Posted 24 November 2012 - 06:12 PM
Marissa 18 'Salty' (under const)
CS 17 Hull#78 "Lively"
Marples 3Meter Constant Camber Tri "Bananas"
17'6" Pigmy Coho kayak
16' Redwood Stripper Canoe
Posted 27 November 2012 - 06:55 PM
Anyhow I cut off some of the extra length and clamped it in a vise and cranked until I achieved failure. (The two outside pieces were several inches longer than the middle one, allowing me to test the strength of the glue up) The joint failed in the wood and not the glue lines. I felt better. Here are some pics.
Dave IMG_5279.JPG 126.02K 86 downloads IMG_5282.JPG 153.29K 100 downloads IMG_5283.JPG 68.84K 98 downloads IMG_5286.JPG 107.36K 73 downloads
Posted 28 November 2012 - 04:25 AM
That stem curve is very attractive - gonna be one pretty boat.
Posted 28 November 2012 - 05:04 AM
As for sanding, it sounds counter intuitive, but a planed surface is better. Storer has a good explanation, which is similar to what I've seen on US Forest Service literature.
Sanding crushes and closes the cells......think of these as a bundle of drinking straws.......a sharp planed edge opens them up to allow deeper penetration of the epoxy. If you really want it to hold, you can brush on a coat of un-thickened epoxy on both surfaces before a layer of thickened goop.....especially so when working with end grain joints. I also add a bit of 30:100 grit walnut shell to act as a spacer to prevent excessive clamping pressure from too thin of a joint. It has the additional benefit of locking the pieces in place to prevent them from sliding around.
Posted 28 November 2012 - 07:38 AM
Posted 28 November 2012 - 09:56 AM
Posted 28 November 2012 - 10:47 AM
The best bond can be obtained from wood where the bonding surfaces have been roughened. If surfaces have been planed beforehand there is a danger of the ‘case-hardening’ effect giving an insecure bond. This can happen whatever glue is used for bonding. To ensure that this does not happen roughen all planed timber by sanding 30° to the grain direction using 40 - 60 grit aluminium oxide paper.
The reference to "case hardening" was what caught my eye. I was of the opinion that related to problems associated with drying wood at different rates, with dry exteriors and high moisture interiors and different rates of shrinking, etc. leading to twists, warping, etc. Not sure how planing affects that.
Another reference is found on the Forest Service site:
Rather than downloading the entire 500 page document, I'd suggest you go for Chapters 3, 8 and 10, the later relates to adhesives. Put that by your bed side reading table and you can forget the sleeping pills!
Posted 04 December 2012 - 06:41 PM
Posted 05 December 2012 - 04:46 AM
With the exception of one or two pieces, my Belhaven was all Douglas fir, #1 select. It always soaked up plenty of straight epoxy before the thickened glue went on. On the other hand the cypress I have been using for my 28 will never quite soaking epoxy into the grain. I have wetted out some joints two and three times before adding the thickened glue. When we glassed my cypress hull we wetted out the wood very heavy, then laid the glass. We had to keep putting the epoxy to the glass to keep it wet, until the first epoxy coat started to kick. I was telling Graham that the epoxy must have been absorbed better than an 1/8 inch into the planks.
Douglas fir would never give me second thoughts about the strength of the joint, if wetted out first or not before the glue went on. When wetting out Douglas fir I have noticed that the smooth hard grain stops absorbing epoxy pretty quick compared to the rest of the grain, but still absorbs to a point it will never fail.
ROMANS 8:1, BELHAVEN 19, SPINDRIFT 12S, 10N, PENOBSCOT 14,
IN OVER MY HEAD CANDICE 28
Posted 14 December 2012 - 05:41 PM
Excellent build, good job. Good information on epoxy/joint application. I've talked to the West guys alot and the information in these posts are spot on. I've had to wet out joint faces more than once many times. The joint stress to failure test sums it up. Never heard of the walnut shell thickener/filler trick before....very interesting. I'm checking these Ocracokes out. I'll build one when I can.
"That looks risky....."
"Life is risky...no one gets out alive....."
Posted 15 December 2012 - 09:32 AM
I can't recall exactly, but the thicker glue line between the two samples may be from using the 20/30 grit walnut shell. That leaves almost a full 1 mm glue line. If that is what you are shooting for, it would work. Again, walnut shell also has sharp, fragmented edges, so they tend to dig in and bite, which helps prevent the pieces from sliding around when the clamping pressure goes up.
Something similar to the 30/100 walnut shell is the plastic granules System 3 sells as a non-skid paint additive. Gives about the same response and thickness of glue line, and does not have the dark brown color you get from walnut shell.
Both the walnut shell and the S3 non-skid glued pieces can be worked with edge tools, although the combination of epoxy and walnut shell it going to be rough on them. You could do the same thing with various grit sizes of sand, but don't plan on working the finished piece with wood working tools unless you want a damaged tool.
Posted 18 December 2012 - 07:53 AM
Just was reading this and wanted to interject as a long time wood worker-
The "case hardening" that is referred to is for material that has been planed, then stored for a while, as in lumber yard stuff. Exposure to air for a period of time is what does it.
Freshly planed wood is NOT casehardened- hasn't had time to do so. That's one method of getting RID of any case hardening.
Also- I've built many boats and masts, rudders, dagger boards, etc, including all stringers on a 35 foot trimaran, using Doug Fir- good stuff, but pick the wood so it's clear.
Posted 19 December 2012 - 07:57 PM
Were in for some weather here and I have to set the planer in the door and work outside because of their length. Supposed to blow a gale, which will hold me up a few days. All well, back to work on the basement.
Posted 26 December 2012 - 07:59 PM
Posted 27 December 2012 - 08:38 PM
Posted 09 January 2013 - 08:26 PM
Posted 10 January 2013 - 10:34 AM
Posted 20 January 2013 - 07:48 PM
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