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Vintage La Pavoni Re-build
I think this would respond well to PIDing. My guess is that you'd have to flush some water in order to stabilize the grouphead temperature. After that, if the PID was adjusted just right, you should be able to pull a few shots in a row. The problem is, will you have enough water to purge some and still have enough water left for brewing?


allenb wrote:


jkoll42 wrote:
You need this next to it with the temp reading :)

Jon, I think you're mistaken, isn't that a victorian era time machine?

What's wrong with a steampunk La Pavoni? :)

I wouldn't be worried about seeing a screen imprint post pull - the puck will expand. As long as you aren't seeing contact with a dry puck you should be fine. That's strange to have a channeling hole that large (can imagine why the shout would taste thin :) ) Did you have the screen apart during the rebuild? It does sort of sound like a water dispersion issue. Or a million other things!
Honey badger 1k, Bunn LPG-2E, Technivorm, Cimbali Max Hybrid, Vibiemme Double Domo V3
Finally some good results.

Desperate times call for desperate measures: Made a bottomless portafilter.

Sure enough...It gave excellent visual feedback during the pull.
Always thought they were kind of trendy, and not worth the trouble.

Found the #3 setting on the Rocky, along with a 30# tamp was producing something resembling espresso. The preheat routine is the same as the earlier post.

Here's some video action:
(cant get it to embed)

The 4 pumps at the top help build pressure in the chamber.
It's now producing crema with some regularity. The last 6 or so pulls have come out roughly the same. Tastes good too.

Dan, Jkoll,
At this point I think you're right. A pid would help on the temp control side of things.
Looks like RayJohns at HB has blazed this trail already:
He installed an RTD through the boiler (element) plate. I'm thinking of going into the side of the boiler, just above the heating element.

What do you think?

Russ, I think that would work fine. PIDing will also give you some time to deal with tamping and pulling the shot without having to worry about what is going on with the temperature. I've used the 3/16" SS thermocouple probes for this type of thing.
Much appreciated Dan,

A friend just stopped by. He was able to drink a shot I pulled for him "straight".
He's a milk + sugar kind of guy. That's a good sign.

As for the pitting problem in the puck: The shower screen does have some odd sized holes. It looks like somebody in the past used a pin to clean the holes out. The problem seems to be manageable though. It shows up when the tamping and lever pressure are out of sync.

The PID idea is a go. It will have to live under the base. The digital readout doesn't suit the aesthetics of the machine. Jkoll42 was quick to point that out with his nixie tube idea. Luckily, it's not something that requires constant adjustment.

One concern with the location of the thermoprobe is it's proximity to the coil. There's really nowhere else to put it. The IR + boiling action will cause a bit of skew in the temperature reading. Leading to more cycling than necessary. Any ideas to help minimise this?

The major benefit will be the limit control. Currently there is no high temp cutoff to protect the coil. Sooner or later, some distraction will cause the machine to be left on. The water will boil off within an hour or two, and the coil will eat itself. Not good.

I'll order these in the morning:

Any objections, alternatives, or criticisms, are most welcome.

Don't worry about cycling. If you use an SSR there is no harm from cycling. And, most PIDs have a cycle rate setting.

Could you insert the probe from the bottom up through a gap in the heating coils? Only the tip of the probe measures temperature so it might be far enough from the heater. Don't worry about IR under water. There are also bolt-on thermocouple types.

For overheat protection, install a thermal cut-off (TCO) on your hot line. clamp it to the bottom of your boiler. They come in a variety of temperatures. You can find them at an electronic supply house.
You're right about the ssr and thermal cut-off. Thanks.

The 2' type K thermoprobe is in the mail. The jury is still out as to where to locate it.
There is very little room to squeeze it vertically between the coils.

On another forum a guy used an Rtd on a short bolt mounted right underneath the coil. Protruding maybe a half an inch above the base plate. It worked for him.
I'd rather have it mounted as close to the group intake tube as possible. The tube stops about 1/2" above the coil. It's looking like a side mount is better in that respect. With the added bonus of adding another piece of shiny chrome on the exterior to conceal the thermocouple wire. Something like this:

To be continued this weekend.

Edited by Lylabrown on 03/20/2012 1:02 AM
The PID, thermocouple, and relay arrived. With the thermocouple in-hand it appeared to be just small enough to squeeze between the coils. Which is awesome. The side mount was a neat idea, but also a no-turning-back one. The thermoprobe is threaded into the base plate. If one should ever want to remove it - a 1/4" NPT plug can be put in it's place.

The brass base plate was just thick enough to tap. There were about 3 full threads for the probe to grip, with plain ol teflon tape to seal em.

Reassembled for testing. Amazingly - she was water tight the first go around. (never happens)

Wanted to get an idea of the stock temperature range. The Pid is set up to read only.
The boiler was pre-heated on high till it began to hiss from the pressure relief valve, then set to low (200w). The temp held steady at 226f for the first 10 min. Then gradually crept up 1 degree every 5 min. till it topped at 230f at the 30 min mark. When set to steaming (800w) - the temperature rose to 234f and held steady.

It's remarkable how stable the temperature was. In the 200w mode the pressure relief let off a tiny jet of steam, which moderated the temperature quite well.

Based on the inconsistent results in the cup - I assumed the temperature was more chaotic than that. Hmm. Having the pid in control will allow some tinkering with the temperature, which will definitely help, but wont be a revolutionary change. It appears the group head overheating is the real issue here.

Maybe there's a sweet spot - say 220f - that might be just cool enough to lessen the group head's conduction from the boiler housing, yet warm enough to deliver proper temp water to the grounds. We'll see.

I'll put the pid into control this weekend. In the meantime, any input is appreciated.

That was painless.

Scrap aluminium signage material was used as a heatsink for the ssr.
The ssr was pasted + bolted to it. Then velcro'ed to the base. (gotta love that velcro)
It should help isolate it from the base, which gets really hot.

The wiring was straightforward. The only compromise is the HI/Lo wattage output.
With the Pid in place, both coils can't be powered at the same time.
It used to output 200w on Low and 800w on High. Now it's 200/600.
The steaming output will be reduced by 25%.
To steam - the switch is flipped to the II setting, which bypasses the Pid, and powers the 600w coil. Maybe there's some way to power them both at the same time. I just cant think of one at the moment. Any suggestions?

Here it is powered on for the first time. Its currently doing the auto-tune routine.
It's set at 220f for now. I'll pull a few shots to see where it wants to be.
It's incredibly exciting to finally have some form of control over this little beast.

One little concern is heat buildup under the base. I could drill small vent holes in the sidewall of the base at the rear. Anybody know where to find 1/2" to 3/4" mini louvered chrome plugs? Not a common item for sure.

The honeymoon is over!

After 2 weeks of afternoon coffee duty, and no apparent improvement in quality, I'm throwing in the towel. Miss Cranky doesn't deserve her high-tech innards.

Miss Silvia, on the other hand - Does. She's the kind of girl that puts out on the first date. Just how I like it.

So ends the La Pavoni PID project. Thanks for all your help!

Had you considered turning her into a roaster?
She may not put out....but she might be able to cook! -Scott
Any success with the La Pavoni? I see a rebuilder on craigslist, and I'm pondering it. I already have a PIDed silvia.

Hey John,

I kept it on afternoon shot duty for a time. Now it's collecting dust.
The results were too inconsistent for me. I'm thinking of using it as a frothing only machine.
It really blows Silvia away when it comes to steam output.

If you want a more hands-on espresso experience - this is definitely it.

Hope this helps.
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