I'm thinking about playing around with a kit like this http://www.aliexpress.com/store/product ... 56714.html to give digital scale capabilities to the removable drip tray cover on my espresso machine. I was wondering if anyone here has attempted it before?

I'm not too sure if it has done before, but there are several places where you can find some ideas.

A patent filed by La Marzocco has a few drawings that don't seem to be all that helpful.
http://patentscope.wipo.int/search/en/d ... PCT+Biblio

A more successful implementation would be the scale found on the VA388:
http://www.victoriaarduino.com/en/la-co ... logy-va388

Hope it helps!

I saw such a scale built into a new LM machine in Seattle at LM USA a couple of months ago. Seems cool, but also something else to go wrong.

Not sure the model of machine it was on but I believe it was a 3 group model.

The easiest way to do this is probably to make a tray cover and inset one of the many excellent small $20 scales out there into it. I'd make the cover from a stainless steel sheet and sink a rigid plastic food container just large enough to hold the scale into a cutout. Leaving it uncovered risks damage from liquids and dropped coffee. So I'd cut out the top of the container and seal a thin sheet of plexiglas or similar material into it so the rim still seals against the bottom and the "shield" sits directly on the scale. When you put a cup on it, the tare will remove the container lid's weight too.

I just use an American Weigh BL1KG directly on the tray cover - it fits fine, looks fine, and works even better.

The new Victoria Arduino VA388 has "gravimetric" dosing, VA is owned by Nuova Simonelli and there was a bit of stuff on a some blogs when it first came out.
http://www.victoriaarduino.com/en/la-co ... lack-eagle

noidea wrote:The new Victoria Arduino VA388 has "gravimetric" dosing, VA is owned by Nuova Simonelli and there was a bit of stuff on a some blogs when it first came out.

That's a sophisticated system that stops the flow when the shot reaches your preset weight - it's a bit more complicated than a simple scale in the drip tray screen, and the scale parts alone probably cost more than most of our machines.

That aliexpress digital scale kit could be built into a small, watertight box and set into a tray screen. But it requires an Arduino computer, which is an additional $100+ just for the basic starter kit. You'll have to build the Arduino, install the OS, and either install and power the Arduino board in the machine somewhere or put it in a remote box and add wiring and connectors to the espresso machine for power and signal cables.

There are a few small scales with removable displays (e.g. the Oxo) that could be used for this. I'd try to put a drip tray screen on top of it, set it into the tray sitting in a tight-fitting plastic container, and use Velcro or double-sided tape to mount the read-out on the front of the tray. I don't think the display module is waterproof - but if it is, it could be mounted against the vertical surface behind and just above the drip tray and wiped clean after each use.

I've used a scale on the drip tray sending data to a microcontroller controlling pump output for a long time. It provides pre-infusion, flow profiling and gravimetric dosing. It works well, although a paddle wheel flow meter might yield similar results.