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Bending Timbers


hydroped

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Hi All,

Well I'm stumped. I need to bend some timbers to fit some arches I'm working on and I went out and bought some nice balsa timbers about a half inch square - Put them in boiling water and boiled them for about 4 hours.. they still wont bend. I know it has to be done quickly while they're still hot but they just won't go - they bend the tiniest amount and then snap. Is Balsa not a strong enough wood to bend? Any tips or ideas? I'd try dry bending but I don't have a torch and I'm not sure I'd be able to end the balsa without scorching it even if I did - it's just such a soft wood I'm afraid it would really scorch against the pipe.

-David

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Hi David --

You could try to bend them the way you would in "reality".

Thoroughly wet the wood (as in soak overnight). You can use hot water, but the process requires wet, not hot, wood. Clamp the wood on both ends giving the wood a slight bow. Allow it to dry in the clamps. Repeat the process until you have the curve you need.

I know this sounds more time intensive than just hot water & bend, but I'm reasonably certain this will work. There's no reason why balsa wouldn't bend -- it does, after all, warp on it's own. It has a tendency to float, tho', so you might have to weight it down to soak it.

Have fun!

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David I really wish I could help. But I'm sure that you remember me wanting to really "bash" my Lily when trying to bend the roof to fit. The only thing that worked for it was to take a dremel to it and cut very thin lines and then I'm afraid I tortured the poor thing into bending. Wrapped around a coffee can and wetting it and constantly tightening it. Charlene's idea sounds good. I believe Deb wet hers and let lie over the bathtub.

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You could try to bend them the way you would in "reality".

Thoroughly wet the wood (as in soak overnight). You can use hot water, but the process requires wet, not hot, wood.

Well there's nothing to lose by trying a simple wetting though in "reality" for full sized lumber I would use heat. That's the way most full size lumber is bent be it for curved roofs, walking sticks or entire beams for ships hulls the wood is heated - either with steam in the case of full sized beams or dry heat for smaller items like walking sticks so I presumed that using real life methods would translate into mini. Though now that I'm thinking about it.. perhaps too much water is part of the problem since it should have been ready to bend after an hour of steaming and the moisture content suggested for bending is only about 22%.. maybe balsa has too high a moisture content plus I boiled instead of steamed... which could have made it just too wet. Perhaps hardwood methods do not translate over into soft woods

-David

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David, I have bent wood for arches several times, I used basswood not balsa. I soaked each strip in hot water and kinda bent them while still in the hot water a little at a time. Then I clamped them to the arch until.

they dried. Thats when they will hold the shape but you need to use thinner wood 1/2 inch is just too thick

.

terri

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Ok. Called my bro-in-law who is a cabinet maker. He says your 3/4" is too dense (it's not that its balsa, it's the thickness).

If you need the 3/4", he recommends that you laminate three 1/4" flat pieces together and then your steaming should work. But, he says he would also recommend that you make a form of 3/4" ply and cut the shape that you want the arch to be (with a jig or scroll saw) and then clamp your arch pieces overnight into the form. The reason he recommends this is that if you have more than what he called a soft arc, the wood has a tendency to lose the arch.

This sounded simple enough. Hope it helps!! :D

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Thanks Terri,

If I can't get this to work I may move up to bass wood or even one of the harder woods - of I could just faux beam it and cut up a 2X4 in the bent shape ... somehow that just doesn't sound as much fun.. or as cool looking as real bent beams.

-David

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I've only done a few bends, but I'd go the laminated way, but I'd bend first, at least to close to your desired curve, then laminate. The best way I've seen is to bend and laminate at the same time though. We made bows in woodshop that way. There was a pattern, we used thin wood strips with wood glue, laminated the strips, then clamped them in the pattern overnight, they held the shape well. The pattern was simply the profile of the bow cut into a piece of stock so you had 2 pieces you could sandwich the laminated wood strips between. We didn't wet or heat the wood, but I'd bet the results would have been even better if we had. If you want sheer brute strength, wet the strips, use urethane glue, and a pattern.

BTW, great question Bro, gave me an idea for theinside of Marg's church. :D

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Hi David --

After all the technical discussion, I almost hate to ask such a basic question but here goes: What are the bent timbers for? Is it a ceiling? And, if yes, you will share how you build that won't you? :D I'd love to follow along on how to do that.

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David, Andrew's post reminded me you can build a bending jig for your timbers (having a seriously "Duh" moment or more yesterday). you can use a piece of peg board and pegs (for all sorts of curves) or a thickish piece of scrap plywood or board and heavy nails. Set the pegs or nails apart in two rows the width of the timber you want to curve and set it in, dampen it (hold it over the steam) and guide it around the curve until it won't move and let it dry. Hit it in the steam again and advance it , until the wood is into the curve you want, and when it's all dry it ought to hold that curve. If it's for half-timbering you oughtn't need that tight a curve to get the effect.

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Thanks everyone :)

It's a fresh day and afresh start :o And I could have had the pieces too wet because last night they finally started to bend (after sitting out on the counter for several hours) I would like to hit them with heat again before puttng them in the jig. One other thing I Defintiely did wrong! I didn't cut them long enough. I did cut too long to allow for the bend but I should have cut them almost twice the length I need them to allow for a center bend and then trim down to size ... that I didn't do :D just figures huh?

Holly you're a gem! I'm gonna do just what you said hit em with heat again and toss em in that jig.. I think I was also getting them in too slowly - after some more research I realize that If I dont' get it in there within 5 seconds ( and that's the estimate for much larger wood.. I'm thinknig less time for such small wood because it will cool more quickly) then I've already lost most of how far it can bend.

Doogster we're on the same wave length with this one! I'm going for Gothic arches on the interior of a medieval chappel -... a bit of an over enthusiastic project for me.. but when the bug bites you just gotta go for it I guess.

And yep, Charlene, there will Definitely be pictures! :)

Thanks again everyone!

-David :)

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Just an update -

I think it's gonna work! I checked and doubled checked the arc I wanted in the wood - drew 2 patterns (the first wasn't quite right and had to get help - took 4 hands to hold the wood in place and draw a pattern from the one timber I got hand bent to the right curve) - once we got the curve right and got the pattern transfered to the block it was easy enough to cut it and Violla! a jig - a couple of C clamps to tighten it down and I was ready for a test run. I tried 4 pieces of balsa this morning (not wet or hot, just dried out from the soaking the got the other day) and of them one cracked the other three are taking the bend and after an hour and a half beginning to hold the shape - I think they will work better once I get the right length wood - soak them and let them dry in the form.

Thanks to everyone for all the encouragement and especially Terri and Holly for the great advice. There will definitely be photos when I get the actual timbers to hold their shape :rolleyes:

-David

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Marie,

You're so sweet but I have to confess next of most the folks here I'm still just a beginner! <_< The cool thing is - it's Ok to be a beginner :) Minis - like Enthusiams are two of the best contagious things ever :D

Holly - this is what really bugs me - I could have done this SO much simpler and I even have the tools.. but do you think I can find them?.... <sigh> - To be honest I"m not even sure I still have them I was sure I didn't get rid of them but one never knows what I'm liable to do in a moment of "Oh I'll never use this" <sigh> but a couple years ago I picked up a flexible curve you make the curve you want with it - it holds its shape then you just trace around it. Doh!.. but I couldn't find it anywhere! I'm such a dolt I think I'd walk off and lose my feet if they weren't permantly attached :rolleyes:

- David

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Doh!.. but I couldn't find it anywhere! I'm such a dolt I think I'd walk off and lose my feet if they weren't permantly attached :rolleyes:

- David

<_< Y'know, David, before we retired to the mountains, DH used to blame the boys for walking off with whatever he couldn't find -- no longer having that excuse, I've heard him wail the same sad song more often than you can imagine. Hold tight -- as soon as you need something else, you're sure to find it! :)

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I can't wait to see your arches David, I'm sure they will turn out beautifully just like everything else you have done :) . I wanted to try to put an arch in the addition I'm building for my garfield but I just couldn't get it so I gave up :D . Maybe I'll try again with another project if DH allows me to get another dh :rolleyes: .

<sigh> - To be honest I"m not even sure I still have them I was sure I didn't get rid of them but one never knows what I'm liable to do in a moment of "Oh I'll never use this" <sigh>

- David

I know that to well, as soon as I get rid of something no matter what it is I end up needing it a month or two later <_< .

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