I am starting a crown molding project in our library/office. I am using stained wood so the corners need to be tight. I have two questions.

If I use the proper bevel and miter setting on my compound miter saw can I achieve good tight corners or should I cope the inside corners?

Several of my walls are long so I need to join two pieces of molding together with a scarf joint. I have seen this done with a 45 degree miter cut a 45 degree bevel cut and both, which way is correct?

Thanks in advance for any advice.

Yes cope is the only way in that situation and glue the scarf over a stud so you can fasten it.

Have a look at my crown tutorial for further help. It's in the owner's notebook section.

Alter Eagle Construction & Design

[This message has been edited by Altereagle (edited March 23, 2003).]

Thanks, for the advice. I was afraid coping was the proper way to go.

Since my molding won't fit against the fence of my saw, I assume when cutting the scarf joint I can place it flat on the table and set the bevel to 45 degrees instead of the miter.

[This message has been edited by Gene&Sue (edited March 23, 2003).]

Yes.

you can do it either way, but a cope joint is actually 'eaiser' to achieve a "perfect" fit than 'inside' mitered corners... this of course implies that one is accomplished at the actual coping process. This will mean the excersize of practicing until proficient if you are not! :-) I install crown moulding in new construction at least once every week.. sometimes 3 times a week ( trimming out 3, 3000+ sq/ft homes in a week is alot of work!) and each house has 3-5 rooms of crown.. including 2 story foyers. Some of the little tips I've learned are:
1. do not nail the ends or 'inside' corners of your moulding until you are actually placing the adjoining piece...keep fasteners back 16" or so until rdy to finish nail. This will allow you to move the first piece slightly as you fit the coped end of the second peice so that you can achieve the "perfect" fit. Sometimes you may be forced to nail the end up because of ceiling contours but then only 1 or 2 nails, keeping in mind that you will likely have to adjust the fit as mentioned above. Use a block of wood and hammer on the first peice as you fit the second and tap the crown up toward the ceiling to 'roll' the top of the crown out closing up any slight gap, or tap the top of the crown ( at the ceiling ) back against or toward the wall to roll the bottom of the crown downwards to close any slight gap at the bottom.
2. Whenever possible, run 2 parallel walls of crown ( or any moulding ) and then cope both ends of the piece that runs between them, having added some extra length to the overall measurement (determined only by experience and what materials are used and the construction environment) so that the piece that is coped (on both ends) going inbetween the others, has a bow in it which when it is pushed to the ceiling or wall will push the coped ends outwards and into the adjoining pieces this making the fitted cope joint super tight. It is because of this tip that coped joints are much easier to achieve that "perfect" fit over mitered inside corners. Also keep in mind that as wood contracts and expands, your mitered joints will open whereas a "sprung" coped joint will be less likey to ever open up.
3. Regarding the long lengths and scarf joint...I used to cut my joints at 45 degrees and in the same manner as any outside corner...until I got smart ;-) now I simply stand the crown up flat against the saw fence and cut my joint (as apposed to trying to make a bevel and angle joint as an outside corner) You can pretty much use any angle you prefer, I personally use a preset close to 31 degrees on my chop saw table. There's really no practical reason to increase the amount of difficulty in making such a joint by increasing the surface area that has to be fitted! it's a KISS principle.
And lastly, in both the double coped end installation process I mentioned AND the scarf to coped end situation, you will inevitably have to start nailing at one end and work towards the other..more so in the latter than the former. and if the piece you have to scarf must also be coped on the other end, the amount of bow in it will need to be reduced or the sarf joint may be forced to ovelap too much. However if possible, run the wall with the scarf joint first then cope the other walls coming into it.
GL!

>>Since my molding won't fit against the fence of my saw, I assume when cutting the scarf joint I can place it flat on the table and set the bevel to 45 degrees instead of the miter. <<

you can always attach a fence to the saw's fence.. I used cabinet fillers screwed through the back of the saw's metal fence. The process of changing the saws bevel angle and mitre angle for cuts got real old real fast for me. If that's still not an option you can always run down to the tool rental store and grab a 12" Dewalt chop saw for an afternoon for cheap... they have high fences.

Never try and fit a non-coped wood finish crown it will end up looking like production work. I would agree for mdf paint finish you could miter & glue then fill...

I also wouldn't bother adding a fence you'd be better off cutting on flat if your saw isn't the right size. Or going to rent a saw if you can just cut the scarf on flat with a bevel...

Also you won't want to cut a scarf at the 31 on angle, it will cross the stud. I used to do that when I was doing production work 25 years ago too.. you want the 45 for more glue area, but more importantly if the joint is off slightly a 45 won't show, and when the piece shrinks it won't seperate but slide on the joint and keep the look a year down the road when the installer is long gone, also if you cut the scarf at a 45 flat (against the fence or on the table) you'll have a wider surface and a straight cut over the stud for nailing.

Other than that some great tips... except snapping in two ends coped, you'll want to work around the room, from straight cuts to coped corners.. it's easier to keep the crown at the proper spring angle and deal with the irregularities you'll inevitably find in the ceiling plane... use a short crown for the coped corners then go back once you have that next run up.. also if it's a new home with trusses you'll want to use the backer as in the tutorial.

>>I also wouldn't bother adding a fence you'd be better off cutting on flat if your saw isn't the right size. Or going to rent a saw if you can just cut the scarf on flat with a bevel...<<

I ran a fence on my 12" makita for years and years cutting crown...worked beautifully.

>>Also you won't want to cut a scarf at the 31 on angle,...you want the 45 for more glue area, but more importantly if the joint is off slightly a 45 won't show,<<

actually a longer joint multiplies the misalignment and requires much more effort to correct...even for seasoned mechanics. Someone new to running crown will struggle unecessarilly with the method you've describe. Gluing and using brads to secure a mitre works at 15 or 45 degrees. The 45 degree method is only a preference much like some carpenters preferring to use a sawbuck to do trim vrs a contemporary compound crosscut saw. The logic is obvious, the results the same with less effort. The 32 degree option I use, and suggest, is a compromise between glue surface area and installation time/effort...with professional results.

>>and when the piece shrinks it won't seperate but slide on the joint <<

glued and pinned joints don't move ;-).. if they're done adequately...the shrinkage will pull from the opposite end. And crown/moulding doesn't slide on a 45 degree joint...if it shrinks apart, the whole joint opens.

>>Other than that some great tips... except snapping in two ends coped, you'll want to work around the room, from straight cuts to coped corners.. it's easier to keep the crown at the proper spring angle and deal with the irregularities you'll inevitably find in the ceiling plane...<<

I started out doing it the old school way also.. but learned to produce a superior result in much less time. One obvious problem with working around the room in this manner is the difficulty in adjusting the mouldings angle when fitting a coped joint.. unless of course your pieces are lose fitting (cut short).. which will result in opened cope joints especially after a short period of time (shrinkage). In fact it's far easier to install a double coped joint than the method you've described... I show guys the method I use,that have been doing crown for years in the manner you describe, and they shake their head in disbelief because of the simplicity and superior results in less time. But some grognards will just never change ;-)

>>use a short crown for the coped corners then go back once you have that next run up..<<

using a test peice only gets your moulding angle "close"... even after using a short test piece, adjustment will be necessary. So nothing is gained. I find I only need a 3 ft test peiece when doing outside corners in a high foyer on a very long piece...I never use a test piece on inside corners.
Nevertheless even when you work around the room as you've mentioned you will inevitably end up with a piece that needs to be double coped...the installation process is much faster and has superior results when using double coped ends and springing the moulding into place between pieces... even with shrinkage, the joint stays tight.

>>also if it's a new home with trusses you'll want to use the backer as in the tutorial.<<

just use a longer nail and run it into the top plate. A backer would be nice, but unecessary extra effort. Of course if one is doing crown as a hobby, then you could take your time and play around with all kinds of things that people imagine.

[This message has been edited by Cornerstone (edited March 31, 2003).]

There are so many issues there... it's apples and oranges, production vs craftsman. So many of my apprentices know it all after 4 or 5 yrs, it's typical for young pups. I did production work to put myself through college the second time, did that nasty subdivision route with a stair & trim company... someone has to do it, and it's a good place to learn.

A 45 scarf joint will seperate, all joints will to a degree. Crown shrinks in length it's the nature of the wood, a larger surface more secure joint the added degree of cut less degree of seperation simple, but you would need to go back and see your work 1 or 2 years later. High end work you need to take care of the finer details.

Cutting crown on flat is also preferred, as it is precise control of the angles but it takes an understanding of the mathematics involved, so a little more intense for beginners. Making a mock fence to cut on the spring angle will produce the quality it implies paint grade production, but fast albeit.

The old school way system of placing crown became that over years of professionals going through the phases you are at now, perhaps in time you will, as I did, come back to it.. but doing a project as fast as you can as in production work doesn't call for that quality of work understandably. Who cares, get it up get on to the next one and another 3000 ft.

Using a long nail into the top plate? I suppose that would work with a 3" crown and a looong nail, 6 1/2" dental mahogany may prove a little more difficult.

Anyway, it's good to have discussion on basics sometimes. You get to see both sides from the ancient "grognard" craftsman to the pups who have done it and now know. ;^)