DIY Dipper Lever

A haven dedicated to manual espresso machine aficionados.
pizzaman383

Postby pizzaman383 » Mar 07, 2015, 4:37 pm

Edited to refer to the latest thread. I replaced the boiler due to unrepairable pinholes.
Here's a link to version two:
Double Dipper Lever


I went from this:
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To a PID-controlled dipper with a commercial spring lever group I'm still working on the temperature control and I'm waiting for parts to install the sight glass.
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Here's the copper plat that allows the group head to fit the boiler flange. I'm planning to put cartridge heaters in the plate. Since it's directly connected to the group head that should let me control the temperature of the adapter plate. Until then, I'm using it as a classic dipper with the boiler temp high so the group head cools it to the proper shot temp.
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It's plumbed in with a fill switch. It requires about 30 pounds of weight in the back to keep it from tipping when pulling the lever. I decided to use counter-weight because the boiler is only 1.2 liters so it would never be heavy enough to keep the machine from tipping. Since I never steam milk I put a vacuum breaker in place of the steam wand.
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Here's how tall it is. I mounted the group head so that there is plenty of room above the drip tray for tall cups, spouts, and a scale.
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TomC
Team HB

Postby TomC » Mar 07, 2015, 6:01 pm

Very interesting. Is that a Rossi group? Clever build! I look forward to seeing how the group temp managment works out for you. That's a big group to heat up!

baldheadracing

Postby baldheadracing » Mar 07, 2015, 7:06 pm

That is awesome. I am inspired. Thanks for sharing!
What I'm interested in is my worst espresso being fantastic - James Hoffmann

pizzaman383

Postby pizzaman383 » Mar 07, 2015, 9:02 pm

TomC wrote:Very interesting. Is that a Rossi group?

Yes, it is one of these:
[FS] Rossi / Brasilia lever group (double spring)
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day

Postby day » Mar 07, 2015, 9:15 pm

That is really incredible, especially from the front. Though i shouldn't i have to ask anyway because I am a jerk, if you dont care for steam why not build it as a gravity fed system?
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FotonDrv

Postby FotonDrv » Mar 08, 2015, 12:26 am

That is quite the project!! Good luck with the rest of the build :)
That Light at the End of the Tunnel is actually a train

pizzaman383

Postby pizzaman383 » Mar 08, 2015, 8:55 am

day wrote:if you dont care for steam why not build it as a gravity fed system?

Good question. I thought long and hard about making the Graziella into a gravity fed, open boiler machine. In the end, there wasn't a good way to do it because of the positioning of the heating elements in the boiler, the location of the water entry tube, etc.

After putting a pid on the Graziella, I realized that I didn't need to shift away from the dipper system. Setting the PID at 240 degrees F and letting it fully preheat for 30-40 minutes let me my typical 3-4 doubles with stable shot temperature.

I've looked at the designs of a lot of spring-lever dipper machines. They all are a little different and it looks like they're trying to have a boiler that's much hotter than the espresso needs with some mechanism to reduce that down by the time it reaches the coffee puck. My theory is that by heating the group head (like the Strega does) I can run a lower boiler temperature and make the brew temperature more consistent.

Most of the newer lever designs seem to use the thermo-syphons to keep the group head nearer to the end temperature so this is just another way to do the same thing. Since I had a dipper boiler and it was a dipper group that became available I decided to take this path. I picked copper as the material for the plate in case I needed the cartridge heaters. It wasn't until I put it the thing together that it became clear that I would need them; I can only get reasonably close shot temperatures when I run the boiler at a very high temperature.

The other variable I can play with a bit is the heat transmission from the boiler to the plate and from the plate to the group head by varying the thickness and material of the gaskets. The current plan is to have fairly thin gaskets for good heat transmission; I'm now using food-grade RTV between the plate and the group head because it's the thinnest-possible seal I can get.

If anybody knows where I can get some soft copper-foil gasket material that would be perfect!
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EspressoForge

Postby EspressoForge » Mar 09, 2015, 1:11 pm

Awesome project, I love the build. Reminds me of the Robo-Pavoni thread.

What size copper do you need?
http://www.mcmaster.com/#copper-gaskets/=w8iaio

Or you could try just a copper sheet and cut it:
http://www.mcmaster.com/#copper-shim-stock/=w8ib6s

You can get some copper foil even thinner there too.

For a big selection, I usually check mcmaster, but sometimes for certain things, they aren't the best. One other caution is that after you order they just charge you whatever they feel like for shipping. :( Not the best system to say the least. But once you find something there, you can usually find it somewhere else a little easier. I wish I had a better recommendation for a supplier that could do it all in one and I could support more often. But just my opinion on them from recent experience on my own projects.

pizzaman383

Postby pizzaman383 » Mar 09, 2015, 1:47 pm

I did some more googling and found a sample pack of 4"x4" squares for around 15 bucks. I also found out how to anneal it so that it will (hopefully) adapt to surface imperfections. I lapped the copper plate to minimize the defects.
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pizzaman383

Postby pizzaman383 » Mar 22, 2015, 5:28 pm

I've installed the cartridge heaters, hooked up the PID (using temporary wiring), installed thermocouples to measure the temps, and installed the plumbing. I broke my sight glass tube so that's not yet hooked up.

There is one cartridge heater installed and one still out to see the location.

I decided to use the Graziella's skin to keep the looks clean until I build a case. I can use it like it is for a while.

I found that my drip tray leaks at the back corners. I'll try some plumber's clear silicone. If that doesn't work or is too smelly I'll return the part to 1st-Line for a replacement.

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