Miter saw gauges confuse a lot of finish carpenters for one simple reason—they aren’t designed for finish carpentry, they’re designed for framing and stairs. Let me show you what I mean.
When a framer builds a roof, they first establish the PITCH of the roof—4/12 or 6/12. That pitch is the angle the rafters follow. All of the cuts made to that rafter—the ridge cut, the plumb cut, and the birdsmouth are all measured off the BACK of the rafter—off 90 degrees to the angle of the roof.
That’s why most miter saw gauges are set up off 90 degrees to the back of the fence! In fact, some miter saws even include roof pitch angles on the miter saw gauge.
But the angles on a miter saw gauge are off 90 degrees to the angles on a protractor, which causes a lot of confusion. Some carpenters opt to use a Starrett Protractor. But I prefer to have the guys on my crew use a standard protractor, so they’ll know at a glance the difference between an acute angle and an obtuse angle. That means when they visualize the miter, they’ll be starting off on the right foot!
|Miter saws didn’t always come with miter saw gauges that were set 90 degrees off from protractors. Back before framers used miter saws, finish carpenters could use a protractor to read corner angles without any confusion.
Miter saw gauges like this one (see photo, right) were easy for finish carpenters to use, and didn’t cause another problem: Let’s say you’re installing base molding at a corner that measures 86 degrees. You first bisect the angle and determine that the miter should be 43 degrees. But when you set your saw at 43 degrees and cut the piece, the miter is NOWHERE near close! That’s because 43 degrees on a standard power miter saw gauge is really 47 degrees.
The easiest way to solve this whole problem is to use a Sharpie to mark your miter saw gauge with protractor numbers.
In fact, some manufacturers include protractor angles on power miter saws:
I just wish they all did!!!
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Jesper Cook was born in Stockholm, Sweden in 1977. He grew up in family homes in both Sweden and Denmark until the age of 18, when he moved to Los Angeles, CA. He has worked in the construction trade for over 10 years, gaining experience in everything from movie sets to tile installation.
More recently, he has focused on high-end finish carpentry. He is currently a Project Manager at Millworks By Design, a finish carpentry company located in Agoura Hills, CA.
Jesper enjoys SCUBA diving, mountain biking, and especially photography, which he practices in his free time. Recently married, he and his wife, Julia, spend their vacations traveling Europe and visiting castles, museums, and other historical sites. He often draws inspiration for his finish carpentry work from classical architectural details that he has photographed in cities throughout Europe, such as Paris, Rome, and Seville.