Hello everyone. I have done a bunch of crown molding, but this is a first for me. I typically will cope my inside corners. This particular instance of this tilt a bookcase, I am working on, there is a 3/4” block I’m bumping around.

Here’s the problem…

The crown is a 45/45, 1”x 4-3/4” plain concave cove

Everything was all good until I went to cut the coped piece into the main crown on the unit. The back side of the coped return was hitting the face of the crown on the unit. I tried to sand back the top side back side of the coped piece, but then it started to get into the profile of the cove, leaving me no choice but to miter all of my inside pieces.

What am I not seeing that I could have seen before I started to bother coping the pieces?

I included a picture of the unit. The problem Child care at all of 3/4” blocks I’m bumping around

TIA

View higher quality, full size image (4032 X 3024)

In general I use coping any molding when I am applying it to sheetrock. Sheetrock moves when you fire that nail into the molding which moves it and makes a crappy looking joint.

When you have a solid non moving surface like a cabinet I find no reason to cope and just use miters. It's easier and quicker and there isn't going to be any movement to make the joint open up when nailing it to the cabinet.

Leo,

The crown goes to the ceiling, so ill be adding a 2X4 backer to glue with caulk and nail it with my 23 gauge micro pinner

Agreed, if it doesn’t go to the ceiling, then I’d miter it as well

Run your short piece out from the face of the unit to uour ousode miter forat then cope to that.

Sorry typos... run the short piece out from the face of the unit and wrap the snall block first. Then cope your long piece along the unit into that.

Ty Mark. Makes total sense….but is there something I’m not seeing and is this sort of thing with any crown regardless of size and either 45/45 or 38/52?

The angle at which the crown lays doesn't matter. It is what it is.

You need to imagine the cabinet with no crown between your "bumpouts". They would be mitered U shaped pieces. The long straight sections are coped at both ends.

Ceilings are notoriously not level or flat. You need to do one of two things. You have to use compound miters to follow the shape of the ceiling or you need to scribe the tops of the crown to the ceiling. Sometimes you have to accept that you can't make it level on the cabinet because the ceiling isn't going to let you.

I see it all the time in my installs where the crown follows the ceiling and you can see it in the cabinet.

It's hard to understand your description of the problem without a close-up photo of the pieces. To cut the copes you first cut an inside miter, then relieve the material that would intersect with the square-cut piece using a coping saw, rasps and files. The intersecting line at the face is the same whether the joint is mitered or coped.

I don't favor twisting the molding to meet the ceiling or running it out of level with the cabinet. If the ceiling is reasonably level I prefer leaving a slight reveal or shadow line to caulking the joint. If it is way out of whack, plan on adding a square molding that is scribed to the ceiling above the crown or have the ceiling floated to meet it.

2 things:

1. The crown is not capable because part of the profile is horizontal/in the same plane as the top and bottom. You will cut into the profile to make a cope work

2. No need to cope because (as someone else said) it won't move when nailed and also, the angle should be an actual 45 and not some variation/deviance of 45 like. A framed and sheet rocked wall.

3. The link will show you some stuff you probably didn't know.

https://www.miterclamp.com/Installing_crown_molding.htm