Extending cherry stock with MDF

Ken Close

Member
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69
I have about 200 bf of cherry in the basement and as I am considering various projects to use it on, the following thought came to me...yet I need some experienced reactions before proceeding.

Instead of machining up 3/4 boards of cherry could I not take a 1/2 MDF and laminate a 1/4(+) resaw of the cherry to it? Edge treatments would obviously have to be taken into account in the design, but what about non-obvious concerns with this approach:
- what about the cherry expansion/shrinkage? you must glue it over the entire surface, yes?

- what about joinery? Perhaps the laminate would only be used for "large area" pieces (such as tops and side panels), with narrower pieces being full cherry.

- what other considerations might apply?

I assume this is a time honored technique, but I have never attempted it, and so far some searches have gotten me a lot of furniture sites with ads but no "how-tos".

Thanks for any ideas.
Ken
 
MDF core plywood is similar to what you describe, with a couple of significant differences. The major thing is that you'll notice there is veneer on both sides of the MDF. When it's balanced this way, a little expansion or contraction in one material compared to the other does not cause the whole thing to cup. The other difference is that veneer is quite thin, and its tendency to shrink and swell can be overcome without too much force. A full 1/4" might be a much bigger problem.

You can find the sort of composite you mention in some engineered flooring, where the bottom 1/2" is plywood, and the top 1/4" is solid wood. These tend to be narrow boards with the grain running lengthwise, so the expansion and contraction will be almost exclusively sideways, causing only slight cupping.

If you want to try this, you could resaw some veneer at maybe 1/8", and put some on each face of the MDF. The veneer on the back obviously does not need to be as nice as that on the front. If there is a significant structure holding it flat, you might get away with covering only one face.
 
Ken,

I agree with Alan, put veneer on both sides, the side that doesn't show can be any inexpensive hardwood such as maple. You should be able to use veneer on MDF without any problems. I believe that I read somewhere that MDF makes a great substrate for veneer work because it is of consistent thickness.

You might want to consider that it is still MDF even if you put veneer on both sides. For example, I'm in the process of finishing up an aquarium stand that I put veneer on to make the quilted maple go farther. I thought about using MDF for the substrate, but decided that and aquarium with water, and the inevitable spills would cause the MDF to fail. So, in that application, I went with plywood as the substrate. I was also concerned about the strength of MDF in supporting the weight.
 
This is a case where thinner is better. "Standard" veneer is 1/42 inch thick, and works because expansion is forced to vertical rather than sideways... no splitting. But as you get thicker "veneer" it may delaminate or cause the piece to split. I consider 1/16 inch a "thick" veneer.

I love to put a thin layer of pretty walnut (or whatever) on a blah piece... since they are similar wood, I don't bother with veneer on the back. No problems (yet) but my target is about 1/32" thick shop cut veneer.
 
I think the solution would be to just use 1/2" baltic birch as the substrate. There is enough variance in the wood direction that the cupping gnomes will leave it alone. I think for furniture pieces no wider than 20", this will be a great solution. If you are building a table top then I would use the same amount of wood on the bottom as used for the top to ballance out the force accross the core. In this case MDF would work fine.

Mike
 
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