If you are struggling to punch holes in the centre of flat bar, then the Metalcraft hole punch guide could just be what you are looking for.
Just simply lossen and drop the platform on your punch and shear tool, bring the handle down so the punch pin is fully inserted to the punch block, then offer the gauge underneath the pin at the desired hole. Lift the platform to fully support the gauge and lock the platform in place. Next retract the pin and remove the gauge, the tool is now set.
The gauge works with steel widths of 10,12,15,16 and 20mm for 3mm holes
20,25 and 30mm for 5mm holes
N.B. As there is a slight taper to the punch pins, it is recommended that you try to locate the gauge neared the end of the punch pin at its widest point.
Size: 83mm x 20mm x 2mm