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Flexable wood filler.

PostPosted: Wed Sep 06, 2017 6:04 pm
by dancam
Hi, is there a flexable wood filler available? I built a tongue box for my trailer out of 1/8th plywood. Made 2 mistakes. One was we glued one part on rough side out and the other was it was made 4inches too wide so i had to cut 4inches out of the middle.
What i would like to do is seal the whole thing with 'the mix', let that dry, fill the knots and seam that is in the photos with some flexable filler, then paint it.
The tongue box will flex a lot so rigid filler will crack and pop out. The filler also needs to have decent enough adhesive properties to stick to sanded 'mix' and be paintable.
Testing lepage no more nails interior gap filling adhesive and exterior 'mono' caulking on some scrap pieces right now.
Thanks for any help!
ImageImageImageImage
Last photo was before cutting it in half...

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Re: Flexable wood filler.

PostPosted: Wed Sep 06, 2017 6:30 pm
by tony.latham
I think what you need to do is see if you can't delaminate a piece of scrap birch and cut this thin laminate into into a football shaped piece that you could inset into your knot area. Just like a football patch in a sheet of plywood. I would think would be doable with an Exacto knife and a small chisel.

Tony

Re: Flexable wood filler.

PostPosted: Wed Sep 06, 2017 7:33 pm
by featherliteCT1
Nice looking box!

Re: Flexable wood filler.

PostPosted: Thu Sep 07, 2017 12:37 am
by dancam
tony.latham wrote:I think what you need to do is see if you can't delaminate a piece of scrap birch and cut this thin laminate into into a football shaped piece that you could inset into your knot area. Just like a football patch in a sheet of plywood. I would think would be doable with an Exacto knife and a small chisel.

Tony

Ok, thanks. Ill try that on the knots and see how it goes. Should work i would think. Any suggestions for the seam?
featherliteCT1 wrote:Nice looking box!

Thanks :)

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Re: Flexable wood filler.

PostPosted: Thu Sep 07, 2017 7:40 am
by tony.latham
How are you going to finish it? I'd toy with using a thickened epoxy and make sure it's squeegeed level. I assume there's wood behind the joint?

Re: Flexable wood filler.

PostPosted: Thu Sep 07, 2017 7:59 am
by dancam
tony.latham wrote:How are you going to finish it? I'd toy with using a thickened epoxy and make sure it's squeegeed level. I assume there's wood behind the joint?

Just how i had said in the first post- coating with the mix and then painting. Using exterior latex paint is the plan.
I have some epoxy which is super thin, what do you thicken it with? There is wood behind the seam but i am still worried about something rigid like epoxy cracking away from the sides as the wood flexes. Or would that not happen?
Thanks

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Re: Flexable wood filler.

PostPosted: Thu Sep 07, 2017 8:03 am
by tony.latham
dancam wrote:
tony.latham wrote:How are you going to finish it? I'd toy with using a thickened epoxy and make sure it's squeegeed level. I assume there's wood behind the joint?

Just how i had said in the first post- coating with the mix and then painting. Using exterior latex paint is the plan.
I have some epoxy which is super thin, what do you thicken it with? There is wood behind the seam but i am still worried about something rigid like epoxy cracking away from the sides as the wood flexes. Or would that not happen?
Thanks

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If there's that much flex, they make some flexible caulks you may want to use. There are several fillers specifically made to thicken epoxy but in a pinch sawdust works.

T

Re: Flexable wood filler.

PostPosted: Thu Sep 07, 2017 2:10 pm
by Esteban
I'm a proponent of using fiberglass, i.e. epoxy and fiberglass cloth. PMF (poor man's fiberglass) may be good enough for you needs. You can fill the plywoods knots and defects after you bend and install it, then reinforce the plywood with fiberglass or with painted PMF for longer time durability.

If you choose to use epoxy to fill the plywood joints and defects you can thicken the epoxy with sawdust or Cabosil (fumed silica powder). An electric sander with a filled up sawdust bag might be your source of finely textured sawdust. Cabosil is inexpensive

Re: Flexable wood filler.

PostPosted: Fri Sep 08, 2017 1:21 pm
by dancam
tony.latham wrote:
dancam wrote:
tony.latham wrote:How are you going to finish it? I'd toy with using a thickened epoxy and make sure it's squeegeed level. I assume there's wood behind the joint?

Just how i had said in the first post- coating with the mix and then painting. Using exterior latex paint is the plan.
I have some epoxy which is super thin, what do you thicken it with? There is wood behind the seam but i am still worried about something rigid like epoxy cracking away from the sides as the wood flexes. Or would that not happen?
Thanks

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If there's that much flex, they make some flexible caulks you may want to use. There are several fillers specifically made to thicken epoxy but in a pinch sawdust works.

T


Its just 1/8th plywood, so the top flexes a lot. The curved sides dont though.
Ill have to look at different caulking, the one i tried dried way too soft.

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Re: Flexable wood filler.

PostPosted: Fri Sep 08, 2017 1:24 pm
by dancam
Esteban wrote:I'm a proponent of using fiberglass, i.e. epoxy and fiberglass cloth. PMF (poor man's fiberglass) may be good enough for you needs. You can fill the plywoods knots and defects after you bend and install it, then reinforce the plywood with fiberglass or with painted PMF for longer time durability.

If you choose to use epoxy to fill the plywood joints and defects you can thicken the epoxy with sawdust or Cabosil (fumed silica powder). An electric sander with a filled up sawdust bag might be your source of finely textured sawdust. Cabosil is inexpensive


Thanks, the issue with doing pmf is the compound curves on the lid. I had just wanted this done quick and figured this would be easy so i never looked into fibreglass. Should have just made a quick foam mould, made a fibreglass tongue box over it and pulled the foam out and been done.

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Re: Flexable wood filler.

PostPosted: Mon Sep 11, 2017 4:13 pm
by Atomic77
Use 3M body filler. I've used it in such circumstances many times. I would suggest against thickened epoxy, not that it won't work because it certainly will. It's just much harder to sand. We use filler on plywood a lot in the boat shop and on molds for parts. Check out the walls of my build in my build journal for a few pointers.

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Re: Flexable wood filler.

PostPosted: Mon Sep 11, 2017 4:19 pm
by Atomic77
Here's what we use. Its flexible and has built in adhesion promoters. Its pricy but if you keep it sealed and away from freezing temps, it will last a long time. It's Pro-quality and we use it on million dollar boats on the regular.

Image

Re: Flexable wood filler.

PostPosted: Wed Nov 15, 2017 4:43 am
by kielyjw
Bondo or body filler works great also durabond drywall powder works great. You must get the durabond in the brown bag not the white bag. Brown bag sets up like a rock where as the white bag dries to the easily sanded dusty powder. The brown bag is also waterproof.


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