Re: Crown molding coping question
A 90* corner, divided by 2 is 45*, regardless of the spring angle of the crown. You will cut the molding at 45*. Where you are probably running into trouble is proper placement of the molding in the saw when you're making the initial cut. If it is not oriented properly, then it's not going to mate up properly when installed.
I recommend adjusting the placement of your trim in the saw until you're getting the correct cut, then either draw a scribe line or install stop blocks on the saw to line up the trim perfectly every time.
Once you've got the cut right, then you cope the end with a 5* back bevel, this will give you tight face joints that stay tight.
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