HG One travel chest

Over the past weeks, Willi Egger has been building and finishing a travel chest made out of elm wood which he designed for my HG One grinder. No nail has been used, all wood-on-wood connections, just a few screws for the piano hinge of the front which has magnetic locks. One of the details I am very impressed with is the handle which is strong enough to carry the 10 kg of the grinder and the chest itself and yet it does not look crude, hiding inside the chest when resting.

Willi Egger is the versatile typesetter and book binder from http://www.boede.nl who has previously prepared the 2006 edition of "Het voorbeeldige boek" by Johan Polak for Balans publishers in Amsterdam. He also hand bound two copies of this book (as featured on  http://www.kostverlorenvaart.nl/voorbeeldig/ ). Recently he has adapted software to typeset himself a very complicated English book of math for a publisher in the UK. And a few years back he was on the team of experts who did technical research to the options to save the Anne Frank tree in Amsterdam.

Thank you Willi for a great job on this chest! Next time I go on the road the HG One grinder will be traveling along safely and the hotel room will look splendid with this excellent piece of craftsmanship ;-)

It reminds me of the times when the famous explorers, adventurers and butterfly hunters would employ locals to carry their espresso equipment through the Amazon forest and over the plains of Uganda and whenever they would chance to run into each other, their teams would compete to make the best espresso and all would stay up very late.

Voel de autoklaaf

De probe die met z'n vinger in het koffiefilter zit tijdens het koffiezetten is stuk en het was lastig er een vervanger voor te vinden. Idealiter is het maar een kort staafje, maar liever geen draad omdat die weer kwetsbaar is en altijd net weer iets anders kan staan waardoor je ook wat anders meet, het hete water boven de koffie, de gezellige warmte midden in de koffieprut... en de meeste zijn erg lang, ontworpen om ergens in te steken, een stuk vlees in de oven, een lang meetinstrument, een ventiel tussen twee ruimtes.

Gelukkig vond ik er een en die heeft nog een pracht naam ook. "Miniatuur Autoklaven Voeler." Autoklaven. Ik wist niet dat die bestonden, maar het is wel goed er een te hebben. Als je eenmaal een autoklaaf hebt, kun je al snel niet meer zonder. Bietjes heb je zo gaar.

 

 

Modifying the Mazzer Mini

The hopper on my Mazzer Mini is a bit big for my method of single dosing. I typically grind just 14 to 20 grams of beans at a time, enough for one cup of espresso. This way the beans stay as fresh as possible in their bag. In a cafe environment this would be too fussy and there the hopper is very handy as a lot of coffee can be thrown in. There, kilos of beans are used every day so the freshness of the beans should not be at risk.

 

From the top, the beans travel downward, through the burrs. Peter van der Weerd exchanged the original burrs for the ones made for the heavier Super Jolly model which are identical in size but different in cut. They grind faster which is a bit of a strain on the engine but no problem in a home environment. 

Below you see a metal sheet cut and bent to cover the chute, the little tunnel from the side of the burrs into the metal funnel. It is supposed to protect the fingers of any curious kid so they can't be grabbed by the burrs. I wonder about that, because there's still a mesh of wire behind the metal sheet.

In a grinder that's been used for a while, you can see a firm buildup of old coffee grinds caught in the grid:

 It's possible to clean that chute behind the grid but it clogs up easily again.

See for instance: https://vimeo.com/58487456

I took away this grid:

I read that without the grid, ground coffee would clump together, stick to the chute and fly away from the basket, all because of the static electricity. I don't have that problem at all since I usually add two droplets of water to every dose. Again, not something one can take time to do in a commercial production environment where the grid may indeed help. I also stir the grounds with a tiny whisker so any disbalance in the distribution of fine and coarse particles gets corrected as well.

Next, I got rid of the hopper. I took the grinder to the guys of Aluminium Centrum Amsterdam, asking them if they could produce a fitting for the acrylate pipe that I had bought at Damme.

The guys at ACA have their own video:

This is what they made:

I think it fits the industrial look of the heavy grinder very well. The height of the acrylate tube helps to keep the coffee beans inside, as the last few beans to get caught in the burrs sometimes 'popcorn' way upwards before being finally crunched to espresso powder.

Cleaning Mahlkönig Vario

The little Mahlkönig grinder needed te be cleaned as it hadn't been for a few months. I'm playing with the idea to have it modified and if I take it to a workshop, it should not be clogged up with coffee grounds.

The grinder standing up (note the ugly smoke-dark seventies look of the hopper):

 

Lying down, hopper and top burr taken off:

The burrs after a bath -- screws on the left burr need a scrape still:

The grinder beneath the lower burr before and after the vacuum cleaner:

The micro switch that 'feels' if the hopper is in place. If I replace the ugly hopper, I need to make sure the switch is still on:

Lower burr re-installed:

Upper burr tightened in as well:

Soldering Pipo

A friend handed me a Pipo M3 tablet that's gone into some kind of screen freeze and asked me if I could fix it. Although I do have a soldering iron, I'm not really good at such things but I was willing to try. And it worked:

This is what I did. First a picture of the two diodes that I bought:

There's a website (http://www.slatedroid.com/topic/41687-solved-mod-pipo-m3-touchscreen-issue/page__st__20__gopid__749161#entry749161) with a brief description of a possible fix and I used that as a guideline. The trick would be to solder a Schottky diode 1N4148 or 1N5819 to bridge two very tiny parts on the board. I bought both diodes and used the tiniest of the two.

Opened the back using a credit card to un-click the front/back connectors. The electronics were insulated by thin plastic sheets fastened with sticky tape.

I used the soldering iron to temporarily disconnect the red wire (the plus wire from the rechargable battery). Then I used gaffer tape to isolate the parts the diode would be touching, to make sure no unintentional shortcut would be made:

 Bent the legs of the diode to fit the two connectors it needed to connect with:

 Stuck the diode in place:

 ... did some soldering, using the camera with macro lens and a magnifying glass to check what I'd done. The left leg should maybe have been heated longer but if the tiny blob had spread it would have made more connections than I needed.

Espresso brew pressure profiling: dual OPV on the Rocket Giotto

Yesterday morning I took my Rocket Giotto to visit Peter van der Weerd from http://www.kafko.nl in his espresso machine workshop.

He has made me a temperature probe to fit in a portafilter basket:

 (I will post more about this nifty device soon)

Since I was there anyway, he took an extra back panel and cut out a square so I could change the setting of the OPV while working with the machine. This way, I wouldn't need to disassemble the covers if I wanted to change the brew pressure setting:

I  had been lowering the brew pressure on the OPV but noticed that it would leak water when turned down below 8 bar. Here a few images of this original OPV connection:

To be able to easily change the setting of this OPV through the back panel opening, Peter created a bend in the spanner:

 An image of the spring inside this OPV:

Peter could cut the spring to allow the threaded part to go in deeper but he didn't like this idea as the spring has its own use and characteristics.

Still, the threaded part needs to go in deeper to be able to turn it out a number of turns before the rubber gasket leaves the space it fits in to close it off. Turned back more, it enters the threaded room and water seeps through.

Peter made the OPV a little deeper:

Now, it would be possible to lower the brew pressure without leaks.

At this point, Peter discussed an idea he had been thinking about for a while: why not create an optional extra OPV, with a solenoid valve, controlled from the front panel, switching between two very different OPV settings during any extraction? You could start the extraction, building up the pressure calmly to 6 bar, then briefly use 9 bar and finish the extraction at 6 bar again, for instance, or any thinkable combination. And both settings could be adapted independantly.

One would need something like this:

 I liked the idea very much so Peter set forth:

To control the new solenoid, the on/off light was sacrificed for now (we can install it in another place later) and an identical switch as the original Rocket on/off switch was installed:

 

The second OPV got wired too. After first having it use the mains power from the on/off switch, Peter changed this. Now it is only active when the vibe pump is active. This way, if the solenoid OPV selection switch is "ON" and selecting the lower pressure OPV, the solenoid will only be ON when the pump is ON too, and won't be ON for long periods of time if the machine is idle.

 Setting the new OPV to 6 bar involves temporarily disconnecting the back hose/plug, adding a temporary hose and changing the setting using a long slender screw driver:

The tube prevents water from the OPV flowing into the machine.

Next the tank went temporarily back in for testing, the machine was blow dried and we did some testing to see if there were any leaks (none).

In these first test, the espresso was delicious so I look forward to play more with this dual OPV setup!

The switches on the front panel are very straightforward: the top is ON (up) / OFF (down) and the lower switch is HIGH-9bar (up) / LOW-6bar (down).

 

One last picture of Peter satisfied after a number of hours of work and play! I want to thank Peter for his time, his enthusiasm, help and his inventiveness.