We were puzzled by the little belted-together blocks that were stuck between pieces of plywood alongside Bruce’s lumber rack, and received eye-opening instruction.
“Plywood or other sheet stock can warp, especially if it’s stored surface to surface. The blocks separate the sheets so air can circulate on both sides. Flat sheets from the lumberyard stay flat this way, no matter how long they’re stored,” Bruce said.
The leather is flexible, so you can use them on any combination of thicknesses of sheet goods.
The blocks are a snap to make from scrap wood and leather. Cut two 1-in.-wide strips of leather (or vinyl or heavy cloth) and space and screw 2-in. x 3/4-in. x 1-in. blocks along the strap.
“The air space also keeps them a lot easier to grab when you need to pull one out. For full sheets, use three sets of spacers, one at each end and one in the middle.”
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Veneer core is made up of many layers of hardwood bonded together. The layers are assembled with alternating grain direction, called cross banding. This makes a strong, rigid, lightweight sheet with excellent screw holding capability. Because of these qualities, veneer core is my first choice in most cases.
Check out these 16 Tips to Get the Best Plywood for Your Buck.
MDF core has a few advantages over veneer core. The thickness is more consistent, and MDF gives a smooth, even surface for the face veneer. It’s also more stable and it’s typically flatter. However, MDF core isn’t as strong as veneer core, it doesn’t hold fasteners as well and it’s heavy. But if I’m making one-piece doors, I’ll choose MDF core every time because of its flatness and stability.
We take the mystery out of the plywood grading system and show you what you will get in each grade. The higher the grade the better quality you should expect.
Particleboard Core is the least expensive option. Like MDF core, it’s flat and stable with consistent thickness. But particleboard core options are a bit worse in the screw holding category. Also, it’s a special-order product, at least from my lumberyard, whereas MDF core is readily available.
Combination Core weds the best attributes of MDF core and veneer core. The center cores are cross banded hardwood, providing strength, light weight and screw-holding capability. The outer cores are MDF, giving a flat, uniform surface for the face veneers. However, combination core is a compromise: It doesn’t have the screw-holding capability and rigidity of veneer core, or the flatness and stability of MDF core.
The Family Handyman DIY expert, Spike Carlsen, will show you how to cut construction grade plywood and finish grade plywood with a circular saw.
Lumber Core consists of edge-glued strips of wood, usually basswood. On both sides of the core, there’s a cross banded veneer, then the face veneer. Like veneer core, it has excellent screw holding capability, strength and rigidity. But it’s considerably more expensive and harder to find than veneer core, so I almost never use it. However, it’s a good choice for long shelves.
Baltic Birch and Appleply
Baltic Birch and Appleply are top-notch veneer core plywoods, which you’ll only find at a lumberyard. Their 1/16-in.-thick core options veneer offer better stability than typical plywood with 1/8-in.-thick core veneers. The raw edge is attractive when finished and often used as a design element. Baltic birch or ApplePly is my first choice for drawers and shop jigs. ApplePly is available in thicknesses from 1/4 in. to 1-1/2 in., and in many face veneer species.
Check out our guide to Plywood Veneer: This is Why the Cut Matters.