Sawdust on the Floor

I was in one of the big home DIY stores the other day, and over heard the following conversation between a husband and wife. They were looking at paint grade door molding, and from what I over heard it was molding for just one standard door. So basically the guy should have been buying a couple of 84” pieces for the sides and maybe a 36” piece for the top molding. But the guy had selected three 12’ pieces of trim on his cart. When his wife questioned why he had selected so much trim, his response was, “I need a lot of extra, because I make a lot of mistakes on the angles, actually I am not sure I have enough”

I can sympathize with this guy’s plight, however purchasing 200 % of the amount of trim needed is a bit extreme. A little extra is prudent but this was excessive. So, where did these poor guys concerns come from? I can answer that with just one word, assumptions.

The first place we make an assumption is with our miter saw.  When you cut trim, you will normally move the blade to either the right or left 45 Degree stops, and then we cut the wood. How do we know that the stops are at the right angle? Did you check if the stop is set correctly, or did you just ASSUME that the manufacturer made it right? To verify that stops are set correctly, simply take two pieces of stock that are the same width. Cut the first piece, with the saw  at either the right or left stop. Without moving the stop, cut a second piece of wood. Now if you were to take these two pieces and put them together at the angles, you should get a perfect 90 Degree angle. One of the easiest ways to verify this is to then place both pieces along the inside of a framing square. If the joint is tight, and there is no room along the sides then your stops are set correctly. The longer the trial pieces are, the more accurately you can judge the fit. If the pieces don’t fit together correctly, make an adjustment to your saw’s 45 Degree stop. Once you have made this adjustment, move to the other stop and make the same checks. One other thing along this line, all of these adjustments are made with the assumption that the blade is at a 90 degree angle to the table. Use a square or digital protractor to verify that the angle is correct. If you have a compound miter saw, check that the vertical zero stop is set correctly.

The second assumption that we make is the side Jam and top jams are always at a 90 degree angle. I don’t know of any door that is 100% square. A small error shouldn’t be a problem, if the door is truly out of square, then the angle of the miter should be adjusted. Either check the angle with a known good framing square. Hold it up and into the corner, does it fit completely into the corner, is there any space along the sides. Or if you have access to a digital protractor, use it to verify the angle. Just don’t assume that the angle is 45 degrees.

The third assumption is that the side jam(s) are totally plumb. Here is where we get into trouble, everyone always tells us that the reveal (the amount of the jam is revealed) must be even top to bottom. So, if the jam is not plumb, and we install the trim with an even reveal top to bottom, then the trim will be out of plumb. The result will be an open miter joint.

So where does this leave us? The first is let’s stop assuming anything about the door, check and verify that it is in fact plumb and square. If not can you make it so? Consider the use of shims to bring it back in. If you are unable to square it up, then install the trim with the correct reveal, and adjust the angle of the miter. The time spent checking the door and your saw before you ever start cutting can save you a lot of time and trouble in the end. And unlike our friend from the DIY store, you can actually buy the correct amount of wood.

The attached picture may help you understand the components of the typical door frame

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