CMA grouphead venting

A haven dedicated to manual espresso machine aficionados.
DougCanuck
Posts: 7
Joined: 3 years ago

#1: Post by DougCanuck »

I think it would be a good idea to vent the spring area of the cylinder of a CMA group head, as is done in the attached photo. It would prevent the accumulation of water and corrosion of the spring when water manages to eventually leak through the lip seals. Is there any reason not to make the cutouts? Has anyone done this?


User avatar
BaristaBoy E61
Posts: 3512
Joined: 9 years ago

#2: Post by BaristaBoy E61 »

I just want to say that's one gorgeous looking machine!
Is that a temperature gauge mounted on the group?

I otherwise don't have the experience or knowledge to comment on your thread.
"You didn't buy an Espresso Machine - You bought a Chemistry Set!"

User avatar
pizzaman383
Supporter ❤
Posts: 1730
Joined: 13 years ago

#3: Post by pizzaman383 »

The spring on the LSM group sits higher and more outside the cylinder than the CMA and Condor groups. You would need to modify the group cap while maintaining sufficient structural integrity. It is an expensive and important part to experiment with. It might be doable by a skilled machinist.
Curtis
LMWDP #551
“Taste every shot before adding milk!”

User avatar
JohnB.
Supporter ♡
Posts: 6579
Joined: 16 years ago

#4: Post by JohnB. »

I think it would be far more productive to machine the top of the piston to accept a 4th seal as Bosco does. That way you'd never have to worry about water getting up in the spring area.
LMWDP 267

User avatar
pizzaman383
Supporter ❤
Posts: 1730
Joined: 13 years ago

#5: Post by pizzaman383 »

I think that an open top like the LSM group would bleed heat faster after a shot.
Curtis
LMWDP #551
“Taste every shot before adding milk!”

DaveC
Posts: 1743
Joined: 17 years ago

#6: Post by DaveC »

BaristaBoy E61 wrote:I just want to say that's one gorgeous looking machine!
Is that a temperature gauge mounted on the group?

I otherwise don't have the experience or knowledge to comment on your thread.
That is a pressure gauge, so you can see the pressure during the shot and also stop the shot by indicated pressure....which will get you to within a gram of any target weight.

the temperature of the independently cartridge heated PID group, Brew Boiler and Steam Boiler are all shown on the electronic panel top right of the machine.

NelisB
Posts: 970
Joined: 14 years ago

#7: Post by NelisB »

ACS Vesuvius EVO Leva. Best machine I ever had.

bgn
Posts: 560
Joined: 17 years ago

#8: Post by bgn replying to NelisB »

Very nice. Are those machines still in production?

User avatar
BaristaBoy E61
Posts: 3512
Joined: 9 years ago

#9: Post by BaristaBoy E61 »

DaveC wrote:That is a pressure gauge, so you can see the pressure during the shot and also stop the shot by indicated pressure....which will get you to within a gram of any target weight.

the temperature of the independently cartridge heated PID group, Brew Boiler and Steam Boiler are all shown on the electronic panel top right of the machine.
Thanks Dave.

What are the determining factors involved with where the gauge is situated on the group as it relates to the vertical axis of the group cylinder sleeve? Is the gauge display liquid filled?

What machine/model is depicted in the original post?

TNX
"You didn't buy an Espresso Machine - You bought a Chemistry Set!"

DaveC
Posts: 1743
Joined: 17 years ago

#10: Post by DaveC »

BaristaBoy E61 wrote:Thanks Dave.

1. What are the determining factors involved with where the gauge is situated on the group as it relates to the vertical axis of the group cylinder sleeve? Is the gauge display liquid filled?

2. What machine/model is depicted in the original post?

TNX
1. I'm not sure I fully understand the question fully. The Gauge is not liquid filled, as it really doesn't need to be.

As far as the position of the gauge, the cylinder is double chambered and because the water inlet port is below the lower piston seal at all times, the pressure seal never passes the port. It can register the preinfusion pressure, and the pressure applied to the coffee during the entire shot, showing 0 when no more pressure exists.

This is in contrast to the Fiorenzato style 58mm group, which would not support a pressure gauge mounted there, because it could only register preinfusion pressure. As soon as the piston moves, the lower pressure seal passes the inlet port and pressure can no longer be registered with a gauge mounted as in the photo..

2. The Machine is the Vesuvius Evo Leva, there is only one model, but a choice of left or right-hand steam/water wand mounting and a mix and match choice of wands.

Post Reply