Smart! Yeah I thought of pre-infusion regulation firstJohnB. wrote:You can use that threaded adjuster to regulate the amount of flow somewhat. Primary use in a cafe according to Roberta Bosco is so that you can shut off flow completely when you want to service a group on a multi group machine without shutting down the machine.
A haven dedicated to manual espresso machine aficionados.
found the explanation also in Paul's video (2:13)