Henry wrote: except of course in photography we have the depth of field... but I wonder if in espresso there is an equivalent.... hummm... so much to ponder.

We have grind size

Lol. Right. That!!!! Never heard of grind consistsncy

Denis wrote:The flow is reduced in a few seconds after the water hits the needle valve, not at the end of the shot when you have more flow. So this doesn't work exactly to help you.

I'm not quite sure what you mean in regards to the hot water hitting the valve. Since the needle valve sits above the brew valve, and in fluid contact with the thermosyphon loop, it is in the hottest part of the group. As the thermosyphon brings hot water into the group chamber, convection should ensure that the needle valve is surrounded by the hottest of the hot water, minus any heat loss on the short path from the hot TS pipe through the mushroom. I saw your measurements earlier, so I've no doubt that you've measured inconsistencies, but I am not so convinced that what you've measured is actually impacting how you pull your shots. Have you experienced issues while pulling shots?

LM has the same conical valve on GS3 and it is made out of PEEK, a material that is inert to temperature, used in guns, and used in KWDW machines as well (dispersion plate).

I assume you mean this conical valve?

La Marzocco GS3 MP Conical Valve Upgrade
True, they used a polymer for the seat, but I think this was for friction and sealing properties, and not so much thermal stability (I thought LM used Ryton over PEEK, but that's neither here nor there...). The valve shaft itself is stainless steel:

La Marzocco GS3 MP Conical Valve Upgrade
The LM valve does not function as a needle valve. It is much more closely related to a single handle shower valve cartridge, but instead of mixing hot and cold water, it blends between the pressure and exhaust ports to achieve different brew pressures, while exhausting excess brew water to the drain box.

Cheers!

- Jake

I have been this weekend at Vienna coffee festival where I spoke to their technician about this problem. The GS 3 conical is made out of peek.cheers

Anyone else in here that has had a leakage from their Bianca? Bellabarista answered me that the leakage isn't from the nut but from somewhere inside the machine I'm afraid.

I'm not at all handy with these kind of things so I'm not looking forward to opening it up myself (I live in Sweden so I'm not anywhere near Bellabarista).

It turned out it probably isn't a leak but rather water from after I release the pressure after each shot. I don't know what the "pipe" is called that runs from the group head down to the drip tray... It's a bit short imho so it splashes a bit.

Livin wrote:Any feedback after using it for a month now?

At this point there are a few small issues I'm having, mostly with shot to shot consistency using custom profiles and volumetric's. But I have found a work around for it. All in all I do like the machine for many reasons, but I'm kind of refraining from having heavy opinions on it until I have more time with it.

I'm still messing around a lot with profiling.....endless possibilities. But as of late I've been way to busy to experiment with profiling, so I've been using a more traditional style shot with a slow ramp to 8bar and a set ml output. When time allows, I'd like to really buckle down and do some testing....but who knows when that will be.