# Puck suck



## Greenblood (Jun 8, 2017)

As I'm a newbie, about to hopefully buy a lever machine and doing tons of research... can I ask about puck suction? I.e., it seems to me that as the lever is bought down and the piston above the puck of coffee raised, a negative pressure is created directly above the puck and therefore air is drawn into this area just before the water inlet port is uncovered? Is this correct? Does this create issues with channeling through the puck in the subsequent pull? Or is there a valve to prevent air being sucked in through the puck?

id appreciate your thoughts.

cheers,

steve


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## Mrboots2u (May 10, 2013)

Have a look at this


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## Split Shot (Sep 24, 2016)

The answer is: yes, levers do pull air through the puck and into the group head. I've seen some advise pulling the lever in a slow/steady manner to avoid 'puck jump'. In practice it's a non-issue, and I'd argue that the excellent preinfusion that you can achieve with a lever far far outweighs any theoretical risk with respect to channelling.

Furthermore, at the end if the shot cycle, the bit of air now at the top of the group head chamber gets pushed back through the puck, after the water has gone, giving you a lovely dry puck to knock out every time.


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## MildredM (Feb 13, 2017)

Love it. There are some superb videos via his blogspot link.


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## igm45 (Mar 5, 2017)

I'm no lever user but those videos are mesmerising


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## Greenblood (Jun 8, 2017)

Thansk for the replies. I surmaise if one does have chaneling issues and tamps fine grounds firmly, one needs to be very careful when pulling the lever down...it would be interesting to see a video of a naked PF with a normal pull and a faster pull to see if there is an increase in chaneling on average over a number of shots. Can't wait to actually have a lever and get experimenting!

steve


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## Split Shot (Sep 24, 2016)

See 1:25 here:


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## Greenblood (Jun 8, 2017)

Excellent vid splitshot! Be great to have seen it used with the Londinium, Strega and other lever machines though.

It seems that a gentle initial pull down of the lever really needs to be gentle to allow air to gently permutate the puck, otherwise any weak spots will be exaserbated and may worsen chaneling.

Its possibly the issue here -






steve


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