A friend who lives in Oregon, Jack Davis, and I were having an online discussion about building small metal boats, and during the conversation we remarked about our backs not being 25yr. old, any more.
Jack and I decided to do something to put the joy back in skiff building, and this was our preliminary idea. This rotisserie jig is call the Davis Jig after Jack's innovation of the features. Here there is a jon boat or garvey planned on the jig. the after former is shown attached to a metal angle frame, and the lines of the keel and chines are shown roughly.
The jig as it first appeared in our shop, with a 4" x 6" x 3/8" rectangle as the strong back. Its mainly made of scrap pipe and parts we had around, so the pivots and clamps are a little random.
The vertical uprights are pinned into the pivot housing so they can be raised and lowered. This puts the skiff at "old man's" height for working, easy to reach and not get too tired to make a decent weld.
Just a close up of the concentric pipe sizes used to make most of the jig's moving parts.
These aluminum station frame clamps hold the skiff or stations or sub jigs onto the Davis Jig strong back allowing different skiffs to be set up in a few minutes. They are two pieces of 2" x 1/4" T welded to a piece of 4" x 3" x 1/4" and drilled outside the main 4x6 box.
Here is a 17' rowing dory tacked up on the Davis Jig, note the stations are only 4" channel tacked flat to the deck in three places
Here a 14'er is being tacked up, the station frame clamps hold an after bottom forming jig and the forward point only holds the keel for a very short distance. This cupped after frame allows the bottom's (roughly) cylindrical shape to be tacked into the bottom panel without permanent internal transverse framing.
I realize that not everyone is as completely "skiff crazy" enough to spend the time and materials to make a fixture of this size. I include it here to show how much more simply we could build small boats if we can rotate them round their keels or waterlines, and pick them up and down.
I would not have been able to build these skiffs without the fixture as my old joints won't contort enough to fit into the spaces I'd designed -unless I could move those spaces so I could stand and reach into them. That included working overhead, flat footed on the shop floor with the skiff upside down over me, where i could just reach up and weld, or fit and not have to bend below the knees to reach in some tight corner. [My days of casually kneeling down and welding at arm's length below by bent knees is pretty much gone.]
If you look closely you'll see the rotisserie power/gear in the first sketched image was never added; we'd intended hydraulics and roller chain to pivot the main beam and its uprights, but the monorail overhead lift does fine. By lowering the verticals nearly to the floor or raising them to nearly the hubs, you can get a rotation that makes every single seam about shirt pocket high. Just about right, not to high but not too low, and if they are one or the other; roll her just bit more to make the weld seams more available.
Personally, I think this would be just as handy- maybe more so than for metal, for a wooden boat project? I don't think you'd have to buy every piece of metal in one of these jigs, making them too costly for very small shops. I think most areas would have enough surplus metal around to improvise the majority of the Davis Jig, we didn't machine any parts, they all fit concentrically in their original sizes.
cheers,
Kevin Morin
In fact, as far as I'm concerned, when it comes to home made tools that work, ugly is cool. And they give your work shop that aura that stuns people when they take the nickle tour. If you don't believe me, take a look at Ray's True Grit build and just study the background in the photos. There's so much stuff there that I myself want to take a trip up there just to see the place. ...if he'll let me. lol
sounds confusing when I say it. The cross pieces limit the travel of the router to cut perfect 2" wide notches.
