Miter Angle Settings Please .....

Vermonster

Hi - I am installing 45 degree crown molding in an attic bedroom. There is a transition where the ceiling meets the angled ceiling to the knee wall. Therefor the molding has to be installed on the same plane, just in an angle following the ceiling down to the knee wall.. In my case it's 39 degrees. Does anyone have the numbers or math to use for my compound miter saw? e.g. if it were a normal return it would be 35.3 and 30.

Thanks for the help ....

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tinner666

Not sure. Just run first piece square like you normally would, then use a scribe to figure angle for the piece that gets coped.

Mrmac204

I am not completely sure that I understand how you measured this angle. This is important! is this 39 deg. from vertical? or is it 39 deg. from the horizontal ceiling?
I am going to assume that you measured this from the ceiling (horizontal). this angle is greater than 90 deg you have to take that into account.
so your measurement is 39 deg, so add that to 90 deg... you get 129 deg. run that thru your trusty "costruction master pro" calculator and you get the following:

Miter 18.64 deg

tilt 17.72 deg

I may be wrong as I am not sure that I completely understand how you measured this angle.

the best book that I've found on this is "Crown Moulding and Trim" by Wayne and Kathy Drake. It explains all of this with excellent photo's.
www.compooundmiter.com

Vermonster

Thanks for the replies...
Mrmac, you understood my poor explanation perfectly. I'll go with your numbers.
Thanks again ....

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Mrmac204

holy crap, ya mean I got something right??? must be my lucky day

glad to help!

Mac.

El Dorado Wood

Are you talking about running crown down a rake wall and cornering onto a horizontal wall?

If that's the case... it's not possible to do it with one cut/joint and keep both pieces at a 45 degree spring.

You either need to cut one angle for the corner and then another to run up the rake (leaves you with a little wedge), or you need to tip the horizontal piece back and decrease the spring.

If that's not the case... ignore me.

But, either way, I strongly suggest the Bosch angle/miter gauge.

Vermonster

thanks ... yes, I tried the angles but something is not lining up. Just to be sure and explain myself here is an elevation view of what I'm doing. I want to run crown along the horizontal and slant ceiling portions. By the way I'm using the Starrett angle/miter tool and so far I've been very happy with it. Not the Bosch, I know.
Thanks again ....

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... factor it in and move on ...

Mrmac204

OH man, I got it wrong

Doh! ok I see now where I screwed it up..

the horizontal is 180 deg.....

your measurment is 39 deg

180-39 = 141 deg...

141 entered into the calc. with a spring angle of 45 deg

miter 14.06

bevel 13.65 (75.94)

I owe ya a beer.

Vermonster

Hi and thanks .... don't be so hard on yourself. I know it was my poor explanation. I'm just glad you answered at all. I'll try these new numbers today. One more thing ... with these angles/miters being on the same plane does the same cutting setup apply? Meanin the left cut is upside down on the miter fence? I'll take you up on the beer though next time I'm in Vancouver .....
Thanks again ....

__________________
... factor it in and move on ...

Mrmac204

no it wasn't your explanation- I just messed up - was workin from the vertical, and I should have been workin from the horizontal...

I do know that some places on the net advise cutting opposite miters upside down- but that changes the spring angle on ya! I've done that and found out the hard way, it doesn't work. - think in terms of the face of the moulding being the starting point in regard to your measurements. It always has to be cut face up or face out. some saws have a big enough back fence that you can just place your crown on the saw bed itself at the correct spring angle, then all you have to worry about is the mitre- and that's just 1/2 of whatever your corner measurement is (1/2 the reciprocal) or if you cut it on the flat, then the numbers (above) apply.
If you can get ahold of that book I mentioned, it explains stuff like this very clearly.

Mac.

Vermonster

thanks again for your help ... I'll let you know how it went with the new numbers.

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... factor it in and move on ...