# Calibrating My Chop Saw to Make a Perpendicular Cut Using a Bit of Geometry

Quote of the Day

All heiresses are beautiful.

- John Dryden

My co-workers and I are pretty serious DIYers so we always talk about new projects and tools we're getting into. In fact, the last few weeks has consisted of us trying to find the best 90 degree drill because one of them is about to start a project that's in a lot of tight spaces. But, no matter how much we talk about them, we don't know if we're going to like the power tools when we try them out and one of my co-workers was very disappointed with his purchase of a DeWalt DW717 miter saw because it does not make a perpendicular cut. Figure 1 shows a picture of his saw.

Figure 1: DeWalt DW717 10-inch Miter Saw.

A little while ago I needed to get a miter saw for a project I was doing. I did my research and decided to choose a cordless miter saw over a corded one because then I wouldn't be restricted. This means that I have a similar saw (12-inch version) and I am very happy with mine. I thought for a moment and asked my co-worker "Have you calibrated your saw?" He told me, no and he did not know it could be calibrated. Time for a little geometry -- construction always presents me with the best classical geometry exercises.

Very few tools come from the factory accurately setup -- at least to the accuracy I expect. I regularly calibrate both the 90° and 45° settings on my miter saw. In today's post, I thought I would show how I calibrate my saw for perpendicularity (i.e. 90° cut). I will discuss how to calibrate for a 45° cut in a later post. Figure 2 illustrates my approach. I was taught this in my youth and I do not remember by whom -- my dad spent all day at a saw cutting wood with a DeWalt saw and I think he might have taught me. He loved DeWalt and I think of him every time I use a DeWalt product.

Figure 2: My 90° Calibration Process.

My co-worker went home and proceeded to tune up his saw nicely. He is now a happy woodworker.

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