Best way to cut pipe at an angle?

[Fxfymn413]

Hold the beam in place with jack stands and follow the line it creates on the post.

 

[bigtiller]

Tan table. Readily available on the internet.

tangent(9°) = 0.15838	tangent(25°) = 0.46631	tangent(41°) = 0.86929
tangent(10°) = 0.17633

draw a straight line one inch long. Add A vertical line .15838 inches high. Connect the start of line to the top of vertical line and you will have a 9 degree angle. Lay it out larger on a piece of wide tape and wrap on the pipe to be cut.

For 9.5 degrees extrapolate between 9 and ten degrees.

Thanks Egon. I had no idea what a tan table was. I'm glad you came back to explain it some. I printed out the first table that came up in my search. MAN, I wish I would have had something like this chart decades ago.

Now I can make any angle I need without guessing...Now to start saving template material.

 

[LD1]

Thanks Egon. I had no idea what a tan table was. I'm glad you came back to explain it some. I printed out the first table that came up in my search. MAN, I wish I would have had something like this chart decades ago.

Now I can make any angle I need without guessing...Now to start saving template material.

If you have a smart phone, or even a $8 scientific calculator....they have sin, cos, tan functions.

If you are building or dealing with angles (triangles)....getting good at the three functions is priceless

 

[bigtiller]

If you have a smart phone, or even a $8 scientific calculator....they have sin, cos, tan functions.

If you are building or dealing with angles (triangles)....getting good at the three functions is priceless

I liked and was good at math in high school, I can still spout off the multiplication tables without thinking about the answer. But I stopped at algebra in my junior year. Spent my senior year in the shop building.

I have no idea what those 3 functions mean or what they can do.

 

[LD1]

I liked and was good at math in high school, I can still spout off the multiplication tables without thinking about the answer. But I stopped at algebra in my junior year. Spent my senior year in the shop building.

I have no idea what those 3 functions mean or what they can do.

I think this is fundamentally where the education system let so many people down

They tried to teach the stuff with no context or how it can apply to the real world.

Basically, what sin, cos, and tan can do is give you the missing angles of a right triangle if you know two of the sides.

Some people use the tables, and that's fine....but if you have a calculator...you can be exact.

In the OPs example.....9.5 degree angle....you can punch into your calculator...9.5tan. (or some calculators tan9.5=)

That will give you 0.167. that is basically the ratio of rise/run in a right triangle. So it don't matter if the run is 3" or 30'....multiply that by 0.167 and you can find the rise height to equate to a 9.5 degree angle.

And you can do that with ANY angle.

Or....you can find the angle if you know the rise and run. For example....what's the angle of a 4/12 pitch truss. (Useful for setting a miter saw or cutting truss tails, etc. 4÷12 = .333 so you can use the calculator or tan tables and see what angle = .333. which happens to be 18.4 degrees.

You can do that with any pitch roof. Or any thing else you want to know the angle of.

Since tan is just the relationship of rise/run (or opposite and adjacent sides of the angle your are working with)

Sin and cosine are the relationships of the other two sides. Sin is the opposite side and the hypotenuse. Cosine is the adjacent side and hypotenuse.

Then comes the old Pythagorean theorem. A²+B²=C² this is derived from the law of cosines. Lots open people learned this in school but didn't retain the info because they lacked the real world connection and how they would ever apply it.

But let's say you have a 30' truss with a 4/12 pitch. How long are the roof panels you need to order for the building. Can you figure it without waiting til the trusses are on site and measuring them?

I use this stuff daily. But I build alot of things with both wood and metal. Anytime you have to deal with angles....the knowledge of sin, cosine, and tangent are priceless

 

[Egon]

Thanks Egon. I had no idea what a tan table was. I'm glad you came back to explain it some. I printed out the first table that came up in my search. MAN, I wish I would have had something like this chart decades ago.

Now I can make any angle I need without guessing...Now to start saving template material.

No problems. The tan was often used to make angles when drafting without the use of a protractor. Quick and easy. Of course, if six figure log tables got involved it could be tedious!

magnetic stick on sheets may work well for templates.

 

[tomplum]

I liked and was good at math in high school, I can still spout off the multiplication tables without thinking about the answer. But I stopped at algebra in my junior year. Spent my senior year in the shop building.

I have no idea what those 3 functions mean or what they can do.

That was me too. Algebra? I told the teacher I figured I needed this crap a) if I was going to be an engineer or b) an Algebra teacher- and I intended to be neither one. I still whip through numbers in my head to the amazement of my other half. We've built many specialized things with specific angles. Solar greenhouses, trapezoidal buildings, etc. etc. etc. She's the calculator and spreadsheet queen and fortunately for me- she's good at it. With out her it's measure, measure, cut, recut...Hopefully for the OP, he's a great out of position welder up in the air. I get good at it again, once I'm near the end of the project!

 

[lostcause]

it's never too late to learn new skills. i entered the work force a few years before the internet age and before the pc was a household appliance. everyone on here who is my age or older learned to use a pc well after they were in school. For some it may have been necessary for a job, but for a lot it was a desire to learn it for their own usage. the same is true with any sort of math. if you want to learn something, you can. it's even easier now because you have every possible online resource at your fingertips.

back to the original topic... i just googled and came across this:

looks like the same thing i showed above. mostly just projection of lines - very little math needed.

 

[rScotty]

I liked and was good at math in high school, I can still spout off the multiplication tables without thinking about the answer. But I stopped at algebra in my junior year. Spent my senior year in the shop building.

I have no idea what those 3 functions mean or what they can do.

I know what those functions are because I sort of learned them... but I hear you. The trick to getting through arithmetic class is to sit at the back of the room drawing goofy cartoon characters and counting how many times the teacher says, "pay attention".

Math teachers all show you how to do the problems in class anyway. Math isn't thinking, it's doing...same as welding. When it comes test time, just do it like they showed in class.
rScotty

 

[BravoXray]

I liked and was good at math in high school, I can still spout off the multiplication tables without thinking about the answer. But I stopped at algebra in my junior year. Spent my senior year in the shop building.

I have no idea what those 3 functions mean or what they can do.

I liked math in school, it was a good thing, because my 6th grade teacher, Mr. Hershberger, loved to give us pages full of multiplication and long division problems. I hated them at first, but eventually started enjoying doing them. The other kids thought I was crazy. After that, geometry and trigonometry were pretty much a breeze. I still like solving math solutions to practical problems just like this thread involves. I even liked algebra and still occasionally use it to solve some problems. I'm even working on how to manually solve square roots, that has a lot of practical applications.
But when I got to college and into calculus class, I really struggled to make it through the first semester. I just never "got" calculus, I read several books on it, even one just recently on the history of calculus, but it just never soaked into my brain.

 

[ROUSTABOUT]

I'm down in oilfield counytry. Y'all are giving some complicated info.

Just shoot with a transit on every post and establish level. Pipe is metal, so magnets are your friend. You can put a magnet on your mark and measure up from that. Figure your pitch and Mark the thing. Like stated earlier, take a piece of cereal box and use it for a wrap around. Cut a short piece of pipe with your angle. Wrap the paper around the pipe and let it hang over an inch or so. Mark around the inside of the paper and follow the angle. Unroll the paper and cut your line. Bottom should remain square and line the edges on bottom each time so your top will be the same. I have long gooseneck trailers built out of pipe except for the steel on floor and the hitch. Trailer for hauling pipe. Shop is 36x48 and framed with pipe. C purlin and tin. I've used many joints of pipe in my life. I'd cut it with a torch. We just show up in a welding truck and build it. Built my brother a 60 x 80 with 26' ceiling. But it was a lot of I beam.

 

[gsganzer]

I wish I had the time to sketch it or a photo to show you another way I've seen it done. I've seen them notch the vertical pipe by cutting halfway through the diameter and then removing the notch material by cutting straight vertical with a cut-off wheel, so your truss will rest on the shelf of the remaining diameter. This lets you still slightly adjust the angle of the truss and do a vertical, rather than overhead weld.

I hope that makes sense, I'm in the middle of cooking dinner.

I was just at the deer lease and snapped some photo's of what I was trying to explain.

 

[LD1]

I was just at the deer lease and snapped some photo's of what I was trying to explain.
View attachment 730741View attachment 730742

That's definitely a better option for channel.

But wouldn't work too well for I-beams which the op said he was gonna use.

Perhaps it's not too late for him to change and go channel iron?

 

[jigs_n_fixtures]

Trigonometry for the trades, in terms of rise, run, and slope distances:
Tangent = rise/run, Sin= rise/slope, Cosine =run/slope.

But you don’t need trig. This is baby math.

The diameter of your pipe is 2-7/8-inch = 2.875 inches.
Your slope 2/12
Thus your rise in the 2.75 inches is: rise/2.875=2/12; rise= (2*2.875)/12
= 0.479166666. Or, approximately 1/2-inch

Mark a level line around the pipe at grade. measure up 1/2 inch on the inside

Run a piece of tape from the 1/2 mark around the pipe to the grade on the outside, as close to straight as you can get it.

Cut the pipe off, following your tape. Cut so any error is to the high side of the 1/2 mark.

Get an adjustable bevel gauge, and set it to the 2/12 pitch. Touch up the cut with the grinder until the bevel is clean across it.

tip: Get teh high point set with teh bevel gauge, and don’t worry about the sides. Then grind the sides till you get a sheet of polycarb to lay flat cross the beveled cut. You can buy the polycarb in 8X12 pieces as replacement window glazing at most big box or hardware stores. The clear poly carb lets you see your high points, and how close you are to teh tip.

 

[Egon]

Templates:
Drawing it out on the flat and then wrapping is the same thing only faster and more accurate.

Baby Math=???

 

[jigs_n_fixtures]

Baby Math=???

Calculus is “Big Kid” math.

Differential Equations, Numeric Analysis, Vector Calculus, and Calculus based Statistics, (basically all the 400-level, two semester sequence classes), are bigger kid math. You don’t get Adult Math until grad school.

 

[Egon]

Calculus is “Big Kid” math.

Differential Equations, Numeric Analysis, Vector Calculus, and Calculus based Statistics, (basically all the 400-level, two semester sequence classes), are bigger kid math. You don’t get Adult Math until grad school.

Hmmm

http://www.edu.gov.on.ca/eng/curriculum/secondary/math1112currb.pdf

 

[MoArk Willy]

I have a small Klutch table top band saw. I suspect the vise would support the saw if I wanted to hang it on a pipe.
Then I can adjust the angle while it's hanging there....or set it up before attaching it.
If the vise can securely hold a 3" piece of tubing it can certainly hold the saw in place on a piece of pipe.