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A home espresso machine that provides commercial quality temperature and pressure consistency at an affordable price.
1,546 backers pledged $369,569 to help bring this project to life.

Onward and Upward

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Hi Backers!

A quick update to let you know things are still moving, slowly but surely. We’ve yet to receive all of the beta units back, but we’ve refurbed the hardware we have and are waiting for firmware updates before machines can be sent out again.

Solved: Wet Pucks

One of the bigger hardware issues we encountered during beta was that pucks were wet after extraction. We knew we’d get some wetness using the VST baskets, which are known for being very dose-sensitive, but beta testers were seeing a large amount of water remaining in the pucks, regardless of portafilter basket used.

Though the jury’s out on whether wet pucks are actually a problem, it does make for messy cleanup. We determined that excessive wetness is due to the group head screen sitting too high over the portafilter basket, leaving space for water to collect once the brew cycle ends.

To resolve this, we’ve modified the thermoblock/group head assembly to lower the screen about 3mm into the puck, and changed the check valve design.

Solved: Group Head Dripping

Another issue was that the group head dripped after a shot, and dripped water when the steam mode was active. We’ve reworked the plumbing to include a shuttle valve that keeps dripping at bay (pictured below). The shuttle valve opens the block’s water path to the drain valve without opening it to the group head - sort of like two opposing check valves.

Drip = conquered!

Water path assembly with new shuttle valve circled.
Water path assembly with new shuttle valve circled.

In Other News, UL

We’re also still waiting on our UL designation. All of the tests are complete, and we’re assured we’ll have our number by the end of this week. Of course, we thought all of the tests had already been completed. What happened?

After our last update we got a call from the certification agency saying that one of the tests that had been performed needed to be redone. The test in question consists of running a continuous brew cycle for 5 minutes without water in the machine. If the machine overheats (as UL had expected), the machine gets a “pass.” If it doesn’t overheat after 5 minutes, the test is performed 4 more times, and if it still doesn’t cut off, the machine is given a “pass.”

Our machine didn’t overheat but the test wasn’t repeated, and the oversight wasn’t noticed until two weeks ago when we were notified. It then took a week to determine exactly what was needed to complete the test, and get it on the schedule for completion.

As far as we know now, all UL tests have been complete (for real this time), and we should expect our number designation by the end of this week. Fingers crossed!

Calibration Rig

Something else we’ve discovered in testing (with the gracious help of a few of our trusty beta testers) is that the pressure sensors actually have a slightly parabolic curve response, not a linear one as indicated in their data sheet (which we foolishly believed!).

We had been using 2-point calibration to calibrate the pressure sensors. This means that, for each machine, we use an automated rig to test pressure readings at known values of 0 and 10 Bar, then do the calibration math to write unique code for each machine, based on its sensor’s performance.

We’re now using a 3-point calibration, meaning that we’re using three data points to describe the sensor performance. This means that the testing will take a bit longer (about 3 minutes per machine), but performance will be more accurate.

We’ve also finessed the PID algorithms for better performance across brew, idle, and steam modes.

The gating items now are the revisions to firmware and completion of the calibration automation suite.

With love,

Your Team

info@zpmespresso.com | Google+ | Facebook | Twitter | Store | Forum

Brian C. Thayer, sydlexius, and 21 more people like this update.

Comments

    1. Creator Zach Fine on May 14, 2014

      I hope there's a new update coming regarding the UL certification. i just find the manufacturing process and its complexities fascinating.

    2. Creator Wayland Chan on March 28, 2014

      This has been a long journey. I'm impressed with your dedication. I'm more curious about what your guys plans are after fulfilling this KS campaign. Has the experience turned you on or off continuing with this aspiration?

    3. Creator Gleb Polyakov and Igor Zamlinsky on March 24, 2014

      @Roadrunner All but two have made it back. We've refurbed them, but are waiting on UL before sending them out (because if we have to make further changes for certification, it would render any final verification useless). Obviously we're experiencing more problems with UL - fuller update to come.

    4. Creator Roadrunner on March 18, 2014

      Have all the beta units been shipped back out? Also, do you anticipate another return and re-shipment of units to beta testers after more testing? Thanks for all your efforts. I think the extra time spent will result in a significantly better machine.

    5. Creator Michael K on February 25, 2014

      This the link, but there's no code there yet:

      https://github.com/zpmespresso

    6. Creator Grant Grundler on February 25, 2014

      Now would be a good time to (re)post a link to the SW so people with ability and interest could review it.

      Even if I don't have a machine yet, I been reviewing (linux kernel) code for 14 years (and other OSes before that). Some things are obviously wrong in review or using static code analysis tools.

      Thanks!

    7. Creator Michael K on February 25, 2014

      Colin said what I was thinking, except that I think that the issue with running in brew mode without water is less that the thermoblock could overheat, and more that the pump could. The PID loop can't keep the pump from overheating.

    8. Creator Colin on February 25, 2014

      Javier, I think the options are overtemperature shutdown within 5 minutes (pass), no overtemperature shutdown and no fire after 25 minutes (pass), and fire/smoke/melting/dangerous temperature (fail).

      The Nocturn has a hardware overtemperature cutoff fuse, but its PID can maintain 95°C in a dry thermoblock without difficulty, so it does not go into shutdown. Thus the need for repeated/extended tests to ensure that even if someone leaves it dry and walks away from it, nothing catches on fire.

    9. Creator Peter McKeon on February 25, 2014

      I was wondering the same thing.. overheat = Pass! doesn't overheat = Pass!

      Perhaps posting a timeline with milestones would be a good idea, breaks down the progress into more bit sized chunks.

    10. Creator Ted Bradley on February 25, 2014

      Thanks for the update. I'm a little unclear as to what happens next though. Are the beta machines being sent out again and then we wait for feedback - another couple of weeks?

      I think it would help me a lot if each update had a really short list of the things which need to happen next and roughly how long they'll take :)

    11. Creator sydlexius on February 25, 2014

      I'm glad I wasn't the only one confused by that!

    12. Creator Javier Parra on February 25, 2014

      Huh… I really don't understand the purpose of the missing test. If it overheats it passes and if it doesn't overheat it passes?

      Anyway. we can see the light at the end of the tunnel. Great job guys and gals, keep it up. We all love you. <3