Bending Birch

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Bending Birch

Postby TomS » Mon Jun 13, 2005 3:56 pm

I don’t know if anyone else has used Bending Birch to skin the inside of their roofs. So, I thought I’d provide this mini-product review.

Bending Birch is specially laminated flexible plywood intended to mount on curved surfaces. It comes in 1/8” or ¼” thickness. When purchasing this material you need to specify the direction of bend. Since I’m building a five-foot wide tear, I needed to bend it across the short or 4-foot dimension. Someone building a 4-foot wide would want it to bend across the long or 8-foot dimension. I bought mine from Boulter Plywood in Somerville, Mass., about an hour drive from my home near Worcester. The cost was $35 per 4 x 8-foot sheet of 1/8” thickness. I bought 4 sheets, enough to skin the cabin roof and galley hatch.

I was initially very disappointed with the surface quality of this plywood when I go it home. There was a lot of glue on the surface. It also had scratches and marks on it. I briefly considered taking it back. I really didn’t want to drive back to Somerville. And, I didn’t have another local source for flexible plywood. I decided to make the best of it. I was pleasantly surprised when I sanded it. It cleaned up very nicely with 150 grit sandpaper and my orbital sander. I followed up with 220-grit. The veneer held up that sanding with no problems.

Prior to mounting on my roof spars, I applied 3 coats of Minwax Helmsman Spar Urethane, sanding with 220-grit between coats. The urethane really brought out the beauty of this wood. It looks really, really nice with the urethane on it. I never dreamed that it would come out that nice. This photo doesn’t do justice to it.

Image

I mounted my inside roof skins yesterday. That bendable birch handles like thin piece of cardboard (just a bit stiffer than pizza box laid flat). My son and I had a tough time keeping it down on the surface of the table saw when we cut it. This material is so flexible; we rolled it into a tube and passed it through the door opening in the side wall. We had a little trouble when nailing up the piece that goes against the flat portion of the roof. We didn’t realize it at the time; it. It sagged just a bit on the flat portion of the roof. This caused a small gap to between the first and second piece. The sag will come out when I mount my overhead lights and the galley fan. I’ll hide the gap with a small trim piece. So, it’s not a disaster by any means.

It's utterly amazing how that much that flimsy 1/8" thick plywood stiffened up the trailer body. By the time I get done putting the 3/8" flexible luan on the roof, my roof will be incredibly strong. It's true. We really do overbuild these things.

Bending Birch is pricey and hard to find. However, it finishes very nicely and is much easier to apply to a curved roof than conventional plywood. For someone building a Rimple or other design with tight curves on the roofs, it's the only way to go.
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Postby Chris C » Mon Jun 13, 2005 4:16 pm

Looks nice, Tom. :applause: Flexible plywoods can come in real handy sometimes. :thumbsup: I build custom furniture for a living and have had some experience with it when there was just no other way to duplicate the look without charging the customer an arm and a leg to cooper the front of a curved piece of furniture. Have to admit, I've thought more than once about using it for the curved portions of the enterior of my tear when I start it. :thinking: Still think I'll use a standard material for the top.

Keep up the good work. Can't wait to get started on mine.
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Re: Bending Birch

Postby TonyCooper » Mon Jun 13, 2005 9:55 pm

TomS wrote:It's utterly amazing how that much that flimsy 1/8" thick plywood stiffened up the trailer body. By the time I get done putting the 3/8" flexible luan on the roof, my roof will be incredibly strong. It's true. We really do overbuild these things.


Tom,

It looks great.

I used 1/4 birch inside, 1/4" luan on the outside. I honestly believe I could jump up and down on the roof. It is that strong!
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Postby Arne » Mon Jun 13, 2005 10:05 pm

One thing to remember is these tears don't sit still. They do get beat around a lot on the road. So, I'm not sure I'd try and go too light.

I used 1/4 ply inside and out with 3/4" thick studs... I think the only think I might do differently is skinny up the studs..... and maybe go to 1/8" on the inside walls.... but the 1/4 inside has gotten a few things attached to it, so am not sorry I used it.
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Postby doug hodder » Mon Jun 13, 2005 11:30 pm

A point to consider when bending these materials. I built the frame for my galley lid and had the curves just so. When I installed the interior material with the grain running from the top to the bottom of the lid, I screwed up and did it in 1/4 as that is what I had left over, it was a little stiff and I didn't support the lid frame and the plywood actually took some of the curve out of the frame, I had to build it back into it using shims and other material as it didn't fit as well. Oh well, a lesson learned for the next one. Just my experience. doug hodder :oops:
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Postby Chris C » Tue Jun 14, 2005 8:25 am

Doug, great post. I've been concerned about "springback" on the hatch myself. Keeping the exact arch in the hatchlid has me wondering if "bending" plywood wouldn't be the way to go for the interior and exterior of the hatch itself. You are the first person to make a comment which is making me lean towards doing that. Thanks.
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Postby rjhager » Tue Jun 14, 2005 9:50 am

Tom,

I also had trouble trying to cut 1/8" (and even 1/4") ply on the table saw -- particularly when it was still a full sheet. I found that I could do much better by laying a straight-edge down (I have an aluminum "meter" stick) and a sharp utility knife. With 1/8" material, all it took was about 3 passes and I had a nice, straight cut and none of the hassles of trying to keep it on the table saw!

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Postby Arne » Tue Jun 14, 2005 10:06 am

When I built my tear, the outside roof was doubled 1/8 ply. Problem was, I went the long way up and over the tear. Bending in this direction is a lot more difficult than if I had laid the sheets sideways. But, I didn't want a lot of scrap and I was doing a quick build.

If I did it again, I would put the long way across the tear and bite the bullet on the scrap.. it would have made the bend a lot easier.... another live and learn thing...
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Postby TomS » Tue Jun 14, 2005 1:29 pm

Thanks for the comments guys.

arnereil wrote:One thing to remember is these tears don't sit still. They do get beat around a lot on the road. So, I'm not sure I'd try and go too light.

I used 1/4 ply inside and out with 3/4" thick studs... I think the only think I might do differently is skinny up the studs..... and maybe go to 1/8" on the inside walls.... but the 1/4 inside has gotten a few things attached to it, so am not sorry I used it.


The Cubby plans call for 1/8" inside roof skin just aluminum skin mounted directly to 3/4 x 1 1/4 spars. I doubled up all my spars and I'm putting 3/8 flexible luan on the outside.

rjhager wrote: I also had trouble trying to cut 1/8" (and even 1/4") ply on the table saw -- particularly when it was still a full sheet. I found that I could do much better by laying a straight-edge down (I have an aluminum "meter" stick) and a sharp utility knife. With 1/8" material, all it took was about 3 passes and I had a nice, straight cut and none of the hassles of trying to keep it on the table saw!


I tried cutting 1/8 plywood with a utility knife. I wan't very happy with the results.

Prior to finshing, I cut the pieces to width with a circular saw and an aluminum straight edge.

We used the table saw to cut the finished pieces to length for a couple of reasons. I have a brand new carbide plywood blade that produces a perfect edge with no tearout whatsever. Also, by using the table saw, I could cut it with finished side up so it wouldn't get scratched.

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Postby IraRat » Wed Jun 15, 2005 2:10 pm

Tom, you can't get this stuff down here, so I went to the Boulter site on Monday and asked for a quote with shipping. No response, so I just gave them a call.

They can indeed ship to South Florida UPS, so I gotta call tomorrow for a quote on 2 pieces.

I guess that deep inside, I want to order 3, but I really don't need 3. Just want to think ahead in the event of a c r a c k..................
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Postby surveytech » Wed Jun 15, 2005 3:30 pm

cox lumber has bendable plywood.
they have locations throughout florida.
I am sure there are others.
they gave me a quote for 1/8 inch luan
and 1/4 inch bendable birch.

not affiliated with them, just thought you could use the info.

did you check any of the boatyards/marine suppliers there?
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Postby TomS » Wed Jun 15, 2005 6:09 pm

IraRat wrote:Tom, you can't get this stuff down here, so I went to the Boulter site on Monday and asked for a quote with shipping. No response, so I just gave them a call.

They can indeed ship to South Florida UPS, so I gotta call tomorrow for a quote on 2 pieces.

I guess that deep inside, I want to order 3, but I really don't need 3. Just want to think ahead in the event of a c r a c k..................


Ira,

I wouldn't worry about cracking this stuff. It's extremely flexable. Check out that local vendor. I'd hate to think what UPS shipping charges would be.
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Postby Guest » Wed Jun 15, 2005 10:15 pm

Dumb question time... Other than time and effort, what's the difference between bendable plywood and cutting kerfs on one side? :thinking:
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Postby madjack » Wed Jun 15, 2005 10:33 pm

...essentially "bendy" ply is a ply with the grain running in one direction...either in 4x8 or 8x4 sheets(short explanation). It is extremely flexible being able to bend into extremely tight radius's(6" or better)...no kerfs cuts (and attending problems from cuts) needed
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Postby IraRat » Thu Jun 16, 2005 7:30 am

surveytech wrote:cox lumber has bendable plywood.
they have locations throughout florida.
I am sure there are others.
they gave me a quote for 1/8 inch luan
and 1/4 inch bendable birch.

not affiliated with them, just thought you could use the info.

did you check any of the boatyards/marine suppliers there?


Didn't think about the boatyards OR marine suppliers--but I went to one of the really better specialty lumber yards around here and no luck. They had no suggestions either.

I never heard of Cox, but I just went to their website and they don't have a single location in this huge section of southeast Florida. I can either drive 2 hours to Naples, or hop a flight to their Cayman Islands location--because it's pretty close to the same distance!!!

However, if they ship, I'm assuming it would be cheaper coming from Naples than from Massachussets! Gonna call right now. (Noon update--they dont have or ship to here.)


Spars are going up this weekend, gonna fix the electrical, so the interior roof is definitely next. Gonna need this stuff by next weekend.



-------------------------------------------------

Noon update:

No one's got the stuff, so I called Boulter again. Great guy there named Chris Boulter, and they're shipping me 3 pieces next week when it comes in. (I got the third piece to use for other trim; probably could have gotten away with a cheaper, non-bendable birch, but what the heck--the other type wouldn't fit in a tube!)

Just $30 shipping to South Florida, via FedEx yet, so that's not bad at all.

With gas prices these days, and with the driving I would have to do if I ever COULD find it down here, plus the time...it's well worth the 30 bucks. Plus, no tax!

Thanks for the tip, Tom. Now I just gotta be careful I recognize the correct side for finishing and for the bending, when it's ready to go in.
Last edited by IraRat on Thu Jun 16, 2005 10:50 am, edited 4 times in total.
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