Ok... I have been working on a project for a couple days now and ended up needing to cut a piece of 3" SCH. 80 pipe at a 45 degree angle. Now, I do not have any special tools... mainly just a grinder, portable band saw, and a sawzall. I am not a professional pipe fitter by no means so I had no clue how to achieve this. After thinking and thinking and pondering and pondering and searching online but only finding elaborate 30 step processes , I finally figured it out. So I wanted to share this piece on knowledge to the people who are ever in the same position as I was. What this will do is help people make a stencil / jig / template for drawing your line to cut on the pipe....
For example I am going to use my situation.
I needed a jig that would allow me to trace my cut line onto the pipe. So here we go.
Determine your O.D. (Mine was 3.5")
Now on paper Draw a box that is exactly O.D. x O.D. ( Mine was 3.5" by 3.5" )
See Step 1 Picture
Now Measure from bottom left corner to upper right corner ( My result was 5" )
By going from corner to corner we are actually creating a 45 degree angle.
See Step 2 Picture
Now the interesting part ... Draw a Oval that is Angle Length by O.D. Height ( Mine was 5" x 3.5" ) Now cut it out leaving the OUT SIDE PAPER AND NOT THE OVAL, this is part you need. Once done, trace the oval onto a piece of thin but stiff metal or plastic. Once again cut the center oval out but leaving the outside untouched. And thats it you have a jig. you can now slide the jig over the pipe and then **** it as far as it can go. you can trace a line onto the pipe and be ready to cut. this jig is reusable. the angle length is what allows you to **** the jig and get your angle if you change that length the angle will change with it. i hope you all enjoy this bit of info!