Single dosing on the Compak K3 and E8

These are two quite different grinders sharing one hopper fitting, and the numbers show it. The K3 Touch runs 58 mm burrs from a 210 W motor at around 1340 rpm, with a bean hopper holding roughly 800 g. The E8 is the commercial machine: 83 mm burrs, a 610 W motor at about 1290 rpm, and a 1.7 kg hopper.

Whichever you own, the hopper is sized to be filled and worked through, not to hold one dose.

Different sizes, same problem

On the K3, 800 g is roughly forty espresso doses sitting above the burrs going stale. On the E8 it is closer to ninety. Neither is a workflow that suits weighing each shot, and neither lets you change coffee without emptying the hopper first.

This blow-out hopper replaces the stock bean hopper on either machine. You weigh in the dose you want, grind it, then press the silicone bellows so the air pushes grounds out of the burr chamber and chute.

On the E8 in particular that matters — an 83 mm burr set has a large chamber, and grounds left in it between doses are the reason back-to-back shots of different coffees taste less distinct than they should.

Version 3

Every unit we ship today is Version 3. The bellows is a custom branded, factory moulded silicone part — it is no longer 3D printed, as our earlier versions were.

How it is made

• 3D printed: lid, lid lock ring, connector, air-leak prevention gasket
• Factory machine moulded: silicone bellows

Materials

• Lid, lock ring, connector: PETG hard plastic
• Air-leak prevention gasket: TPU — material info
• Bellows: factory moulded silicone

Fitting

This hopper is made for the grinder named on this page. Fit tolerances vary between units and production runs, so minor adjustment may be needed to seat it perfectly on your grinder. Every unit is covered by our 2 year warranty.