pic: What could this be for?

[IndySam]

Is that the jig used to make all the lovely holes on the King Krab?

[Bertman]

To help greenies learn to count by 5s without a computer?

[Aren_Hill]

looks like it might be involved with the whole frame mounting setup you got going on.
each hole is 1/2" from the previous one, and you simply move the drill bushing to the distance you would like, to accurately locate a hole

[samir13k]

monocoque template!!! just like 1501!
...But we space ours a little farther apart,
you are gonna need alot of rivets if thats
your spacing!

[AdamHeard]

Originally Posted by IndySam

Is that the jig used to make all the lovely holes on the King Krab?

Lol..... Awesome guess, I bet the guys who fabricated King Krab wish they had such jigs then (actually the same guys that made the jigs). All the holes on the crab were done by one dedicated (and I guess technically abused) kid on a converted manual.... All 1000 or so.

However, with a drill press and this jig's sister jig, we should be able to put such holes on the 1" and 1.25" face of any extrusion rather accurately. The other jig has an end flange that aligns the holes 1/2" from an edge, this is able to "piggy back" on existing holes to finish the piece.

[Aren_Hill]

I win!