is created by putting a piece of hardened and tempered keystock in the milled channel in the fixed die.
The diameter of the hole in the fixed die will need to equal the diameter of the movable die plus some amount of clearance.
The dies are aligned by using a temporary movable die with diameter larger than the hole in the fixed die and a tapered (conical) end.
Procedure is: align the fixed die to the temporary conical movable die, clamp the fixed die, replace the temporary movable die with the d-shaped movable die, insert keystock in fixed die, insert work and punch.
Questions: 1) will it work?
2) what radial clearance is needed between the dies, relative to the sheet metal thickness?
3) should the cutting edges on the dies be dead sharp, or radiused?
4) should a lubricant be used?
Thanks in advance for your wisdom.
I'm thinking of doing this in a small hand or hydraulic press, as follows:
The movable die is a piece of drill rod with a flat milled on one end, hardened and tempered.
The fixed die has a hole bored in it, intersected by a milled channel. It is also hardened and tempered.
The female d-shaped hole is created by putting a piece of hardened and tempered keystock in the milled channel in the fixed die.
The diameter of the hole in the fixed die will need to equal the diameter of the movable die plus some amount of clearance.
The dies are aligned by using a temporary movable die with diameter larger than the hole in the fixed die and a tapered (conical) end.
Procedure is: align the fixed die to the temporary conical movable die, clamp the fixed die, replace the temporary movable die with the d-shaped movable die, insert keystock in fixed die, insert work and punch.
Questions: 1) will it work?
2) what radial clearance is needed between the dies, relative to the sheet metal thickness?
3) should the cutting edges on the dies be dead sharp, or radiused?
4) should a lubricant be used?
Thanks in advance for your wisdom.
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