Heat control mod for 2nd Generation La Pavoni Levers - Page 7

Equipment doesn't work? Troubleshooting? If you're handy, members can help.
NickD
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#61: Post by NickD »

The only disassembly needed is removing the group and the diptube. No futzing with the element is required! It's worth watching DanoM's video, but the idea is that you want to prevent the boiler steam from continuously flowing into the group head (which leads to the overheating issues). To accomplish this, you

1) Use a snug-fitting stopper in the neck of the group to block steam from entering the group (DanoM and I both used a modified La Pavoni group insert).

2) Pass the diptube through the stopper (you want a snug fit here, too), and cut a small hole in the diptube just behind the threads. This allows pressurized water to flow from the boiler into the area of the group above the piston.

The result is a machine that heats the group with hot water from the boiler, and a ''fresh'' batch of hot water is added to the group only when you do half pumps with the lever (Raising the lever forces the cooler water out of the top of the group, and lowering the lever allows hotter water in). This gives you (almost) complete control over how the group is heated.

I admit that more experienced users can likely produce reliable espresso without these mods, but as a new user, this makes driving the La Pavoni a much more pleasurable (and less hectic) experience.

Nick

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redbone
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#62: Post by redbone »

That mod sounds tempting and doable. Might even give that at go on my 76. Thanks.
Between order and chaos there is espresso.
Semper discens.


Rob
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max
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#63: Post by max »

This mod is very good and certainly doable. For Christmas I modded my mother's machine, and it is wonderfully stable!
It was so good I decided to buy a 2nd gen with the intention to ultimately replace the 3rd gen in my office. It should arrive within a week.

However, I've been wanting to make it a bit more reliable than that plastic piece and have some ideas/designs. Work is busy right now, but will post some them in the coming weeks. One of you with more hardware skills should be able to construct it.

Inspired by this, I also made a similar mod for the 1st gen machines which seems to also make a considerable improvement. I did this last Sunday, so will do some more testing to make sure before I recommend it :)

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drgary
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#64: Post by drgary »

max wrote:Inspired by this, I also made a similar mod for the 1st gen machines which seems to also make a considerable improvement. I did this last Sunday, so will do some more testing to make sure before I recommend it :)
1st gen machines have a water heated group. I'll be interested in your elaborating how the mod helps or if it does.
Gary
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What I WOULD do for a good cup of coffee!

max
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#65: Post by max replying to drgary »

Based on my tests the last two days, I'm quite sure it does. And don't worry; I have every intention to share it soon.

DanoM (original poster)
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#66: Post by DanoM (original poster) »

I tried a few different ways to limit the heat flow to the group, and the standard La Pavoni dipper tube adapter for generation 3 machines worked great. If you have a bolt that will thread through the adapter you can mount it in a drill and file those threads down until it just fits the group with a little force. You want a tight fit.
Then I used a narrow, stepped drill bit for the dipper tube to pass through - turning it by hand as the plastic cuts easily. Get it open enough that it's hard to push through, but still passable. These will give you a mostly water tight seal for the group.

As stated above the only part you mess with is the group itself. The original dipper tube works - you just cut a hole in it, so it doesn't change in height or endanger the heating coils in any way. There is a bit of work involved in getting the threads cut to size, but after that even a slightly, leaky plug will probably work just fine.
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max
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#67: Post by max »

Even though the dipper tube is easily replace, I like reversible mods and prefer a suitable metal over plastic. Therefore, I thought a bit about how to accomplish this reversibly and in metal. It won't improve performance, but it would satisfy at least me.


One way would be to take a straight tube of the same width as dipper tube and thread it in both ends. A hole would be made in the middle.

The plastic 3rd gen piece-the "cap"-would be replaced with a metal version with a bit more depth, with a threaded hole through the center. The simplest version of such a piece could consist of only two sections (cylinder extending on top of a slightly larger disc). A gasket could be placed around the cylinder, on the disc, or in a groove on the side of the cylinder.

The tube would be screwed in place of the dipper tube. At the other end the "cap" would screw onto the tube. Finally, the dipper tube would screw into the same hole from the other side, i.e., on the back of the disc.


I believe the outer dimensions of the cap would not at all need tight tolerances, if a gasket is placed appropriately. Therefore, the only sensitive part would be the threads in the cap and on the tube.
Having no experience with metalworking, how hard would this be to make?
I tend to have great respect for these things, but this seems rather trivial.

DanoM (original poster)
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#68: Post by DanoM (original poster) »

max wrote:Even though the dipper tube is easily replace, I like reversible mods and prefer a suitable metal over plastic.
Just buy another dipper tube for your modification then. That way you can go back to the "original" part if you want. Cost is under $10 for a dipper tube.

As far as making the plug from metal that's probably not a bad experiment. Get a piece of brass, turn it to the correct size, bore a hole, tap and thread it all together and let us know how it performs. The brass is going to conduct more heat from the boiler than the plastic cap, so my guess is it's going to run warmer, but if you give it a try let us know.
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max
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#69: Post by max »

DanoM wrote:As far as making the plug from metal that's probably not a bad experiment. Get a piece of brass, turn it to the correct size, bore a hole, tap and thread it all together and let us know how it performs. The brass is going to conduct more heat from the boiler than the plastic cap, so my guess is it's going to run warmer, but if you give it a try let us know.
Do you think it would make a significant difference?
The plastic piece you suggested is working really well, so I'm just thinking there is some margin at least. Maybe not enough?

DanoM (original poster)
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#70: Post by DanoM (original poster) replying to max »

If you want to experiment with a longer lasting piece of hardware the brass insert will last forever!

Personally, I think the plastic piece works great. It might not last for much more than 10-15 years, but it's a cheap replacement part. On top of that, it conducts heat far less than a piece of brass, and I like the way the plastic "plug" works on my system for heat control. I don't see a need to replace the plastic with brass, especially since it's plastic designed for in-group use I assume it should be safe for long-term heat exposure.
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