Lever machine pressures.

[LeoZ]

Has anyone measured actual brew pressures (and temps) of their lever machines?

I tried measuring the brew temp once but it wasnt accurate, at least I dont think so - temps were around 187F through the shot with a thermocouple snaked into the basket.

I am more curious in brew pressures though. HX machines max (adjusted obviously) at around 8.5-9.5 bar, and brew temps of 195 -205F.

Any correlation?

It would be nice if there were some sort of OPV setup on levers, this way you dont get stuck waiting 20mins if you grind too fine

[faberic]

It shouldn't be hard to measure, i've calculated that if I need to press down with a force of approximately 15kg to move the lever, there's a pressure of 9 bars in the brewing chamber of my la Pavoni Professional (pre-Millenium).

You just need to know how much 15kg is.

[LeoZ]

It shouldn't be hard to measure, i've calculated that if I need to press down with a force of approximately 15kg to move the lever, there's a pressure of 9 bars in the brewing chamber of my la Pavoni Professional (pre-Millenium).

You just need to know how much 15kg is.

spring machines wouldnt translate that way. sorry, I should have clarified!

[faberic]

spring machines wouldnt translate that way. sorry, I should have clarified!

Oh yes of course. Interesting question indeed!

[gscace]

Has anyone measured actual brew pressures (and temps) of their lever machines?

I tried measuring the brew temp once but it wasnt accurate, at least I dont think so - temps were around 187F through the shot with a thermocouple snaked into the basket.

I am more curious in brew pressures though. HX machines max (adjusted obviously) at around 8.5-9.5 bar, and brew temps of 195 -205F.

Any correlation?

It would be nice if there were some sort of OPV setup on levers, this way you dont get stuck waiting 20mins if you grind too fine

Paul Pratt sent me some data on one of his restored spring lever machines. As I recall the max pressure was 8 bar, falling to 6 at the end. I measured the PV Lusso brew pressure as part of the Lever machines smackdown. I think it produced fairly low pressures - not anywhere near as high as what is customarily used.

I built a one-off thermofilter for measuring brew temps on the Lusso as part of the smackdown. I made preliminary measurements with it, then sent it off to Dan Kehn, who is sposed to do more exhaustive work with it. For boiler pressure of 1.1 bar, Lusso Brew temps are in the ranges that we accept as pretty decent - around 200ish, but decline sharply throughout the extraction (6 degrees F or so). The Lusso has a pretty small piston chamber and double espressos require two pulls. The temperature of the second pull rises quite a bit compared to the first, but exhibits the same declining profile. I'll let Dan fill in the details when he gets time. I don't have my records here and as i mentioned, the measurements i did weren't exhaustive by any means.

-Greg

[r-gordon-7]

Having never used or had any experience with a spring machine - only my Gaggia Factory springless lever... Can one increase the pressure on a spring machine's pull by pushing up on the lever (presumably while one holds the machine down by holding on to the pf handle or some such with the other hand) while the spring is engaged and is pulling the pistion down (and the lever back up) on its own - or, at that point in a spring machine's operation, is the lever not "attached" to the piston in such a way that the lever can be used to increase the piston's pressure over and above that which is created by the pull of the spring?

[LeoZ]

Having never used or had any experience with a spring machine - only my Gaggia Factory springless lever... Can one increase the pressure on a spring machine's pull by pushing up on the lever (presumably while one holds the machine down by holding on to the pf handle or some such with the other hand) while the spring is engaged and is pulling the pistion down (and the lever back up) on its own - or, at that point in a spring machine's operation, is the lever not "attached" to the piston in such a way that the lever can be used to increase the piston's pressure over and above that which is created by the pull of the spring?

ive done this to try to speed up a pull that ive ground too fine - it works. dont know that there is any taste benefit though. you just push on the lever, or the pin at the top of the machine.