Some like it hot: Cafelat Robot Temperature Mods

A haven dedicated to manual espresso machine aficionados.
cooperpwc

Postby cooperpwc » May 13, 2019, 12:24 am

(20190602: I have renamed this thread to encompass a variety of ongoing temperature experiments for the Cafelat Robot. All feedback, ideas and mods welcome in relation to controlling temperature on this remarkable lever machine.)

The Cafelat Robot User Experience thread keeps telling me that I should consider starting a new thread, so I am actually going to do that. This is a quick report on my Pink Spout Mod (PSM) for the Cafelat Robot:

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I made the PSM this using Smooth-Sil 940 Food Grade Mold Making Silicone Rubber. (The mixed pourable compound is distinctly pink, hence the mod names.)

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The reason I went down this path is domestic harmony. I make flat whites with my Cafelat Robot, steaming milk separately with the Welhome MS-130D. My favourite lady had consistently been complaining that the second drink that I make for myself tastes better than the first drink that I make for her. And it really does. When the Robot is heated up (such as after pulling a shot), it produces a better espresso to our mutual tastes. So I wanted a method to get the Robot preheated for that first flat white.

The PSM seals the spouts of the portafilter spout attachment. Thus when attached to the portafilter, it allows you to fill the portafilter with hot water. This mod is used without a basket installed in the portafilter. You fill the portafilter halfway with hot water - any more and it spills over the top as the piston enters the hot water when you attach the portafilter to the Robot.

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You install the sealed off portafilter on the Robot with the Robot's arms down. The PSM thereby immerses the piston in hot water for direct heating.

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The PSM is removable. (So, for example, you can still use your spout attachment with the pressurized basket.) After removing, I trimmed the plugs to allow for easier reinsertion. A bit of Dow Molykote (included with the Robot) eases the reinsertion and produces a good seal.

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So how does it work? Brilliantly! Complaints that the second drink is better than the first have gone away.

I am actually using the PSM on both the first and second drinks. There are a few minutes in-between them as I steam milk and prepare the first flat white. If I do not use the PSM again, the first flat white is actually better than the second. I posit that if you are preparing two espresso shots back to back, the second PSM preheating is probably not necessary.

I highly recommend this mod if you want consistent heated shots on the Cafelat Robot.
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cooperpwc

Postby cooperpwc » May 13, 2019, 12:46 am

Related to the PSM, I tried another anther experiment that was less successful: The Pink Puck Mod.

I created the Pink Puck Mod with the same Smooth-Sil 940 Food Grade Mold Making Silicone Rubber. It has an embedded Wacaco plastic tamper mounted upside down for ease of removal.

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The puck fits into the basket which is filled with hot water.

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You then install the portafilter just as you would if you were about to pull a shot. The puck holds the hot water in, with the Robot's arms staying up. The basket, portafilter and piston all get pre-heated by the hot water.

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However the PSM works much better. Firstly, preheating the basket is not very useful. They are made of such light metal that, unless you can fill with coffee, WDM, tamp, add hot water and install on the Robot in less than about 20 seconds, the heat dissipates. The basket is quickly just a bit warmer than room temperature; I have found it to be at most a minor difference over not preheating at all. Actually I find that the advantage goes the other way since the PSM stays installed on the Robot while I fill and tamp the basket. This keeps the piston hot; there is minimal time when the piston is exposed to ambient room temperature to cool down.

Secondly, the puck mod heats the piston by rising heat, i.e. the Robot arms are up in pre-shot position and the piston is above the hot water. By contrast, the PSM immerses the piston in hot water for direct heating, making the piston (and the portafilter) much hotter. It produces a hotter shot, and to our tastes it is a better shot for our flat whites.

While it was fun playing with the Pink Puck Mod, I recommend the PSM. It works better.
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drgary
Team HB

Postby drgary » May 13, 2019, 2:26 am

Great idea! Essentially you're creating a blind basket. My Maximatic has a rubber piece that fits at the bottom of a filter basket and accomplishes the same thing for group flushes. Since I have a variety of gasket material, I went out to my shop and cut a soft piece of silicone and a thicker and harder piece of silicone gasket material and tested them with cold water. Neither held the seal perfectly by itself. Then I positioned the soft silicone under the harder one, and it works. Removal is easy with a pointy chopstick.

Since the molded version is more precise, if you try a circle of gasket material like I did, please test it first using cold water, and might as well have a catch cup underneath if there's a slight leak.

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Gary
LMWDP#308

What I WOULD do for a good cup of coffee!

cooperpwc

Postby cooperpwc » May 13, 2019, 3:26 am

drgary wrote:Great idea! Essentially you're creating a blind basket. My Maximatic has a rubber piece that fits at the bottom of a filter basket and accomplishes the same thing for group flushes. Since I have a variety of gasket material, I went out to my shop and cut a soft piece of silicone and a thicker and harder piece of silicone gasket material and tested them with cold water. Neither held the seal perfectly by itself. Then I positioned the soft silicone under the harder one, and it works. Removal is easy with a pointy chopstick.

Since the molded version is more precise, if you try a circle of gasket material like I did, please test it first using cold water, and might as well have a catch cup underneath if there's a slight leak.


Thank you!

That is a good alternate way to do it.

Precision moulding with Smooth-Sil 940 is ideal for me as I am using this mod every time I use the Robot. I have so much of it in the 'trial pack' that I purchased, I plan to make some spares.

jpender

Postby jpender » May 13, 2019, 9:59 am

I heat up my portafilter (and basket too sometimes) by setting it on the lid of a pot of boiling water. Through contact with the hot lid and also steam passing around the sides of the lid the portafilter gets quite hot.

But I also have two "pink" silicone mods for my Robot.

The first is a boot for the portafilter handle. It gets too hot to hold in my hand and I grew tired of using a pot holder. So I sewed and glued a boot out of some pinkish colored food grade silicone sheet material that I have. Now I can hold the portafilter even when it's really, really hot:

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Another thing I found awkward about installing the portafilter was the need to raise the arms. I found it was difficult to do this by raising one of the arms; the piston would bind in the Robot interior. So for a while I was jamming a clothespin in the hinge of one of the Robot's arms to keep them raised. Then I came up with a more elegant solution, which again involved the pinkish silicone.

Basically it's a loop, an armband if you like, that provides just enough friction between the arms when they are fully raised to keep them up:

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I still have one more mod I want to do. I find the Robot arms attractive but not very ergonomically shaped. I am going to change that somehow but I haven't figured out quite what to do yet.

cooperpwc

Postby cooperpwc » May 20, 2019, 9:47 pm

jpender wrote:Another thing I found awkward about installing the portafilter was the need to raise the arms. I found it was difficult to do this by raising one of the arms; the piston would bind in the Robot interior. So for a while I was jamming a clothespin in the hinge of one of the Robot's arms to keep them raised. Then I came up with a more elegant solution, which again involved the pinkish silicone.

Basically it's a loop, an armband if you like, that provides just enough friction between the arms when they are fully raised to keep them up:
....
I still have one more mod I want to do. I find the Robot arms attractive but not very ergonomically shaped. I am going to change that somehow but I haven't figured out quite what to do yet.


That arm loop is great. My Robot will keep its arms raised on their own if I lift by the right arm (but not if I lift from the left). If that stops working, I will need to do a loop like yours.

I also would like find a way to soften the shot pull. If you come up with something functional (and perhaps even elegant), please report back.

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MB

Postby MB » May 20, 2019, 10:32 pm

cooperpwc wrote:I also would like find a way to soften the shot pull. If you come up with something functional (and perhaps even elegant), please report back.


Oven mitts on your hands, maybe? A squash ball or a mini pet-sized tennis ball like this?

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LMWDP #472

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drgary
Team HB

Postby drgary » May 21, 2019, 12:24 am

cooperpwc wrote:I also would like find a way to soften the shot pull. If you come up with something functional (and perhaps even elegant), please report back.


I rest the edge of the heels of my hands on the place where the arm joins the loop.
Gary
LMWDP#308

What I WOULD do for a good cup of coffee!

jpender

Postby jpender » replying to drgary » May 21, 2019, 1:24 am

That's what I do too, but "rest" isn't quite the right word. It's more like pressing down hard. The relatively thin metal arm invariably leaves a red mark on my palm that lasts for about 30 minutes. It doesn't really hurt but it seems, to my mind, unnecessary.

I've thought of different sorts of handles that would be more comfortable. Bicycle grips would be one option. Rubber monster hands would be kind of fun. Or perhaps, to be somewhat provocative, silicone dildos. The problem is how to attach the grips securely. I don't want to mar the finish of the Robot's natural arms.

I'll figure something out eventually. Meanwhile it works okay as is.

cooperpwc

Postby cooperpwc » May 21, 2019, 2:49 am

I just remembered where I once ordered bicycle grips like these on Taobao:
https://item.taobao.com/item.htm?spm=a2 ... =18#detail
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Some bicycle tape like this might work even better:
https://item.taobao.com/item.htm?spm=a2 ... =18#detail
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These are cheap options to play with here in China. I am not sure. Deserves some contemplation...