What Do You Know About Annular Cutters?

I've got 15 of them in sizes from 10mm to 49mm and use them regularly in the lathe and mill for cutting holes. They produce accurate size holes, much better than the Starrett hole saws I have, and sometimes the cut slug is useful. In the BP mill I just hold them in a 3/4" collet, in the lathe I use a modified MT to MT adapter to take them although I subsequently found you could buy holders for them to suit various MT sizes. I think you can tell I like them.

I do more machining (mostly CNC) than fabrication, but recently in a fabrication project I had to punch 4 1" holes in 1/4 wall tube, and a 1" hole in a piece of 3/8 flat bar. I smoked a decent Lennox bi-metal hole saw, and drilled the 5th hole with Silver and Deming bit on the mill. It got me to thinking about annular cutters, and yes that the slug might be usable had not escaped me. If nothing else so I could give away bags of slugs. LOL.

FYI: The S&D bit (with a web diameter pilot) cut its hole as fast or faster than the hole saw, and it doesn't even look like it needs to be sharpened. Ok, it is a 5HP mill and I put it in back gear.

Thanks for the feedback. I'm seriously considering adding a set or two now.

I forgot to mention that they come in 2 types. Most if not all the ones I have will only cut through a single thickness of material, I presume this is due to the slug having a thin flange the size of the hole which would spin an any material underneath preventing further cutting. The other type is obviously ground differently so they can cut through multiple material layers, I presume producing a cylindrical slug without the flange.

I've got 15 of them in sizes from 10mm to 49mm and use them regularly in the lathe and mill for cutting holes. They produce accurate size holes, much better than the Starrett hole saws I have, and sometimes the cut slug is useful. In the BP mill I just hold them in a 3/4" collet, in the lathe I use a modified MT to MT adapter to take them although I subsequently found you could buy holders for them to suit various MT sizes. I think you can tell I like them.

----------------------

I have a small Clausing mill in a crowded basement shop, so I usually cut and drill structural steel such as the gantry track outdoors. I learned to locate, drill and tap holes in steel fairly accurately with hand drills when building large custom machinery. My 16' gantry track assembly has about two dozen 3/8" (0.370" shank) bolts in 3/8" drilled holes. Most can be started by hand.

Do you think annular cutters would work hand-held, or in a Portalign drill guide which isn't all that much steadier?

I save thicker hole saw cutouts to make bushings, spacers, drilling guides etc on the lathe.

I think if I was to try it hand held I would put the annular cutter in a pre-drilled hole in some plate clamped in place as a support guide, the Portalign may be OK as is and should hold it square to the plate. Once the cut is started it seems to be self supported/guided by the hole and the centre stub soon to become the slug. I did ask a company selling them if they were OK to use in a mill but got a non committal answer as I expect it was out of their comfort zone in this age of liability. I've used them for cutting material square on, at angle, cutting tubing, notching ends of round bar, even cutting semi-circles out of the edge of plate. I've had no issues so far but if doing an unbalanced cut I'll take it easy at first until the cut is established just to be on the safe side.

I think if I was to try it hand held I would put the annular cutter in a pre-drilled hole in some plate clamped in place as a support guide, the Portalign may be OK as is and should hold it square to the plate. Once the cut is started it seems to be self supported/guided by the hole and the centre stub soon to become the slug. I did ask a company selling them if they were OK to use in a mill but got a non committal answer as I expect it was out of their comfort zone in this age of liability. I've used them for cutting material square on, at angle, cutting tubing, notching ends of round bar, even cutting semi-circles out of the edge of plate. I've had no issues so far but if doing an unbalanced cut I'll take it easy at first until the cut is established just to be on the safe side.

---------------------

Thanks, I'll look for one to test. The support guide with the pre-cut hole could be done on the mill. Mild steel drill guides usually last long enough for the few holes in my one-off home projects and when worn can be recycled to a larger pilot drill size. Much of my work is too large for the mill and has to be match-drilled to a guide or another part. I wouldn't design for production that way but it's fine for making one unit.

This is a good tool for punching the center of a large hole into a piece clamped underneath:

spring-loaded outer sleeve slides forward against the work to hold the punch square.

I've used hole saws to fish-mouth tubing for practice welding clusters, and the surface finish was good enough for welding but not much else.