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Coping Crown Moulding

I have just spent a very frustrating day, as i am sure many others have, attempting to install crown moulding in my kitchen. My house is rather old and the walls are far from true angles which is why I elected to cope my inside corners. I have moderate knowledge of woodworking tools and feel like such an idiot right now because my corners have such large gaps!!! I am totally dissatisfied and am ready to tear it down, trash it and start over!! Only I don't know what I am doing wrong!! I am cutting my angles on the 45 degree upside down and back cutting the profile with a coping saw. I hold it up and its not even close!! My question is does the size of the moulding matter when setting your mitre saw angle? And does it matter if the moulding is hung upside down? I am using the reversible "easy to install" (HA!) pre-primed moulding from local box store. Please help, my husband is very aggravated with me right now and ready to hire out for what I think should be fairly easy project.


Re: Coping Crown Moulding

You have to leave the last 16" or so of the first piece un-nailed. When you bring the coped piece up to it, you can then tap the molding more down the wall or more across the ceiling to make the joint meet.
You could also cut a trial corner joint with a butt and a cope, place them in the corner so that the joint looks good, then marl in pencil where they rest at the ceiling and wall. Measure these points and use them when putting up the butt ends , at least you will be close. Further, use these dimensions when holding the molding against the fence of the saw. This keeps the angles true in every way necessary.

Re: Coping Crown Moulding

Then dont cope them. Miter,glue and nail the molding.

Re: Coping Crown Moulding


several thoughts:

1. Get on the manufacturer's web site. Hopefully there'll be some step-by-step instructions on how to install their product effortlessly. :rolleyes:

2. When you cope your miter, DO NOT just cope it. You actually want to UNDERCUT the line you're coping so the pieces meet nicely at the front, but there's a gap that can't be seen behind. That makes touching up the fit with a sanding block so much easier because there's much less material to remove.

3. Whenever you do this kind of work, even if you have a good idea on how to proceed (which you apparantly do), always start working in the least conspicuous spot first. That way, as you learn and get better, your improved joints will show in the more conspicuous areas.

4. Don't tear down what you've done. Use a trick called "sponge caulking". Buy a tube of paintable latex caulk. Caulk each gap and then immediately use a damp sponge to wipe the excess caulk out of that gap on your inside corners. That will effectively eliminate any gap. If you paint your crown molding, it'll look like a perfect inside corner.

Re: Coping Crown Moulding

1) crown molding is not an easy project, especially for a beginner. when apprentice trim carpenters start out they dont get to go anywhere near crown, they have to work their way up

2) its an old house, you can not assume anything in regards to the angles that your cuts will be, whenever i go into a old home which ill be trimming i carry my starrett angle finder. from there i make test blocks, i cut 3 or 4 sets of scrap pieces with different angles on them to find the angle of the corner which vary from 88 deg up to 92 deg. using these blocks i can find the angle much quicker and efficiently than simply contantly going back to the saw and changing the angle on my peice of crown. if i do need to recut its only to shave 1/2 a degree off one of the two peices

3) if its paint grade do not cope, mitre it. most big box mdf trims arent actually mdf, its ldf which makes it much less durable and more prone to flake when coping. however if you do cope run a light bead of dap on the back of the coped peice in the joint before it even goes up, this will fill the joint that much more so when you face caulk the joint its filled better

Re: Coping Crown Moulding
jkirk wrote:

1) crown molding is not an easy project, especially for a beginner. when apprentice trim carpenters start out they dont get to go anywhere near crown, they have to work their way up

2) its an old house, you can not assume anything in regards to the angles that your cuts will be, whenever i go into a old home which ill be trimming i carry my starrett angle finder.

(1) JK yrs ago when I started out I was lucky enough to learn the ins and outs as an apprentice early on. Thats when mostly all crown was stained. All the cuts "had" to be tight. Caulk or colored fillers wernt an option......

(2)I use the Miter Master Plus angle finder for pretty much everything.You know Im the inventor also,situations like the one Loveswood is in at the moment is why I created the tool. It allows the diyer and pro to find angles for pretty much any angle or Miter cut.



Re: Coping Crown Moulding
Loveswood wrote:

I am cutting my angles on the 45 degree upside down and back cutting the profile with a coping saw.

Not sure by your description here but you might not be holding the crown molding correctly on the saw. What you need to do is set up your cut so that the side of the crown molding that will be on your ceiling is on the bed of the miter saw and the side of the crown that will be on the wall is on the fence of the miter saw. The crown molding will be at the same angle that it will be put up on it will just be upside down. Set your saw at 45 degrees to make your cut and then cope it following the line. Now of course depending on whether your ceilings and walls are square you may need to make some adjustments. It's usually a good idea to make some test cuts to get everything right.

If you are still having difficulty with the corners you could get some corner blocks and put them in the corners and then you just but your crown up to them instead of having to miter or cope the corners. Seeing your walls are probably not square you will probably have to do a little tweaking even with the corner blocks but it will be a lot easier than coping the corners. Hope this helps you out.


Re: Coping Crown Moulding

Chuck Norris can cope an outside corner.

Re: Coping Crown Moulding

It sounds like you understand the process of copping. If you have gaps it is usually caused by one of two mistakes. The undercutting may not be at a big enough angle and it is hitting the other piece of crown. Mark the undercut with lipstick and slid into place if it is hitting it will mark the area that needs to be removed. The second error is not holding the crown in the miter saw at the right spring angle. It is important to have a stop clamped to hold the crown at the right spring angle and to keep it from slipping as the saw is brought down.


Re: Coping Crown Moulding

you may also have 52 degree crown...

there are two different types of crown, there is 45 degree and 52 degree

52 degree sits more on the wall and less t the ceiling. where as 45 deg has the same lie on both wall and ceiling. because of this the angle of the cut ends up being different

Re: Coping Crown Moulding


Lemme cover my A$$ by saying right up front that I've never installed crown molding. But, I'm intimately intimate with plaster walls and I've coped more than my fair share of miters.

Loveswood said: "My house is rather old..."

If that's the case, she has PLASTER WALLS, and that means she has EXPANDED METAL corner beads where walls meet ceilings.

(only an inside corner bead instead of an outside corner bead)

As anyone who's ever done any renovations on plaster walled buildings knows, the plasterers would have put the plaster on thicker at the corners to cover the nails and expanded metal corner bead. I've seen plaster in corners that was a full 1 1/2 inch thick (instead of 3/4 inch)!

So, maybe the root of the problem is that Loveswood's wall/ceiling corner isn't a 90 degree angle like you're more likely to get between a wall and a floor. If she's got something LARGER than a 90 degree angle between her walls and ceiling, then fitting crown molding into inside corners where walls meet is gonna be darn near next to impossible to get right.

Same for outside corners where walls meet.

Loveswood: Do this:
Check the wall/ceiling corner angle with a carpenter's square.
Also, if you have some crown molding's you've already cut, try fitting them in at a 90 degree corner, between fridge and floor, say. If your wall/ceiling angle is funky, but your crown molding fits well when the corners are all close to 90 degree angles, then that's what the problem is... you're trying to fit crown molding that's meant for 90 degree angles into corners that can be considerably larger than 90 degrees.


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