Plywood is the foundation for so many of our customers CNC related projects. It is a typer of sheathing that acquires its strength form laminating thin layers with alternating 90 degrees of grain direction. Attributes are often referred to as grade, cores, finish and thickness. Front side grading system for the face veneer is designated by letters: A is the best and D is the worst. Back side grading system: 1 is the best and 4 is the worst. A1 or A2 are common here. A1 Would have to very good sides, A2 would have one good side and one okay side.
The more layers the stronger the material and more resistant to warping. The type of adhesive used will match the plywood use case.
For example a roofing sheathing will be subjected to extreme temperatures. Plywood used for boat building need have a marine grade epoxy adhesion.
Cabinet grade plywoods must be millable. Both from traditional equipment like a table saw and with digital manufacturing equipment like the CNC.
This plywood can not have voids or pockets inside that you would find with a framing grade plywood (CDX).
The lamination adhesives can not be such that they gum up the bits, blades and end mills.
Finally finish plywood often has two good sides. Sometimes one side is a hardwood veneer such as maple, walnut of cherry, own as hardwood plywood.
Some sheet stock comes pre-finished with a clear coat and is ready to cut and go.
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Extended Plywood Article at Fine Woodworking
Understanding Plywood Grading:
|A||Plywood Standing Desk||Face and back veneers practically free from all defects|
|A/B||Flat-Pack Furniture||Face veneers practically free from all defects. Reverse veneers with only a few small knots or discolorations|
|A/BB||Workbench Cutting Table||Face as A, back side permitting jointed veneers, large knots, plugs|
|B||Both side veneers with only a few small knots or discoloration|
|B/BB||Face veneers with only a few small knots or discolorations. Reverse side permitting jointed veneers, large knots, plugs, etc|
|BB||Both sides permitting jointed veneers, large knots, plugs, etc|
|C/D||For structural plywood, this grade means that the face has knots and defects filled in and back may have some that are not filled.|
|WG||Guaranteed well glued only. All broken knots plugged|
|X||Knots, knotholes, cracks, and all other defects permitted|
|WBP||Wood Bike||Weather and Boil Proof used in Marine Ply. Designation replaced by EN 314-3|
Price Per Sheet Rough Guidance:
|49 x 97 x 0.xx||Various||Call (804) 359-1374||Wurth Wood Group|
|48 x 96 x 0.75||Maple||PRO SEL||$50.00||Northland Forest Products|
|48 x 96 x 0.75||Red Oak||A-3||$50.00||Northland Forest Products|
|48 x 96 x 0.75||CHERRY||A-3||$60.00||Northland Forest Products|