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Odd Wall Angles for Baseboard install

Jon Hanson's Avatar

Join Date: Apr 2005
Posts: 26

03-06-06, 01:20 PM   #1  
Odd Wall Angles for Baseboard install

I have some angled walls that I am trying to put baseboards on, and am having difficulty figuring out the angles to properly mitre the edges and join them. For instance, I have 2 walls that rather than meeting at a 90 degree angle, meet more like at a 120 degree angle. First, is there a tool out there to easily measure the angle, and 2nd, when you have an angle either inside or outside greater than 90 degrees, how do you mitre it properly so the 2 pieces when joined match up properly?


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marksr's Avatar
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Join Date: Mar 2005
Posts: 42,787

03-06-06, 03:47 PM   #2  
You can buy an adjustable angle gauge. The mitre is always half of the angle - 90` = 2 - 45`,92` = 2 - 46`,120` = 2 - 60`, etc. Without a gauge it is just trial and error, just use scrap [doesn't have to be base] to figure the cut needed.

retired painter/contractor avid DIYer

XSleeper's Avatar
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Join Date: Dec 2004
Posts: 19,282

03-07-06, 05:54 AM   #3  
Marksr is on the right track and has given you correct information about bisecting angles. So to arrive at the proper miter saw setting it's actually:
180-your angle = X/2 = the setting on your miter saw. For example:

90 degree corner:

180-90 = 90
90 / 2 = 45 Set the miter saw at 45.

120 degree corner:

180-120 = 60

60 / 2 = 30 Set the miter saw at 30.

135 degree corner:

180-135 = 45

45 / 2 = 22.5 Set the miter saw at 22.5

For a corner that is close to 90, like a 92, it would be:

180-92 = 88

88 / 2 = 44 Set the miter saw at 44.

Usually you can use the sliding bevel square to find the angle, then use your miter saw to determine the angle. If you put the bevel square into an inside corner, then take the bevel square to the miter saw and put it against the fence and turn the miter detent until it matches, just add 90 to that reading to find the total sum of the angle. Then use the formulas above.

Last edited by XSleeper; 03-07-06 at 06:08 AM.
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