Understanding Angles

[Chris]

I was hoping someone here might be able to throw some light on measuring angles and transferring those measurements to a miter saw. I measured an angle the other day on some baseboard. I had to use a sliding bevel to get the angle, before I measured it I would have swore it was less than 90 degrees. When I measured it I had a choice because the scale goes both ways, it could have been 88 degrees or 92 degrees, as I said I felt it was less than 90 but it was the cut using two 46 degree miters that gave me the required joint. Does anyone have a good resource for understanding angles better?

Regards, Chris

[nospam]

Sometimes when I get into a spot like that I use 2 sliding bevels and a protractor. set the 2 bevels in the joint so that they together make the angle. check them against each other- if they are different, squeeze them together splitting the difference, then recheck the corner. repeat this until they jive, then take the angle with the protractor and set the saw.

it's inelegant but for my numbers challenged brain foolproof. Bridger

[Bruce]

Resource, no. I prefer to think of the angles as relative to 90. If it was an obtuse angle (> 90) then you would have had to use the 44 degree setting.

Using your example, you had an 88 degree corner. An ideal corner is 90 degrees, both sides 45 degrees. If the angle is less than 90, you will have to take more cut to get it to fold closer together. How much more is:

90-88 = 2 degrees 2 divided by 2 sides = 1 degree per side

the angle formed is going to be 46 + 46 = 92 , 180-92 = 88

I know it seems weird that you add angle to make it less than 90. Your thinking that when you set your miter to 46 degrees, that should give you

92 degrees, right? It is easy to see if you take it to extremes. If you mitred 2 boards at 0 degrees, you can see that would make a straight board (180 degrees) and if you mitered them at say 60, it would make a 60 degree angle.

I don't know if this helped or not.

[Chris]

Thanks it does help, though it's as I expected, sort of thinking backwards about it. I remember measuring an angle one time that was beyond the scale of my miter saw say 75 degrees, then I realized if I set my saw to 15degrees I could get it. The problem is it does not come naturally, it seems to require more thought than it should.

Thanks Chris

----- Original Message ----- From: "Bruce" Newsgroups: rec.woodworking Sent: Saturday, December 27, 2003 12:32 AM Subject: Re: Understanding Angles