What drill bit do I need for making big holes?

[rsgaz]

Forstners are the better drill type, but cost more, need more torque and turn ALL of your 80mm circle into sawdust to clear up, rather than just the perimeter of the hole turning into sawdust.

So, for this application, holesaw wins IMO.

 

[aveatry]

A little heads up on hole saws is that the bigger diameter ones need a bigger arbour and depending on your cordless the fatter arbour may not fit in the chuck. I used to have a worxs cheap cordless but the bigger arbour would not fit so I always had to use my 1 speed corded drill - not fun with a big holesaw. My new 18v dewalt has a bigger chuck and is fine with the larger hole saw arbour.

 

[Nozzle]

Good point - the larger arbors are 13mm, the smaller ones 10mm - make use of the torque limiter do prevent shagging your drill/wrist. They seem to work a little better at a higher speed, don't push too hard, let the dust come out/unblock the teeth regularly.

Nozzle

 

[rsgaz]

depending on your cordless the fatter arbour may not fit in the chuck.

That's what the little adapter is for that comes with most sets, to use the smaller arbor with ≥31mm holesaws...

Grease it up or everything becomes inseparable after prolonged use! Especially if you don't have a bench vice nearby!