putting in extra stringers?

[doc]

Y’know, as Sundance also said…

“Y’think you used enough dynamite, there, Butch??”

When I run into something that is driving me bughouse and I just can’t find an answer and I’m slowly drilling myself into a hole in the ground, it’s been my experience that I’m looking at it the wrong way. Or,

‘Doc, you IDIOT - don’t raise the bridge, lower the river’ - take another look at the problem and try a very different approach -

Lets take another look at what we’re dealing with here:

Given a very crude drawing of an outline shape, this or a variation is what you’re looking to wind up with. But you’re whittling the blank into four pieces that will want to slip sideways, get longer and deform and lots of nasty little pieces of wood that want to go sproing and fit wrong and every other damn thing.

What’s wrong with this picture and this approach? I’ll show ya -

Cut like this first

Lay in your stringer, glued up, clamp it. Instead of four slippery slidey pieces of foam ( or more) , you have two. Instead of lots of nasty little pieces of wood, you have one. Relatively easy to clamp too. When that’s done it’s thing, repeat for the other side, mirror image. You’re done. Yeah, you got two separate glueups, not one. Yeah, you sliced right through the center stringer…in this example. Don’t have to, you can do it like this one below, just means you gotta use two pieces of wood- , clamping and fitting and all is still relatively easy. Either way, you have a pretty big, stiff piece of foam that isn’t gonna want to get longer or deform much, it’ll hold the other piece pretty much where it wants to be.

Awright, that’s my take on it anyhow.

Don’t raise the bridge…

doc…

[RichardMc]

The bad guys just kept closing in and they couldn’t figure out how to get out of trouble. Sundance: “I can’t do that, can you do that, how can they do that?” That’s what we say about your illustrations: “How can Doc do that?” I like the idea of two long cuts. Much easier and makes more sense…yea.

With figure 8 stringers in general, does the old adage apply here: “A 100 mile long fence is only as good as its weekest 1” section." Where the two stringers cross in the center you effectively have no through rib of strength. Sooo, seems you gotta keep a center stringer intact from nose to tail.

Now you’ve made me want to try one on my next balsa board. I have so many thousands of hours milling out the balsa and all the stringers that it would be pretty scary to take a beautiful fresh blank and rip it end to end only to blow it with the figure 8.

Good work figuring it out. What’s Jim’s take on the new approach?

[doc]

Well, now… at the beginning of the movie Sundance is playing cards and he’s winning pretty good. In fact, he’s won everybody else’s money. One of the other cardplayers asks what’s the secret to his success? Sundance says ‘Prayer’.

One of these days I am gonna save all the stages of one of these horrible sketches as I do it and put together a thumbnail page. I just have a lot of time in with Paint so I can make my screwups and recoveries that much faster. The first six times I hated the outline shape on that one, so it was redo part of it and erase and so on. Then, copy and paste a bunch of it when I finally do get it to work. .

Before doing one with balsa, I’d get some insulation foam and random, reasonably clear wood strips for practice stringers and set up your gluing jig so you don’t have any probs or panics. Let me show ya how I’d think about building the gluing jig:

First of all, this would make a lousy production jig. You’d want to build in a lot more adjustability, to start with, and mebbe use some small screw clamps built in. And for anything other than a really good board it’s probably overkill for a one-off.

Construction method: first, take your bottom rocker and bend your first lauan piece ( length plus a foot, width plus a foot) to that curve, using maybe a pneumatic finish nailer and hot glue to get it pretty rugged. Draw your outline shape, both sides, on the lauan, use a block to hold your pencil out 1/4" or so from the outline shape…

Next, make some side strips. Use two strips tacked together, call it 6" x board length plus 2’. Measure your heights to correspond with points on the outline shape and measure from point to point around the shape -probably best to start from the tail and use a couple of pencil compasses or dividers. Go over ( distance plus a little 'cos of the curve) and up ( height ) and make a mark. When you’re done, connect the dots with a batten, cut with a bandsaw, set your bandsaw fence at a good ( 3" or so) width and run the curved side against the fence - you should have two identical strips.

Tack down ( plus mebbe some hot glue ) blocks along one side of your outline shape and tack one strip to that. I didn’t do it in the sketch above, but siting your blocks above the blocks that give you your bottom rocker would let you use nice heavy nails to fasten the blocks that define your outline shape. Leave the heads sticking out some so they can be pulled easily. Put another block at the nose of the other sideand fasten the other strip of lauan to that. Put your blank in there, quickly bend your floating strip of lauan around it and mark good spots for clamping blocks. Tack those on.

You’ll want to use weights to hold the blank to the bottom curve form, but the rest of the clamping should go ok. Bend your floating strip around, clamp, bend it some more, clamp more, come back through and check it and there you go. Pull the nails when done and repeat in mirror image.

Anywho - on that note, I have to get something to eat and catch a little sleep - out on the tide again tomorrow…

doc…

[RichardMc]

Jim, Let’s see a pic of that new model J. I love to see “style” coming back into boards again after a few decades of vanishing (stringers, nose/tailblocks, wood skegs).

[red_boards]

I was searching for stuff on multiple stringers. Rather than posting the question in a new thread I thought this old one worth reviving seeing as there’s been so much discussion on parabolic stringers - just check out some of the wavy pattern stringers in this thread and imagine the complex twisting they induce…

My multiple stringer question is slightly different.

I’m thinking of using multiple glue line stringers down a 1lb EPS blank, and no wood.

How much benefit will this be flex and strength wise?

I was thinking of doing a glass lam with epoxy for each stringer line. Over rigid and brittle?

Probably won’t skin the first one. It will be interesting to see how the deck dents work out.

Thanks for your input.

Red