Looking for a math whiz

[Skinny Shooter]

I'm making trivets and need to locate three legs in the circle.
The center is not known. Here is a sample of what I'm working with. The ring is approx 8" across and is made of 3/4" flat stock.

http://i141.photobucket.com/albums/r78/skinnyshooter/Trivet1.jpg

I used a cloth tape measure to figure the OD and then located the legs shown in the photo.
There has to be an easier way. Have thought about using a triangle to find the three points.
thanks.

[gumpokc]

easiest way i know of....

you need a protractor, ruler, and something to mark with.

measure top/bottem, left/right to find center point from inside of circle.

lets say your staring with 0 degrees.
place far left end of proteactor at 0, use ruler to run out from center at 120 degrees, mark spot, relocate protector, remark at 120 again, the repeat for third spot. wala all done.

or you can eyeball it, just depends how accurate you want it, but for three points, each mark is 120 degrees from the other two.

so one mark at 120, 240 and 360/0 degrees.

[huntingvet]

Figuring 8" across equals 8" diameter which equals 4" radius. Circumference (or total distance around the circle) is 2 x pi x r = 2 x 3.14 x 4" = 25.12" or roughly 25 1/8". 3 equal distances around the circle therefore would be 25.12 divided by 3 = 8.37" or roughly 8 1/3 inches. I doubtyou needed it that technical!

[Swift]

Eyeball it! :D

[Skinny Shooter]

Originally posted by gumpokc
easiest way i know of....
you need a protractor, ruler, and something to mark with.
measure top/bottem, left/right to find center point from inside of circle.
lets say your staring with 0 degrees.
place far left end of proteactor at 0, use ruler to run out from center at 120 degrees, mark spot, relocate protector, remark at 120 again, the repeat for third spot. wala all done.
or you can eyeball it, just depends how accurate you want it, but for three points, each mark is 120 degrees from the other two.
so one mark at 120, 240 and 360/0 degrees.

I understand marking a point every 120 degrees.
So no matter what size protracter I use, the ruler should be laid across the top of it and just follow the ruler out to where it intersects the material?
I want to do this fast with minimal movement.
I'll look for a 360 degree protractor and then make a "jig" or pattern with a known center and 3 lines running out at 120 degree intervals. It can be printed on heavy paper.The ring would get laid on top of the paper and then make my marks that way.
I also make three-legged candlestands that can have a spread of 24" or so.
Once I get the correct dimensions for that, I'll make a metal jig for the feet to lay on and will use that for the correct adjustment.

Most of my blacksmithing is done by eyeballing the work but this part needs to be a bit more precise.
thanks for all your help,
Allen

[toxic111]

I could probably create a pdf for you that would have the centre point, and the angles come off it for a template.... and you could always have it blown up to any size as needed, if you like.

[muledeer]

Just eye ball it and call it "Skinny's fubar trivet":D
muledeer

[Skinny Shooter]

toxic111, that would be great and I'd much appreciate it.
Yeah thanks MD, could I consult with you when I need to name some other items? ;)

[toxic111]

No problem Skinny.. I will get it done tomorrow... it won't take too long... I will send you a couple different sizes.. a 11x17 & 8.5x11.. the 11x17 you should be able to get printed at a copy centre if needed...

[Skinny Shooter]

thanks, I have a 44" epson printer in house that will work.

[toxic111]

Hell how big of template do you want then.. I can go as big as you want!

[gumpokc]

thats just the way i would do it.
You may have fun finding a 360degree proteactor, most are 180degrees, but as mentioned simply reposition and remark.

once you get it setp, you should be able to plot the leg positions in around 30 seconds for each unit. it's really easy .

[toxic111]

Skinny, I have your template ready... but need your email address...

[Swift]

We have a perfectionist in our midst.

[Skinny Shooter]

Shhh, who is it :confused: :D

[PaulS]

I am coming to this a bit late but here is an easy and accurate way to get 3 or six positions for any circle.

Mark a center point on a paper that is lager than your circle.

Draw a circle using a compass (a divider with a pencil) close to the size that you are going to put the legs on.

Mark a point on the circle to use as a new center

Using the same compass set at the same radius that you used to draw the circle make a mark that crosses the circle on both sides from the marked point on the circle

From each of those marks use the compass to mark another mark toward the unmarked area.

From those two marks use the compass to make a new mark - they should end up in the same place if you have been careful and the compass didn't move.

You end up with a center point and six equally spaced marks around the circle. All you have to do now is draw straight lines from each oposite side of the circle through the center point and you have six lines from the center out - equally spaced.

Use that as a template to mark your work and you have equally spaced legs.
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MARIJUANA PICTURES (http://trichomes.org)