Is a tubing notcher really necessary?

As long as you stay close to 90 degrees. When you try to cut an angle you are very likely to butcher it.

What is it that the notcher adds if I were to do angles other than 90?

The #1 thing is rigidity. With a pipe notcher the clamp is connected to the spindle by a heavy steel plate over a few inches. With a Drill press you have the table, table arm, column and drill head in between over several feet.

When you cut square the saw is working on opposite sides equally which cancels out the side forces. At an angle one side of the saw is cutting and the saw tends to wander causing off center holes. Also it tends to bounce making the hole ragged. The more rigid notcher minimizes those effects.

I have been cutting 1" polished stainless tube for my pulpits, dorade guards and mast rails. With these rails you want the welds to be almost invisible. A nice clean cut makes for a tight fit which makes getting an even weld a lot easier. Started off trying to do it with my 20" Delta DP and quickly upgraded to a notcher after screwing up enough tube to have paid for the notcher in the first place.

The other advantage is material handling. When you need to notch a 10' piece at 30 degrees on a drill press the other end will be bouncing against the ceiling. You can clamp a notcher on the work bench and keep everything at a reasonable height. .

There are always several ways to do any job. When notching pipe to weld together, a really pro shop will have several different techniques, depending on material, size, wall thickness, and end use. A tubing notcher, like the manual ones sold by williams lowbuck tools, will notch tubing- they wont work very well on schedule 40 1 1/2" pipe, as they are made for much thinner walls. Rigid conduit is thinner than pipe, might work with a tubing notcher. But when you need a very precise notch, you wouldnt use a mechanical notcher anyway, either hand powered or one that fits in a punch press or ironworker. These mechanical notchers are not too precise, and are used in applications like roll bars, where a mig or tig weld will not even be sanded out. For real precise fits, a hole saw will work- I use annualar cutters, like Hougen makes for mag drills, instead of ordinary hole saws, in an "ol joint jigger" set up in my bridgeport, and it will give very accurate notches, at any angle, in most pipes. Other techniques include abrasive pipe notchers- basically belt sanders with the end roller interchangeable, so the size of its radius matches the pipe size you want notched. Or mechanical mini milling machines that use end mills. Or, in extreme cases, laser or plasma cnc machines with 4 axis of movement.

How big a hammer you need depends on the nail.

You ought to be able to to some notching with your drill press. You will find on larger stuff that the drill press is just not rigid enough, and probably a woodworking tool, and wont go slow enough, for some metalworking. The morse taper slip fit of the chuck in not intended for heavy loads, and past a certain size of hole or thickness of material, you will find the chuck comes loose and spins free- This happened to me with a much bigger drill press than yours, when drilling hundreds of 1 1/2" holes in 1/2" stainless bar.

These guys sell a range of device to do this job- the purple hole saw guide would be the logical next step for you, as it would allow you to do angles as well-

mark with a template, and grind to fit.

A shaped grindstone on a bench grinder works good too. Either is faster than the joint jigger. We tried all three building our fuselage. (all tig welded, and BEAUTIFULLY fitted.

That's what I did too. But I used a program called WinMiter to make cutting patterns. Now THAT works nice...

Richard

That's what I mean by templates, but my partner in crime is a professional fabricator, and he carved the joints faster freehand than I could with the template.