Crown Molding Scarf Joints

I just put up white crown molding. I used angled (45 degree) scarf joints where two pieces meet along a wall. I matched the joints very carefully but slight differences in the elevation of the two sides seem magnified. I've tried caulk, wood filler, and lots of paint, but the joints still seem visible. Is there a trick I am missing?
Thanks, Tim
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If there's differences in elevation, it sounds like you scarfed them a hair too long. It's much easier to hide the joint if they're a hair too short. When they're long, the only way I know to fix it is sanding them flush. Be careful not to soften (or round over) the sharp edges of the crown profile itself when you're sanding across the scarf joint.
jc

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On Mon, 9 Feb 2009 22:30:23 -0800 (PST), snipped-for-privacy@yahoo.com wrote:

Lots of tricks. A lower angle would be better than a 45-degree angle. Fit the two pieces on a workbench, glue up, reinforce the back with a thin stock, and allow to dry overnight. Using various dowels and other objects sand the joint perfectly smooth, carefully inspect, prime, paint. You could use a biscuit which will make the alignment easier.
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On Mon, 9 Feb 2009 22:30:23 -0800 (PST), snipped-for-privacy@yahoo.com wrote:

Trick one- avoid if at all possible. Buying another 16 foot piece of crown molding hurts when you do it- but the payback is forever.
#2 - If you must, scarf that joint at 30 degrees. [and don't buy your molding at the borg or you'll never find 2 that match]
Jim
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Check that your saw is cutting both pieces accurately (proper angle) and that the pieces are not moving while cut.
Also check your stock, I have seen trim that was slighter wider/thicker depending on which line it came off of or what day.
Cheers, Jim
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snipped-for-privacy@yahoo.com wrote:

In addition to the other suggestions, a few tricks...
1) set up the saw to cut the pieces at the proper angle by using a clamp block on the table to rest the piece against. Then it's a simple miter cut rather than compound and at a fixed position not relying on holding the piece manually.
2) use blocking on the wall to set the angle precisely when mounting. In particular, a backing block at the joint would help significantly.
The points about ensuring the material is actually uniform are spot on--w/o that, there's nothing other than fixing up the mismatch after the fact to be done.
--
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Thanks to all who replied.
Couple of follow-up questions:
1) What do you mean by backing blocks? Does this mean ledgers?
2) A few of you suggested angles other than 45 degs (e.g. 30 degs). Does this mean more vertical or horizontal (as viewed when the piece is on the wall)? In other words 30 degs measured from a vertical axis or the horizontal axis?
Thanks, Tim
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snipped-for-privacy@yahoo.com wrote: ...

No, not ledgers but angle blocks of the right size/angle for the crown to set against solidly to establish the proper angle to the wall and particularly to provide solidity at joints, etc.

...
I didn't read that so not sure what the other posters intended but the dimensions may not be perfectly 45 on many crowns so need to check what the run and rise are w/ a square to ensure are cutting the proper angles.
As I suggested, using those dimensions and a guide on the miter saw lets you cut at a 45 vertically.
Oh....now I realize what they were speaking of...rather than making the scarf cut at 45, make it longer/shallower than 45 to provide a longer surface. Can make the fitting somewhat easier and help disguise the joint. But, if the material isn't uniform it won't solve that problem.
If the mounting angle isn't precise which is difficult w/o blocking often to get consistent owing to imprecise framing, drywall compound buildup, etc., et., etc., it just compounds getting two pieces to meet precisely. Longer surface are (shallower angle) helps somewhat there, too.
Just so happens I was picking up the last couple of days being sorta' laid up w/ a cold and not doing much -- in the pile of stuff I leafed thru as was doing so happened to notice a very nice article on crown in Fine Homebuilding No. 194 (May '08) that is worth the read.
Talks of all these points and more in length, with pictures... :)
--
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On Tue, 10 Feb 2009 11:26:43 -0800 (PST), snipped-for-privacy@yahoo.com wrote:

Take a DIY look at this book at a local HD store. It should be on the shelf next to trim and molding material. It helped me as a diy guy.
It explains blocks, measuring a corner that is not square, etc...
http://www.compoundmiter.com/index.html
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snipped-for-privacy@yahoo.com wrote:

Hmmmm never had much problem with this. I always put a nailer on the wall and ceiling behind the scarf, because its almost impossible to line up the scarf on a stud. I cut a compound miter, so one side of the miter locks into the other. I put up this \\ angle first then the other locks into it. You can also use a backing block to help lock them together. A little filler and sanding and youre done. You can click on my website addy below to see the results...
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