Dec. 2008 Tips and Tricks

[thelittleboxshop]

I looked over the Dec. tips and tricks newsletter written by Doc Wheeler. Doc explains this process of replacing different woods into "cutouts" made in the base wood with plugs of different woods. First off...why? You could do the same thing by carving out the recesses and insetting the other wood carvings into the recess later. I would not do this unless the base piece had been sealed VERY well first. Secondly, Doc advocates gluing grain in different directions! If this thing is not sealed and in an environment where moisture level is constant...you are going to end up with kindling in a year or two. Wood moves all the time and what Doc is advocating is a no no from woodworking 101. I think a lot of people are going to be very disappointed if they follow this procedure. As an example, Doc has made a plaque of with horses wherein he incorporates this procedure. He has the bulk of the plaque with grain running east and west but then incorporates a different wood with grain running north and south. Wood is not a canvas, there are "rules" that must be adhered to if you expect your projects to last. Just a thought. It looks very nice, BUT......

[brdad]

Regarding the second comment, if gluing wood in opposite directions is a no-no, explain plywood!

There are many things in building that you can't or shouldn't do as a rule. That doesn't mean it can't be done and be perfectly acceptable. We're talking about thin stock and relatively small pieces (especially compared to a full sheet of plywood). The difference between how one piece of wood can expand radially compared to the piece it is attached to expanding tangentially is very minute and not enough to overcome the strength of the glue.

For example, consider 5" squares of white ash and red maple, and a change of relative humidity from 20% to 40%. The white ash will expand .03 inches with the grain and .05 perpendicular, while the red maple expands .02 inches with the grain and .05 perpendicular. So that accounts for a maximum of .03 inches difference in expansion, just under 1/32 of an inch. If you want to get real technical, you'd have to figure in the strength, expansion, and elasticity of the glue as well.

I am sure you could find woods that would agree less, but I think you'd be safe most of the time.

Numbers calculated from The Shrinkulator.

[pine acres woodshop]

Theres nothing wrong with running the grain in different directions, It's done all the time with great results. Have you ever heard of plywood, each successive layer the grain is placed perpendicular to the last, very strong, lasts a long time.
When you veneer a table top you do the same thing, if you use more than one layer of veneer you use the same principle, each successive layer is placed perpendicular to the last.
Have you ever looked inside an acoustic guitar at the bracing, the grain is running in all different directions, look at the bridge plate, it is of a different wood and running perpendicular to the grain of the top, and these pieces of wood are only 1/8" of an inch thick, so I don't see a problem with his method.
I personaly like his idea of routing a recess then placing the different wood in the recess, and then routing his project, If you routed each one separate, that would waste alot of wood. If your concerned about moisture you could seal your project with a marine varnish. I say carve away, let the wood be your canvas, Thumbs up Doc.


Mark

[thelittleboxshop]

Solid wood IS NOT plywood! By gluing NUMEROUS thin strips of wood in alternating directions layer by layer, plywood is much less likely to expand or shrink based on moisture in the environment, and the alternating construction creates a board that is much stronger in each direction than a similarly sized board cut from a single tree.
Most plywood is made from an odd number of layers, called plies (typically 3, 5 or 7), with an equal number of plies on each side of the center ply. In this manner, the surface plies are always parallel, and the grain of the surface plies usually follows the longest side of the sheet (although not always). The sheet is strongest parallel with (as opposed to against) the two surface plies.

Knock yourselves out! I have been woodworking for 20 years and have seen a lot of projects fail because of this technique. The stable way to do a project such as this is to you an engineered (stable) substrate and glue your pieces to that (intarsia).

[mtylerfl]

...I have been woodworking for 20 years and have seen a lot of projects fail because of this technique. The stable way to do a project such as this is to you an engineered (stable) substrate and glue your pieces to that (intarsia).

Hello Rollie,

Thank you for sharing your expertise with us.

The technique of the multi-layered wood is beautiful, and of course we want it to be stable for the long-term as well.

I also like the "look" of a dark/light layered design that is carved all at once so that the two layers blend/fade into each other. A look that would be difficult to achieve by simply using separate onlays.

Based on your own experience, how can potential problems be avoided while at the same time allow for the use of, for example, a maple and walnut layered glue-up that could be carved all at once in the machine?

Thanks in advance for your help.

[thelittleboxshop]

Michael;

If folks want to use this technique...I would advocate using 2 part epoxy to set the different wood pieces in the cutouts instead of wood glue. This would allow more flexibility in any movement that may take place. The difficulty arises when the base piece experiences movement. Because the horse pieces are so thin, the lateral movement of the base piece will be more than a match for the thin cutouts which may crack laterally because of the rigidity of the glue. By using an epoxy, you would allow these different wood pieces to move ever so slightly with expansion and contraction.

I did not mean to disparage Doc or his technique...I just have been working with wood long enough to recognize potential problems that may present themselves over time.

[mtylerfl]

Rollie,

That's great news. I think the 2-part epoxy is an excellent recommendation - makes sense that it would allow/tolerate possible movement.

I'll remember that tip! Thanks again for your advice.

I didn't take your previous posts as disparaging in any way towards Doc or the technique - we appreciate anything that will enhance or improve our success with our precious projects!

[DocWheeler]

Rollie,

Your concern about the structural integrity of two pieces of wood glued together at an angle is well founded and I should have pointed out the danger involved. My concern for brevity (which was difficult since I tend to ramble) caused me to not include that. My 1/4" walnut material was only 3.5" wide so I did it that way to avoid a glue joint and I thought the grain going that way would look better - oh well.

The oak base material is going to overwhelm any thin material glued to it no matter what. If I recall, the only mention that I made on that subject was to seal the project well to limit moisture increasing the movement of the materials.

Your thoughts about using epoxy to give some resilience to the joint is a good idea.

I have included a picture of a project that I created in woodworking 101 some 55 years ago that shows what happens to wood dimensions over time. This was glued with hide glue - I still remember the the smell of the glue-pot.
Note the edges where the maple shrunk less than the walnut.

[Amonaug]

I was going to ask and point out, how does applying a laquer finish for example affect expansion? Wouldn't that in fact reduce moisture absorbsion?

[twinpeaksenterprises, LLC]

I think the December tips and tricks was great and Doc Wheeler did an excellent job as he always has. I think the project that was shown was an example that can be expanded or tweaked, mostly it shows another great capability of the CW. I have seen alot of professional woodworking that in my opinion would work better "my way" or a different way.
Thelittleboxshop- That is good information, i never would of thought of that, you seem very experienced and knowledgeable. Look forward to your future insights.