wolfman Posted March 9, 2014 Report Share Posted March 9, 2014 Can a stinger/gunwale/keel have more than 1 scarf joint? I know I'm not the only one whos having diffaculty finding lumber that'll suit my needs. Quote Link to comment Share on other sites More sharing options...
wolfman Posted March 9, 2014 Author Report Share Posted March 9, 2014 This would allow me to use 8 foot blards vs 12, not sure if I can get cedar in 16 foot boards or not in my area. Quote Link to comment Share on other sites More sharing options...
Aimless Posted March 9, 2014 Report Share Posted March 9, 2014 Once the cedar is down to 1" or 1.5" it is very bendy. The thing I'd be concerned about is the minimum length you need for a specific bend. A short stick doesn't bend like a long stick, and the ends are harder to bend than the center, etc. I imagine that if you have at least 4' of board you wouldn't have much trouble making any bend. As for the strength of the joints, I'm curious what some of these experienced guys have to say. I imagine that the forces on the center board could stress both joints in a different way than they would stress one as energy moves through the board. Quote Link to comment Share on other sites More sharing options...
wolfman Posted March 9, 2014 Author Report Share Posted March 9, 2014 I can get 12 ft boards no problem from lowes and the few I looked at had good end grain just trying to ask all the questions and do all the research before I dive into a build. Quote Link to comment Share on other sites More sharing options...
Pickman Posted March 9, 2014 Report Share Posted March 9, 2014 A well made made joint, with modern glues, will out preform the soft woods. Such as, cedar, redwood ...ect, all the conifers. Knots are the weakest points. Cut out the knots that equal 1/4 or more of the dimension of the stock then try not to over think it. Remember that you are working with a natural product. Logical compromise from perfection will be necessary. You can always clamp it in a vice and test the break strengths. It will make you confident in the process. Quote Link to comment Share on other sites More sharing options...
Kudzu Posted March 9, 2014 Report Share Posted March 9, 2014 Yes you can. I do it all the time. 1 Quote Link to comment Share on other sites More sharing options...
msaxton Posted March 9, 2014 Report Share Posted March 9, 2014 Am I right in my calculations here: Doing a 8:1 scarf in 3/4" stock would make the scarf 6", Doing it on a miter saw with a 90 degree jig I calculate the miter saw needs to be set at approximately a 9 degree angle,, is this correct? Quote Link to comment Share on other sites More sharing options...
mitchmellow Posted March 9, 2014 Report Share Posted March 9, 2014 A six inch cut would be correct. I set the angle by trial and error and I'm not sure I ever looked at how many degrees it was. It was small and 9 is probably correct. My non-sliding 10 inch miter won't do a completely finished 6 inch cut and the one "corner" of the cut has to be cleaned up a little. Quote Link to comment Share on other sites More sharing options...
mitchmellow Posted March 9, 2014 Report Share Posted March 9, 2014 I should learn to be a little more descriptive. As I understand it, the length of the scarf joint should be 6 inches. Because you are making an angled cut to create the joining surface for the scarf, the actual cut will be slightly longer than 6 inches. This may be somewhat academic. Many recommend above waterline scarfs that are 6 to 1. I have also found this interesting post: http://www.kayakforum.com/cgi-bin/Building/index.cgi/md/read/id/210618/sbj/skin-on-frame-scarf-joint-ratio/ . Quote Link to comment Share on other sites More sharing options...
DURRETTD Posted March 9, 2014 Report Share Posted March 9, 2014 I've seen most scarf joints defined as a ratio of the thickness of the material to the length of the cut. As I recall from reading boat building books the recommended ratio varies widely. I've used a ratio of 10:1. According to my geometry a 10:1 joint means an angle of 5.71059313749964 degrees. and a 5:1 joint means an angle of 11.3099324740202. I'm not sure I can measure quite that many significant digits on my miter saw, so I'll settle for about six degrees, or I'll measure and mark ten times the thickness along the length of the wood and adjust my miter saw as necessary to get close enough. Quote Link to comment Share on other sites More sharing options...
msaxton Posted March 10, 2014 Report Share Posted March 10, 2014 Once I got to the shop, I built the jig and just played with it a bit till I got the length and angle just right, 6 inch length in 3/4" stock ended up being about an 8 degree angle on the 12" mitre saw. glued up a sample scarf and looks good, will torture test it tomorrow. Got all my 1x2 cedar ripped today, just needs a little planing. Strongback built with shelves underneath, clamps all laid out and ready to go as soon as I get my ply and cut out the stations. oops, meant to post most of this on the nimrod build thread Quote Link to comment Share on other sites More sharing options...
wolfman Posted March 10, 2014 Author Report Share Posted March 10, 2014 Thanks for all the info! Quote Link to comment Share on other sites More sharing options...
msaxton Posted March 10, 2014 Report Share Posted March 10, 2014 You might notice on my jig that the inside corner is actually placed into the cutting path, and the corner is cut a little bit making the start of the scarf cut actually about 1" out from the fence. My reason for doing this was that the gap between the jig and the right side fence was wide enough that the stock would not be up against the fence at all. So I did it this way to keep the blade from pulling the board into it even though the board is clamped, just an extra safety measure. Quote Link to comment Share on other sites More sharing options...
wolfman Posted March 10, 2014 Author Report Share Posted March 10, 2014 I'll probably just built a custom miter box with a set angle and use a pull saw. I've seen people cut nice scarf joints free hand with a bandsaw but not this guy. My hands are steady as heck till I have to cut a straight line. Quote Link to comment Share on other sites More sharing options...
Hirilonde Posted March 10, 2014 Report Share Posted March 10, 2014 I've seen people cut nice scarf joints free hand with a bandsaw but not this guy. My hands are steady as heck till I have to cut a straight line. I used to do them this way, and maybe dress them up on a belt sander. It works fine with a little care. I just find the table saw jig so much easier, faster and quite safe if set up well as Jeff has pointed out several times. Quote Link to comment Share on other sites More sharing options...
msaxton Posted March 10, 2014 Report Share Posted March 10, 2014 As far as glue for the scarf joints, is epoxy generally considered the best to use? If so what brand? I used PL premium 3x because it was what i had on hand and I can get it really cheap here at the Habitat for humanity store. Will be torture testing the sample today to see how good a bond it was. Quote Link to comment Share on other sites More sharing options...
Hirilonde Posted March 10, 2014 Report Share Posted March 10, 2014 Some people argue that Titebond III is fine for use on kayaks. I always use epoxy for all things boat. You can't go wrong with epoxy, with the possible exception of clamping too tight and forcing so much of it out that you starve the joint for glue. Nothing is more waterproof or stronger. Quote Link to comment Share on other sites More sharing options...
wolfman Posted March 10, 2014 Author Report Share Posted March 10, 2014 I planned on using titebond III since i have alot of it from building primitive bows. I can atleast vouch for its durability under the extreame tension on a longbow. Ive also heard of people using gorilla glue its its water activated and how well it spreads. Quote Link to comment Share on other sites More sharing options...
msaxton Posted March 10, 2014 Report Share Posted March 10, 2014 My sample was a 30" piece and I twisted and bent it by hand, heard creaking but didn't break, set one end on the floor and other end elevated 3.5 inches and stepped on it with both feet right at the scarf, it snapped mostly in the wood itself, but also about 1 inch of scarf. Not satisfied will try both epoxy and gorilla nextSent from my iPhone using Tapatalk Quote Link to comment Share on other sites More sharing options...
Kudzu Posted March 10, 2014 Report Share Posted March 10, 2014 .... one end on the floor and other end elevated 3.5 inches and stepped on it with both feet right at the scarf, it snapped mostly in the wood itself, but also about 1 inch of scarf. .... Everything I read and my experience backs this up, if your glue joint breaks, you did something wrong. That would apply to any quality wood glue or epoxy. Joint strength is not a problem if properly glued. Titebond III is all I use now. Epoxy works and I have used it, have a gallon in shop too. But Titebond doesn't require any mixing and there is minimal waste, so the convince factor wins out. Quote Link to comment Share on other sites More sharing options...
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