Welcome to the DoItYourself Forums!

To post questions, help other DIYers and reduce advertising (like the one on your left), join our DIY community. It's free!

Crown Molding - Calculating miter/bevel settings for l45 degree inside angle


sainteditor's Avatar
Member

Join Date: Jan 2015
Posts: 2
AL

01-03-15, 06:26 PM   #1  
Crown Molding - Calculating miter/bevel settings for l45 degree inside angle

I'm having problems calculating the miter and bevel settings for 145 degree inside angles over bay windows. The crown is 5 1/4" with a 38 degree spring angle.

I have access to dual bevel, sliding compound 12 inch Dewalt 780 and can cut nested or on the flat. No problems so far with cutting inside and outside 90 degree corners but the bay is getting the best of me trying to calculate the correct miter and bevel settings.

Thanks for the help.

 
Sponsored Links
czizzi's Avatar
Forum Topic Moderator

Join Date: Jul 2007
Posts: 6,978
VA

01-03-15, 06:38 PM   #2  
I have always done the upside down and backwards method - self taught and it has served me well. I think that trial and error may be used to zero in on your optimal settings. Start with upside down/backward and instead of the saw set at 45 degrees, set it a wide 22.5 degrees and make cuts to both outside corners from opposite directions. See how they fit and adjust until you zero in. Is this stained molding or PFJ to be painted?

 
Handyone's Avatar
Forum Topic Moderator

Join Date: Aug 2000
Posts: 5,451
CAL

01-03-15, 07:10 PM   #3  
Using the upside down and backwards, it should be about 27.5 degrees. Cut a few small pieces and see how it fits.
This is assuming you can place the molding against the fence as it would be attached to wall.


Brian
Cal Contractor

 
XSleeper's Avatar
Group Moderator

Join Date: Dec 2004
Posts: 19,338
NE

01-03-15, 07:36 PM   #4  
Yep, upside down and backwards, "in position" against the fence. No bevel adjustment that way, (which is tough to adjust and be accurate). You only have to worry about bisecting the miter which you can figure out with any old scrap of wood.

 
sainteditor's Avatar
Member

Join Date: Jan 2015
Posts: 2
AL

01-03-15, 09:23 PM   #5  
Thanks for the help.

I was trying to cut flat and will try nesting the crown and adjusting the miter while leaving the bevel stationary. I'm also finding out that the spring angle is probably inconsistent throughout the run of molding I purchased. It seems the majority is 45 rather than 38. Czizzi - does that change the suggested settings you mentioned? Also, were you describing a nested position or flat position of the molding for cutting?

I appreciate the help. I've been putting this project off because all the youtube and internet research I've done has not addressed these larger angles. Glad I found this forum and hope I can contribute at some point rather than ask too many questions.

 
XSleeper's Avatar
Group Moderator

Join Date: Dec 2004
Posts: 19,338
NE

01-03-15, 10:41 PM   #6  
Cutting in position, or "nested" as you say, means the bottom edge of the crown moulding will be facing upward against the fence. The fence represents the wall and the base plate is the ceiling. If you know the rise of your crown, you can place a backer (plywood or a 1x ripped to the same width as the rise of the crown) behind it as you cut, so that when you flush the two up together you will always be holding the crown at the same correct spring angle.

 
chandler's Avatar
Banned. Rule And/Or Policy Violation

Join Date: Dec 2005
Posts: 39,968
GA

01-04-15, 04:48 AM   #7  
Just for quick reference here are the "flat" settings for normal crown corners. You would have to adjust the miter for the increase in angle.

Name:  miter saw settings.jpg
Views: 1783
Size:  35.3 KB

 
czizzi's Avatar
Forum Topic Moderator

Join Date: Jul 2007
Posts: 6,978
VA

01-04-15, 06:15 AM   #8  
Make sure that your stock is sufficiently supported on adjustable horses away from the saw so that you are not fighting trying to get the stock to sit correctly. I kind of float my stock a couple of mm's away from the back fence and play with it until I get the angle that it sits on the fence perfect. I then take my pencil and scribe a line on the deck of the saw for reference. Kind of a cross check while cutting. It also is important to maintain this angle if you are coping your corners as the cuts need to be back beveled to clear the detail in the molding (use your eye line of sight as the same angle as the stock on the back fence). But for these complex angles, it is best to make several test cuts on small pieces. Set one to perfectly bisect the angle. Then do a series of 1 degree off from that angle in both directions. Mark each according to what you adjusted. Then dry fit these on the wall until you find a "pair" that works. These test pieces also help when you are installing your most recent cut to make sure the length is correct as well as the angle on the wall.

Working around the room, decide the direction that best works for you. If cutting a right hand miter with cope is more comfortable (don't have to hold the coping saw upside down) then continue all your cuts in that direction. When you finally get the the end and you have to make a double coped miter cut on both ends, use the following to get a good measurement. I always measure from the bottom of each piece of molding (already installed) across the final wall (that would put your mark on the up side of the molding when cutting upside down and backwards). I use a known length of scrap that I cut to exactly 1ft or 2ft long. I hold this in to one of the lower corners on the wall and stretch your tape to the other. Take the measurement to the other wall and add exactly the length test scrap to the measurement. Cut one coped miter and then measure from the coped bottom (up on the saw), mark and make your second cope. In the beginning, add 1/8" to the first cut as you usually can "flex" the molding in for a super tight fit. If the large molding you are working with will not flex, nibble off a little and try again. Remember, you can remove more, you can't add some back on a short cut. If this proves futile, make a 45 degree lap cut approx 2 ft from the end and seam two pieces together.

 
Search this Thread