Why Is Coping Better Than Mitering?

fr8train

I've seen a few discussions about moulding and trim, and it peaked my curiosity. The only thing I can come up with is ....

Since nobody is perfect, the corners are rarely 90 degrees, and coping allows you to get a tight joint without it having to be exact.

Am I right here?

jproffer

You got it.

__________________
Jim P.

Railman

fr8train,
It's not so much to compensate for the corners being off from 90 as it is about the joint pulling apart when you nail mitered inside corners. You can also preload the joint's fit easier without mismatching when you cope. Typically, you make the pieces a little long, (1/8" or so on 10' to 16'), & then pop the pieces in place. That compresses the joint, & also the length of the piece so as to have less chance of shrinking later.
That's pretty nuch the jist of it.
Joe

Railman

fr8train,
It's not so much to compensate for the corners being off from 90 as it is about the joint pulling apart when you nail mitered inside corners. You can also preload the joint's fit easier without mismatching when you cope. Typically, you make the pieces a little long, (1/8" or so on 10' to 16'), & then pop the pieces in place. That compresses the joint, & also the length of the piece so as to have less chance of shrinking later.
That's pretty nuch the jist of it.

Rolling the corner will compensate for being a little off from 90'.

Joe

send_it_all

If it's worth saying, it's worth repeating.

trav007

Also, pay attention to which piece you cope. IF by chance the pieces shrink a little ( which we know will happen ) you will see the seperation where the cope meets the full piece, but mostly within a limited range of view. EXAMPLE....at the end of a hallway cope the long pieces not the short, that way nobody will notice the joint/gap.

IF your pieces shrink and seperate with a MITRE, you can see the speration anywhere in the room..

Get the idea.

__________________
Travis
www.customkreations.ca
"The most perfect technique is that which is not noticed at all"
-Pablo Casals

JLTrim

Also measurements are much more critical if you're mitering. If you're 1/16" long or short on a miter it really shows, you have to either cut it again or shim the other piece out... When coping it's not that much of an issue since one end will be mostly covered by the overlapping piece.

Railman

How do you do two post with the same post number? I don't know, but I just did it above! Second post was just an edit to add note.

trav007, & JLTrim both bring up good points. The shrinkage factor is reduced by 1/2 when you cope, which is probably the most important one of all.

Coping is also more adjustable on fitting short pieces together, without adjusting the cut.
Joe

clampman

It's also faster and easier to install coped crown - especially if you're working alone.

toolwiz93

It is great to see someone else but me understands that putting cope joints in a certain spot is something to consider. I might as well talk to the wall sometimes when I tell my guys to figure out where the best place is for the cope joints. What is hard to figure out is that you have the same amount of copes in a room so why not use them to your advantage. Have you heard this response, "I like to do all right or left copes". That is followed by, "You don't make all left or right turns when your driving do you". Then, "What about the double copes". Followed by, "Measuring is still the same".

Now back to the original post, 95% of the time coping is better and/or easier. Many times in cabinetry you will have to miter corners because of small offsets that make it almost impossible for coping. The nice thing is that cabinetry corners are 90 degrees. Good luck which ever way you go.

JLTrim

I just put all my copes on the right, it's easy because I'm right handed, cut right side, cope right side. If it's tight and glued, why does it matter which way you look at it?

orson

When a joint is coped the wood shrinking only opens the joint as one of the pieces shrinks, whereas a mitered joint opens from both of the pieces shrinking. Also as noted above you can preload the joint by springing a long piece in and completely eliminate the joint opening.

www.rubycon.us
Ruby Construction LLC
Lancaster Kitchen Remodeling
Lancaster Bathroom Remodeling

Railman

I think you mean left copes. Remember, it's upside down backwards in the saw. So if your right handed, the crown would be off to your left, left hand would hold crown to fence, & right hand would be on trigger...right?

Base board would be right copes if your right handed, since it's typically cut right side up.

I always liked to lay out a room first also, for apearance, & also for ease. On hallways/foyers etc, I usually liked to do the most dificult short runs first, & then have the longer pieces cope into the shorts.

On std 4 wall rooms, I always wanted the least visible wall to be the last up. That would be a dbl cope. So the 1st piece , 90 both ends, would be to the left as viewed from the most likely view, & then go around room clockwise, resulting in 3 left copes, & 1 right.
Joe

angle wrangler

Copes are also known as blind miters.The advantage being that, if it opens the shadow is only visible when looking perpendicular to the cope. If a mitered joint opens it is visible from the center of the room.
COPE ON!!!

Trimcat

I've never seen baseboard that is mitered look good. The miter almost always opens when you nail it........... and a lot of guys don't seem to care...... which is really beyond me why that is. The only thing that separates a professional trim carpenter and a hack is the quality of the joinery. You can't call yourself a pro if you leave your joints wide open. Sorry.

Crown that can be coped, should be coped...... not all crown CAN be coped, but mitered crown is easier to make look good than baseboard.... I don't know exactly why that is but it probably has to do with the drywall being much better at the ceiling than it is at the floor most of the time.

Now the real issue......... COPING SAWS OR JIG SAWS!!!!! HAHA.......

stp57

The few times that I tried using a coping saw, I had a really difficult time. After just a few practices with my new Collin's coping foot on my jigsaw, I am ready to say goodbye to mitered inside corners. I guess the fact that I sucked at the coping saw meant I didn't have to re-train myself with the jigsaw. Pretty good instructions came with the coping foot too.
Thanks for the input guys.
Steve

send_it_all

While I agree that it is best to cope base, I have successfully mitered base by clipping about 3/8" off all but the top 1" of the miters' points. Hard to explain, but it eliminates the problem of the base rocking against the little wad of dried joint compound at the bottom of the wall, which is usually the cause of the miters opening up when nailed.

Quiglag

Wow, I pretty much never cope base, and never have problems with corners. I cut the insides at 44 degrees, and also take a degree off the bottom, to account for walls always flaring at the bottom. I cut outsides at 46 degrees and add a degree to the bottom. Those tricks work just about every time. I also use liquid nails behind all the base, and use wood glue on the joints. We also use color matched caulk on all inside corners coped or mitered. Never had a complaint about bad joints.

As for coping... Jig saws.

toolwiz93

Jig saw