Scarfing Questions

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Gufer
Posts: 4
Joined: Fri Jan 28, 2011 5:18 pm
Location: Mukwonago, Wisconsin

Scarfing Questions

Post by Gufer »

Am I being too picky?

First a little background….
I recently started building my first cedar strip kayak, it’s a 16’ 6” Resolute. First of all, I want to say thanks for everyone sharing their knowledge and ideas on this forum. I have turned to it many times for advice already (and will probably do so many times down the line) :laughing . This is my first attempt at building a kayak or any form of watercraft for that matter. I went the bargain route on buying my cedar. A local lumber yard went out of business and I got a deal on it. Problem was, it was rough sawn 5/4 in 10’ lengths with quite a few knots. That translates into a lot of extra work. I don’t mind the work, but when it comes to getting long enough strips I have A LOT of scarf joints to cut and glue. I wanted a way to make it repeatable and somewhat efficient.

I made a jig for cutting the scarf on my table saw. I combined the ideas of using a disc sander and a sled for cutting the scarfs. I mounted a sanding disc in my table saw and adapted the sled to be stationary. I tried using just the sled and a blade, but I could never get a clean edge on the tip of the scarf. When I tried using just the sanding disc alone, I couldn’t get a consistant result. Combining the two works nicely for me, all scarfs are uniform and have a nice crisp tip. I built a jig for gluing the joints as well. Thanks to John Michne! His website has also been very helpful.

Now to the picky part….
My main question is how clean do the completed joints need to be? When sanding the finished product, will that hide any imperfections in the joint? How does applying the glass and epoxy affect the way the joint looks?

Since I have never built a strip kayak, my main fear is finding out that the joints look bad after the kayak is complete. Especially when it’s too late to do anything about it. :crying

Any advice would be much appreciated.
bluedcanoed
Posts: 20
Joined: Thu Jun 08, 2006 7:16 am
Location: Kawartha Lakes

Post by bluedcanoed »

I would think that your only concern would be to match the colour of the strips at the joints so you don't end up with little straight line "slashes" in the finished hull.

Good luck!

Bob
willo
Posts: 156
Joined: Sun Jul 15, 2007 12:48 pm
Location: Echo Bay ON.

Post by willo »

The main thing to keep in mind if you plan on scarfing all your strips is to match colour best you can. I always try and scarf two ajacent strips from a board and match them at a common end so the colour will match. Joints will blend in nicely as long as they are tight. The epoxy will magnify them if they are poorly done. It sounds like you are doing it right , John's site does explain it well. Do not feel you have to have all your strips full length. With a kayak it is nice to have the sheer planks full length , but only the first 4 strips on the deck will be full length (each side) the rest can be 1/2 the length and joined at center since this will be the hatch cut out. Personally I only scarf a few strips for starting then use butt joints for the rest but for your first boat full strips will be nice to work with. What your doing sounds right , don't worry and have fun building.
BearLeeAlive
Posts: 196
Joined: Tue Aug 18, 2009 7:00 pm

Post by BearLeeAlive »

I scarfed a few of joints in the canoe I'm building. I did a 4:1 joint on the strips before the final planing, and milling the bead and cove. You can hardly tell where the joints are in most of them. I used a sliding jig on the table saw using a thin kerf blade to cut them, it made nice clean cuts. I then made the jig below to glue them up in. The darkness you see at the joints is the glue, and once removed by planing or sanding does not show. Doing up 12 scarf joints, including the cutting and gluing, took about 15 minutes to do.

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-JIM-
Gufer
Posts: 4
Joined: Fri Jan 28, 2011 5:18 pm
Location: Mukwonago, Wisconsin

Post by Gufer »

Thanks for all the advice.

I am scarfing my strips "through the thickness". That results in a vertical seem, not a diagonal one. I dont own a planer but i do have access to one. That means either i have to transport all my strips to the planer or maybe be able to borrow the planer. I can see that if i dont plane the strips the joint could cause trouble when i mill the bead and cove. Is there an alternative to planing the strips? Sanding seems very risky to me. Is using a block plane an option?

Here are some photos of a test I did with some pine strips...
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Last edited by Gufer on Sun Jan 30, 2011 10:31 pm, edited 1 time in total.
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John Brice
Posts: 38
Joined: Tue Oct 20, 2009 8:14 am
Location: Oxford, Michian

scarfing strips

Post by John Brice »

I built a Bob's Special last year and used the long diagonal splice since the boards I had were only 8 to 9 feet. As mentioned, the color matching is important, and frustrating. I wasn't sure the vertical scarf would be strong enough when it came to some of the extreme bends. One advantage I have is the use of an electronic "wood welder" which cures the glue in seconds. See my set up at www.tinyurl.com/jb-scanoe. I am currently building a Ranger 15.

Good luck, John
rstruck
Posts: 2
Joined: Wed Feb 09, 2011 10:15 am
Location: GTA, Canada
Contact:

Post by rstruck »

I'm currently at the same point in the project as you appear to be. I've routered the strips and am using a belt sander to make the desired angle (it's a lot easier than using a block plane). I have a half-inch block at the end of the sander and have marked a line on the bed of the sander to indicate how far I have to extend the end of the strip. I rest the strip on the block and then lower the end onto the spinning belt. A few seconds later I've sanded away enough material.

To ensure a reasonable match in terms of grain and color, I scarf the same end of neighboring strips.

You just have to be careful to remove any fine curls of wood that the sander leaves. When glued, these little curls invariably get in the way of a nice fit.

You can have a look at my setup at http://greybeardcanoes.wordpress.com/20 ... -scarfing/
KenC
Posts: 190
Joined: Tue Jun 01, 2004 10:42 pm
Location: Oakville, ON

Post by KenC »

Gufer ... I also made my scarfs "through the thickness" ... and I also used a sanding disk on the table-saw ... but rather than a sliding sled, I just clamped a guide fence (a scrap 2x2) at an angle to the disk, and fed the strips in along the fence, then pulled them back when done ... clean consistent "cuts" every time.

Some of the scarfs are nearly invisible under glass/epoxy, but others are a little more noticeable, even with careful attention to grain matching. Its no big deal. Many of the visible scarfs appear as slightly curved lines (because after fairing, the surface of the strips are no longer flat) and curved lines don't seem to catch the eye as much as straight lines would.

I milled my beads & coves before scarfing, so I didn't have the problem of joints causing trouble, but I know what you mean about the possibility of slight imperfections in thickness around the scarf. I managed to minimize that by dry fitting each scarf joint first, using short bits of scrap strip along each side to help judge when the joint was the correct uniform thickness, then making a pencil mark across the joint. Then when the glue was applied, it was a simple matter to line up the pencil marks, and clamp.

It only takes about 10 to 15 seconds to set up each dry-fit and make the pencil mark, and you probably get those 15 seconds back by doing less fiddling with the joint while its slippery with glue.

That's what I did and it worked well for me. Good luck.
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