Hole Saw for Bulk Monotubs - 76mm / 3"

A 3" (76 mm) bi-metal hole saw for cutting large gas-exchange holes in bulk monotubs and fan-driven setups. The biggest of the three standard mycology hole sizes, this is the saw you reach for when you're running a 60 L+ tub, a martha tent, or want to duct a humidifier outlet directly into a chamber. Ships with a quick-change hex shank arbor.

The bulk-tub and martha-tent size

What this hole saw is for

A 76 mm hole is overkill for a standard tub but exactly right when you need serious airflow: bigger fruiting chambers, fan-driven setups, or rigs where you're piping in humidified air from outside. The big patch covers it without bowing in the middle.

• Matching filter patches — the 90 mm filter patches are made exactly for this hole size: Bulk Monotub Filters 90 mm — Self-Adhesive 8-Pack .
• Bi-metal teeth — cut clean through plastic without melting; also handles thin metal and wood.
• Hex shank arbor — included. Fits standard 1/4" hex chucks and three-jaw drill chucks. Larger saws benefit most from the quick-change shank because you swap them often.
• Big enough for inline ducting — if you're running a 50–80 mm humidifier hose into a chamber, this is the size that matches.

How to drill clean holes in a monotub

• Use a strong drill — a 3" saw needs more torque than a 1" or 2". An entry-level cordless can do it, but a brushless drill or a corded model will go through cleanly without bogging down.
• Drill in reverse, slow — bigger saw = more chance of grabbing and cracking thin tub walls. Reverse rotation prevents this. Keep the trigger gentle.
• Brace the wall firmly — press a scrap block of wood behind the tub wall. The block stops the wall flexing and stops the saw snatching at break-through.
• Clean burrs — a 3" hole leaves more rough edge than the smaller sizes. Trim everything flat with a sharp blade so the adhesive patch can seal all around.

Specifications

• Cutting diameter — 76 mm (3 inches).
• Material — HSS bi-metal teeth on a carbon-steel body.
• Shank — quick-change hex shank arbor included with pilot drill.
• Best for — bulk monotubs (60 L+), martha tents, fan/duct setups, thin metal, wood.
• Pairs with filter — 90 mm self-adhesive patches.

Safety: Wear eye protection when drilling. A 3" saw throws large plastic chips. Use a stable work surface and brace the tub firmly; the saw can snatch under high load. The saw body stays hot after cutting — give it 30 seconds before touching. Keep out of reach of children.