Balthazar_B wrote:I've often wondered whether there's a way to accomplish the same thing with a pseudo-shot, using something in the PF (cotton?) that is porous, but will mimic the resistance of an espresso shot.

I usually use spent coffee puck to reach the desired grouphead temperature. It has not the same resistance but it is a fairly good solution (much better than an empty flush I think).

Balthazar_B wrote:Dan, did you find that the first shot or two after warm-up were sink shots (i.e., because it takes one or two shots to bring the grouphead up to a consistent temp? From threads I've seen on Londinium, Bosco, etc., lever machines, that seems not to be uncommon. I've often wondered whether there's a way to accomplish the same thing with a pseudo-shot, using something in the PF (cotton?) that is porous, but will mimic the resistance of an espresso shot.

My dipper lever (same group as the P800) takes two simulated shots to come up to temperature such that each of the three shots I make have the same temperature and most importantly taste the same between shots.

While it looks like it in the diagram of the group, has anyone confirmed that they are using the two-spring version of the Bosco?

My Quickmill Achille uses two springs, but I am pretty sure that the Londinium only uses one.

Nice looking machine, and a good discussion.

(I have had my Achille for about five years now and still love it. Just replaced the seals with silicon from Cafelat. Easy)

Dan

Londinium uses 1 spring. I do not know if the spring rates of compression are the same for single springs and double spring groups. What I mean by that is the main spring the same compression rate all across the various buyers of the Group and is the secondary spring the same across the Groups??

I'm not familiar with the spring rates in the 2 spring groups. I do know that Roberta Bosco refers to the single spring used in their Bosco machines as a 9 bar spring but in actual use pressure peaks just over 8 bar & slowly drops to 6 bar before the shot blonds & tapers off.

Good info John, thanks!

please explain to a lever novice, what is the function of the part with screw and a ball between the group and the boiler?


also, based on the experience with the P800 posted here, looks like it can be used in a light commercial setting without any issues, right guys?

Not a lever owner as of yet but I have seen similar arrangements in industrial applications. The ball and spring act as a one way valve to allow water from the boiler to enter the piston chamber but not return to the boiler. When the piston is raised to uncover the water port, boiler pressure pushes water into the chamber for pre infusion. As the piston raises further the boiler pressure fills the cylinder with water due to the pressure reduction (if you will, vacuum) as the piston raises. When the lever is released and the piston begins its downward excursion the pressure inside the cylinder increases and exceeds the value of the spring above the ball which pushes the ball against the seat and seals the flow from returning to the boiler. The water is then expelled through the ground coffee in the portafilter.

Great, thanks!

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.