LumberJocks

Is wood movement affected by thickness?

  • Advertise with us

« back to Designing Woodworking Projects forum

Forum topic by ChiefDJ posted 06-27-2018 03:39 PM 721 views 0 times favorited 11 replies Add to Favorites Watch
View ChiefDJ's profile

ChiefDJ

11 posts in 1340 days


06-27-2018 03:39 PM

Since I started woodworking as a hobby my wife has come up with all sorts of requests that she wants me to build.

Her latest is that she wants a chest with Japanese marquetry designs on the top.

Heres a picture of the type of design shes looking for:

It may look like a nightmare but the designs are surprisingly not that difficult to create – even for someone with limited skill and experience as myself – and I enjoy fiddly things like this.

In Japan these designs are made in blocks and they shave very thin strips off and use it as a veneer.

I dont have the equipment or skill in handtools to do something so delicate so my thought was to cut the patterns into 1/8” or 1/16” blocks and glue them to 1/4” plywood or mdf (that would then float over the 3/4 cedar of the lid).

But then I began worrying about wood movement. The idea was to have a 16” x 24” section of this pattern.

How much movement can I expect out of a 1/8 or 1/16 thick piece of hundreds of triangles glued together over that large of an with grain going in all different directions?


11 replies so far

View ChiefDJ's profile

ChiefDJ

11 posts in 1340 days


#1 posted 06-27-2018 03:41 PM

H

View Aj2's profile

Aj2

2321 posts in 2217 days


#2 posted 06-27-2018 04:55 PM

I think I understand what your thinking of doing. And my experience is that veneers 1/8 or less can be glued down to plywood and bypass wood movement.
Are you familiar with hide glue or Old brown.?

-- Aj

View ChiefDJ's profile

ChiefDJ

11 posts in 1340 days


#3 posted 06-27-2018 05:06 PM

Thanks for the response.

No Im not familiar with those. Still a newbie.

View Aj2's profile

Aj2

2321 posts in 2217 days


#4 posted 06-27-2018 05:42 PM

I’m thinking old brown glue might be a good choice for your project.
It has a long open time, it’s reversible and will not add water to your pieces.
Maybe keep it in mind as a back up if your have problems with regular PVA glue.
Good luck sounds fun:)

-- Aj

View theart's profile

theart

106 posts in 973 days


#5 posted 06-27-2018 05:57 PM

Movement is independent of thickness, though it will occur more slowly with a thicker piece. The force generated by swelling or shrinkage, however, is going to scale with cross sectional area.That’s why thin veneers can be glued down to plywood, as suggested above. When a thin veneer tries to swell or shrink, it can’t generate enough force to exceed the shear strength of the glue.

With a pattern like the ones you linked to though, each piece is also constrained by the ones around it. I wouldn’t expect total movement to be too bad at any thickness.

View splintergroup's profile

splintergroup

2728 posts in 1641 days


#6 posted 06-27-2018 06:38 PM

Alternatively you can glue up your pattern (as thin as you feel comfortable working with) and then reduce its thickness by sanding or scraping.

You do need to get it reasonably thin to avoid expansion problems when glued to another substrate (warping is most likely to happen). You could also keep it thick and make a frame around the edges (allowing your design to “float” inside the frame).

View Rich's profile

Rich

4555 posts in 1008 days


#7 posted 06-27-2018 09:09 PM

No need to worry about the veneer moving. Regarding technique, if you watch the marquetry guys, they often work on an assembly board. That’s simply craft paper stretched over, but not glued to, a flat board. They create the pattern using veneer upside down, that is, the surface that will show on the final piece is face down on the paper.

By using hide glue, when the piece is complete, they are able to cut the craft paper away and glue the pattern to the final surface, paper side up, and then use warm water to wash off the paper and hide glue. It’s truly amazing to watch the pros do it.

Here are some Patrick Edwards videos that might help. https://www.youtube.com/user/3815utah/videos

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

View ChiefDJ's profile

ChiefDJ

11 posts in 1340 days


#8 posted 06-28-2018 01:19 PM

Aj2 said:
”I’m thinking old brown glue might be a good choice for your project.
It has a long open time, it’s reversible and will not add water to your pieces.”

I hadnt considered issues due to adding moisture through the glue I used. Would you also avoid water based finishes for the same reason?

I had intended to finish with a water-based poly because it seems to not dull the colors as bad, but should I consider something else so no more moisture is introduced?

View ChiefDJ's profile

ChiefDJ

11 posts in 1340 days


#9 posted 06-28-2018 01:28 PM

theart said:
”With a pattern like the ones you linked to though, each piece is also constrained by the ones around it. I wouldn’t expect total movement to be too bad at any thickness.”

Thanks for the response. That was one thing I wasnt sure about. Since they will essentially be little tiles glued together with some grain going north/south and other grain going east/west, I wasnt sure if that was going to cause some tiles to pop out from the pressure or if they would sort of cancel each other out. What you said about the shear strength of the glue makes a lot of sense though.

Ive read that a lot of people put backer veneers on the other side of their substrate material to cancel out the warping. Do you think this is necessary or even practical since we cant really say which way it will warp?

View Robert's profile

Robert

3436 posts in 1899 days


#10 posted 06-28-2018 02:36 PM

Won’t be an issue so long as the veneer is dry and acclimated.

Ply or MDF are fine. Yes, use a backer especially important on thinner ply.

As rich said, assemble the sheet upside down edge glue pieces and tape.

Then glue entire sheet down at once.

I don’t think the type of glue matters that much. If you do it as a sheet, you will need to plan ahead as how you will clamp.

-- Everything is a prototype thats why its one of a kind!!

View TungOil's profile

TungOil

1273 posts in 914 days


#11 posted 06-30-2018 11:27 PM

You might want to PM Shipwright, he is one of the most knowledgable regarding veneering and marquetry here on the forums.

-- 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"

Have your say...

You must be signed in to reply.

DISCLAIMER: Any posts on LJ are posted by individuals acting in their own right and do not necessarily reflect the views of LJ. LJ will not be held liable for the actions of any user.

Latest Projects | Latest Blog Entries | Latest Forum Topics

HomeRefurbers.com