DAvis Jig for Building Welded Boats

[kmorin]

A good friend and very innovative fabricator from Oregon, was gearing up to build a series of small welded alloy boats and didn't want to try laying down and kneeling all the time to weld out.

At the same time a few years ago, I was having some serious creaks and catches in an old welder's carcass that has been worked a bit rough sometimes. So his ideas during a post exchange on the Metal Boat Society lead to our exchanging countless emails while we roughed out his ideas into a large rotisserie that would make skiff building easy enough for us older guys to do.

The final quality of MIG or TIG can be seriously improved if the weld is at waist high horizontal and downhand! That means I don't have to kneel, bend to speak of, or work overhead or at arm's length. Younger guys, and I recall those days myself, can do this work without breaking a sweat and won't wake up sore the next day: I can't.

So here is the Davis Jig that I built and used to build the little 14'er posted as Wife's Skiff.






sure beats a sore back and it almost looks like I can weld again.

cheers,

[Sculpin]

Nice looking tool for sure. Bruce Cope had a similar tool that he made for his smaller style boats (16'-12' models). Great idea and you can do most of your welding in the flat, semi horizontal, and semi vertical positions. Great post and pic's. Did you say downhand...........that's pipe line welder talk................

[warthog5]

I don't know if it would be worth it to you, but you could add a additional electric turner and have a foot treadle to turn it on. Have a radical gear ratio on it so it will turn slow. Just have it as a belt drive.

[kmorin]

warthog5,

I agree completely that a power roll would make the Davis Jig more handy. If you look at the CAD sketch there are a couple of big chain gears (purple colored to visually separate them from the other parts) mounted to the main axis.

The other power feature needs to be a pair of long stroke, slender bore and rod, hydraulic cylinders mounted to the end vertical square tubes; to move the beam toward or away from the axis.

Since the Jig is parked under a monorail with a chain fall when I do most of the skiff work, I've gotten away using the chain fall to roll the work. I also use this Jig to carve fairly large format wood panels and that work needs more instant mobility/rotary positioning so the hydraulics are coming but they weren't critical to get the project ready to help with the last few skiffs.

I've thought of roller chain and cog belt and one of my friend's provided a sketch for rotating the main axis with two cylinders on a pair of compound levers.

Cheers,

[CTMD]

Is there room for a tray of hot coal under the jig? I've never had a spit roasted cow before.