Tuesday, April 8, 2014

in the shop: A new porch for the travel trailer: welding

Actually today, a day of welding and grinding and welding and grinding and welding - well - you get the idea, didn't go too bad. The auto-darkening shield was working, all my cuts were the right length first time and things squared up nicely.

That's not to say there were no challenges for the day. I had to stitch up some holes where I welded right through the steel in a few places, I had to redo, and in a couple cases, redo the redo, some of the welds, and there are some pits in a few of the welds, but all in all, as a welder with, well, let's be honest, virtually no skill at the craft, I call that a good day.

I started by moving the van off the parking pad because, other than the shop floor, that's the only flat place I have to work, and I wasn't about to weld inside the shop. First the welder is gas powered and I hear running it inside the shop for an extended period of time could be bad. Also my shop is full of stuff, much of which I don't want to set fire to!

With everything laid out on the parking pad I tack-welded the two short support sections together, rechecked my measurements and made sure everything was square, then turned them over and started welding the seams for real, using a piece of left over steel siding as a shield for the concrete. I also used a pair of channel-locks to twist the joints tight where the tack-welds had shrunk the metal and pulled the other side of the joint away slightly. With that side welded up I turned the sections back over and put full welds on the tacked side, then on the bottom side of the top horizontals and the top side of the angle iron horizontals. (With the exception of the top rails, I left the bottom of all the horizontal tubing un-welded so any moisture that might collect inside the tubing has a way out.)

I then used the completed short sections to ensure that the horizontals on the long sections lined up exactly with those of the short sections since that's where the wood deck will sit and it needs to be flat all the way around.

Once I had all four sections welded up I cut a couple pieces of angle, one each for one short and one tall section, these were welded in place along the proper horizontal tubing to act as supports for the wood deck which is designed to slide in place through one of the tall sections. The other two sides of the deck will rest directly on horizontal tubing.

With all the welds done, or at least butchered, I took the grinder to them, marking bad welds with a soapstone stick as I went.

I went back and re-welded the marked welds then ground them down again. I repeated this process until I felt that each weld was, if not pretty, at least going to hold. (Of course I might have just gotten tired enough of repeating myself over and over that my quality control standards got lower and lower as I went. . . If the whole thing falls apart down the road I guess we'll know for sure.)

The original plan was to cut and fit the diagonal bracing once I had the vertical and horizontal members welded up, that way I would be sure to get the lengths correct, but as I finished up each section of the porch structure I began to think it was going to be plenty stiff enough to resist racking without the diagonals. If this was a wood structure I would still install the diagonals because I would expect the joints to loosen up as the wood expanded and contracted over time, but with welded steel there are no joints to loosen, everything is monolithic. Besides, if I leave off the diagonals that's one heck of a lot of cutting, fitting and welding I can avoid!!

I tested this (slacker) theory by clamping the sections together about where the bolts will be when it's finished, thowing the deck up on it then climbing up and dancing around for a while. Nothing moved. In fact the thing was stiffer than the original wood porch was when it was brand new, and a whole lot stiffer than it was near the end of its life, so for now the diagonals will stay off. (Anyone need some steel tubing?? I seem to have extra all the sudden.)

Next step, pun intended, is to fit the angle iron support for the steps then measure, cut and weld the step railing, but enough steel for the day; I need to go get my hands on some good ol'  wood!!

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