Reasons we use a Lever machine beyond superb shots - Page 2

A haven dedicated to manual espresso machine aficionados.
truemagellen

Postby truemagellen » Aug 07, 2019, 12:10 am

Here was a video from back in the day one of you guys posted that covered why the Lever is so much cleaner and easier to use.


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AssafL

Postby AssafL » Aug 07, 2019, 2:40 am

Where does the bit about turbulence in pumps come from???

Did someone measure it? Pumps are used in the semiconductor industry (try to keep a nanometer line with turbulent flow), massive inkjet printers (where turbulence will make bar Refaeli into Bart Sinpson), etc. pumps are in places and sizes where they can do major damage if not damped properly. It isn't hard to do.

Where does this silliness come from?

(I have no doubt levers are nice - I've fooled around with quite a few - always happily - but it is a pump of sorts. Manual or spring - it is afterall a pump - quiet and nice ).
Scraping away (slowly) at the tyranny of biases and dogma.

Seacoffee

Postby Seacoffee » Aug 07, 2019, 7:39 am

The beauty of lever machines for me is its ability to clearly reflect the timing of the shot so adjusting the grind directly changes that timing. With pump machines????

OldNuc

Postby OldNuc » Aug 07, 2019, 8:53 am

AssafL wrote:Where does the bit about turbulence in pumps come from???

Did someone measure it? Pumps are used in the semiconductor industry (try to keep a nanometer line with turbulent flow), massive inkjet printers (where turbulence will make bar Refaeli into Bart Sinpson), etc. pumps are in places and sizes where they can do major damage if not damped properly. It isn't hard to do.

Where does this silliness come from?

(I have no doubt levers are nice - I've fooled around with quite a few - always happily - but it is a pump of sorts. Manual or spring - it is after all a pump - quiet and nice ).


Not having watched the video provided I can not opine on the technical aspect of the pump comment but having more than passing experience with most types of pumps the turbulence in the discharge is primarily the result of the instantaneous flow velocity in the discharge piping and if the available suction pressure is below the net positive suction pressure required the pump will cavitate which induces discharge turbulence.

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AssafL

Postby AssafL » replying to OldNuc » Aug 07, 2019, 11:31 am

So the claim is that if the water debit at the inlet is insufficient it causes cavitation? What about a plumbed in - or a flojet or a full Reservoir machine?

I think in the video of the transparent puck the coffee seemed to dance. Nowhere was it stated that it was pump related - may be a gicleur squirting or CO2 discharged from the beans. No comparison was made to coffee in a lever so I am not sure if and how differently the two behave.
Scraping away (slowly) at the tyranny of biases and dogma.

truemagellen

Postby truemagellen » replying to AssafL » Aug 07, 2019, 11:53 am

Well the turbulence can take on many forms with a pump machine and what type of pump is used.

-vibration pump you can have turbulence in the flow you can also have vibration in the entire machine causing ultrasonic vibration being sent through the group, portafilter and basic

-rotary pump and vibration pump when you have water flow into the group head (particularly on a non-preinfusion machine) the flow is rapid as it fills in over the puck causing turbulence on the top of the puck. To compare a lever has a low pressure preinfusion then the piston acting as Yes a pump compresses the mostly calm water column through the puck to bring it up to pressure

-Turbulence of under pressure pumped water being expelled out the 3 way solenoid drawing up grounds into the group

Also now looking through your GS3 work that machine like that can delivery much less turbulence on the puck as you have control to emulate a lever if you want. You still have a 3 way solenoid to contend with though. But the GS3 is an awesome machine and the 'chimera' looks like quite the interesting setup for a hobbyist!

Also we have had the exact same S20 in the past...what a monster that machine was. Perhaps I may see your Chimera in Tel Aviv sometime!

OldNuc

Postby OldNuc » Aug 07, 2019, 12:08 pm

The vibratory pump may never reach turbulent flow velocity but it makes up for it by the pressure pulses. Centrifugal pumps have a smooth delivery and rotary vane or gear pumps are pulsating flow until reaching shutoff head or bypass opening head. The only turbulence in a lever machine is in the velocity of the fill water hitting the puck top on initial fill. This can be rather violent depending on design.

Katzer

Postby Katzer » Aug 07, 2019, 2:58 pm

I got my la pavoni used. It literally fell apart on the third shot, the internal sleeve broke. Long story.
I bought the parts, restored it completely and it was a piece of cake.
Maintaining it is so easy. Once in a month or two I take out the piston, clean it and apply some grease to the piston seals.
That's it.
I have been using it extensively for two and a half years. About 4 shots in the morning, every morning, more on the weekends.

The group head seals are still great condition. The only thing i dealt with since was the heating element gasket.

truemagellen

Postby truemagellen » replying to Katzer » Aug 07, 2019, 3:40 pm

This is great to hear. I've always wanted one of these.

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Almico
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Postby Almico » Aug 07, 2019, 6:12 pm

This might be the single best feature of a lever espresso machine: Once you get used to a lever machine, it is very easy to tell flow rate just by looking at the handle. I don't need a scale with a timer any longer to adjust my grind as the day goes along. I just look at the handle. Even my non-coffee-geek employees can make grinder adjustments with ease, which makes it even more mysterious why more cafes do not use levers.

And they're great for your lats.