La San Marco Open Source Lever Machine

A haven dedicated to manual espresso machine aficionados.
Thomas92024
Posts: 21
Joined: 8 years ago

#1: Post by Thomas92024 »

I would like to introduce my take on the Open Source Lever Project (OSLP) started by Andre (Open Source Lever Project). I am grateful for all the ideas and discussions that went into the original project by Andre and other members of HB. The OSLP was started at the right time for me, as I would otherwise have ended up with a commercial lever machine and missed all the fun of a DIY project :-)

Many of the priorities and considerations for the design were discussed in the original OSLP thread, by Curtis in the thread about his lever build (DIY Dipper Lever) and I have been communicating with Jorian (From Scratch DB Home Lever) as well since he was also using the LSM group for his project. Credits to everybody for sharing their ideas and experiences!

Current version (steam is not connected yet)


Overview of the main components for the build:
  • La San Marco lever group. The group I got appears to have a new design that includes a sleeve with three entry points for water into the cylinder. It also has an extra seal (quad seal type) on the spring retainer compared to the documents I have been able to find on-line (see pictures below).

    Ascaso 110V/1000W thermoblock (same as the OSLP).

    Active heating of the group using two 110V/100W cartridge heaters attached to the group using custom aluminum adapters.

    Temperature management by PID control with solid state relays (SSR) of both TB and group using Arduino (easy data collection).

    Frame build from Unistrut with steel front plate and concrete base.
First a bit about current performance. The warm-up of the group is the limiting step during start-up and currently takes about 20 min with the active heating. The group takes about 3 min to recover between shots. I am considering adding another 200W of heating when I build the next version of the adapters to see how much it can be improved. The TB is super fast and gets to temperature in less than 3 min with about a minute in recovery time between shots. The plot below was captured from the Arduino serial port and plotted in MS Excel. Each "shot" on the plot is about 60 ml of water and the temperature probes were placed on the TB and the side of the group as discussed in the OSLP thread. Note that the PID parameters were not optimized.



I am really happy with the way this came together and loved the espresso I was able to make right away (so I kept going). I do not have access to a lot of specialized machining tools, so everything for this build was created by me with hand tools and off-the-shelf components (and hours of hands-on work). I am still working on a bunch of smaller things and will update with more data on temperature stability etc.

Thanks for reading this far and please comment or ask questions... cheers,
Thomas


La San Marco lever group






Adapters for cartridge heaters




First prototype making espresso


Making the front plate using a hole saw


And finally the concrete base with the Unistrut frame



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#2: Post by EspressoForge »

First of all, Thomas this is amazing! I know I emailed you already, but I really love the concrete base, to me it is genius! I've seen some very nice concrete counter tops in kitchens, so I know you can polish them and coat them to get them shiny if you wanted.

I'm also liking the LSM group a lot. In some ways, I do wish I had gone with that. Wheels are turning, and even though I've got my plate full with other machine builds, I'm thinking of re-building my machine already with a smaller plate to heat the group. Really digging the concrete. CONCRETE!

aves
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Joined: 8 years ago

#3: Post by aves »

Bravo, very nicely done. I love your project (as well as EspressoForge's). Thanks for sharing.
Your concrete solution is great.

moxa
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Joined: 12 years ago

#4: Post by moxa »

What an amazing project, well done!
Can I ask where you sourced the wooden handles? I have a La San Marco 85 leva coming and would love to upgrade the plastic handles.

Cheers
Ralf

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TomC
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#5: Post by TomC »

Nice project!

I'm jealous of your group sleeve with it's 3 well spaced inlet ports. I'd love to see a group flush if you can. My Izzo Leva just has two small holes in the front of the group (at 6 o clock if looking up from below) and the gush of water is rather chaotic. I try to mitigate the aggressiveness of the water entering the group when extracting by very very gently easing into the spot in the pull where the piston slides past the inlet ports and lets water enter. IT seems to add some forgiveness factor to the extraction's pre-infusion evenness, especially on all my large flat grinders.

I imagine it wouldn't be impossible to swap out group sleeves, but it'd probably be cost prohibitive and difficult to acquire.
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#6: Post by EspressoForge replying to TomC »

I'm reasonably sure the spaced holes don't matter as much as the volume of water and pressure behind the group. My Bosco group I think has 3 holes and the water tends to rush in, even with a needle valve to control flow. There's just a split second where water will shoot in, then it starts going to the lower flow rate. My experience is also that the initial flow matters a good amount.

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TomC
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#7: Post by TomC replying to EspressoForge »

Both the Bosco and the L1 have holes that are smaller and nicely spaced out. You should see the ugly, rapid flush the Leva does. It does make a difference. It's mitigated by going slightly slow till there's a small bed of water laying flat on the puck, but just rapidly pulling the lever down (or in essence, pulling down like any other normal lever) puts quite a turbulent blast of water right on the puck. Once there's a small "table" of water on top, it doesn't matter anymore.
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Thomas92024 (original poster)
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#8: Post by Thomas92024 (original poster) »

Thanks for the compliments - I had the pleasure of pulling about 10 shots back to back today and the temperature recovered consistenly. I am out of town this weekend and will get the computer hooked up next week to collect more data. I need to make a thermofilter to get a better idea of the brew temperature as well.

Ralf, I got the handles from espressoparts.com. They have both M12 for the lever and M10 for the portafilter.

TomC, I will make a video with the group flush next week.

Jorian
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#9: Post by Jorian »

Excellent job Thomas! Looks Great!

Thomas92024 (original poster)
Posts: 21
Joined: 8 years ago

#10: Post by Thomas92024 (original poster) »

TomC wrote:Nice project!

I'm jealous of your group sleeve with it's 3 well spaced inlet ports. I'd love to see a group flush if you can. My Izzo Leva just has two small holes in the front of the group (at 6 o clock if looking up from below) and the gush of water is rather chaotic. I try to mitigate the aggressiveness of the water entering the group when extracting by very very gently easing into the spot in the pull where the piston slides past the inlet ports and lets water enter. IT seems to add some forgiveness factor to the extraction's pre-infusion evenness, especially on all my large flat grinders.

I imagine it wouldn't be impossible to swap out group sleeves, but it'd probably be cost prohibitive and difficult to acquire.
Hi Tom,
Please see the video below for a flush when the machine is at brew temperature. How does it compare to your group? Does your group have a sleeve as well? I have not been able to find any information about the sleeves for the LSM group and don't see them in the diagrams on-line.

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