Take the time to read these wood working tips before you go to the lumberyard to buy plywood. You will save yourself from a lot of aggravation!
Plywood is a great material for the free wood furniture plans you will find on our site, because:
it is flat and more stable than solid wood;
it saves time and money;
it is structurally stronger than wood;
it holds screws well;
it is relatively inexpensive; and
it is readily available.
A nice section of plywood was chosen for this Kreg pocket hole wall cabinet.
Some plywood has a face made from softwoods, such as pine and fir. This plywood is generally used for structural material. Other plywood has a hardwood face, made from wood such as cherry, maple, oak or walmut. It is the appearance of the hardwood face that the woodworker is after.
Plywoood is graded using several scales.
The first aspect of plywood that is graded is the face - that side of the plywood that would be exposed in your project.
The best grade for a face is "AA", and the quality goes down to "E", which could have lots of patches and significant variations in color.
Sometimes both the front and back veneers will be given an "A" to "E" grade. So you may find plywood graded as "AC", with the "A" being the face, and the "C" being the back.
This plywood has 5 layers or plys. The 'back' side had the knot, which was put inside the cabinet. The 'face' side went on the outside.
The back veneer on a sheet of plywood is usually graded with a numeral. The best back would be a "1", and then goes down to "4", which could have a whole hose of defects.
The inner core of the plywood also receives a grade. The best core is graded "J", while the worst is graded "M". The goal is to have a core that is free of empty spaces, called voids, in the interior layers of the plywood.
If you look at the edges of a sheet of plywood and see lots of voids, you can be sure there will be many voids in the middle of the sheet as well.
Check out the 5 ply used on this wall cabinet. It is free of voids on the edges we cut.
The next factor is the thickness of the face veneer. The face veneer on cheap plywood can be almost paper thin - just 1/100 of an inch. There is no room for error. If you sand out light pencil marks, you could easily be sanding the face veneer away.
The better plywood as face veneer that is approximately 1/40 of an inch thick. You still have to take care when sanding - i.e. don't use a belt sander, but there is room for sanding away small problems.
The last factor is the thickness of the plywood. Plywood is rarely as thick as the measurement on the label. The thickness can vary from manufacturer to manufacturer; from sheet to sheet; and within a sheet. Carry a tape measure with you to check for yourself how thick it is.
This plywood measured 3/4 inch. We used a little wood filler to fix a spot. This piece will be painted, not stained.
A 3/4" sheet is usually 23/32". The 1/2" sheet is only 15/32". And a 1/4" thick sheet is really 7/32".
These lower thicknesses can be crucial differences for the accurate fit of your pieces when you assemble your project.
Kreg small bookcase
our first face frame was 1/4" too wide, because the 3/4" plywood was thinner than the plan called for. We had to take the face frame apart, cut and drill shorter rails, before we could assemble it right.