I saw a post about the pressure profiles of la peppinas somewhere. I think it involved some type of probe inserted in the group, I'm not sure though. As I recall the owner was trying to recreate the pressure profile on a LM capable of custom profiles.

Machining New Pistion:

A manager at my job let me use his lathe in his garage to machine some new pistons. I practiced with some aluminum stock, then made the final one out of brass (lead-free, I hope).
Edit: After a little research, the brass has been confirmed to be lead-free.




They both turned out good enough to use, I'm going to put the brass one into service first though:


One minor problem is that I didn't make the grooves wide enough for the seals I bought from OE. Instead of driving back to the shop to widen the grooves on the piston, I just sanded down the seal edge with a dremel. The seals fit nicely after that.


If my coworker wasn't there to help me out, I'd probably have paid for a day pass to a local community machine shop. Or I would have bought a small used lathe. There are cheaper options out there than paying about $200-$300 to hire a machine shop to do it.

If anyone wants a dimensioned drawing of the Cappuccino Amore piston, PM me and I'll send you a PDF if I can find it.

Group rebuild:

I followed the instructions on OE to put the group back together. I put a little Dow 111 on the seals. I also dipped the pivot pins in melted paraffin wax to decrease the friction a little. (I dip my bike chain in wax too ... works great.)

Very nice work, wow. You can now go a step further and build your own machine Enjoying this build.

Boiler Rebuild:

I cut a new boiler gasket from some 1/16" silicone. (In pic, old gasket is on the left, new is on the right).


I also resealed the heating element contacts using the kit from OE:


The temperature probe and thermostat are junk on this machine, so I'm replacing it with a PID system. Here's a pic (old vs. new):


Here's the heating element and temp sensor installed in the boiler bottom plate. The RTD sensor from Auberin's happens to be the exact diameter of the temp probe that I'm replacing (14mm).


The bottom plate is then installed back on the boiler. I slurged and bought all new stainless nuts and bolts. The empty holes are reserved for the bolts that attach the boiler to the base. There are also some silicone gaskets under the heating element and temp probe.

crazy4espresso wrote:Very nice work, wow. You can now go a step further and build your own machine Enjoying this build.

Thanks. Hah, I'm brainstorming that a little... I'm thinking of a CO2 powered one maybe. I doubt I could think of a new espresso machine that would actually be marketable or profitable, but maybe it's time to develop some DIY plans for a cheap homebuilt espresso machine. (I'll start a new thread if I get around to that).

First Shot:

The machine is working now. OK, I'm skipping ahead a little. I stayed up late last night wiring the PID system and putting it together. I'll post about that later. (I'm still waiting for some switches to come in the mail, so I can get the "Steam Mode" working. I'll take some pics when I do the final wiring).

I filled it up and turned it on. No water leaks and no sparks! I changed a few options on the PID controller and set it to auto-tune all the control parameters. It heated and cooled the boiler a few times during the autotune process and then it was ready to go. Pretty easy.

Here's a pic of it warming up. It only took a few minutes.


OK, I've never made espresso before, so for the first shot, I just gave it my best shot at all the parameters:
Boiler Temperature: 104C (just hot enough to get pressure to feed the water into the group. I measured an in-cup temperature of about 90C on the second and third blank shot. So I think the brew temp should be close to 90C-95C.)
Beans: a dark roast from Portland Roasting Company
Grind: 2 "clicks" on the Porlex Mini grinder, (based on what others online have said worked for them)
Dose: 17 grams for a double
Tamp: a light stir in the basket, then tap to settle, then tamp to about 30lbs.

Here's the first puck:


And the first shot ... (drumroll) ... nearly clogged machine and was very bitter. The puck turned to mud.


I guess the grind was too fine, so for the second shot, I tried 4 "clicks" on the grinder.

Here's the second puck:


How does that grind size look? About right?

The second shot was drinkable, but the crema dissipated a little fast I think. (Maybe the beans fault?)


I tried a few more shots after that with various grind sizes. Some too fine and some too coarse. I haven't quite dialed it in yet. I haven't got a very good steady stream yet either. I guess I need to watch some more how-to videos or something.

Any tips?

What grinder are you using? it could be that its not up to the task.

It's a Porlex Mini hand grinder (the stainless steel cylinder with a handle next to the machine in the first pic of the last post.) It's a ceramic burr grinder with pretty good adjustment and grind size uniformity.

That ought to be usable at the least. What is your dose and what coffee are you using?