EM6910 tamper with level bumpstop

thingiverse

This tamper features a deliberate design element - a carefully crafted lip that prevents overfilling of the portafilter basket. The most concerning issue with this tamper is underpacking, which results in one subpar cup of coffee rather than overfilling, which puts undue stress on the group head collar made from a soft alloy and accelerates its deterioration, eventually leading to leakage. Having trouble tamping straight? This lip helps by allowing you to tamp parallel to the portafilter top. Tamp down too hard when the basket is overfilled and the lip won't be able to make contact with the portafilter. Simply tip out the excess coffee grounds and try again, rather than risking damage to your machine - it's just not worth it.