1968 Ford F100 - The Bumpside Build-Off Part 1

With the truck level side-to-side and resting easy on jackstands behind the front crossmember, I welded some 3/4-inch pieces of square tubing to the top and bottom of the front of the frame as well as one that diagonally connects the two to help keep the frame where it needs to be during the surgery. Using our Tech Center's new Miller Spectrum 375 plasma cutter really helped cut out the stock crossmember. Plugged into 220-volt power, I was one with the trigger for a while and never maxed out the duty cycle.

Even with the help of our trusty Snap-On air hammer, this had to be the most unpleasant part-popping out the 1/2-inch rivets! Earplugs and safety glasses are a must.

After a day's worth of bending over, scraping grease, cutting, grinding, air hammering, and just making a mess, I was tired but satisfied with my progress.

Next on the list was boxing the front of the framerails, but the inner edges needed to be cleaned up and straightened out first.

I used masking tape to mark a nice straight line on the top of the frame that I used as a guide to grind up to with my 7-inch electric grinder.

Before the second stock crossmember (it might get cut out at a later date), the bottom of the frame kicks out like this, which I also straightened out.

I bought two 4-foot pieces of 1/8x6-inch cold-rolled steel to box the frame. You can use cheaper hot-rolled steel; it's just lower quality, and it doesn't weld as nicely as cold-rolled. Using Dykem lay-out fluid, which you should be able to buy at a metal supply shop, I sprayed one side of both pieces. Dykem allows you to easily see scribe marks on the metal, which makes a big difference when it comes to fitting critical pieces.

Before I got too carried away, I bought some tools to make this job much easier. You can never have too many pairs or styles of vise grips, so I got some of the big open-mouth kind, some small ones, a pair of 6-inch C-clamps, big and little combination squares, a small torpedo level, a 4-foot level, a metal protractor, a magnetic angle finder, a plumb bob and string, and a 4-foot straightedge. All that, paired with a machinist's scales with fractions and decimals like my little tape measure, a scribe, and a snap-punch make a pretty good fabrication starter kit. All that's missing are some circle templates and template paper.

With the boxing material clamped to the inside of the frame, I was able to trace the frame's shape into the side with the Dykem on it and start trimming. Since the frame starts to angle down behind where the crossmember was, I made the boxing plates out of two pieces. Each side wound up with a 32-inch boxed section.

When boxing a frame, make sure there is a sufficient gap in the material to get proper penetration with the welder. Here, the inside corner of the frame and the inside corner of the boxing plate just barely touch, leaving a "step" in the outside edge that, once welded, will be filled in. A good size chamfer is important, too.

Using a welder with enough power is a big part of a successful job. I wouldn't feel comfortable using a welder powered by 110 volts; luckily, our new Millermatic 210 is powerful enough for the job, but if you have access to a TIG welder, that would be the best way to go. When welding in the boxing plates, only weld a few inches at a time once they're tacked in. Jump around to another spot instead of welding up one side at a time.

When grinding the weld down, make sure you don't take too much off. Try to grind horizontally across the top and vertically on the sides, staying parallel to the frame the whole time. There's no need to grind the corner down, since that's where all the strength is. More than likely, you'll have to add more weld to the seams after it's all ground down the first time to build the corners up to where they need to be. Use a big file to dress the corners and take the sharp edge off after you're done.