Coping an inside corner: what am I doing wrong?

5 years ago

last modified: 5 years ago

I wanted to do this rather than miter the inside corners. It's a cold spot and I am expecting movement of the joints.

I read verbal instructions plus watched a few videos. It seemed straightforward. Cut a 45 degree angle to reveal the profile, then cut out the exposed interior wood along that line.

But it's not working. Are there some forms of moldings where it doesn't work? It's cove molding, which is concave. The videos I watched showed shoe, baseboard, and chair rail, all of which are convex.

Or did I just misunderstand the directions somehow?

First I cut the molding at 45 degrees. Then used a fine saw to cut along that profile.

First photo is how far back I was having to file the back of the molding to get it to lay flush. It never did lay flush. As I understood it, this should not be necessary. "Slight undercut" is what I read.

Second and third show how it does not lay properly against the uncut molding. Not even close to correct. 4th and 5th are just when I gave up and tried winging filing the contour to fit. That didn't work either.

Someone please tell me where I'm going wrong! Thanks.

Featured Answer

Rose Pekelnicky

5 years ago

You cut the 45 wrong.. lay it flat on the miter saw bed and angle the blade.

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Comments (7)

linnea56 (zone 5b Chicago)
Original Author
5 years ago
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PRO
Creative Design Cabinetry
5 years ago
Like said above. Also your cope cut is wrong.

You are overthinking this. Miter each and caulk. It's 3/4 cove moulding.

You cut a 45° miter. Is it a 90° corner? Or 91, 93, 89, etc?
toxcrusadr
5 years ago
last modified: 5 years ago
If you are trying to butt up one piece against another at 90 degrees, this is not the way to do it. What you described is a way to make two 45 degree cuts meet flush at the corner (I think).

You would have to get a profile of the in-place piece of molding, perpendicular to the face, like with a profile gauge, transfer it to the cut piece and cut by hand. It will create curves on the end of that piece that you cannot get with a miter saw, I don't think.

Much easier to do them both at 45 degrees to meet in the corner.
toxcrusadr
5 years ago
@Rose: Can you clarify for the OP what you mean by 'lay it flat'? Which side down? And do you angle the saw left-right (miter) or tilt it, or both (compound miter)?
CYNTHIA JONES
5 years ago
My understanding (from helping husband do our trim) is that you cope when you have an inside corner on crown molding or baseboard. This looks like you are trying to use coping on the corner of a door frame? I don't believe you can cope that joint- you would have to use a miter.
PRO
Creative Design Cabinetry
5 years ago
last modified: 5 years ago
CYNTHIA, it can be coped easily. Put the piece on the miter saw. The edge that is sitting on the wall/floor in the last picture above, will be sitting on the bed on the saw. If you're using a old-fasion miter box, that same edge facing the outside. Cut 1/2 the corner degree measurement. 90° = 45°. Then cope.

Again, that small of paint grade moulding, just miter it.