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Thread: Decent espresso

  1. #1871
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    Quote Originally Posted by decent_espresso View Post
    Each hole in our portafilter baskets can have an error of +/-.05mm. Over the many holes in a basket, the average error mostly cancels out (some ever so slightly larger, some ever so slightly smaller).

    However, if a basket only has 1 hole, and we want to calibrate against it, we're looking for 4x better tolerance. This is quite hard to achieve, which is why calibrated orifices are expensive
    http://www.theleeco.com/products/pre...s/restrictors/ and made by very few companies. The best ones, that we use, are made for the US military, for jet fuel injection systems.

    As to measuring "the actual hole size" with a microscope, I don't know of any practical way to do that. Every basket would have a different labelled hole size, it wouldn't be repeatable, and even this assumes that the hole is perfectly circular, which at these dimensions, isn't usually the case. Here's a photo example I took of a competitor's basket some time ago.

    Attachment 34806
    It is actually a pretty easy calculation given that you know: Pixel size of the microscope camera, total magnification (objective×lens(if any)×cam mount), also take into account if the software acquisition does binning (grouping of pixels, to reduce noise, pretty common on microscopes).
    Plenty of image analysis softwares will be able to do that. When you know the actual hole size it should be an easy calculation, and definitely cheaper than going with calibrated flow restrictors. Only trouble I can think of will be artifacts on the image because of illumination on a smooth metal surface, but seems like you can already get a pretty nice image that should be usable.
    Shoot me a PM if you want to know more, I don't want to be spamming this thread with random information!

  2. #1872
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    Quote Originally Posted by Andreugv View Post
    It is actually a pretty easy calculation given that you know: Pixel size of the microscope camera, total magnification (objective×lens(if any)×cam mount), also take into account if the software acquisition does binning (grouping of pixels, to reduce noise, pretty common on microscopes).
    Plenty of image analysis softwares will be able to do that. When you know the actual hole size it should be an easy calculation, and definitely cheaper than going with calibrated flow restrictors. Only trouble I can think of will be artifacts on the image because of illumination on a smooth metal surface, but seems like you can already get a pretty nice image that should be usable. Shoot me a PM if you want to know more, I don't want to be spamming this thread with random information!
    What you're describing is in fact the software that John Weiss wrote for us, so that we can photographically check our baskets. The output of this program is the area of each hole as a CSV spreadsheet.

    Photo below.

    But I'm not too comfortable using this sort of thing for calibration. I prefer a repeatable, independently verified calibration source, and paying a bit more for my calibration tools to be better than what my own equipment is trying to achieve.

    screen 2018-06-13 at 2.28.45 PM.jpg

  3. #1873
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    Default Hairline Cracks

    hairline.jpg

    We've been talking to our metal fabricator about the hairline cracks that some of our clients have on their espresso machine legs. These paint cracks are hidden by the drip tray, but still, I'd be happier if they weren't there.

    The fabricator today provided a messy, but very useful, explanation of where and how they weld the leg pieces together. As it turns out, the hairline cracks are appearing exactly where no welding is indicating on their drawing.

    I really appreciate this company's honesty and transparency. They indicated today to us that they believe they've found a new approach that would allow them to continuously weld, instead of spot welding. It's really not an easy task, because we intentionally designed the sheet metal pieces to close in on themselves. The goal was to give the visual impression that the legs were made of solid 3cm thick bars of metal.

    We're also working on a design for the leg where the top front would have an added "lip" that bends 90º upwards for strength but is invisible (if we do it right) by being hidden under the mirror panel's lip.

    For the next 200 machines, if a customer gets a damaged leg, I'm going to ask whether it's merely a cosmetic problem, or if it unbalances the machine. If it unbalances, I'll send them a new leg assembly right away. However, if it's merely cosmetic, I'll ask them if it's ok to have them wait 90 days so that we can send this reinforced leg design version to them instead.

    I'm also hoping that the fractures happen less often, as they seem to be caused by UPS tilting our machine 90º and stacking heavy things on it. I'm 100% certain that our THIS WAY UP stickers will 100% solve this problem. Cough.

    For those customers who have already received a machine from us. If they have hairline cracks that are merely cosmetic, I'd like to hold off on sending a replacement leg set, until we have this new, stronger design in stock.

    -john

  4. #1874
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    Default Switches, Panels, Grinder Video, Puck Simulator

    various.jpg
    (clockwise by photo)

    - I've received the waterproof, lit, push-button switches that I'm planning on putting on the front plate of our DE1CAFE model. This will let you put the machine in standby (bluetooth and USB charging on, heaters all off). If this works well on the cafe model, we'll add this feature to our other DE1 models too.

    - samples from other companies making mirror panels are starting to come in. These are laser cut, and using transparent protective plastic lets us see the defects early. Oddly, our laser-etched logo comes out brown with this company--hopefully not a sign of rust.

    - I've made a video https://www.youtube.com/watch?v=b-BlIz7MXpI showing how to assemble and adjust the grinder we sell https://decentespresso.com/pro_grinder - this is a fairly low-tech, low-feature, do-it-yourselfer-friendly product. Instead of made-from-scratch, we modify another company's grinder quite a bit.

    - the company who makes our baskets for us has made us a prototype "puck simulator" with a 0.3mm hole (see posting earlier this week about this). What do you think of that product name for this?

    -john

  5. #1875
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    Default 100th espresso machine built today!

    100th.jpg

    "It's a bit of understatement" to say that we "didn't have our act together" several months ago when started manufacturing the espresso machine we'd been designing for the past 3.5 years.

    If this photo is a bit underwhelming, that's good! This was just an ordinary day, and it took us 5.5 days to make this batch of 20 machines.

    Just a month ago it was still taking us 2 days to make 1 machine.

    I spent an hour myself checking about half the machines in detail for mistakes I've seen in the past and didn't find anything. We'll find out tomorrow if the 9 machines shaken tonight are all ready-to-go, or if we still have hard-to-spot mistakes creeping in in our process.

    screen 2018-06-14 at 5.24.39 PM.jpg


    Two weeks ago I switched our conceptual metaphor to be that of a kitchen. Every day, everyone knows what to do when they walk in the door. No meetings necessary. We complete a batch of machines every 5 days and then start again. The only thing that changes is that (hopefully) this kitchen gets faster and able to feed more people every day. For now, I'm not applying much pressure, because the emphasis is on zero-defects. Once we start achieving that, we'll gently crank up the speed.

  6. #1876
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    Puck sim sounds good!


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  7. #1877
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    Quote Originally Posted by embrya View Post
    Puck sim sounds good!
    +1

  8. #1878
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    +1
    Espresso: Ceado E92 (modified for single dose); Vesuvius; VST baskets and refractometer.
    Other: Aeropress, Sowden and Alessi Moka Pot; Mazzer Robur doser with Auber timer; Mazzer Mini E; Expobar Leva Dual Boiler

  9. #1879
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    John: Are you installing the v1.1 group head on current production?

  10. #1880
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    In Post 1852 John wrote that V1.1 will be implemented for the next batch of 500 machines. So not for the actual batch!


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