Dan

Yes Volumetric dosing is precise, if it is set up correctly and are using high quality components, but only if all the other varibles are kept stable, if not then Volumetric dosing won't be to much use.

I have owned 3 Volumetric dosing machine, of those only the T1 was hitting within a acceptable range (+\- 0,2g) the two other machine where within (+\-)0,5-1g

And you are absolutely right that the 3-Way-valve only engage after the end Of the shot, just as with a blindfilter, but all that water where meassured as well.

malling wrote:I have owned 3 Volumetric dosing machine, of those only the T1 was hitting within a acceptable range (+\- 0,2g) the two other machine where within (+\-)0,5-1g

Well, I'd call +- 1g to be acceptable, so I guess we have a different level of tolerance on that one.

malling wrote:And you are absolutely right that the 3-Way-valve only engage after the end Of the shot, just as with a blindfilter, but all that water where meassured as well.

I guess I could see if you have a group with a pre-infusion chamber that you could be running alot of water through that group also. Water doesn't compress much at all, so if your doses stay to the same weight you'll have roughly the same amount of absorption by the grinds and have roughly the same amount of extract every time. Again, our level of tolerance is not the same.

Automatic espresso machines are a compromise for either the home user that wants to hit a button and then do other things or a barista that needs to do other things. Perhaps the next generation will actually have a weight setting and a scale on the drip tray that plugs into a controller? When your espresso hits the desired weight it will cut the shot off automatically. Could be a good thing if the electronics can be protected.

I've come to love volumetric dosing on my S1 as it eliminates another potential target for OCD-type worry and fiddling (did it just blond, should I end the shot? Now? Is it blonding now?, etc.) But every 20 shots or so I'll get a noticeably small shot -- typically a first shot of the day. This is never the first water run through the machine (I always do a pull or two to warm up the group) and I've no idea what could account for it. Just musing here...

Joco wrote:Ah gotcha. Yea obviously shooting by weight would be better (I actually have seen some cafe's do this with a scale on the drip tray), but I was thinking perhaps eyeballing volume would work too.

Another reason that eyeballing volume doesn't work is that the crema makes it difficult to determine exactly how much liquid you have in the cup. Worse, the amount of cream is different for different coffees and decreases as the coffee ages.