Cutting Mitered Ends on Pipe

I've got some manifolds that I need to make up. They will be made from 3 1/2" pipe.

I've got a DoAll 500SNC saw to cut the miter joints. Luckily all the miter joints are on a 45 degree angle.

The ones where I'm drawing a blank are the ones where each end is mitered. Sometimes the mitered ends are perpendicular to themselves too.

So how do you keep your angles lined up? Tack a piece of angle iron to the pipe before you start? Thus establishing a "plane" you can refer back to (as in measure or level off of)?

Do you eyeball a weld seam on the pipe and go from that?

Lots of the searches I do turn up results to cope pipe. I'm not looking for that. I can make the cut, I'm just not sure how to hold the orientation of the pipe. Ideas welcomed.

Well, there are a few ways to do it depending on how fussy you want to be.

You can time off the first cut with a square or protractor.

You can make a block that slides over the pipe with a set screw. Load the pipe,square up the block and make the cut. Then time off the block on the next cut.

You can buy (or make) a tube rotation gauge that will accurately index the tube so long as you can find a spot to leave it clamped on between cuts. Just search tube rotation gauge in a search engine. They are super simple, and handy to have.

If your saw is well leveled, you could also just get away with using a torpedo across the first cut in a pinch I would think. Though that will take a bit of finesse if you need great accuracy.

I used to do a lot of pipe cutting...

By far the best method is put two pipes above each other and tack weld the ends together and put a few tacks every couple feet to keep them from twisting. To do opposing angles, just flip the pipe upside down.

Now you're twice as productive and dead accurate.

Not long ago I had to make up some pipes with three mitered joints in them. They were not as big as yours but they were 2". I tried pre-cutting the miters and just couldn't get them to fit good enough to mig. I ended up c-clamping the pipes with the proper angles to my welding table with the ends blocked up to come level with my chop saw. I then ran the blade into the joint between the two and kissed both ends just enough to match them up. It worked quite well.

are you talking a cold saw?-any pics of how you got the 2 pieces in the vise?-thanks,pat

Before your first cut, clamp a V block to the pipe and level it. For the second cut, level or plumb as appropriate.

I have a Miracle Point clinometer. It has a pointer in the center of vee, with a 360 degree reading clinometer. You just align the pointer with a center punch mark. Simple to align, or index the pipe to a degree.

Flange Wizard has a similar tool. If you aren't familiar with Flange Wizard's stuff for pipe, you need to look at their site.

You can do the same thing with a centering head and square head from a square set. You just align the center edge of the rule with a punch mark and use the bubble in the square head for plumb.

I do a lot of long shafts that have to have keys in them that are in line.
Some longer than I have the travel for. Also some with keys that are off
at some other angle.

I use one of these. Starret angle meter.

Starrett AM-2, 0 to 90deg Magnetic Angle Meter - AM-200 - Penn Tool Co., Inc

Just use something that can clamp onto the pipe that has a flat surface and is
magnetic. When doing smaller shafts, I use one of those little 2" tool makers
vises.