Nov
26
Written by:
Tom
11/26/2009 11:09 PM
Lots of operations this week to make sure that planks meet rabbets at just the right angle.
For instance, you may recall that the chine log on the Chris Craft had a crazy curved rabbet. Here's a look at how they made that twisting bevelled cut.
They could have painstakingly carved it out by hand using chisels, like you've seen before on the stem. Instead, they worked out a way to use a router guided by a fence to cut the entire thing in one, very careful, pass.
The fence is the lighter-colored wood. It's set up to guide the router to cut the chine log at exactly the right angle. It's a bit of a hairy cut to make, because while the fence guides your router, it requires you to keep the router constantly pressed against the fence as you move. A moment's lapse in attention can leave you with an ugly divot in your beautiful bent chine log.
Lots of concentration.
Ignore all the people with their cameras!
(All photos above by Warren Barker)
And here's the result, a beautiful rabbet.
The little wiggle at the end of the rabbet nearest you is where the router was stopped intentionally. If he had tried to rout that last bit, he could have risked a divot in the rabbet as the router is only partially supported by the end of the log. They'll finish that up by hand.
The other side is done, and looking good.
They're now working out a second fence setup to plane the bevels on the outer face of the chine log.
These pine strips will create a surface to register the plane base for cutting this outside face. The crosswise stick in this photo shows how that face will line up with the planks on the underside of the boat.
Below the chine log, they're notching out the frames to make way for the battens in the seam and batten construction.
And on the 12 1/2, it's planking time. Here, the old planking is set up on the hull
but the real action is happening over on the benches. A number of planks have been spiled and cut out.
The inside and outside faces of the planks are curved to match the curve of the frames that they will be attached to.
The student is using a template that he made from the frame at that particular location on the plank. The curve changes along the length of the plank, so you have to make a whole series of templates to shape the faces of your plank.
But wait a minute, you ask, I said "spiling" before. What is this spiling?
Spiling is the process of copying the shape of a plank from the curved 3D hull to the surface of a flat board. The students tack a thin spiling batten onto the hull in the area where the plank goes.
They use a compass to mark arcs on the batten that locate the edges of the plank. They can then take this batten off of the boat, tack it to a board, and use a compass to transfer the plank edges to the new board.
Connect all these marks with a long batten, and you've got yourself a plank edge. Cut on the line, fair and bevel the edge, and you've got yourself a plank. Oh yes, and then shape your plank to fit the curve of the frames. And then attach it, fair it in…. woah, slow down. One thing at a time.
Sometimes the shape looks a little funky when you lay it out, but if you've done your spiling accurately, you just have to trust it!
Upstairs, the students are finishing up the 12 1/2 spars.
This student is using a home made sanding box to make sure that there are no flat spots on the mast as she smooths it.
Good thing we're working on power boats this year, it means that there's a comfy chair available to relax in during breaks.
Um, we're just testing it to make sure that the supports are solid before it goes back into the boat.
Over on the Gar Wood, the students have been doing the final final Final adjustments in the frame spacing and alignment.
This is one of the hassles when working with wood… it tends to move around with temperature and humidity changes. Comes with the territory.
There's a lot of checking before it's all locked down for good,
but when everyone is happy, the planking is all set and ready to go.
And on the Beetle cats, it's wedge time.
Little wedges are placed on the tops (ok, actually the undersides, but the boats are upside down so…) of the frames.
These wedges provide a smooth transition for the planks as they rest on the frames and span up to the rabbet in the keel.
Here, a student uses a short length of wood called a "fid" as a stand in for a plank. This gives him an idea of the shape of the wedge that he'll attach to the frame.
Instructor Jennifer McNally works with some students here to fine tune the wedges.
Once the wedges are attached to the frames, some students use spokeshaves to get them sloped just right to work with the rabbet.
And of course, it's important to make sure that everything is fair along the length of the boat as you go.
One of the great things about the IYRS shop is that you get to work with some really big tools.
Here, instructor Warren Barker helps some students adjust the lower guide bearings on the big Sawoods ship bandsaw. It's not your basic home saw, that's for sure.
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2 comment(s) so far...
Re: Angles angles everywhere
What are the gaps between the wedges and keel plank on the Beetle for?
By Mike de Angeli on
12/1/2009 5:57 PM
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Re: Angles angles everywhere
Hi Mike,
Those gaps form the limber holes along the sides of the keel. If you imagine the boat right side up, the lowest spot inside the boat will be right alongside the keel. The limbers allow the free movement of water to the lowest area of the boat. This makes it infinitely easier to pump water out of the boat, since you only have to pump (or scoop, or sponge) from one place... that low spot. Without the limbers, water would become trapped in the little bays formed by the frames and wedges where they meet the planks. Not only would it be difficult to quickly rid the boat of water, you'd also end up with many areas of standing water in your boat, and that means rot. And mildew smell. And mosquitos if you wait long enough.
Tom
By Tom on
12/1/2009 6:02 PM
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