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View FarmerintheWoods's profile

DIY Plywood & Router

by FarmerintheWoods
posted 07-21-2017 03:21 PM


15 replies so far

View Loren's profile

Loren

10477 posts in 4036 days


#1 posted 07-21-2017 03:44 PM

1. thickness sand or use hand planes to remove
machine marks. Plastic resin glue is probably
ideal. Commercial plywood layers are made
by peeling layers off a turning log with a
long knife, sort of like a giant pencil sharpener.
Carbide tipped band saw blades leave the
best surface finish for laminating due to the
lack of set in the teeth.

2. Grain should alternate direction for maximum
strength but if it’s the same direction it will
be pretty strong anyway, as strong as solid
wood of the same thickness, more or less.

3. Shouldn’t matter much as long as those woods
are at similar moisture content. Those are
common domestic hardwoods and move at
similar rates.

View MrRon's profile

MrRon

5483 posts in 3631 days


#2 posted 07-21-2017 04:47 PM

I’m not too crazy about using good hardwood for interior layers of plywood. Commercial plywood is made up of layers of a cheaper species of wood and the hardwood is used only for the faces.

View AlaskaGuy's profile

AlaskaGuy

5278 posts in 2697 days


#3 posted 07-21-2017 05:04 PM

Remember all commercial plywood has an odd number of layers ((3, 5, 7).

https://www.google.com/search?q=why+does+plywood+have+an+odd+number+of+layers&ie=utf-8&oe=utf-8

-- Alaskan's for Global warming!

View nkawtg's profile

nkawtg

288 posts in 1639 days


#4 posted 07-21-2017 05:08 PM

John Heisz did a video very recently on this subject.

https://www.youtube.com/watch?v=60NMei0TAic

View bondogaposis's profile (online now)

bondogaposis

5398 posts in 2739 days


#5 posted 07-21-2017 06:02 PM

If you don’t alternate the layers 90°, you may as well use solid wood. The biggest advantage of plywood is it’s stability. You won’t get that if you don’t alternate the layers 90°.

-- Bondo Gaposis

View Rich's profile

Rich

4478 posts in 977 days


#6 posted 07-21-2017 07:14 PM

The April, 2017 issue (#231) of Popular Woodworking had an article on making your own plywood. I’d be happy to share it with you.

-- Knowledge is not skill. Knowledge plus ten thousand times is skill. -- Shinichi Suzuki

View ArtMann's profile

ArtMann

1381 posts in 1204 days


#7 posted 07-21-2017 08:35 PM

I laminated two exterior layers of 1/4 inch cherry plywood with an interior layer of birch plywood because I needed 3/4 inch cherry plywood and already owned both cherry and birch plywood. It is difficult to clamp large pieces together with enough force to form a strong and consistent thickness sheet. My first efforts yielded interior glue gaps due to inadequate and inconsistent clamping. I would suggest several 50 pound bags of sand or something similar to press a 2 X 4 foot piece together. I finally constructed an array of 2X4 blocks that were connected and provided uniform pressure across the surface. The force (~500 pounds) was generated by a hydraulic car jack and a 4X4 from the ceiling down to the clamp table. (By the way, that is also a good way to laminate two sheets of 3/4 MDF to make a router table top). I used Titebond Original and it worked well.

All this is different from what you are wanting to do but it gives you an idea of what is required to get a reliable lamination. The job is absolutely not trivial.

View TungOil's profile

TungOil

1254 posts in 883 days


#8 posted 07-21-2017 09:47 PM

Vacuum bag! Research vacuum veneering.

-- The optimist says "the glass is half full". The pessimist says "the glass is half empty". The engineer says "the glass is twice as big as it needs to be"

View runswithscissors's profile

runswithscissors

3039 posts in 2413 days


#9 posted 07-23-2017 05:05 AM

At one time there was a (construction grade, I think) plywood with 4 layers, and the 2 inner layers were at a 45 deg. angle, not at right angles. I don’t know how well this worked out. I never used any. There is (or was) also solid core plywood. A single inner core, made up of more or less random widths, with veneer on both faces.

-- I admit to being an adrenaline junky; fortunately, I'm very easily frightened

View Loren's profile

Loren

10477 posts in 4036 days


#10 posted 07-23-2017 05:20 AM



At one time there was a (construction grade, I think) plywood with 4 layers, and the 2 inner layers were at a 45 deg. angle, not at right angles. I don t know how well this worked out. I never used any. There is (or was) also solid core plywood. A single inner core, made up of more or less random widths, with veneer on both faces.

- runswithscissors

I’ve encountered “lumbercore plywood” a few
times in old plywood pieces I was demolishing
or working on for some reason. I suppose
it’s still available but I’ve never seen it for
sale.

View cabmaker's profile

cabmaker

1745 posts in 3197 days


#11 posted 07-23-2017 11:40 AM


At one time there was a (construction grade, I think) plywood with 4 layers, and the 2 inner layers were at a 45 deg. angle, not at right angles. I don t know how well this worked out. I never used any. There is (or was) also solid core plywood. A single inner core, made up of more or less random widths, with veneer on both faces.

- runswithscissors

I ve encountered “lumbercore plywood” a few
times in old plywood pieces I was demolishing
or working on for some reason. I suppose
it s still available but I ve never seen it for
sale.

- Loren


View cabmaker's profile

cabmaker

1745 posts in 3197 days


#12 posted 07-23-2017 11:41 AM

lumber core ply is alive and well !

View WAPY's profile

WAPY

56 posts in 715 days


#13 posted 07-24-2017 02:54 PM

FarmerintheWoods,
bondogaposis’ suggestion is very correct: if you want stability you must cross the grains of layers. I can imagine you are thinking of having all layers parallel to avoid grain visibility, but it could work only if the finished piece is to be small. If this will be your choice i’d recommend inverting the fiber direction at least so that each layer goes in opposite direction of the adiacent. I do the same whenever I have to make a through body bass neck with different woods glued together, to avoid it bends up or down. Keep posting on the results buddy

-- the good woodworker feels what the tree wanted to become

View FarmerintheWoods's profile

FarmerintheWoods

36 posts in 837 days


#14 posted 07-24-2017 08:25 PM

Just to clarify a couple things: The reason I’m interested in making my own plywood is that I can put the highly figured wood on the outside, and the more regular stuff on the inside. Switching species between layers would just be a way to add coolness.

My concern about grain orientation has more to do with how the resulting plywood works with a router. I have read that lots of people have problems with ‘tearouts’ when working with plywood and a router. I’m thinking that having the grain all running (mostly) in the same direction will minimize this issue. Perhaps I’m worrying about this too much?

If plastic resin glue is most highly recommended for making plywood, are there any brands/products you recommend?

View Loren's profile

Loren

10477 posts in 4036 days


#15 posted 07-24-2017 08:31 PM

Tearout can be reduced by making template
cuts in small depth increments. To do this
you’d either have to use a template guide
collar or a pin router. Regular bearing guided
bits demand the whole depth of the cut
be taken all at once and this can cause a
lot of tearout if you’re unfortunate with
the grain, especially on curvy parts.

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