Mongo forstner bit

Lee Valley sells a 4 inch saw-tooth. Their Forstner bits only go up to 1 inch.

Stump augers are 12" or more. Do those count?

If you have ever used a Hole Saw in a drill, you know the bigger they get, the harder they kick. You got to be real careful when drilling a big hole with a handheld Hole Saw. I've never used my Hole Saws in a drill press, but I suspect they would be just fine there. Perfect 90 degree plunge. So no danger.

Sure. I use a 4-1/8" hole saw to make holes in 1/2" plywood for the ceiling box, when I hang "fluorescent" fixtures. I use my drill press at 450RPM, IIRC (size vs RPM is marked on a label in the belt housing). It would seem that a Forstner bit would take a lot more torque because it's also hogging out the center of the hole. A hole saw is just cutting the perimeter.

Ever run an 4” exhaust duct through a rim joist. A 70 year old, hard-as-heck rim joist, not the soft 2 by stuff they use these days. Now there’s a fun time. ;-)

Yup... by drilling a bunch of holes around the perimeter and chiseling it out... the hole saw I had wasn't getting the job done but it did give me a nice round circle with a groove into which to put the point of the drill.

Just use the old plumbers trick, get a sawzall. ;>

Ir an electricians trick, a claw hammer to beat a hole in the surface.

I used that EXACT same hole saw to cut holes in the plywood ceiling in the garage to install the round plastic electrical boxes. I just put in the simple screw in light fixtures. AND I used the same hole saw to cut the hole in the subfloor for the toilet flange. It was a close fit but worked. No extra wiggle room so it had to be drilled right where I wanted it.

True on the hole saw just cutting the perimeter while the Forstner bit cuts the interior. But whenever I use the hole saw I always get it a bit cockeyed and it grabs and kicks and bucks and tries to jerk the drill out of my hands. So I might argue the Forstner bit is easier to control because it removes all the wood as it cuts. Nothing to catch. But with the hole saw you always have that interior to catch and throw things out of alignment. The Forstner takes more power, force, torque, but its safer because there is nothing to catch. The wood is already cut out and just empty space left.

I hope I never come across someone who did that. I might find a better use for that hammer. But I have used a jigsaw and a hole started with a drill to make some cuts. Jigsaw is a bit easier to guide than the Sawzall. I always think of the Sawzall as a demolition tool. Not a build it tool.

I've never drilled free-hand with a large Forstner bit but some do have "teeth" or "waves". Wouldn't they have the same problem?

I've never seen the reason to free-hand any hole with a Forstner. It's a specialty bit, best for flat bottoms holes not through holes. Neither are something I'd do free-hand. I've never even thought of using one for anything else.

But you're right. Drilling free-hand with a hole saw is like riding a bronco. It's bad enough with a drill press.

When I drill holes with a Forstner bit using a hand held drill I first drill a hole with it through a piece of plywood on the drill press. Then I use that plywood as a drill guide for the drilling the needed hole. Depending on where the hole is going I tack it down with nails, screws or clamps.

I do the same thing when enlarging an existing hole with hole saw. If there’s no material for the pilot bit to bite into, you’ll never get a good start with just the hole saw.

The last 4” exhaust vent hole I drilled was under a deck. No room for a jig saw in the interior joist bay or under the deck. Maybe a reciprocating would have worked, but I got it done with the hole saw. PITA but doable.

I never seem to need such a hole in an easily accessible location... The last time I installed a dryer vent I went through the foundation blocks as wiring and plumbing was in the way. The time before that it was at a modular home that had a poured foundation, double rim joist, fiber cement siding, and lots of mechanical room things in the way.

A non-trough hole? I'd never get it straight.

SawzAll

Problem with the jig saw is getting it even CLOSE to where the hole needs to be on the rim joist - the floor gets in the way - along with the floor joists - from inside and the siding and bricks or whatever from the outside. Last one I had to do I used a borrowed SDS Plus rotary hammer drill with a stone cutter hole saw to cut the brick and then switched it to roary only and let it smoke it's way through the sill joist. When I don't have that option I've used the sawzall - takes a lot longer and makes a bigger mess. The problem with the hammer drill is when you drop the slug of brick into the cavity between the bricks and the rim joist - and it only falls about half the way and now you have a round chunk of concrete to exorcize from the hole before you can get to the rim joist - - - - That added a bit over an hour to the job - - - -