Replies

1. 
   GLASTARZA | Dec 12, 2008 12:23am | #1

   Trimaran,

   Thanks for your question.

   I am forwarding it to John White.

   Sincerely,

   Gerald

2. 
   JohnWW | Dec 16, 2008 06:03pm | #2

   With a few exceptions it makes little or no difference whether you use maple, oak or any other type of plywood for your projects. The named wood in the plywood only refers to the paper thin outer veneer layer that you see, the core layers are almost always made from some less expensive secondary wood like poplar or luan mahogany.

   It is the core that counts in terms of stability and and screw holding strength, the face veneers have no effect. Cores come in various qualities and can range from superb to abysmal. In the last few years a lot of cheap, but very low quality, "cabinet grade" plywood has been imported from China. This imported plywood is all but useless for even low end projects since it delaminates, warps, and occasionally contains blade wrecking metal debris buried in the plies.

   North American cabinet grade plywoods are generally of good quality and serve well for shop projects and jigs. Much of the price of cabinet grade plywood, and it can be very expensive, is determined by the quality of the face veneers, less expensive shop grade plywood usually has unattractive grain patterns or off colored face veneers but is perfectly usable.

   One plywood stands apart from the pack, this is what is generally referred to as Baltic Birch or Finn ply. This is a plywood made in northern Europe or Russia that contains many thin layers of all birch plies, 3/4" thick has 13 plies. Especially for jigs and shop machinery like router tables it is one of the best sheet materials to use. Again beware of Asian versions.

   Issue #198 of FWW has an article about phenolic plywood. Phenolic is basically a good grade of plywood where the outer faces are coated with a thin layer of a colored paper impregnated with phenolic resin which is a very tough wear resistant coating. It is also quite expensive and you can almost always substitute less expensive sheet goods for it.

   The one caveat is that plywood holds screws quite well, if you substitute melamine faced particle board or MDF, neither of which hold a screw as well, for plywood, you will have to change some of the joinery and hardware to make the finished piece as strong as a plywood cabinet or jig.

   Also MDF and particle board expand and contract with changes in humidity, plywood doesn't, so a jig that needs to be very precise is best made with plywood.

   John White