Equalateral triangle - Woodworking Talk - Woodworkers Forum
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post #1 of 64 Old 03-13-2012, 04:29 PM Thread Starter
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Equalateral triangle

Hi chaps, just a quick question what angle is used to mitre an equilateral triangle? Would I be right in saying 22.5 degrees? And by the way glad I found this site.
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post #2 of 64 Old 03-13-2012, 04:33 PM
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An equilateral triangle has 3ea 60 degree angles. Any triangle has a total of 180 degrees.

George
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post #3 of 64 Old 03-13-2012, 04:41 PM Thread Starter
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I understand that George, but what would the mitred angle be or am I thinking to much?
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post #4 of 64 Old 03-13-2012, 04:51 PM
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Are you trying to make a mitered equilateral triangle? if so, the angle would just be 1/2 of the angle of the triangle or 30 degrees.

That bowl was perfect right up until that last cut...
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post #5 of 64 Old 03-13-2012, 05:02 PM Thread Starter
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Cheers chaps I know it sounded basic but I tried it on the mitre saw and it didn't seem to work but I'll try it again, many thanks though.
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post #6 of 64 Old 03-13-2012, 05:38 PM
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Equilateral means all sides of the triangle are equal. If you cut three sides exactly the same length, with a 30 degree angle on each end, the three pieces should fit together. You actually have six cuts coming together so if you are slightly off, any discrepancy will be multiplied by six.
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post #7 of 64 Old 03-13-2012, 05:47 PM
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not 22.5 degrees!

The setting on the miter saw gives an actual angle on the workpiece of 90 degrees minus the setting. So if you want a 30 degree angle, you need a setting of 60 degrees...but that can't happen. So you can add a spacer block say at 45 degrees, and a saw setting of 15 degrees.

If you set the miter saw at 30 degrees you will get an actual angle of 60 degrees on the end of the workpiece. You need 30 degrees, on each mating piece for a total of 60 degrees when they are assembled into an equilateral triangle. Like stated above you need a spacer block:
Angles and setting on the miter saw

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post #8 of 64 Old 03-13-2012, 10:34 PM
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Quote:
Originally Posted by woodnthings View Post
The setting on the miter saw gives an actual angle on the workpiece of 90 degrees minus the setting. So if you want a 30 degree angle, you need a setting of 60 degrees...but that can't happen. So you can add a spacer block say at 45 degrees, and a saw setting of 15 degrees.

If you set the miter saw at 30 degrees you will get an actual angle of 60 degrees on the end of the workpiece. You need 30 degrees, on each mating piece for a total of 60 degrees when they are assembled into an equilateral triangle. Like stated above you need a spacer block:
Angles and setting on the miter saw
On my CMS, if I put a piece against the fence and set the saw for 30 degrees, that's the angle that gets cut on the end.






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post #9 of 64 Old 03-13-2012, 10:47 PM
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I know what you are thinking, Woodnthings but 90 is actually 0 on a miter saw. The saw swings both ways from that to 45 and beyond a bit on most saws. The 30 mark would be a 30 degree cut on a board. If the saw is accurate.
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post #10 of 64 Old 03-13-2012, 10:48 PM
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Quote:
Originally Posted by cabinetman View Post
On my CMS, if I put a piece against the fence and set the saw for 30 degrees, that's the angle that gets cut on the end.









.
I do not think that I have ever seen a miter saw that went past 45 degrees. Just how far around does yours go?

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post #11 of 64 Old 03-13-2012, 10:49 PM
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Originally Posted by GeorgeC View Post
Any triangle has a total of 180 degrees.
George
Yep... provided of course that our space is flat, or strictly Euclidian... The issue is not settled yet; but not to worry (at least in woodworking shop) : a possible difference could be less than one in many billions...
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post #12 of 64 Old 03-13-2012, 11:14 PM
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Quote:
Originally Posted by GeorgeC

I do not think that I have ever seen a miter saw that went past 45 degrees. Just how far around does yours go?

George
Mine goes past 45 to I think 48 or 50. But I can't remember. Oops That would be 30.

Al

Friends don't let friends use Craftsman. :)



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post #13 of 64 Old 03-13-2012, 11:38 PM
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Triangle

Alwood is right.
Euclid laid out the theorems for Plane Geometry. All objects in this study exist in a single plane, and also exist only in theory! They have only two dimensions, (x,y) aka length and width...but have no third dimension (z) aka depth or thickness, and therefore can't be physically "picked up"...only "slid" around in one plane, and hence are only theoretical, (but very useful) mathematical tools.
A short book (written decades ago), fairly easy read if anyone on this forum wants to enrich themselves with an interesting perspective (no pun intended) within a world based in only one plane and the short story of it's dwellers, and how they must move about.
The title of the novella is "Flatland", forgot the author, but can be found online used @ B & N, Amazon, etc.
Google (flatland), the book, not the Brooklyn neighborhood!
Hey forum, please don't send out the "guys in the white coats" to pick me up, as I already fear I'm on their RADAR ! LOL!
Best, Vinny

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post #14 of 64 Old 03-14-2012, 12:22 AM
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I have the answer, when I tell you this you will think it can't be that easy but it is. Take for example your putting molding and panels up the side of a flight of stairs. You get it all mapped out and you have some very sharp tight corners.

Here's the trick, with a bevel Gauge you determine the angle. Let's just say it reads 22.5 Degrees. You cut your molding to 11.25 but when you put it up it's way off. Frustrating You think what the Bleep the bevel gauge says 22.5 and I know how to divide by two.

Now here's the secret take a piece of 3/4 Plywood 12" x 12" and put it against the fence if your chop saw laying flat with one edge butted against fence. Now put your molding against the plywood edge also butting fence. Set saw to same as before 11.25 and cut. This gives you that long tapered cut your looking for.

This happens because the angle is obtuse. So by butting molding in at 90 degrees to your fence You accomplish the cut. I didn't have a pic of one of my stairs but this one gives the same idea


Equalateral triangle-image-3911394506.jpg
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post #15 of 64 Old 03-14-2012, 12:15 PM
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Quote:
Originally Posted by Lordy04 View Post
Hi chaps, just a quick question what angle is used to mitre an equilateral triangle? Would I be right in saying 22.5 degrees? And by the way glad I found this site.
Why and how did you arrive at 22.5?

Do you know how many degrees are in a triangle? They are all the same. Just divide that by 3
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post #16 of 64 Old 03-14-2012, 03:38 PM
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Setting a mitersaw angle

Quote:
Originally Posted by cabinetman View Post
On my CMS, if I put a piece against the fence and set the saw for 30 degrees, that's the angle that gets cut on the end.





.
Quote:
Originally Posted by Hammer1 View Post
I know what you are thinking, Woodnthings but 90 is actually 0 on a miter saw. The saw swings both ways from that to 45 and beyond a bit on most saws. The 30 mark would be a 30 degree cut on a board. If the saw is accurate.

What I'm trying to get at here is.... the angle that the miter saw is "set" to is what gets cut OFF, not what remains. You cannot make a 30 degree angle with the work against the fence on a miter saw without a spacer block.

You can get a 60 degree angle on the workpiece by setting the saw to 30 degrees, which is what will be cut OFF. The settings on the saw are NOT what you get on the end of the workpiece, they are what gets cut OFF. If you set it at 0 degrees nothing gets cut off, 10 degrees and 10 degrees gets cut off and so forth... leaving an 80 degree angle on the workpiece.

THe OP here needs a 30 degree angle on both of the mating workpieces to make up his 60 degree included angle, because there a 3 - 60 degree angles in the triangle totaling 180 degrees.

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There is no charge for the free advice, but you get what you pay for ... just sayin'

Last edited by woodnthings; 03-14-2012 at 07:35 PM.
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post #17 of 64 Old 03-14-2012, 03:43 PM
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To get a 30 degree angle

You need an angled spacer block against the fence to get a 30 degree angle on your workpiece. I used a bandsaw to freehand the cut here at 30 degrees. My miterguage has a 30 degree setting but it's an older Craftsman and the newer ones may not have that.

When you need a workpiece angle less then 45 degrees, you will need an angled spacer against the fence. In the photo below I need a 22 1/2 degree angle on the workpiece and used an angled spacer block of 45 degrees.

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Last edited by woodnthings; 03-14-2012 at 03:59 PM.
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post #18 of 64 Old 03-14-2012, 05:26 PM
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Quote:
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You need an angled spacer block against the fence to get a 30 degree angle on your workpiece.
I don't know if you've ever installed trim, or made a picture frame. But, here is a little test that you can do at home.

If you have stock that's lets say 3/4" x 3/4", set it on the miter saw table and against the fence. Set the saw to cut 30 degrees. Cut two of them. Then, stick the angled ends together and measure the outside (or inside) angle. What'd you get...60 degrees?

If I remember correctly, the last table I made as a hexagon (six sides) each outside angle has to be 60 degrees. The moulding I cut @ 30 degrees on each end to wrap the edge. Guess what...they all fit.






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post #19 of 64 Old 03-14-2012, 06:15 PM
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Quote:
Originally Posted by cabinetman View Post

If you have stock that's lets say 3/4" x 3/4", set it on the miter saw table and against the fence. Set the saw to cut 30 degrees. Cut two of them. Then, stick the angled ends together and measure the outside (or inside) angle. What'd you get...60 degrees?

If I remember correctly, the last table I made as a hexagon (six sides) each outside angle has to be 60 degrees. The moulding I cut @ 30 degrees on each end to wrap the edge. Guess what...they all fit.

.
That's what I said. You need to cut the pieces so they have a 30 degree angle on the ends, NOT 60 degrees as you see in the example you suggested. When you butt the two pieces with the miter saw set at 30 degrees resulting in 60's on the pieces, you get a 240 degree angle. The equilateral triangle has 60 degree included angles on the corners, which X 3 = 180 degress.

Notice the miter gauge is set to 30 degrees.
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post #20 of 64 Old 03-14-2012, 06:37 PM
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That's what I said. You need to cut the pieces so they have a 30 degree angle on the ends, NOT 60 degrees as you see in the example you suggested. When you butt the two pieces with the miter saw set at 30 degrees resulting in 60's on the pieces, you get a 240 degree angle. The equilateral triangle has 60 degree included angles on the corners, which X 3 = 180 degress.

Notice the miter gauge is set to 30 degrees.
What I said was 30 degrees on each end, NOT 60 degrees. Here is what I said, but using only two pieces:
Quote:
Originally Posted by cabinetman
If you have stock that's lets say 3/4" x 3/4", set it on the miter saw table and against the fence. Set the saw to cut 30 degrees. Cut two of them. Then, stick the angled ends together and measure the outside (or inside) angle. What'd you get...60 degrees?
Here's another little test for you. Using the table and the fence on the miter saw, cut 3 pieces with a 30 degree on each end...all the same length. Then fit the ends together. What do you have...AN EQUILATERAL TRIANGLE.






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