I thought it best to start this as a new thread. It's a work in progress. My boiler has started to develop rust and while I'm sure it will last a long time, I really don't like it. My thought is to make a boiler using ceramic. First, I'm going to make a prototype or two to test two things: sealing and thermal safety. I don't want to put a lot of time into it if it's going to leak or crack. If these two issues are not issues, I'll go to the next step and make something a bit nicer. Part of the challenge is that clay shrinks and changes as it dries, sometimes substantially. So I made everything about 10% larger than I hope it will end up.

Clay as it comes out of the pugger (nicely wedged and 100% de-aired due to wedging under vacuum):



Pug on the wheel:



Rough Thrown (I hate to say it, but these are looking a lot like hornet nests):



Rough Trimmed:



Next steps are to let dry a bit more, clean up, dry, bisque fire, glaze and glaze fire. If it all works out, and everything tests fine for a few weeks on the machine, then I will consider making a very close duplicate of the existing boiler and instead of wheel throwing, I will slip cast it making it look very close to the OEM boiler. To slip cast I need to make a plug (using a wood lathe, I think) the size of the boiler + allow for shrinkage, make a plaster mold and then pour liquid clay into the mold. That's why I can't use an actual boiler for the mold. Or it I did, it would be a bit smaller than the OEM boiler.

What pops out should be very uniform and nice. I will add color to the slip so the clay will be colored all the way through and a clear glaze overcoat. I've never done much slip casting, so this is a nice excuse to learn something new.

I should note that I'm appreciating the basic design of the Peppina more and more. My shots are now all 'tigery" or "tiggery" and it really is a great machine. I'd be interested what Caravel owners who also own a Peppina think as to the pros and cons of the two of them.

One design feature is that the lantern shape of the boiler is purposely designed so that when you press the lever down you don't hit the boiler with your finger tips. I don't know if the ones I threw will work as well in that regard. I could actually 'flat' one side a bit, but I don't think I will. I could also add some text or logos if I felt like it.

dan

I own a Peppina, and owned a Caravel until recently. Peppina has a larger basket which yields a bit more volume, which I like. I found that due to the relatively lower pressure afforded by the spring in the Peppina that the Caravel produces shots with a bit more body, but I found that the Peppina emphasized some of the brighter flavors and that's what I was looking for. Peppina is also the most cost effective way into Spring lever ownership. I have a 220V element, but I still plug it right in to my 110 power, I find it slows the overall heating which prevents it from getting crazy and taking off at boil.

Basically, I like the basket size and volume of the Peppina better, and I find it a little easier to use than the Caravel for some reason. I just wish mine wasn't so rusty and that I hadn't killed all the chrome with citric acid. The Peppina feels more toy-like to me, which is nice so I feel a little more apt to experiment with it.

That is a wonderful idea. Please keep us posted.
~Richard

That is pretty cool DJR! Please, keep on with the experiment. I do not own a La Peppina, but own an Arrarex Caravel (thanks Mike K!). There is something about the simplicity and functionality of these 1950's machines.

Most excellent project, I heartily approve.

I was wondering if it would be possible to find some alternative kettle for the La Peppina. It could even be a novelty kettle, say shaped like a clown head or maybe something more dignified. Keep us posted!

Boiler Project Update

The ceramic boilers are ready to fire, and I'll fire them soon (as soon as I have a few more other things to go in the kiln). I have to say, though, they are really ugly.

My current thought is to use slip casting to make boilers that will look almost like the originals. I'm making a form out of wood and clay (on the lathe). From that I'll make a two part plaster mold. Once that is dry, I can pour liquid clay (slip) into the form. As the water from the slip is absorbed by the plaster, it essentially coats the plaster. The longer you let it sit the thicker it gets.

When it is the right thickness, I'll pour out the slip and it will begin to harden inside the mold. It will also shrink and that makes it easy to remove, but it also means I need to allow for that in the original form. Basically I need to make the form a certain percentage oversize, which depends on the clay formulation.

Bottom line, the work to date is to see how the clay at a medium fire will stand heat cycling. I'll test it on La Peppina a few times and then just keep it in my dishwasher and let it get washed every day along with the dishes. This isn't boiling, but it should provide some indication-- if it breaks in the dishwasher after 30 washings, then it is a bad idea to begin with.

Slightly off topic, but I'm beginning to find the handle to be a bit unpleasant-- I'm not exactly soft-of-hand, but it doesn't feel that good to pull a shot. I'm going to make a replacement handle out of wood. What I thought was odd was that the handle has American, not metric threads. 7/16 x 14 to be exact. I'll post a picture of the handle in the next few days.

Also a bit off topic, but the more I use this machine, the more I like it. I find that doing two pulls makes a coffee that my wife likes (two pulls as opposed to one with water to make an Americano). I tend to make restricted shots straight for myself. After getting used to it and using the bottomless PF that allows any size cup under it, it really is a joy. Takes just a few minutes to heat up and temp is very easy to control using the router dimmer dial. Cleaning is also extremely simple, as is making multiple shots. I load one basket while the other is making espresso. The second (or third) is ready to go as soon as the handle goes all the way up.

dan

Hi!

Nice write-up about the boiler. An inspiration for you may be these photos (from an ebay auction):



The machine pictured looks like custom La Peppina, but it probably is yet another version.(*)

As for your double pull technique, probably you do not much or none preinfusion? On mine I may get 2oz shot before the lever raises fully (the shot blond somewhere at last 1/3 or 1/4 of remaining motion).

(*) edit: yes it is just La Piccolina missing its grate.

I like that old style boiler. Mine is the later, more angular one, and I think the rounded edges look nicer. I'll probably do something a bit in between.

I actually have been doing a pre-infusion with my double pulls. Perhaps I shouldn't. Sometimes I take a small spoon and taste the stream at various times. When it blonds (as yours does), it doesn't taste very good. But it doesn't make me spit it into the sink. I remember that doing that with my Gaggia Classic, the end of the stream really tasted bad. I wonder if it could be due to less pressure at the end? Anyhow, it's what my 'customer' wants, so that's what she gets. I prefer pulling two a bit less than an ounce shots and drinking them both, rather than one large one.

dan

What is the follow-up on your La Peppina ceramic boiler efforts? This is a great idea, and I would imagine many would like to replace the rusting enameled steel ones.