These instructions are for the Excel Miter Box and saw as pictured below:
This miter box is capable of cutting straight cuts and 45º angles on wood, plastic and very light metal up to 1 ¼” deep. You will notice a “lip” on the edge of the miter box. This allows you to put the box on the edge of your table to prevent it from sliding. The edge with the lip is the “front” of the miter box.
Assuming you’ve successfully cut your baseboards, let’s move on to crown molding! Yes, crown molding is a bit more difficult - you have to “think upside down!”
There are a couple main profiles of crown molding (sometimes called cornice). Three are pictured below:
Molding that has a 90° edge is easier to cut because there are only two surfaces that could sit flat on the bottom of your miter box. The negative to this molding design is if you’ve used ceiling paper and overlapped it onto the walls - then added wallpaper, the edges of your ceiling might not be perfectly square (mine never are!). This is the reason that the third design was produced.
OK. Let’s start! I like to start with the room with the longest front wall. Why? Well, WHEN I cut a piece wrong, I have a longer piece to use later! That means less waste in the long run!
Take your piece of molding and prepare to make your first cut. Look at how the piece will sit in the room - you will need 45° angles at both ends. Hold your piece of molding against the back edge of the room (house or roombox) and make a mark just to show the angle you need to cut. Be sure to hold the piece IN THE POSITION in which it will sit in the room.
This picture is from above - the blue mark across the top of the molding is parallel to the ceiling of the room. This shows the 45° angle that will be the LEFT corner. Your mark doesn’t have to be perfect - it basically just shows the approximate cut you’re going to make.
Take the piece of molding and hold it with your line facing UP. Take your miter saw and hold it against your angled mark. (So far, that’s not too hard). Now - some folks have no problem cutting the crown molding "right-side-up" - try it for yourself. If you're comfortable with the molding in this position, the information in MITERING 101 is all you need! However, some folks find it difficult to hold the molding in place with such a skinny edge resting on the miter box. So, the rest of this document is for those of us who like a little more stability on the miter box!
SO, once again, take the piece of molding and hold it with your line facing UP, and take your miter saw and hold it against your angled mark. Then. still holding the saw blade against your angle, turn the molding (and your hand and the saw blade) upside down. Remember...when you put your piece of wood in the miter box, the “top” of the molding - the edge with the line drawn on it - must be on the BOTTOM of the miter box! (Yes, this is where it gets a little more complicated; upside down, inside out, backwards.....)
You can peek if you need to! Look at the direction your saw blade is in relation to the angles on the miter box. You will see that the blade is on a 45° angle with the handle of the saw blade (you can’t see it in the picture) LEFT of the tip of the saw blade. Set your piece of trim in the miter box - “top” edge (where your line is) on the bottom of the miter box and the FLAT edge of the trim resting against the BACK edge of the miter box.
You’re ready for your first cut!
Go for it! When you’re done, turn your piece of molding upside down, and you should see that your cut is at least close to your original line. YAY! One down...and at least a few to go!
Back to your room with the piece of molding. Again, place the piece IN THE POSITION in which it will sit in the room...Parallel with the ceiling and with your now “perfectly cut” LEFT end at the left edge of the room.
Now it’s time to mark for the RIGHT end of the molding. We’re going to do a couple marks: first will be the angle we need (again - approximately)
Then (and this is more important for accuracy), we need to mark for the length of the piece. To do this, take a sharp blade (Exacto, knife, your miter saw) and, from below, make a small cut into the piece of molding at the bottom edge - against the side wall. The goal is to “simply” mark the length on your molding - not to cut through it - and a sharp blade is much more accurate than a pencil!
Back to the miter box. As before, place the saw blade on the mark. Then, turn the piece of molding upside down. Note the mark made is now on top - and the knife blade is below. Also note that the the blade is on a 45° angle with the handle of the saw blade (you can’t see it in the picture) RIGHT of the tip of the saw blade. Set your piece of trim in the miter box - “top” edge (where your line is) on the bottom of the miter box and the FLAT edge of the trim resting against the BACK edge of the miter box.
WAIT - You’re NOT quite ready to cut! Place the tip of the saw blade IN the mark (cut) you made on the bottom of your baseboard. LOOK at the picture.
The tip is at the OUTSIDE edge of the mark! The OUTSIDE mark of the piece of molding is the length of your wall! Now, you’re ready to cut, so go for it! When you’re done, turn the piece upside down and your cut is pretty close to the mark you made!
And, if you put the piece along the wall in your room where it goes, it should be perfect (IF your walls are parallel, and your marks were exact!) Don’t worry if it’s a bit short - that can be filled in. If it’s a bit long, carefully shorten it.
Turn this piece upside down and line it up with the last piece you cut. You should have lines meeting and a pretty good looking corner!
The last step for this piece of molding is it's length. Set it in the room and use your sharp blade (Exacto, knife, your miter saw) to mark where you need to make your cut. Then, make an easy straight cut!
Cutting molding that has the third profile (no 90° angle at the rear edge) is “exactly” the same as the above process. Just remember that the “top edge” - the one with your mark - MUST go flat against the bottom of the miter box!
WRONG - where is my line? WRONG - my line is against the BACK wall of the miter box
RIGHT - okay, it's hard to see - but my line is against the BOTTOM of the miter box!