51 - Band Saw Upgrade, страница 11
TIPS FROM OUR
H The problem with assembling a large project is it's hard to keep it from racking after you add the glue and then try to screw it together.
As shown in the drawing at right, I solved this problem by making several plywood "clamping squares" that resemble a framing square.
When clamped in place, they square up the cabinet and hold the pieces in position.
Miter Joint Corner Clamp
a It's a challenge gluing miter joints. There just isn't an easy way to clamp them together. The store-bought clamps I've tried in the past didn't always pull the joint together. So I came up with a shop-built corner clamp that uses wedges to push (or press) the mitered pieces together.
Looking at the photo and drawing
below, you can see that this corner clamp uses a piece of plywood for a base. Then a square block and two cleats are glued and screwed on top.
What's important here is that the inside corner of the square block is exactly 90°. Then align the inside edge of each cleat parallel with the inside edges of the block.
A pair of wedges sized to fit between the workpiece and the cleat does all the work. They apply pressure in two directions at the same time. When the inside wedge (the one contacting the mitered piece) is tapped forward, it pushes the joint tighter together and firmly holds the pieces in place while the glue dries.
□ Another way to square up a case is shown in the drawing at right. This method uses an insert made from a scrap of plywood that's sized to fit the inside of the case. To provide room for glue squeeze-out, I trimmed each corner of the insert at an angle.
To help hold the insert in place while you add the clamps, screw a pair of cleats across the top of the insert. After setting the insert in place, tightening the clamps squares the box around the insert.
squares are made from w-thick plywood
inside corners to hold pieces in position
(%"-thick hardwood 3" long, make 4)
base, block and cleats are %" plywood
wedges vary in width according to width of workpiece
tightening clamps squares cabinet around insert
for glue squeeze-out