Sometimes good ideas end in tears.
Clearly there wasn't a whole lot of steel connecting the threaded draw stud and the die assembly, I was having a hell of a time pushing the punch through (bending metal was involved). Apparently 8 gauge alumin(i)um is beyond the capacity of this instrument. The instrument in question being a "vintage" (it has a wooden box, no idea on era of manufacture) multi punch set of Japanese manufacture.
I also felt a little elation at rediscovering the root of the word "borked", typographical error in my naming of the file "broken-punch". Sure, this may be in error, but I'm going to demand you allow me this silver lining and refrain from dashing my bit of feel good until you see a pic of the finished panel, thanks!
So close. I figured I was at about the initial shearing point where actual force involved drops dramatically, which was good, as this was proving to be a PITA to punch by hand. Then the force required to turn the screw dropped like a rock.
Well, I've got an idea of where the hole *should* be.
Pretty sure this won't accept the 1 inch lamp body though.
In other news, the scroll saw handles 1/8th inch 6061 (I think) just fine with a 10 tpi (Delta 40-193) regular tooth blade. I went super easy on the feed rate, and ran into no problems. I'll be having a go at using the chop saw as soon as I find a sacrificial 10 inch blade (not my fine finish framing blade).
I did flinch a little at running completely through, but scored as such and with a quick swipe of hacksaw (before deciding to give the brute force method a go) the material snapped pretty well. This is where the metallurgists may pile in and inform me the 6061 is wrong. The extrusion is surplus from seismic joint assemblies, it's either 6063 T5, T6 or T52; 6061 T5, T6 or T51; 6105 T5 or T6, 6005 T5, 6005A T5 or T61, according to current manufacturer datasheets. Anyway, I've got plenty for now, it's nice and thick, and will be turned into stuff that is not part of a building.
In the end, I think this oversized pilot lamp will be worth the effort and headache. In the meantime, in looking at the going rate of Greenlee punches (taking into account the variety of sizes I need) I'm thinking the path of least resistance is to fix my welder, fix this punch and tough it out until I finally get around to completing the CNC build (Couple years? Sooner? Later? Time will tell, taking bets now... ).