Frame Rail Jigs

Now that I had the frame rail blanks cut out I needed to start working on the frame rail jig. This is the contraption that will allow me to weld up the two frame rails from it’s parts.

I wanted to use 1/4 inch or 3/8 inch plate, but after pricing a full plate, I didn’t want to spend that much money just on the jig. So off to Westex Metal Recycling to see what I could find.

I found about 16 feet of 3/16 inch plate that was 14 inches wide and of various lengths. This wasn’t that bad in price, though there was a lot of surface rust and they had a slight curve over their lengths. I did all I could to try to flatten out the plate but I couldn’t get it flat enough. That’s when I decided I’d use angle iron to reinforce the plate to straighten it out and give it added rigidity.


Here I’m laying out a piece that is 14 inch by 48 inch that I’m prepping to weld the first angle iron to. I decided that I would use one angle iron on the bottom that I would line up with the table and clamp to the table rail to keep the jig from moving. The other angle iron I would weld on top of the plate to give it additional rigidity. Here’s a diagram that shows what I’m talking about.

Frame Rail Jig Structure

As I was laying out the angle iron it struck me that I would need to keep the ends of the jig from moving around so I offset the angle iron about 1/2 inch. This gave me a “tab” and on the adjoining piece I would offset the angle iron by 1/2 inch giving me the “slot”.

Here’s a shot (blurry) showing two pieces already welded coming together.


And another showing the fully assembled jig with the original frame rail laying on it.


From this I started laying out small tabs of 3 inch by 3 inch angle iron that I had cut. These were to be used to define the shape that the rail blanks would fit within.


After welding all the tabs to the jig, I removed the original frame leaving the space where I’ll build the new frame rails.


  1. #1 by Eric Duncan on January 15, 2011 - 3:55 pm

    Awesome! So this is what you’ve been up to for a while!

    And doing it right I see. Build a new frame is exactly the way to go (assuming the original is rusted or too weak for the new suspension+engine combo). Now, I wish I was back in Dallas to lend a hand.

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