redoak & tb3

[willie]

Thanks for all the input. Surprised to see so many comments on my choice of red oak, so I am going to try something else for wood. As stated earlier, this bow is sort of a quick and easy test bow for fitting a big guy, and various glue, wood, and tillering techniques that I have been meaning to experiment with.

I have only built a few wood boats with epoxy, most of my others being with metal and that other stuff which will remain unspoken on this forum.
 
I have used system 3 epoxy for all my previous bow laminating. and have also experimented with thermal  techniques to assist in my glue ups. Rather than using additives to control the viscosity
of the epoxy, I have been using the thinnest laminating resin system 3 sells on 150 degree wood as a primer to get penetration. (Conventional wisdom says that epoxy and other glues do not penetrate.) Once that starts to kick to where it wont run and sag, I cool the bow and build up the surfaces with additional coats and wait for that coating to stiffen some, maybe even putting the bow parts outside to chill down. I assemble and clamp when the epoxy wont sag, and let it harden until I can bring it inside by the wood stove to warm up again and cure faster. Working with bow size parts lets you do things that the boat builders would find difficult and are not commonly recommended. I can do bow laminations with a single mix and without using additives.   

I will say this about handle pop off. if your glue line is near the center of the thickness, It will have the most stress to deal with. The center is the neutral plane for bending, but the shear forces are at their max there. adding thinner lams on the back or belly make more sense from a strength of materials point of view. 

willie

[PlanB]

Russ, resorcinol was awful stuff. It may still be used in plywood manufacture -- it has a characteristic maroon-brown color. But using it out of manufacture was a total pain. Glue line pressure had to be very high and uniform, glue line very thin, glue line temperature 70 degrees. It was messy stuff to mix and the proportions were odd -- it was a powder mixed with a syrupy liquid. It stained everything it touched, and it was very expensive (at the time). When epoxies hit wooden boatbuilding, nobody looked back to resorcinol. Oh yeah, it had formaldehyde in it, later proven to be a potent carcinogen. Of course my first W.E.S.T System order contain a bag of milled asbestos fibers for mixing in 

[willie]

Plan B-

I was just rereading your post on dissimilar expansion between the woods in a glue up.

Q. in the boat building world, was any attempt made to predict expansions and limit certain usages?
I have read that tangential, longitudinal and radial expansion rate vary widely, and wide differences between species exist also.Are these quantified in planing glue ups, or are rules of thumb generally applied?
Also, any comments on my epoxy experiments would be welcomed.

thanks
willie

[JW_Halverson]

Wooden Boat Magazine?  Oh man, I buy that magazine for when I wanna fantasize!  Man, there is some mighty fine woodworking done by contributors to that rag! 

I am going to go dream about a51 ft L. Frances Herreshoff...."got 80 ft to the waterline, nicely making wake..."

[RBLusthaus]

Russ, resorcinol was awful stuff.

Sounds like it.  I have heard the same from others as well. 

[PlanB]

Yes, I was kind of disappointed to hear you weren't going to go through with it as an experiment, and I didn't mean at all to be discouraging talking about glue vs oak(s).

It's been a long time since I was boat building, and it's totally different than bows, and so I'm sorry I meandered OT!

I actually hate to laminate using epoxy and thin layers of wood, (always did) much prefer working with whole wood, and especially enjoy what is happening here on PA. Love the bows made from saplings and limbs that I see. That to me is really getting to the heart of of wood working, and a connection with ancient peoples.

Willie, I'm way behind the times on what is current in boatbuilding, so can't say if there are new scantling "rules" other than of thumb for thicknesses in laminating, and, yes absolutely shrinkage and swelling are all over the map for every type of wood, direction of grain, and also individual trees, down to even parts of individual trees. So I would guess that the older rules of thumb still apply in that field. The Gougeon Bros. wrote the book (literally) on wood and epoxy construction back in the 70's, and that book is a must read in that field, if you're interested in the technical aspects.

So I'm going to shut up now, and read about bows again, and try to build this one I'm working on so it lasts more than a month.

[willie]

Plan B

thanks for sharing your expertise about glue tech. Btw, I am still building the bow, just changed species to a more experimental one. I am the one that might be disappointed in the results tho, no sense in reinventing the wheel with R.O for a elb.

I hate  "goo" also, but in the long run, I have been let down less often by epoxy than anything else.

willlie

[JW_Halverson]

It has been said on here more than a few times, you can learn more from a failure than a victory.  That is the other side of the coin from the "no sense re-inventing the wheel". 

I am guilty of taking people's advice to NOT do something bowbuilding as a reason to do it anyway, just to see if I can use the knowledge I have already gained to find a work-around to their rules.  Most of the time, I come to a deeper understanding of why they consider it a hard and fast rule, but just BARELY often enough I learn how to craft an exception to the rule.  This helps me understand those underlying principles better and better. 

So let the chips fly, rip some curls, slather some gloopy stuff.  Just follow the advice I love to give....POST PICS!

[willie]

JW says pics please, so I dusted the sawdust off an old camera.

 Its been years since I made a board bow or did any laminating, and to be honest, I gave up on the red oak because I just did not like the grain in either board I had on hand. I did discover an 1 x 3 of soft maple in the pile. It was flat sawn and I did not like the grain much better so I ripped it in half and glued it into a 2 x 2 and took a quarter inch off it for a "rift sawn" backing for the mystery wood  belly I found in the Doug Fir stud pile a few months ago. It is browner than the usual DF, straight grained, ha svery fine slinters like bamboo, and smelled like turpentine when I bought it. The last pic is how the sander smears in spots. Its dense and dry with no visible pitch pockets , so I am guessing it is Larch. we will see how it tillers out.

learning lots of good stuff, like,  glue in twice the reflex you want it to have after you pull the clamps.

just starting to rough it out, but I will wait a while longer before tilliering to make sure the glue is solid.

 Question; How long should I wait with TB3 before floor tillering?