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Posted: Sat Jun 09, 2007 6:23 am
by Phill Blank
Rich,
I would recommend a scarf joint it is stronger then a but joint with biscuts. You have a lot more wood which is seeing the glue and it will be stiffer when bending forces are exerted against it. Shipwrights always use scarf joints when joining any wood within the same plain where stresses can be applied.
Posted: Sat Jun 09, 2007 7:24 am
by Richp
Thanks! After looking at it a bit I figured I was using the wrong approach.
Back to square one I guess. Good thing I asked before gluing it all up.
This forum is great for us guys that don't really know what we are doing yet.
Now I just have to figure out how to make a jig or something to do one of the
scarf joints in the boat. Otherwise I would have to totally disassemble the bow. Also the front scarf will be pretty close to the bend in the gunwale, wich should complicate things.
Rich
Posted: Sat Jun 09, 2007 3:04 pm
by JoeCB
Rich, I vote for a nice long scarf joint. I'm guessing that the gunnel on that flexable hull has to be a pretty heavely stressed member.
Joe
Posted: Sun Jun 10, 2007 6:12 am
by Richp
Thanks Joe. Not sure what I was thinking there! Andreas even said to use a scarf in a previous post. The board is 7/8" thick. Would a 8" scarf be good enough? I have never made a scarf joint so in the next few days I will practice on some scrap wood. I am going to try and make up some sort of
jig for my router I think.
Rich
Posted: Sun Jun 10, 2007 7:46 pm
by JoeCB
If my memory serves me correctly I think the rule of thumb for scarf joints is an 8 to 1 slope. For a 7/8 board that would be a 7 inch long joint.
if I'm off on the slope someone chim in please.
A tapered jig that clamps onto the board/gunnel/rib to be cut is the way to go, lot easier and more acurate than hand cutting. You can then cut the joining piece to match in a jig on the table saw.
I'll attempt to post a pic of the jig and home made cutter setup I came up with for my 4 inch angle grinder... this made short work of scarfing several rib ends.
Joe B
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Posted: Mon Jun 11, 2007 3:21 am
by Richp
Joe, Wow thats great! I never thought to use an grinder! Where did you get that cutter head on your grinder? I ended up making a jig for my router and didn't like the way it was working (never been comfortable using a router). So I rough cut my scarfs with a hand saw and table saw then cleaned them up with a belt sander and a hand plane. I have at least a few more scarfs to make so I will try the angle grinder next (I am real comfortable with a grinder). I ended up going with a little better than 8 to 1 on my scarf joints.
I am having a lot of fun doing this boat! One thing I have learned already is you need a lot of patience! Something I have never had a lot of (haha).
Ok my next question is ... Before I assemble the gunwale would it be a good idea to seal all surfaces of the boards? Seems like it would be a good idea.
When I took it apart nothing was sealed other than the exterior surfaces.
Thanks Rich
Posted: Mon Jun 11, 2007 3:57 am
by a j r
I typically just use a hand saw and/or hand plane to cut scarf joints. Very simple, old school technology!
YES, seal ALL surfaces of the wood prior to assembly. Just make certain that if stain has to go on top of it, the sealer is compatible with stain.
Andreas
Posted: Wed Jun 13, 2007 6:32 am
by Richp
Well, I redid the new gunwale (about 80 percent new wood). Its all glued and screwed in place. I will let it set up for a day and remove the clamps and hope it all turned out.
Thanks for the help! Next project will be the keelson!
Rich