How to cut angled holes in PVC pipe?

Question

I need to join different sized pipes together at a 45 degree angle, but am struggling when it comes to what methods are available.

The main pipe is 75mm radius, the smaller is ~40mm. I've opted to 3D print the smaller pipe, so I don't need to worry about messing with that at all.

As you can see it's an awkward shape due to the curvature of the main pipe, plus I'm worried about warping the cut by putting excess weight on it. The only method I've come up with so far is using a pair of hand nibblers, but I'm not sure how well they'd work on a curved surface.

Any ideas / suggestions? (I need to do a few of these joins, and the cost of pvc saddles a bit silly).

Answer 1

The appropriate way would be to:

• Make a jig out of wood that will hold the pipe to be drilled
  • The jig could be flat or have the desired 45° angle built into it.
  • Building it flat allows it to be used for drilling holes into pipe at any desired angle in the future, making it more useful
• Clamp the jig to the table of a drill press.
  • Either have the drill press table level (for a jig with the angle built in) or tilt it to 45° (for a "flat" jig).
• Drill the hole with an appropriately sized bit.
  • I would use a hole saw from a set with a replaceable pilot bit.
  • Replace the supplied bit with a long one that will reach the pipe before the edge of the cutter will reach it.
  • Use the long pilot bit to ensure that the center of the hole is where you want it to be.

A hole-saw set like this:

^{image courtesy of lowes.com. No endorsement intended or implied}

Has a pilot bit that can be replaced. Simply purchase a longer bit that will fit so that the pilot bit hits the pipe before the larger cutter hits, like this crude drawing:

^{image courtesy of lowes.com. No endorsement intended or implied. Edited by me.}

Where the red line indicates the pipe and the blue line indicates the longer drill bit.

This is the kind of drill press (or "pillar/post drill" as it's called in some countries) I'm referring to. This model has a 10" (254mm) capacity between the the chuck and the lowest position of the table:

^{Image courtesy of HarborFreight.com customer review. Note that this shows it sitting on the floor, not yet installed on a bench top. Click to embiggen.}

Answer 2

A jig to hold a holesaw and the pipe to be drilled is one method.

Start with a block of wood (or whatever material, it doesn't matter much if it's solid-enough.)

You drill a hole for the pipe, you drill the hole for the hole-saw to run in at the correct angle to the hole for the pipe, you fasten the pipe in place so it cannot slide or rotate, and run the hole-saw into the hole-saw hole to cut the hole in the pipe.

The smaller pipe can be easily done (a lot faster than 3D printing one) by making a similar jig, but with a sanding drum the same size as the larger pipe, that you feed the smaller pipe against until it's fully "fish-mouthed" to shape. That can also be done freehand with some practice, or with a less robust jig/guide, if you use care.