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How to Use a Speed Square

Ask This Old House general contractor Tom Silva demonstrates the amazing versatility of the humble rafter square

In this video, Ask This Old House general contractor Tom Silva demonstrates the amazing versatility of the humble rafter square.

Steps:
1. A Speed Square, also called a rafter square or layout square, has a 90-degree marking edge and a 45-degree marking edge.
2. The square can be used as a straightedge guide when crosscutting with a circular saw.
3. A pivot point allows the square to be used as a protractor for marking angled lines.
4. The square is ideally suited for laying stud locations for walls.
5. Built into the square are several scribing notches, which provide a fast, easy way to mark layout lines or cutlines onto lumber.
6. The perfect 90-degree corner of the Speed Square can be used to determine whether two boards form a precise right angle.
7. To keep the square close at hand, hang it on your tool belt with a hook or get a specially designed Speed Square pouch.
8. You can also custom-make your own Speed Square holder from a PVC baluster.
9. Cut the baluster to length on a miter saw, then cut a stopped slot along one side with a table saw or router.
10. Cut a ¾-inch-thick plywood strip to fit inside the PVC holder, and secure it with short screws.
11. Attach a metal belt clip to the opposite side of the holder.
12. Clip the holder onto your tool belt, then slide the Speed Square into the slot.

 
 

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