What's a sure way to cut a mitered corner for crown molding?

Answer 1

As you've seen here, "sure way" is a kind of elusive proposition. But I can give you a "good" way to avoid frustration:

Where "long runs" are involved from one wall to the next, the real pro can put a single piece up there and make it fit snugly without having to shave off bit-by-bit. But for the rest of us, here's an idea that has worked for me, passed along by an old Italian craftsman who did this work in his sleep.

Take an inside corner, for example. Instead of trying to fit long pieces together at the corner, fit short ones (2 or 3 feet) that you can easily hold in place with one hand (on each piece). Because wall and ceiling surfaces are rarely at an exact 90 degrees, you use a protractor to get your angles, then cut the sections of c/m. Test fit them in the corner and make whatever adjustment cuts are necessary to get your perfect fit. The other problem is that c/m, like any wood, is always bent or warped to some extent and using short pieces don't have to be "forced" into place as much.

Now cut the OTHER end of the pieces at a 45 or other standard angle so the ends are beveled, in or out. Then, for the longer run that will take you close to the next corner, cut that piece at a bevel also -just the opposite direction, so one board will lap over/under the other. These cuts should fall on a stud if possible. Also, at the opposite ends of those pieces cut your bevels so they hit on a stud within, say, 2-3' of the next return in the wall.

Now secure your corner pieces in place. Personally I like glue, cabinet screws and caulk so there is a tight seal wherever surfaces meet.

Now insert a triangular wedge of wood, cut from the end of a 2X4, for example, behind the sloped end of each of the secured pieces, so the slope of that wedge fits up against the back of the c/m. Half of it should be behind that piece, and half exposed, where the sloped end of the next piece of the run will go. Alternately, use 2 wedges, one completely behind one piece of c/m, the other completely behind the other, glued and butted together. Those wedges should all be cut at the same time once your saw is set up right, so all are exactly the same dimensions. Apply glue to all sides of the wedge(s). Now bring up the next piece of c/m to continue your run, and lap it under or over the other piece. Use cabinet screws to secure the ends to the surface of the wedges behind them, and at the top and bottom of the c/m to secure it to the wall stud or the plate. The reason for this procedure is that it not only gives you a little "wiggle room," for adjustment, but also provides a very secure connection. A problem with c/m or any trim is that, over time, cracks appear wherever anything joins. This method will minimize that problem.

To complete the run to the next return, use a piece that is too long, and cut your angles to fit the return just right. Put your wedge(s) in place, and cut the bevel where it should be (or a bit too fat at first) and fit it in.

A variation on this: figure out ahead of time where your wedges are going to be, and install them first. Benefit: they help keep the c/m at the correct angle when you press it against wall and ceiling. Consider using wedges even where you don't have a join -just to keep everything true and secure. It is OK if your wedges are slightly too small; not at all good if too big.

Good luck!

Answer 2

I replied with an answer to this long ago that won best answer. You can look that one up, it would be one the first answers that I gave.

If everything is square and there are not corners that are not 90 degrees, you simply put the crown molding upside down and backwards on the miter saw and cut it at 45 degrees.

However, if the truth were known, there are no 90 degree corners in your house. In that case, you can either use a T bevel and determine the angle by finding the center of the true angle and cutting it to 1/2 of the angle (say your corner is 87.5, you would cut 43.75 degrees). Bosch, however, makes an interesting tool for those who put up crown all the time. You can measure the angle with it and half it, meaning that you don't have to do much table top geometrics, or if you want to cut the boards flat, it will give you both the miter angle and the bevel. That tool is about $150.

Most experts, however, use a coping saw after they cut a 45 degree angle. This necessitates you cutting from the front, right at the miter cut and it can be tedious if you don't know how to do it. The fits, however, are generally better than if you tried to cut everything at just 45 degrees.

To do the standard cut, I would use a straight miter saw and to do the flat cut, y ou would have to use a compound miter saw. If you plan to cope, look that up and practice it for a while before you start your work. The main problem with crown mold is that if you make a mistake, it is usually an expensive mistake since crown cost so much per foot.

Answer 3

The SURE way

One corner goes all the way in, 90 degree cut. Leave the next piece long. Set it on the miter saw against the table and fence just as it will rest against the wall and ceiling, BUT upside down. Set the saw at 45 degrees and cut. you'll need a coping saw to remove the waste. The waste is the wood the saw blade passed through, if you stain the piece first, its easy to see - the bare wood. Now you've created the profile of the first piece. Hold it up to check the fit. Fine tune it with a rasp or file. Now cut the other end square to the length you need and nail it. Repeat.
Coping is a skill that takes practice, but hey, so is measuring.
Master this and you're corners will be perfect.
You asked for the SURE way.

Answer 4

A miter box is just the beginning of the project. You have to be an experienced carpenter and know how to cut the angles on a crown molding. I know people that have been carpenters for years and, don't know how to cut crown moldings.
Go to Home Depot and see the guys in back, they'll show you how. You can even buy pre-cut corners now.

Answer 5

A miter box is your best bet. You can either hold the crown at the proper angle, if it's small crown, or you can buy a jig to hold it in place for you. Another option is a compound miter saw, this is a little more tricky but it is the best option for wider than 3 3/4 crown. With a compound miter saw you can lay the crown flat, but it requires you to tilt the blade to an odd angle (something like 22.7 degrees) and move the angle of the table (something like 16.4 degrees).

Answer 6

Use a compound mitre saw. Most rental shops will have one available. When measuring, use a utility knife to mark the cut point; pencils can often leave marks larger than 1/16 inch. And in finishing carpentry, a sixteenth of an inch is as wide as a mile. The best bet for a "perfect" corner is to cut the molding a bit longer, then slowly shave it shorter until it fits.

You can use a mitre box and back saw, but the process is time consuming and fine tuning the pieces is difficult. Spend a few dollars to rent a compound mitre saw (make sure you get a good finishing blade--the more teeth the better) and take your time. You'll end up with a fine finished product.

Answer 7

Several good answers here, but 1 important thing to remember. "Bottoms Up" The part of the molding that will go up against the ceiling, must go down against the table of your miter saw. The "bottom" of your board will go UP against the fence of your miter saw. This is the edge which will go against the wall when you turn it right side up.

Answer 8

Use a compound miter saw for making the cuts.
Use a protractor for measuring the exact angle to transfer to the saw.

Answer 9

Everything you ever wanted to know about installing crown molding and more:
http://www.installcrown.com/

Answer 10

Use a mitre box. Depending on how careful you are, you may only need something like this:
http://www.comparestoreprices.co.uk/images/em/emir-25a-mitre-box-with-guides-225mm.jpg

However, I have one much like this and I love the way it cuts perfect corners.

http://img.epinions.com/images/opti/cd/fd/Stanley_Contractor_Grade_Clamping_Mitre_Box_20_800_Shop_Tools-resized200.jpg