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-   -   Any good Copers (crown molding) (https://www.woodworkingtalk.com/f2/any-good-copers-crown-molding-209269/)

J.C. 08-07-2019 10:12 PM

I just saw this video today and it reminded me of this thread. So I'll add it for others that find this thread and are new to coping. Understanding The Cope Joint It's a pretty good video but he gets a little carried away with you always cut at 45 to get your cope line. That's not always true.

Terry Q 08-08-2019 12:41 AM

Quote:

Originally Posted by J.C. (Post 2065589)
I just saw this video today and it reminded me of this thread. So I'll add it for others that find this thread and are new to coping. Understanding The Cope Joint It's a pretty good video but he gets a little carried away with you always cut at 45 to get your cope line. That's not always true.



All you are looking for is a line to follow when you cope. The exact angle is not important so long as 45 degrees is close. You are back cutting it anyway and leaving a sharp edge behind. Just the sharp edge has to follow the contour of the mating piece. Its hard to do without a little bit of filing or sanding to get the perfect fit and the hand fitting of the piece will compensate for any angle error.


In woodworking there is always more then one way to accomplish something.

J.C. 08-08-2019 07:03 AM

Coped trim is fairly forgiving for non square corners but a 45 cut only works for 90 corners.

woodnthings 08-08-2019 09:26 AM

Coped VS mitered ...
 
Quote:

Originally Posted by J.C. (Post 2065599)
Coped trim is fairly forgiving for non square corners but a 45 cut only works for 90 corners.


https://youtu.be/Wh7qSR5lWNc?t=417

You have confused the issue by adding the 45 degree miter. The 45 degree cut was mentioned in the video, but not as a miter. It's the starting cut for the cope because it maintains the proper relationship on the ceiling and the wall.... A * plus B* equals C* from Phythagorean theorem. The video does not advocate using 45 degree mitered corners. :vs_cool:

Tool Agnostic 08-08-2019 10:08 AM

We still struggle at it. I hate to admit this, but caulking hides a multitude of sins.

DrRobert 08-08-2019 11:29 AM

Its got to do with the angle you cut it. BTW those tables as shown above are not for coping cuts.

I just miter both sides. Measure the total angle/2 and cut the crown upside and oriented like it will be on wall, down making a single miter cut.


Gluing the miter together before nailing makes a big difference.

Fine Homebuilding IIRC they have a good article about coping crown. Finish Carpentry and Insider Carpentry channel on YouTube have some good stuff.

J.C. 08-08-2019 07:17 PM

What I'm saying is if you watch the video for the first time and have never coped anything before I think some may think no matter what your corner angle is, you cut your trim at 45 to get your cope line and that is always the proper angle to get your cope line. How about if you wanted to cope trim for an octagon room? Your cope is not even going to be close. To get your cope line, you'll need to cut the trim at 22.5.

woodnthings 08-08-2019 09:12 PM

Yes, for sure....
 
The video only deals with 90 degree corners within several degrees more or less, so yes, you are correct. :vs_cool:

NoThankyou 08-08-2019 11:54 PM

I put up crown molding in this house.

The house was constructed in 1962.
Financial consultants took the architects plans and re-did them.
Where I put the crown molding up, not a single wall was perpendicular nor corner 90.
There were inside and outside corners.
I had never done any sort of crown molding woodworking or construction previously.

My solution:
I made a sled for my SCMS. It held the specific crown molding just like you would be looking at it. I have no idea what upside down and backward really means. If you don't have a SCMS, get one. (Mine is an old DeWalt 703) A fine tooth blade helps but not necessary. (Irwin something or other)

Measure the corners with a good protractor and "Adjustable Bevel". Measure the angle ceiling to wall. There are two different angles between ceiling and wall in the corners.

I cut KD 2x4 at the spring angle and put these pieces up with screws into the cap top of the wall behind the wall board. This underlayment does not have to meet perfectly at the corners. Yes, it is extra work but the post work conversation with a neighbor went like this: "Wow that really looks great. Would you help me do it in my house?" "No" "I'll pay you." "No".

The angle that is going to kill you is ceiling to wall. At most it will be a degree and a half off but if you don't account for it, you'll be off by a mile.

Do all the corners first using pieces about 18 inches long. Cut these pieces flat at 45. It is always best for the non corner pointy edge of these pieces to be against the wall. Hold each piece up and you can see which way the corner cut needs to be trimmed. On these 18 inch pieces you can trim a lot to make them perfect. They may only be 16 inches when you're done but the corners will be perfect.

With all the corners done, filling in the space between is simple. Cut these fill in pieces a skosh long. That way you are able to force them into a nice fit. Use something like TiteBond III on the joints. Try not to put nails through the joint area but rather close. My crown molding has been up for over 12 years and looks great.

Editorial comments
IMHO the walls looked just fine without crown molding. However SWMBO said the walls needed crown molding.
I installed pre primed MDF crown molding that I bought at Home Depot. If you are installing natural wood and expect to stain / varnish, you will need a lot more care.
I told SWMBO that I would install but not paint.
Do not worry about filling gaps and nail holes as the painters will take care of that.

NoThankyou 08-09-2019 12:04 AM

I forgot

A pneumatic nail gun is a God Send when doing crown molding. One that shoots 18 gauge nails about 2 inches is great. Mine is a Porter Cable and works very well. Remember to do the 5 drops of air tool oil before connecting the air hose.

BigJim 08-09-2019 10:41 AM

In all the years I did trim work, I never cut an inside corner for 90 degree walls to any other degree than a 45 degree. I never had a problem at all with making a very tight joint. Just roll each piece of ceiling mold until it fits, it is just that simple. I always coped one piece and did not nail the square piece closer than 4 or 5 foot to the corner until I had the joint made. Leaving that square piece loose will enable you to roll the molding to fit perfect.

You would not believe all the unsquare, unplumb, wavy walls I have trimmed

TimPa 08-09-2019 12:17 PM

following on Jim... the installation is just as important as the cuts. it is so important to get the first piece flat and tight to the wall (based on the small vertical "flat" on the back of the crown moulding), so that the next mitered piece can (when also flat to the wall) form the perfect miter. if either of the pieces are not flat to the wall, the pic in the original post is the result.

i always leave the last 3 feet or so of the first piece "not nailed" so that it can move a little as the mating piece is installed. once all is tight, i go back and nail them.

gj13us 08-09-2019 02:58 PM

I like the idea of not nailing down the last few feet until you're tightening it all together.


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