Boat Building Forum

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Re: What about a router
By:Paul Jacobson
Date: 11/24/1998, 4:31 am
In Response To: What about a router (Mark Bodnar)

> I was considering using a router to form a single step
> ~3/4"-1" long (similar to a dado cut?), removing 1/2 the
> material from each side and then mating them together with epoxy.

> XXXXXXXXXXXXXOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO
> XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXOOOOOOOOOOOOOOOOO

I believe this is called a lap joint. As witha scarf joint, the longer the joint, the stronger it is. As for delamination potential, that depends mostly on the glue you use.

Consider the joint you have proposed to be one with a single step. Now try to think about what a joint with 2 steps would look like. Since the plywood has typically three plies, a joint with two steps would effectively be three offset butt joints, on for each ply of the plywood, with each joint backed up by a significant amount of solid wood. This is the same way the make the plywood, so if your 'steps' were far enough apart the joint should be as strong as the wood. The problem with lap joints is getting them to be precisely the correct depth. This is particularly difficult with large panels of thin material, as flexing of the material affects the depth of the cut. ans you have to be a little more careful that the laps are precisely perpendicular to the length of the material so that there is no gap. Scarf joints tend to hide some of thes problems, as the tapered edge can be sanded flush should it overlap a bit too much, and the result will still be a very slight line.

There are jigs for cutting scarfs with your router. They are pretty easy to make, and there should be pictures around showing them. You could probably make a jig for cutting lap joints from a few wood scraps.

I'm not too sure about how well a lap joint is going to take to being bent -- and stitch and glue definitely involves bending those plywood panels into shape. You want a smooth bend over the entire length of the part. If you use epoxy it will probably work just fine. A test is fast and simple to do. Best of luck on this Paul Jacobson

> - I thought this would be a simple joint to make and line up, plus have
> some of the joint overlap benefits of a scaft joint.

> (Concerns - ie. would this promote delamination?)

Messages In This Thread

SCARF JOINT, QUALITY, RADIAL ARM SAW
Tom Jablonski -- 11/22/1998, 10:47 pm
Re: SCARF JOINT, QUALITY, RADIAL ARM SAW
Don Beale -- 12/1/1998, 12:57 pm
Re: SCARF JOINT, QUALITY, RADIAL ARM SAW
Jay Babina -- 11/30/1998, 11:42 am
What about a router
Mark Bodnar -- 11/23/1998, 9:08 pm
Re: What about a router
Jerry Weinraub -- 11/25/1998, 7:05 am
Re: What about a router
Paul Jacobson -- 11/24/1998, 4:31 am
Re: SCARF JOINT, QUALITY, RADIAL ARM SAW
Mike Scarborough -- 11/22/1998, 10:47 pm
Re: SCARF JOINT, QUALITY, RADIAL ARM SAW
jeff warrick -- 11/22/1998, 9:19 pm