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View Full Version : How do you measure pipe to put three legs on it?

Humbertslawncare
05-13-2012, 08:57 AM
If you have a piece of 1" or 2" pipe that you are using to put a sprinkler head on, how do you figure out where to mark and put three legs on it, so that it will stand up in a field. I can look at the pipe and can not figure out the right way to place three flat bars or 1/2" tubing to make it right. Just like building home made jack stands, how did you fugre out where the legs were spaced out on the main pipe or tubing? I have been fitting and welding structual steel for 18 years, but I have never worked with pipe. Thanks in advance for your help.

DSW
05-13-2012, 10:08 AM
If you want to make a 3 legged item equally spaced around a round pipe, you dived the 360 deg of a circle by 3 giving you 120 deg between each leg. I usually rough a scale drawing out on my table where I want the legs to fall around the center and use that to help position the legs for tacking.

WyoRoy
05-13-2012, 10:08 AM
Cut a piece of paper to wrap around the pipe, come in 1/4 of the way on each end of the paper and place a mark at each location. Wrap the pipe and mark where the ends meet and the two 1/4 way-in marks and you'll have the pipe marked out for 120 degree placement for your legs.

Farmerboy
05-13-2012, 10:19 AM
circumference is diameter times 3.14 then divide that by three, I would most likely use the paper method that was stated above, that way you can Mark out a few locations and even at top and bottom point so they all line up on the pipe, (the paper is just a flexible rule), I like the use of paper dry wall tape.

to get a straight mark on the pipe, lay the pipe down put a block of some thing along side of the about 1/2 the height of the pipe and mark it , it should be straight if your block and pipe are on a flat surface,

Humbertslawncare
05-13-2012, 10:48 AM
Thank you all very much. You all make it sound and look simple. I am going to get working on this now. Thanks again and have a great day.

BD1
05-13-2012, 09:02 PM
If all you want to do is make a pipe stand for the head ; take the length of two inch pipe and divide into thirds. Then mark at the height you want the legs the long way.If you want legs about 24''.mark at 30". Cut the line with cutting wheel to desired height. Heat at height mark end of cut and separate pipe into three pieces that will be the legs forming the tripod. Then you just add steel to base to hold together, rebar would work too.

Warpspeed
05-13-2012, 09:53 PM
I would get an ordinary compass and set the legs say an inch apart, to draw a two inch circle (for two inch OD tube). Draw the two inch circle on a piece of paper, then go around the circumference of the circle, and divide the circumference into six equal parts using the compass at the same setting. With a ruler you can then draw lines from the center out in six equal sixty degree lines. Three of those lines will give you exactly what you want.

DSW
05-13-2012, 11:03 PM
I would get an ordinary compass and set the legs say an inch apart, to draw a two inch circle (for two inch OD tube). Draw the two inch circle on a piece of paper, then go around the circumference of the circle, and divide the circumference into six equal parts using the compass at the same setting. With a ruler you can then draw lines from the center out in six equal sixty degree lines. Three of those lines will give you exactly what you want.

A simpler way is to simply run a straight edge thru the center of your circle drawing the center line in my original drawing and then using a 30 / 60/ 90 triangle to draw a line to center 60 deg on each side of the original line.

I keep an old cheap drafting square ( a drywall square works well for larger stuff.) and a 30/ 60 triangle as well as a 45 deg triangle by the tool box for layout.

Sandy
05-14-2012, 12:35 AM
Sneak into the house, find your wife's sowing stuff, get that neat cloth tape they use for their sowing, put that in your pocket and get back out to the shop. Now wrap that nice flexible cloth tape around your pipe and make three equal distance marks.

Hide that tape in one of your secret hidy holes because she'll catch ya trying to sneak it back into her stuff. :)

That's what a guy told me he did anyway. He says it works great for pipe.

Scott Young
05-14-2012, 02:03 AM
Sneak into the house, find your wife's sowing stuff, get that neat cloth tape they use for their sowing, put that in your pocket and get back out to the shop. Now wrap that nice flexible cloth tape around your pipe and make three equal distance marks.

Hide that tape in one of your secret hidy holes because she'll catch ya trying to sneak it back into her stuff. :)

That's what a guy told me he did anyway. He says it works great for pipe.

:laugh:yep the last time I got caught was when i was trying to sneak something back into her goodies.

denrep
05-15-2012, 12:20 AM
This is really simple, but difficult to explain. I was gonna try to just say it, but I figured some pictures would help.

About everything described above will work, but the methods may require more tools and memory than you may have the next time the need to divide a circle arises.

So I suggest to simply remember that at it's most basic aspect the layout of locating the three legs is the same as centering over a circle with a triangle which has all three sides of equal length, an equilateral triangle.

I know that you know that drawing a 24" line over a steel L square, from one leg's 12" mark to wherever it lands on the square's other leg (20.79") mark) would create a right triangle, with one 24" side and one 12" side, which is half of an equilateral triangle with all three sides being 24" sides. Thus, flipping the square 180 degrees and again connecting a line from 12" to 20-3/4" (okay, 20.79") would create a completed equilateral triangle.

But who's gonna remember all that?
Although you can remember that all three sides of an equilateral triangle are the same length, and that basically you are creating an equilateral triangle to be centered over a circle. And since 24" levels and rules are common, you also can remember that half of 24 is 12.

So...
1) Split the circle at it's largest diameter with a line and rest a square against the line; center 10-3/8 (close enough to half of 20.79") at the circle's center. In my example the square's heel happened to land almost on the circle's edge, so that it would rest in place for the picture.
2) Using a 24" long rule, or whatever you have handy that's 24" long, connect the 12" mark on the square's short leg, to wherever the other end of the 24" thing lands on the square's long leg. (Hint - it'll land at 20.79" exactly, but you don't need to remember that.) You've just drawn A-B, of an equilateral triangle.

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3) Now, flip the square and repeat connecting 12" to 20.79" or again simply wherever 24" happens to land on the long scale. Hint - it'll be 20.79" exactly, again.
4) You've just divided the circle into three equal parts.

Confirm accurate centering by comparing a few points.

Of course for dividing larger or smaller circles you can apply the exact same principles of starting with a right triangle with one side being the same length as the final equilateral triangle's sides, and one side being half the length of the final triangle's sides. If you happen to have access to two L squares and two same-length things, this can all be laid-out without the flipping.

It's not as complicated as I made it sound. :laugh:
So if anyone has a simpler way to describe it, chime in.

Good Luck

denrep
05-15-2012, 09:00 AM
Stop the presses! That's wrong.
I just realized that I goofed, when I had shifted the square so that it would rest on the circle for the picture taking.

The above description will draw an equilateral triangle, but to center the triangle with the circle the 12" mark needs to be placed at the circle's center during layout.

Apologies to everyone who's circle dividing work was messed up last night. :blush:

Good Luck

papaharley03
05-15-2012, 12:12 PM
Use a compass to draw a circle on paper the same diameter of the pipe. Use a straightedge aligned with the center mark left by the compass to bisect the circle. Use protractor with straight edge placed against the line you just drew. Make a mark at the 120 degree line. Flip the protractor to face the opposite direction and repeat another mark at 120 degree line. You now have your layout line to transfer to the pipe. This is how I marked fuselage for attaching balsa fins when I built model rockets as a kid.

Papa

Insaneride
05-17-2012, 08:28 PM
Will this work as a template or something?

Warpspeed
05-17-2012, 08:38 PM
Yup, compass method is the easiest.

denrep
05-17-2012, 09:50 PM
Lots of ways to skin this cat, interesting to see 'em all.

So far though I think that Sandy's suggestion to use a tape to measure the circumference and then divide by three is the simplest and most practical for the legs-on-pipe application.

Good Luck

Insaneride
05-19-2012, 02:26 PM
denrep, I like your method as it has its real world advantage's. I couldnt get it to work for me. The compas method has its disadvantage like, how would you apply it to the op's project? My only solution would be to trace it out on cardboard or a 5 gal bucket lid and cut the center out to fit over the pipe. Can you rexplain your process?

Humbertslawncare
05-19-2012, 02:44 PM
Thank you to every person that responded to my question. You guys gave me a lot of different answers and they all are great. I used the method that DSW told me about and it worked great. I am going to make more and use the different methods that are on this thread and see if I can do them as well. One more question, where I can info on how to use a pipe wrap around, I searched and did not find anything.

BD1
05-19-2012, 03:28 PM
Not sure what you want to know but check this.

http://www.shopfloortalk.com/forums/showthread.php?t=27516

denrep
05-19-2012, 08:35 PM
. . .Can you rexplain your process?
Me? Not very well. :laugh:
But I'll try again.

For our purposes today in most basic geometric shapes we want to end up with an equilateral triangle sized to center over a circle (pipe) with three points spaced at 120 degrees on the circumference of a circle, ideal for locating three mounting legs.

This time lets start out with no shortage of squares and 24" levels and soapstone:
A - We start out not knowing anything except a future center point and a line drawn through it.
B - At B we locate 12" on each square's short leg at center point. Then draw a line from short leg's 12" mark to wherever the 24" level lands (20.79) on the long legs.

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C - The 12"-to-20.79" lines drawn in step B, along with the original line in A, gives us 120 degree spacing marked off.
D - Any size circle centered this way will of course be equally divided in three parts.
E - Basically, dots connected, it's an equilateral triangle centered over a circle.
For a quicky you can just slide three rules around to end up with three equal length sides.
For a "longie" when there's a shortage of squares and rules, of course each mark can be made separately by relocating one square.

Good Luck

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Okay, but you'd better not lose my work. :angry:

Insaneride
05-22-2012, 02:55 PM
Thanks for xplanation denrep. I havnt had a chance to try it but, from what it looks like, 12 and 20.79 are the magic numbers for the equilateral triangle method. Right? Or in other words, for 24 I would use 41.58?
What I mean is, for any other size, I would use the ratio 12 : 20.79? Right?

denrep
05-23-2012, 08:59 AM
For most shop layout work some calculations are just too much to cipher and to remember, with formulas ratios and angles and degrees and minutes and such. I prefer to keep things as simple as possible.

For example: Insaneride wants an equilateral triangle with 24" sides... We know that bisecting such an equilateral triangle from one point to another side's 12" mid-point would leave two identical right triangles, placed back-to-back. So of course the triangle splitting can be reversed to create an equilateral triangle from two identical right triangles, placed back-to-back.

Then... if Insanerides's goal is an equilateral triangle with 24"sides, we could start by using a square to draw a right triangle with one 24" side, and one 12" (half of a soon-to-be 24") side, and then close the third unknown side with whatever length line it takes to complete the triangle. Then at the unknown side, "mirror" this right triangle with another identical right triangle, so that the two 12" sides join to make one 24" side, and of course the other two 24" sides will complete the equilateral triangle.

Presto! No math protractor nor degrees involved, the result is one true equilateral triangle, with 24" sides - guaranteed.

And of course the same principles can be applied to any size triangle desired .

Good Luck