1  Material choice

I followed the plans closely in framing the floor or deck. The framing for this is 2x4s split lengthwise. If you use 2x2s instead, your frame will be only slightly less robust, as a 2x2 is only 1½"x1½" and a split 2x4 will be 1½"x1¾" minus half of the saw kerf. This may not seem like much, especially considering the aggravation of splitting the 2x4s. There are other benefits, though. If your lumberyard has 2x2s, they may not be as high a grade as the 2x4s. Also, at my lumberyard I can pick through the lumber and choose the 2x4s I want, at no extra charge. I am pretty sure that Home Depot™ will allow picking as well.

2  To make the frame square

I did not bother with making a big right-angle jig to keep things square. The naked wood frame is easy to rack one way or the other, so I just used the plywood flooring to square the frame. Just make sure your plywood is square. Measure the distance across diagonal corners. If the two diagonals are equal, the plywood is square. Fasten the plywood along one four foot end and then rack the frame to match the plywood along its length. Fasten the rest of the plywood edges.

At this point, I had a welded steel frame, on its axle, with wheels attached. The wheels are blocked so my trailer won't move. The floor is framed and covered with plywood and resting atop the steel frame. The floor assembly is not fastened down at this time. Yet.

3  Checking for straightness, flatness

I check things out to see how the floor assembly matches up with the trailer frame, and adjust the position of the floor with respect to the frame, until I am satisfied with the lineup. I know that my frame is still a little bit warped, even after straightening, but this is not the end of the world. Y'know, wood isn't so perfect, either, so there are gaps between the floor and the frame, here and there. No big deal. I check the flatness of the floor with a stringline, to see just exactly what its geography is, where the high and low spots are. I've already checked the frame and know its high and low spots. 		4  Bolting floor to frame

I use clamps to hold floor and trailer frame together. I use wedges or shims between floor and frame, as needed, to adjust the flatness of the floor. Again, I use a tight stringline to check floor flatness. I use an extra long drill bit  to drill  through the floor and frame in one shot, with no need to move things around for drilling one layer at a time. I substitute steel flat washers for the wooden shims and bolt the frame and floor together so the floor is true to flat, within a sixteenth of an inch over its ten foot length. I counterbored the plywood deep enough so that the carriage bolt heads would not stand proud of the plywood surface. I used blue thread locking compound on the bolts.

This sturdy flat bed trailer will be my work table for the next several steps of construction.



first page the frame the floor the sides the roof the flooring the shell wiring and insulation sheet metal molding the hatch lid doors fenders light fixtures cabin cabinets solar panel tanks other stuff

If a link is "404" I probably have not written that material yet. Please bear with me.