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billyg 04-26-2009 07:07 PM

cutting crown molding for cope cuts
 
I'm planning on using 45/45 spring angle crown, 4.5 inch wide and will be using a 12 inch compound miter saw.
What angles should the saw be set at to cut the face profile of the molding so I can make the cope cut with the coping saw. A chart I'm reading says I should be using a miter angle of 35.3 and a blade tilt of 30.0 for 45/45 spring angle crown for a 90 degree corner. Am I interpreting this chart correctly?

bjbatlanta 04-26-2009 07:14 PM

If you're cutting a compound miter, you don't have to cope and the crown is cut laying flat. If you're coping, you cut on a 45 with the molding "bedded" on the saw upside down...

Ron6519 04-26-2009 08:53 PM

Quote:

Originally Posted by billyg (Post 265921)
I'm planning on using 45/45 spring angle crown, 4.5 inch wide and will be using a 12 inch compound miter saw.
What angles should the saw be set at to cut the face profile of the molding so I can make the cope cut with the coping saw. A chart I'm reading says I should be using a miter angle of 35.3 and a blade tilt of 30.0 for 45/45 spring angle crown for a 90 degree corner. Am I interpreting this chart correctly?


To check the angle combination, just take some scrap 1x4 and cut them. If they come together at 90 degrees, that's the setting.
Ron

Willie T 04-27-2009 01:10 PM

4 Attachment(s)
Forget trying to manage the tilted 'compound' bevel on a miter saw. Besides the fact that you don't need to bother with it at all, very few walls are square enough in all the planes involved at a corner to make any of those numbers work much of the time. You will end up with much beter work if you cope your inside corners and cut your molding "UPSIDE DOWN, AND BACKWARD" with nothing but a 45 (more or less, depending on how bad the corner was built) angle on the saw for all cuts.

Just remember that phrase,"UPSIDE DOWN, AND BACKWARD" and you will soon begin to see how it works.........

You always put your molding on the saw table....... "UPSIDE DOWN".

And you simply remember to turn your saw the direction shown in the pictures I show below for each of the desired cuts, and place your molding on the saw table "BACKWARD". In other words, if you want to cut a piece for the right side, you place the wood on the left of the saw blade. If you want to cut a piece for the left side, you place the wood on the right side of the saw blade.

Why all this "UPSIDE DOWN, AND BACKWARD" craziness? Well, think about it.

You are installing molding against the intersection of your wall and your ceiling. Those two planes (or surfaces) create a 90 degree angle when they meet. That's pretty simple. You can look right up there and see that.

Well, the table and the backing fence of your miter saw also create a 90 degree angle where they meet. Think of the fence (the upright part) as your wall surface... and the table of the saw as your ceiling. That's cool. You can look at the saw and see that, too. That's all well and good. You need a 90 degree setup like that to help align the molding. But here comes the aggravating part.

Because of the fact that a miter saw happens to have its blade mounted ABOVE the table you're cutting upon, it cuts the molding the opposite of what you need for it to install properly up there on your ceiling.

Envision this: If it were possible for you to lie on your back like Michelangelo did to paint the ceiling of the Sistine Chapel... and if you could bolt your saw, upside down, directly onto the ceiling... then you could make all your cuts just like they look like they need to be cut. Because the saw would then be oriented along the same plane as the ceiling. But that's a huge hassle. And totally ridiculous to even attempt.

So... you just need to keep remembering that you are, in effect, doing everything in reverse. Because of the saw being on the floor, and not the ceiling, the molding is actually being prepared in reverse, (until you turn the cut piece of molding over and lift it up into place on the ceiling), so all your cuts are going to also have to be done in reverse.

A good way to begin to understand this is to realize that if you were installing this crown molding on the floor where the baseboard goes, you would be cutting "RIGHTSIDE UP AND STRAIGHT FORWARD AS IT RELATES TO ONE SIDE OR THE OTHER". But you are NOT installing on the floor. You are installing on the ceiling... and your saw is UPSIDE DOWN for that.... it is constructed and set up on the plane of the floor for cutting floor pieces, not ceiling pieces.

Just try to keep in mind that for the cuts you are making, the back fence of the saw is always considered to be the 'wall'. And the flat table of the saw is considered to be the same as the 'ceiling'.

I know it doesn't seem to make any sense right now, but as you read through this a few more times ... slowly... it will begin to come into focus.

************************************************** ************************
Here is a fantastic exercise to help plant the 'UPSIDE DOWN & BACKWARD' concept in your brain.

Using the 'nested' method, but NOT cutting anything 'UPSIDE DOWN or BACKWARD', simply cut two pieces of crown molding to go around an outside corner at the bottom of your wall... at the baseboard.

This is not a trick. This is straight forward. You cut what you're looking at.

See how easy it is to cut? And how easily it fits together down there at the bottom?

NOW............................. pick up those two pieces of molding, and take them straight up to the ceiling.... left piece in your left hand, and right piece in your right hand. Same corner, but up at the ceiling this time. Try to get them to fit. They won't work at all, will they? No way.

BUT............................. put the left piece on the right, and the right piece on the left. (or BACKWARD) at the same time rolling them UPSIDE DOWN................. and What happens?

THEY FIT !!!!!!!!!!!!!! Wow! How about that? It's called The 'UPSIDE DOWN & BACKWARD' concept

Here's another neat tip for remembering which way to cock the saw.

For INSIDE corners, the LONG POINT of the molding cut will be on the INSIDE of the saw bed... (farthest away from you)

For OUTSIDE corners, the LONG POINT of the molding cut will be on the OUTSIDE of the saw bed... (closest to you)

************************************************** ***********************
Pictures for the 'UPSIDE DOWN & BACKWARD' concept:

Inside Left ................................................ Inside Right ...........................................Outside Left ............................................Outsid e Right

bjbatlanta 04-27-2009 01:18 PM

I tried the compound miter method once. Never again. Good explanation Willie. I forgot the "backward" part...

Gary in WA 04-27-2009 03:59 PM

And...... check out the niffty install tool:
http://www.google.com/url?sa=t&sourc...VLV6WguQE-RLug
Be safe, GBAR

Joe-J 05-04-2009 06:18 PM

Wow!!! You guys are good!!


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