|Written by Toelken69|
First lets start with base board. The easier trim of all to cut. To measure your baseboard pull your tape from one side to the other. If it's an inside to inside corner. That measurement will be long to long on a 45 degree miter. Start by cutting a 45 degree inside corner on the right side of the trim. Hold your piece of trim on the saw and turn the miter saw all the way to your left until it hits the 45 degree mark and make your cut.
Next take the measurement that you have and pull your tape across your trim piece and mark the trim. Now slide the trim down to your mark. Turn the Miter Saw to the opposite side at the 45 degree mark. Make sure you look closely with your safety glasses on to be sure that the angle comes down on the right side of your mark. Cut just at the outside of the mark. This will be an inside to inside corner, long to long cut.
To cut a piece from an inside corner to an outside corner. you must measure from the wall on the inside to the wall on the outside corner. This will be a long to short cut. It's best to work from your left to right when measuring so you always remember what you need and how you measured it. Cut the left side of the trim piece at a 45 with the saw on the left side. Pull your measurement from the left (the long side)to your dimension on the right. Mark the trim. Move your saw to the right side on the 45 and cut just on the outside of your mark. This will give you an inside corner to an outside corner cut. Long to short cut.
Now we are going to make an outside to outside corner cut measure the wall from corner to corner at the base. This will be a short to short 45 degree cut. Cut the right side of the trim at a 45 with the saw turned to the right. Now measure from the short or the inside of the cut and make a mark. Slide the trim down and turn the saw to the opposite side. Make your cut just to the outside of your mark. If the piece is too long you can cut it. If it's too short it can get costly.
That is the basics of cutting Base Board trim molding on 90 degree walls if you have something other than 90 degree walls divide the angle by two and that should give you the desired angles for the cuts.
There is also door and window trim. For a door measure across the top of the door jamb on the inside and add 3/8ths to your measurement. This is to leave enough room for the reveal on each side of the door. Cut the trim on a 45 with your short to short measurement. I normally hang that piece level with the same 3/16ths inch reveal first. Measure from the floor up to the bottom of the 45 on the trim.
Pull your tape from the square side of the trim to your dimension and mark. Make your right hand side cut first. Turn your saw to the right side 45. Cut from the inside of the trim out. just on the out side of your mark. Now measure the left side. Turn your saw to the left 45. this time you will be cutting the outside of the trim first. Make sure to stay just to the outside of your line.
Basically do the same thing for window trim. Make sure to leave the proper reveal. Crown molding is a whole other story. I'll get back to you on that.