How do you determine angles? - Woodworking Talk - Woodworkers Forum
Old 01-09-2016, 01:27 PM Thread Starter
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How do you determine angles?

When making edging ... How do you determine what angle to cut at to make the two fit together at the angle?

I'm new and can not figure out how to do this.
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Old 01-09-2016, 02:29 PM
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first determine the angle ....

You must determine the angle first. Then you bisect it, then divide it into two equal parts. You will need to know the number in degrees ... which is what you set your miter saw to. For example for a 90 degree corner, the most common, the miter saw is set to 45 degrees, or 1/2 of 90 degrees. A 45 degree corner would have 22 1/2 degrees per piece.

Now is where it gets interesting... there is no setting on a miter saw for 22 1/2 degrees. Miter saws are scaled to cut the amount subtracted away from 90 degrees.

For a complete and through discussion of this go here:
'http://www.woodworkingtalk.com/f27/angles-setting-miter-saw-9644/

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)
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Old 01-09-2016, 03:10 PM
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My old (1985) 10" Delta miter saw actually has pin stops at 90, 22.5 and 45 degrees. It was cutting crown molding upside down and backwards that jiggled my tiny brain.
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Old 01-09-2016, 03:13 PM Thread Starter
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Thank you both.

My main question is, HOW do you determine the angle?

For example, how do you look at a wall or box you are trying to trim, and know, that is a 60 degree angle?

Where do you get the 60 from? How do you determine that?
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Old 01-09-2016, 03:22 PM
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Originally Posted by Microscopes View Post
Thank you both.

My main question is, HOW do you determine the angle?

For example, how do you look at a wall or box you are trying to trim, and know, that is a 60 degree angle?

Where do you get the 60 from? How do you determine that?
A protractor would help in that case

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Old 01-09-2016, 03:41 PM Thread Starter
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Originally Posted by epicfail48 View Post
A protractor would help in that case
OK i guess i'm screwed haha.
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Old 01-09-2016, 04:11 PM
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Do you have one of these:
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Old 01-09-2016, 04:35 PM Thread Starter
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Do you have one of these:
I do not, but I could buy one.

How does it work?
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Old 01-09-2016, 04:55 PM Thread Starter
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I found this: http://www.homedepot.com/p/Husky-5-i...822H/206007248

Seems like it would work well for me.

So... For a miter saw. If I have an angle of 90 degress. Half of that is 45 and then 22.5. You then subtract that from 90 = 67.5.

So for a 90 degree angle, you set your miter at 67.5 ... correct?

Last edited by Microscopes; 01-09-2016 at 04:58 PM.
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Old 01-09-2016, 05:15 PM
where's my table saw?

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Quote:
Originally Posted by Microscopes View Post
I found this: http://www.homedepot.com/p/Husky-5-i...822H/206007248

Seems like it would work well for me.

So... For a miter saw. If I have an angle of 90 degress. Half of that is 45

and then 22.5. You then subtract that from 90 = 67.5.

So for a 90 degree angle, you set your miter at 67.5 ... correct?
Bisect means divide in half... stop there.

You need an adjustable protractor something like this:

http://www.ebay.com/itm/General-Tool...59684866&rt=nc

You had it correct and then went bonkers....

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)

Last edited by woodnthings; 01-09-2016 at 05:19 PM.
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Old 01-09-2016, 05:20 PM Thread Starter
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Originally Posted by woodnthings View Post
Bisect means divide in half... stop there.

You need an adjustable protractor something like this:

http://www.ebay.com/itm/General-Tool...59684866&rt=nc

You had it correct and then went bonkers....
Haha bonkers!

Ok thank you!
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Old 01-09-2016, 06:49 PM
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Use your T-bevel, one leg on each piece you're trying to find the angle of to get the included angle.

Then take a look at this: http://strader.cehd.tamu.edu/geometr...sectangle.html to bisect that angle.

Set the T-bevel to the bisected angle and use it to set your miter saw.

"If I agreed with you, then we'd both be wrong!"
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Old 01-09-2016, 08:06 PM
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I use, and recommend, a digital protractor like the Husky linked to above.

I guess the one 'obvious' thing to keep in mind is when you make an angled cut in a straight board, you are essentially generating two angles - one angle on the board you keep, and another angle on the scrap.

Now, on a simple 45, you make essentially the same angle in each piece (of course, the orientation is different, if the board has a molding along one edge).
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Old 01-09-2016, 09:06 PM Thread Starter
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Ok bought the protractor, and it has 2 readings.

132 inside
237 outside

At the risk of sounding very stupid, which do I use??

This is what I am trimming?

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Old 01-09-2016, 09:07 PM Thread Starter
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THANK YOU to everyone by the way. It means a lot that the advanced woodworkers are willing to take time out of their day to answer amateur questions.
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Old 01-10-2016, 06:21 AM
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Originally Posted by FrankC View Post
Do you have one of these:
One of these is a must in any shop....
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Old 01-10-2016, 10:31 AM
where's my table saw?

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OK, it's greater than 90 degrees...

For an example you can't fit a cardboard box in the intersection....NOPE. So it's more than the 90 degrees like on the corners of a cardboard box. Then what? How much more? Well, a straight line would be 180 degrees or zero degrees of angle. It's less than that... RIGHT. So, it must be the 132 degree for the interior angle, which is "obtuse" or more than 90 degrees. An "acute" angle is less than 90 degrees, like 45 or 30 degrees.... FYI.

I recommend a "digital" protractor like this:
http://www.ebay.com/itm/7-Electronic...MAAOSw8lBTq1nA

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)

Last edited by BigJim; 01-10-2016 at 06:06 PM.
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Old 01-10-2016, 05:53 PM
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One other thing to do is to use a board or just a piece of paper to eyeball (and mark) what the general cut should look like. You'll only use this to confirm your exact angle is in the ballpark.

If you need to, lay it out with two overlapping pieces of paper (one on each wall) so you can visualize what the cut should look like.

You can also set your protractor to 1/2 of 132 degrees (66 degrees) which should be your miter cut. Use your protractor to set your miter saw (assuming that is what you are using). If you are using about a 5" digital protractor, like the one linked to above, it will fit in/around a miter saw so you can set the angle on the saw from your protractor. It would be harder to do with the other (non-digital) ones shown.

By the way, there is some error in your measurement, as the inside and outside angles should equal 360 degrees (the number of degrees in a circle). Adding your 132 inside plus 237 outside equals 369 degrees. Something there isn't quite right.

Last edited by pweller; 01-10-2016 at 05:56 PM.
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