Double Dipper Lever

A haven dedicated to manual espresso machine aficionados.
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pizzaman383
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#1: Post by pizzaman383 »

The Graziella boiler I used in my DIY Dipper Lever had a slow steam leak. After I took it apart to try and fix the leak it became apparent that the leak was a substantial weakness in the boiler. Since I can't leave anything alone I took that as a sign that I needed to make the machine into a Double Dipper Lever :D .

So, I searched for a boiler I could use as a steam boiler and I took the boiler from my KA Proline and started figuring out how to put it all together and make it work. In the end, there is a steam boiler controlled by a pstat that feeds water into a PID-controlled brew boiler (through a coil to allow the water to cool before it reaches the brew boiler) . The group is still heated by the copper plate with cartridge heaters. The coil between the steam and brew boilers lets the water temperature cool to about 200 degrees F so that the brew boiler just needs to do the final heating to brew temperature. The brew boiler (with its coil wrap) is about three times the volume of the group cylinder so that all the water for a single shot comes in a very nearly the same temperature.

My goal was to allow the group head and brew water temperature to be independently controlled and this design does that. Although I'm still running test shots and working on the final connections and packaging it seems to work well. I can run it like a saturated group with only 60 seconds between shots and the group head temperature never varies. I can run it like a classic dipper where the group head temperature is lower than the brew water temperature but I can choose the temperature difference (typical dippers run 25-40 degrees of difference between the group head and brew water). I haven't determined what tastes best but that will come after I've finished the construction and can focus on using the machine for making espresso.

If I was the craftsman that Paul Pratt is it would look like this masterpiece (I had to give a plug to Paul's amazing work):
Cafelat dual boiler lever
Cafelat dual boiler lever close-up
Cafelat from scratch lever machine front

Instead, here are the pictures of the progress I've made on my Double Dripper. I'll post some updates as it gets buttoned up and I use it more.

I had a steam boiler from a (Gaggia) KA Proline espresso machine. I used that because since it is all aluminum it doesn't have the same pitting problem that causes leaks in the Gaggia Classic boiler and it has both input and output fittings to make easier to connect. Since I'm not using it for steam I'm hoping there won't be too much of a scale problem.

I found a steam boiler from a Gaggia Asso machine on eBay and I was able to get it at a good price. I'm taking water out the bottom fitting that was designed as the boiler drain. This gives me the coolest water in the boiler which is what I want for brewing. The machine still uses manual fill controlled by a switch/solenoid. It will have an improved sight glass once the parts arrive from Italy.


Figuring out how to fit the boilers into the frame I already had was a little bit of a challenge. It's not pretty but it does work.


Here's the cooling coil. I borrowed this idea from some of the classic espresso machines and it works well as long as there is at least 30-45 seconds between shots. This makes it operate like a classic dipper with preinfusion driven by the steam boiler pressure.


I think that a double dipper like this would be ideal in the hands of someone like Jim Schulman because it gives control as well as variation. I don't have the patience nor the refined palate but I respect those that do.
Curtis
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“Taste every shot before adding milk!”

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pizzaman383 (original poster)
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#2: Post by pizzaman383 (original poster) »

As I said, this functions like a dipper in that the steam boiler pressure sets the preinfusion pressure. I am using a PID to control the steam boiler (instead of a pstat) so it is quiet. The steam boiler, brew boiler, and group head each have their own PID controllers.
Curtis
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“Taste every shot before adding milk!”

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pizzaman383 (original poster)
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#3: Post by pizzaman383 (original poster) »

I've been using the double dipper for the past couple of months and I really like the way it works. I run the group head set point at 203, the brew boiler at 215, and the steam boiler at 255. This lets me pull a shot every 60-90 seconds with stable group head and shot temperatures for every shot.

In addition, I finished buttoning up the externals of the double dipper. Here are some pics of the finished machine. The wood is teak finished with a drift-wood weathering stain. The color is a little more gray than it shows up in the picture. I will probably make some knobs and handles of teak when I get around to it.





Curtis
LMWDP #551
“Taste every shot before adding milk!”

randyh
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#4: Post by randyh »

Very nice work! Love the wood panels and compact size. Any chance you'll post some videos of it in action?

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pizzaman383 (original poster)
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#5: Post by pizzaman383 (original poster) replying to randyh »

Sure, I can do that but it will be a couple of weeks because I am traveling this week and weekend.
Curtis
LMWDP #551
“Taste every shot before adding milk!”

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aecletec
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#6: Post by aecletec »

The controllability sounds fantastic!
Have you also experimented with a rising or falling temperature profile?

jwCrema
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#7: Post by jwCrema »

Thanks for posting this - excellent work!

samuellaw178
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#8: Post by samuellaw178 »

Looks great Curtis!

Just curious what kind of SS-braided hose are those (what's the inner liner material)? They seem like those commonly used for plumbing/cold water application. Is it okay to use them in this application?


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pizzaman383 (original poster)
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#9: Post by pizzaman383 (original poster) »

I used those lines to test the setup and the water paths. I did melt one of the lines when running boiler temperature water for more than a few seconds :oops:

I have since switched to copper lines with soldered mushrooms on the ends. I should probably take some pictures of the completed internals.
Curtis
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“Taste every shot before adding milk!”

samuellaw178
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#10: Post by samuellaw178 »

Ahh! :oops: They are so convenient & flexible to set up though! I was thinking of toying with the water path arrangement on my machine, but have no tools for copper tube shaping/soldering. Thought these might have been OK, especially if they're teflon-lined. They are not rated explicitly to be food safe so I was hesitating... (more for automotive use).


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