Gluing Pine to Ply to make thicker lumber
eagerbeaver71
| Posted in General Discussion on
Hi Folks,
New subscriber here from Australia. I need to make some rails and stiles, I got some 7mm plywood and 12mm pine to make up 19 x 65 x 750mm.
Will I have any issue with wood movement of the pine?.
Replies
Not something I would recommend.
Can I ask why you feel you need wood thicker than 19mm(3/4")? That is the most common cabinet door thickness used here in NA and the thickness most door making router bit sets are made to accommodate.
I don't have any solid Red/White oak for the door R&S, so I thought maybe I could just make some up using offcuts from the 7mm panels I have and glue them to some solid wood to make up 19mm
“[Deleted]”
Excuse me I missed the part about the pine being only 12mm I only saw the 19mm and assumed that was the pine. It pays to read more closely.
Either way I would not laminate plywood and solid wood like that. Aesthetically it won't look good and even with narrow rails and stiles there could be enough wood movement to cause issues in what I imagine, is an environment prone to wide humidity swings. I will add, I have never tried it or known anyone who has, so my opinion is based purely on approaching 50 years of experience and what I have come to know as being good practices.
If you are making doors or something similar, you could laminate the pine for rails and stiles and use the ply for panels. That would work just fine.
I think that because most rails and stiles are so narrow, seasonal movement would not be an issue with gluing the pine and ply together, but if aesthetics is a concern, I wouldn't do it. It would be somewhat like building a car out of parts from several makes.
Plywood tends to be more rigid in one direction. If you try this, I suggest that you orient your strips in the most rigid direction. Even then, it might not be as stiff as a solid piece of wood. Test it and let us know how it works out.
Most plywood is more apt to bow over time as well.
I would laminate the pine if I couldn't get thicker stock. But really, I would definitely just get some 19mm pine.
I understand he wants an oak face, I don’t see a problem glueing a quarter inch plywood over a half inch solid wood dry substrate for such narrow stock other than the look of the edges.
The plywood will shrink and swell more than the pine along the grain creating a bimetallic strip effect.
I would keep any lamination symmetric. Ply-pine-ply or Pine-Ply pine. I know that doesn't get you to 19 mm, but it is a good general rule. The longer the part, the more important this is.
Look at plywood as an example. The grain direction alternates between layers for an odd number of plys. If there are four plys, the inner two plys are parallel with the outer layer at a right angle.
It'll be fine.
The width of the parts is sufficiently small that wood movement will be utterly trivial and easily accommodated within the thickness of the pine.
It's not ideal though, and you have to ask if the additional effort and cost involved in doing the lamination, combined with the chance of screw-ups is worth it to save buying a bit more lumber, though of course that very much depends on how far you have to drive to the store.
If making doors with a ply panel, I would simply create a rigid frame with the pine and glue it to the panel that is to be the door, cut to be exactly the size of your frame outer dimension. This will look almost like a proper panel door, and if painted will look quite good. Only the closest inspection would reveal the subterfuge.
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