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Separating Laminated Plywood

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Forum topic by BareFootWoodworks posted 07-21-2017 07:30 PM 1183 views 0 times favorited 7 replies Add to Favorites Watch
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BareFootWoodworks

6 posts in 145 days


07-21-2017 07:30 PM

Topic tags/keywords: tip question trick resource plywood refurbishing veneering

So the gist of the story goes:

A guy I met wants a sign for his historical building repaired. The gentleman whom previously repaired the sign used Bondo, (sigh). This caused the sign to rot even further.

The two faces of the sign are made from solid wood, there is a piece of plywood in between them and they are all laminated together.

My problem is removing the plywood from the center, the guy is fairly attached to this sign, and I would love to save his original sign by replacing the plywood in the middle. I’ve had a hell of time trying to think of a way to separate these pieces without using a bandsaw with a 3-foot opening (which I don’t have, nor have access too).

part of my problem is the way the plywood rotted some of it is perfectly good and the center of the piece is rotted through top to bottom.

So far I’ve tried using a 14 in spackle knife that I cut the metal from, to use as a shim to separate them, that kind of worked until I hit a pocket of rot and well it’s stuck now.

I have a Japanese hand saw I didn’t mind sacrificing for the cause, but it just continually gets clogged up, at the pace I removed the saw to clean the gunk out of the teeth it would take me two days to separate each layer.

I am thinking of trying a 4-foot limb saw but I’m not sure if that would be any better. I don’t have that large of a limb saw so I’d rather hold off at least for now.

Any suggestions?

-- ~That Guy~


7 replies so far

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Kazooman

867 posts in 1787 days


#1 posted 07-21-2017 08:06 PM

You didn’t give the size of the sign or the thickness of the plywood, so we will have to guess a little. I think you are on the right track You would need a saw with a long enough blade, but with some careful effort you should be able to split the sign in two. My best thought on removing the remainder of the mess would be with a router and a router sled. You could remove the junk and at the same time create a flat surface for re-gluing the faces to a new substrate.

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Loren

9612 posts in 3483 days


#2 posted 07-21-2017 09:25 PM

I can’t think of any reasonable solution
to the problem that doesn’t entail
a risk of damaging the sign.

This is a difficult client-relations issue.
Probably the lowest risk is to buy a
hand saw with the capacity you need
and go to work on it. You’ll need to
remove the remainder as Kazooman
suggests. I hope your client is paying
you fairly for your time because it
sounds like a real pain to do the job.

You can make one or more hardwood
wedges and try to split the plywood in
half. This could be reasonably quick to
do but could damage the face boards.

You could rip the sign into sections on
the table saw and reassemble it later with
those sections still separated by the
kerf width. This approach would make
removing the plywood with the table saw
feasible. It would also be reasonably quick
and you could plane the plywood off
without going to the effort of making an
using a router jig to do it.

Finally, if you steam the plywood it may
eventually crack open on its own.

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BareFootWoodworks

6 posts in 145 days


#3 posted 07-23-2017 01:38 AM

!https://s3.amazonaws.com/vs-lumberjocks.com/otiryrd.jpg

Thanks for the suggestions!

I ended up spending about two hours to separate the two faces. At the same time I discovered that the faces where molded in plaster and inlaid in plywood, to make the two faces, and the center lamination was some high grade plywood from 30 years ago. Might I add that this sign is most likely just older than I am, lol. I wish I would have taken a picture of how I actually started it. I started but using a chisel and tapping it in about two inches around the entire thing to create a score line I could wedge into. I then used a good portion of my collection of standard screw drivers to tap into my score like I was try to split a large piece of stone. Evenly tapping each one in succession. However, I ran out of screwdriver pretty quickly and it had not separated nearly enough, so I ran down the big orange box store and grabbed some pieces of 2’ rebar and used my angle grinder to make a large metal wedge. And, I was pretty surprised when it actually worked without cracking the plaster. I only really realized the faces we’re part plaster after it was separated and could see the plaster. The sign had been painted so many times over the years that there is about 3/16ths of an inch of paint on it. Before I started working on this sign, I had told the gentleman who commissioned me I would save it if I could but if I couldn’t I could make another replica because it’s for a historic building. So all in all I just have to find someone really nice exterior plywood round where I live and it should be good as new. The dimensions are 37×26x3.5.

-- ~That Guy~

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BareFootWoodworks

6 posts in 145 days


#4 posted 07-23-2017 01:39 AM

-- ~That Guy~

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AlaskaGuy

3644 posts in 2144 days


#5 posted 07-23-2017 02:10 AM

I’m glad I’m 73 and retired. Now if it ain’t easy I don’t take on the job. :) Not to say I don’t like a challenge I just want to pick my challenge

-- Alaskan's for Global warming!

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Kazooman

867 posts in 1787 days


#6 posted 07-23-2017 03:10 AM

Glad to hear that you got it apart. The rebar wedges were a great idea.

In the picture I see a round sign but you gave rectangular dimensions, so I am a bit confused. If it is a rectangle, I was wondering if it might be a good idea to make the plywood piece smaller and wrap it with some hardwood edging. That might help keep water out of the plies.

How about a nice pic of the final outcome when you are done?

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BareFootWoodworks

6 posts in 145 days


#7 posted 07-23-2017 05:00 AM

It’s an oval sign, so it’s the best of both shapes and I’ll be glad to post a snap shot of it all back together.

-- ~That Guy~

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