how to make square holes in metal bed strips

As I continue on my labor of love. I have cut all the boards for the bed from a tree that I cut down, hauled to the saw mill to be milled, and the stickerd the wood till it was cured. I used 7 boards instead of the usual 8 or 9.
Here is my problem, because when I took the truck apart in 1987, I stored the bed supports some place safe(wherever that was). I made my own bed supports out or 1 x2 steel boxes. I did not put the supports in the stock locations, didn't think of this when I did it 2 years ago.
Now I need to drill holes in the bed strips,and then punch square holes. Any Ideas how to punch a square hole??
I figure on only 5 bolts per strip (to cut dowm on the number) but that is still a lot of holes to punch.
The second question are the carage bolts 5/16??
Herman quail

 

The best thing to do would be find a welding shop in your area that has a Iron Worker. They most likely would have the right dies that would work in that machine to punch the holes you want. You could drill holes a few thousands under the diagonal dimension of the square part of the carriage bolt and wedge the bolt in there as you tighten it also....Big Tim

 

A long trip, but take 'em to THESE guys.

 

If you use the right size drill bit that will allow the serrated shoulder of the bolt to grab the holes don't have to be square. Of course it helps to have a helper in the bed putting pressure on the bolt head while you are under the truck tightening the nuts.

 

This is really cool but I dont think it is the answer you were looking for.

http://wiredcpu.com/how-to-drill-a-square-hole-video/

 

I guess I will keep looking.
thanks herman

 

One way I've found to make square holes is to drill a hole the same size as the square flats on the carriage bolt, take some tape and square off the the hole and get a small traingle file and file the corners out, little labor intensive but it works but it works good for thin metal work like the bed strips..

 

If you already have your strips then this is no help. But...they do sell strips that have no holes in them and secure from underneath. Personally just drilling the hole big enough and running the bolts through will work just fine. Thinking outside the box all the time.

Flashlight

 

A better look at how they do it:

http://www.youtube.com/watch?v=L5AzbDJ7KYI&NR=1

 

Well over the weekend I drilled 1/4 holes then used a ground square tool bit that was 1/4 in size and used it as a punch, I set the bed strip on the end grain of a block of wood. After punching a square hole all I had to do was clean up the burrs and a lite tapping on a flat surface to make it all flat.

Now I have square holes in my bed strips

Thanks for all the Ideas on how to drill a Square hole.
Herman quail