Chair Rail Mitering

[Rick Orwig]

I need some advice on how to miter chair rail that transistions from running parallel to the floor to, for example, 30 degrees up a stair case. If I only take a 30 degree cut on one piece the two pieces will not be the same length where they marry. Is this correct and what is the best way to do this? Thanks for any advice.

 

[Monty]

I would cut 15° from each piece, but I would try a test piece first with some scrap (to make sure the angle is right). To determine the angle, lay a long board on the stairs across at least two steps, and another board or bevel gauge on the floor at the bottom or on the landing. Once you have that angle, divide it in half to set your miter saw. Lay your test pieces out the same way you did your marking boards to test the fit.

 

[Gotcha6]

A sine block is helpful. Cut a triangle of wood by standing on the steps a square piece of wood longer & taller than the rise & run & scribe from tread nose to nose. This will give you the stair pitch. The complimentary angles to the right angle can then be calculated and/or divided for the proper angle. This method also helps if you are doing a transition to a radiused rail. It won't work if your steps are uneven in rise & run.

 

[Gofor]

One way to do it if you do not have a protractor to accurately measure the angle:

Lay a straight board along the top or bottom on your horizontal chair rail and extend it to the steps.(you can use a piece of the chair rail molding if need be). (Also, if working by yourself and you are sure the existing molding is parallel to the floor, you can lay it on the floor)
Run another against the wall laying on top of the steps so the two intersect or at least meet
Tape a piece of paper to the wall behind the intersection
Trace the top edge of both boards on the paper
Using a square (carpenters square, squared off piece of scrap, or anything that is a 90 degree angle) draw a line perpendicular to each top edge at the same distance back from the intersection on both boards. Its best if the distance back from the intersection is a least equal to the width of the molding.
Extend the perpendicular lines on the piece of paper until they intersect.
Using a straight edge, draw a line between this intersection and the one formed by the top edge of the boards. This is the angle line you want to cut.

This will split the angle exactly in half. If you cut or fold the paper on either of the lines from the top of the board and lay this against your miter saw fence, the last line drawn is what you set the miter angle of the blade to. If you are using a table saw, set the cut /folded edge against the miter guage and adjust it so the blade is parallel to the angle line.

When cutting, realize the angles will be opposite for each board, (ie, the angle will go to the left from the top edge on the right board and to the right from the top edge on the left board. In other words, the long end will be on the bottom after you cut it for the bottom of the stairs, and on the top edge for the top of the stairs.)
On a dual miter saw, you cut one board with the blade angled left and the other board with the blade angled right, keeping the same edge (either top or bottom) of the molding against the fence.
On the table saw, you will cut one board with the miter guage on the left of the blade and the other with the miter guage reset to the opposite angle and in the right miter slot.

Hope this is not too confusing. Best to try it with a couple of pieces of scrap first to get the angle perfect and to work out any confusion as to which way to set the boards against the fence or miter guage. Getting a nice fitting miter joint takes a little practice and patience, so try not to get into a hurry. Stairs are built by "rise" and "run" or "riser " and "tread" specs, and are built considering the structure of the building and to meet the local codes. Rarely will this result in a nice easily divided angle such as 30 degrees, 45 degrees, etc. Each set will be a little different, so splitting the angle that really exists is the key to getting it to look good.

Go

 

[Jim Murphy]

For everybody whose eyes rolled when teacher mentioned trigonometry or tangent, wake up and smell the wood. The tangent is your friend, and learning how to use it properly may be as worthwhile as learning how to accomplish a manual skill.
Since you're reading this website, you have a computer. If you have a computer, chances are you have a calculator in the utilities. Start -> Programs -> Accessories -> Calculator if you're using Mr. Gates software. To determine any angle from horizontal, use a level and tape measure. A known length level makes it easy. For example, assume you have a 2' level.
Place one end of the level against the uphill slope and center the bubble. With the tape, measure the distance from the other end to the slope. The level length is the "run", the taped distance is the "rise". The tangent is rise over run (don't be thinking about recess just yet, stay with me). If you use the calculator to DIVIDE the RISE by the RUN, the answer is the TANGENT of the angle. On the Windows calculator, if you check the INV box [ ] and then click tan, the angle is displayed.
Okay, here's the test. Using a 2' level, you measure 15" vertically. What's the angle?

This will help: in the calculator, key in 15, press the "/" divide key, key in 24 and press ENTER. Now, click the INV box and then click tan. Whaddya got?

 

[MikeH]

32.005383208........

Thanks for the lesson Jim. This will come in very handy. I don't use any of this on a reglar basis so I've forgotten most of what I learned in Trig and geometry.

 

[DavidF]

Jim, you forgot to mention to click "View" and select scientific. Other than that, great tip!

 

[Rick Orwig]

This web site is so fantastic and loaded with talented people who take the time to share their knowledge with others so unselfishly. Thanks so much to each of you for helping me.