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How do I bend/form luan plywood?

17K views 24 replies 10 participants last post by  DanTwoLakes 
#1 ·
I did a search-it's probably here but i missed it-

I have found some 1/8" luan plywood (as opposed to PVC foam board) that I would like to use for the interior panels in my Model A (to be covered with vinyl). I am going to need to bend and form them to match the curvature at the rear corners of the cab. What's the best way to form them and to get them to stay formed?

Thanks
 
#2 ·
The way to bend plywood is to steam it, but you need to make a form to hold it in place til it dries. Another way to bend it is to cut saw kerfs in the back side about half way through from top to bottom about 1/4" apart. I wouldn't trust it to keep its shape given the temperature changes a car goes through.

If I were you, I'd forget about 1/8" luan plywood and use 1/8" PVC foamboard. It will bend easily and stay in the shape you want after heating it with an industrial heat gun. That will be 10 times easier than trying to bend the plywood.

The picture is 1/8" PVC foamboard that I bent without even using any heat. It took me less than a minute to do that.

You could also use waterproof panel board. Anything would be better than trying to bend plywood.
 

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#3 ·
Do you know that you can buy a set of rear panel boards for your model "A"? What model car do you have? This is a 1930 tudor.

I am a dealer for Mac's Antique Auto Parts, and can get you anything you need. PM me if you're interested.
 

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#4 ·
Thanks for both replies. I've looked at the posts for ABS/PVC foamboard and luan. The plywood would be available 3 miles from my home-50+ for the closest plastics supplier.

My '31 coupe has a 3.5" chop so I am not sure how Mac's preformed panels would work.
 
#5 ·
My '31 coupe has a 3.5" chop so I am not sure how Mac's preformed panels would work.
I'm sure you'd only have to cut them down 3.5"

Don't you have a sign shop near you? PVC foamboard (Sintra, Komatex, CelTec, or Palight) would be standard stuff for a sign shop.
 
#6 ·
Todays luan is very hard to bend. Steam will most likely de-laminate it (from personal experience) and even with kerf cuts it wants to crack and break. You used to be able to get bendable plywood (still available but extremely hard to find). You could use masonite but you will need to make a form so it holds its shape, it warps very easily, making it very hard to work with. I too use PVC foam board. Like Dan said, its easy to bend and hold its shape. I also get mine from a sign shop.
 
#7 ·
Don't use Masonite for a car interior, it's too susceptible to water damage, it is very brittle, and there are just a lot of things better to use in your car than Masonite.
 
#9 ·
bending wood

In the 70's I built 4 model t speedsters, I had access to a school metal shop, so I made mine from sheetmetal, At the same time when I was in N Calif a guy was bending 1/2 in boat plywood enough to make the curved seats , Idon't know where you can get the material today, but as Dan said you need a good form. My nephew in calif was making skim boards that kids use at the beach, he had forms and a big frame made from 4 X 4's and glued and laminated the thin ply and a 12 ton Hyd jack to press them.
 
#10 ·
In the 70's I built 4 model t speedsters, I had access to a school metal shop, so I made mine from sheetmetal, At the same time when I was in N Calif a guy was bending 1/2 in boat plywood enough to make the curved seats , Idon't know where you can get the material today, but as Dan said you need a good form. My nephew in calif was making skim boards that kids use at the beach, he had forms and a big frame made from 4 X 4's and glued and laminated the thin ply and a 12 ton Hyd jack to press them.
That sounds like an awful lot of work/equipment to form a couple of curved panels to fit the rear corners of a chopped A coupe. but,thanks.
 
#11 ·
About equal to bending 1/8" plywood and getting the correct curves on the first try. No matter how much you save by using something that doesn't bend easily, you will lose it in the time and effort you use to find out how difficult the process actually is.
 
#12 ·
I bend Luan all the time, this is how I do it, not necessarily the best or only way, just my way. I found that if I set the board in place, with the grain opposite of what "looks right" as far as bending, I sand the backside of the board with a 36 grit flap disc, sanding a single layer from the back side. The board will now bend more than 90 degrees. It is very fragile at this point, but you can mix up some fiberglass resin, apply it to the board in place, and should have a pretty solid panel. Hope my explanation makes sense. May not work for this scenario, but may help someone else on a future project
 
#13 ·
I have used this method many times when building a buck for fiberglass pieces, and I have also used it for building bucks for foamboard items. It's a fast way to get a template made. Compound curves can be accomplished by laminating a couple of pieces together, a little filler, and you are all set. Landau foam makes a good body filler for interior panels, in some situations.
 
#16 ·
Just as an update-I got a sheet of 3mm Sintra from a local sign shop and ordered the DAP spray adhesive as Dan suggested. I might as well TRY to do it right the first time. Harbor Freight had $30 spray guns on sale for $10 (plus a free LED flashlight!) and shipped my total order for $6.99. So if it would juts warm up a tiny bit, I'm set to go. Thanks.
 
#21 ·
Just a head's up. I found an online promo code for yourautotrim.com (scottkeen) and saved 15% on the order. No idea who he is, but the code is listed on several coupon sites and it is still active. Never hurts to look.
 
#17 ·
In upholstery work, there is never just one way to do something, but there is always a better way to do some things. You will be thrilled when you find out how easy it is to use the PVC foamboard.

I'm curious, how big a sheet did you buy, and what did you have to pay for the Sintra?
 
#18 ·
4x8 and it was $55. I did not shop around because a) it's pretty rural here and there aren't a lot of shops b) moderate savings would be eaten up by hauling it and c) I like to shop locally when I can ven if it's a bit more. Local folks are my neighbors and customers.
 
#22 ·
I received the glue safely today, one day earlier than UPS has predicted. The company also included a very nice can koozie. Nice folks to do business with.
 
#23 ·
trying to bend plywood is not easy, the best way is to make a form and use thin veneers which can be bought on Amazon or some lumber yards, spread a thin layer of glue on each veneer until the desired thickness press it into the form clamp over night then trim to fit. I just went out a bought a piece of sintra sign board to do the same thing in my coupe door panels. good luck, SC
 
#24 ·
Luan will not hold the shape for long especially if your bend is sharp, I would recommend using maralite, it is much more flexible and is sold at your local lumber store, and is about the same cost as luan... it is more like a peg board material and resists cracking or breaking. Just a thought!! Chas
 
#25 ·
Read the rest of the thread from the beginning, and you will find that no-one is recommending trying to bend luan plywood or anything else you can buy at the lumber yard. There are many things that are intended to be inside of a car that will work better, and bend easier.
 
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