How do I make holes for cage nuts???

I have reached the point in my floor replacement where I need to punch the 3/8" square holes for the cage nuts that hold the transmission cover to the floor. I have searched and cannot find anywhere that tells how to punch them. I have looked at Greenlee hole punches but cannot find one in the 3/8 square size. has anyone done this before?

 

3/8" drill and a square file. Shouldn't take long, thin metal = quick.

The time you spend trying to get a square punch you could be done IMHO.

 

There were some instructions a while back on making your own broach...Might be able to search for that and find the thread.

 

got about 15 holes to do, not sure my arms can take filing all of them

 

They do make a square drill....drill bit inside a square stock...I had several different sizes between cleaning house and two restorations..I will keep looking for you and send them to you...

 

You sure those aren't for wood only:? Kinda like this:
http://www.amazon.com/Grizzly-G1514...f=sr_1_65?ie=UTF8&s=hi&qid=1195772434&sr=1-65

I've never seen a "square" drill for metal...:?

If you know something I'll just wait...:lurk:

 

Thats it...little 3 in 1 oil keeps them cool...

 

Paul, thanks for the offer. I found a way that was actually rather quick and neat. took a 3/8" square file and stuck it into the 3/8" pilot hole. move the handle of the file around and back and forth and the teeth of the file do their stuff until the file fell through the hole. completed 15 square holes in about half an hour. the edges of the holes had to be dressed slightly to make them flat again. the cage nuts fit just like the stock holes.