I'm starting this thread, hoping the others who are working on their Mini Gaggias will contribute and perhaps we can be of help to each other. Here are the issues I'm having and progress:

1. Bought 25 feet of self adhesive teflon tape from McMaster. I haven't tested it, but it should work perfectly as a gasket tape since that is what it is designed for. If anyone needs enough to seal their boiler, let me know and I can mail you some. It will work better than trying to put a bead of silicon seal. I'll test it after the below is done.

2. Tried and failed so far to replace the piston gasket. I removed the brass head that holds the gasket, but I can't separate the two pieces even with a long soak in Kroil and a special home made pin wrench. Tomorrow I will try heating it to free the two pieces. I can't believe how tight together they are. If I finally can't get them apart, it might be easier to turn a new end from stainless and scrap the old one. I'm not a highly experienced machinist, but that would probably take me 2-3 hours max. I've already spent and wasted an hour trying to get the two pieces apart!

3. Bought and am making stainless "L"s to replace the primered red ones that it comes with. That's because I'm getting rid of the plastic housing.

4. Bought and will bend a new heating element. The bendable heating element is easy to bend. I will weld a jig and if that work well, make it available to anyone who wants to borrow it. The trouble is that I will need to cap the existing exit holes and drill two new ones since it will be easier than bending to suit the old ones and even if I did that, I would have to make bushings to assemble the new element which has different terminals -- much smaller.

So, I'll make a couple stainless steel plugs for the old two holes. I'll also plug the thermostat hole since I won't use that either.

5. Haven't decided how to get the piston end back onto the spring once I get it separated and a new gasket installed. I'll probably compress the spring in my big vise and try wiring it closed. Then assemble and clip the wires. (I know, this sounds a bit dicey.)

6. Bought some thin aluminum diamond plate to make a smallish surround that will wrap around the boiler. Have not tried bending it yet, but should be easy.

I'll post pictures of the above in the next week or so.

Note to Marcio -- I'm not so sure about your quest for a new spring... You might try putting a washer of stainless or brass in between the plunger and the old one which would minimize the loss of pressure towards the end of the spring extension, but I'm not an engineer and am mathematically challenged, so this might not get you what you want.

Another note to Marcio -- I wonder if one could use a compressed air cylinder to directly or indirectly drive the piston. One could then dial the pressure repeatably and even dial in with the right equipment a profile that could be of any shape. I just don't know if that is even worth thinking about, so I'll try not to. Every house should have compressed air outlets next to the wall outlets for such things.

dan

Wow...big projects can come in small packages!! Not clear why you need to take the piston apart to install the seal....just stretch it over the piston into the groove....if you have a problem getting it to stretch enough heat it in hot water then install....or am I missing something?
Look forward to the full resto report.

Thanks Doug! I can't believe I fooled myself into thinking that there were two halves of the plunger. The pin holes fooled me... They are decoys. I ordered a new set of seals from you and will have this thing running in a week or two.

(In my somewhat lame defense, the parts diagrams I have show a multi-part assembly. However, I can't really tell if mine comes apart or not. But assuming I can get the seal on, it's moot.) Making a new one part piston end done in stainless would only take an hour or less.

dan

Reassembling the spring/piston

This is not a job I'm proud of. First, it was unnecessary. I shouldn't have taken off the spring. To say getting it back on safely and easily would be a lie. So, I am not going to recommend this procedure. There has to be a better, safer and more elegant way. It involved compressing the spring using my 5 ton arbor press with one hand and with the other hand tying a sort of wire basket around the spring, kind of like a Champagne cork basket.



The wires criss-crossed in the center, which meant the spring had to be mounted off center and then coaxed into place. It also meant that the wires were trapped by the spring. The whole thing took 10 minutes, but it seemed like an hour. I'm sure now that it is done someone will tell me the "real" way.



Anyhow, it is done and I didn't hurt myself. I might mention, however, that before using the arbor press I used a vise and the spring jumped out with considerable force and potential to injure.



Next step is to bend the new heating element, but I'll save that for another day.

If you can, Marcio, you're a stronger (or heavier) man than me. I tried and didn't get close to engaging the shaft. If you do it, might use some olive oil at each end of the spring so you can turn the thing tight. If I had to do it again, I'd machine a miniature spring compressor like they use in car suspension springs. It wouldn't be that hard to make, but I'd rather forget the whole experience.

As a former Mini owner (it hurts to say that), I was personally always rather impressed by the strength of the spring, and this story confirms it. That spring exerts considerable force on the puck, reduced vs. what it would be on other home levers of course, because of the large cross-sectional area of the piston face. In any event if creates more than enough pressure to make great espresso in the 58-mm basket.

It seems like its easy enough to maintain the piston and seals without removing the spring? When I did it I just cleaned everything externally and it looked ok when completed.

As I write this my mini is en route to its new home, and it will be sorely missed. I still think it is a simple, elegant approach to getting enough perfect-temperature water into a piston, to be gently and evenly forced through 20g of ground espresso beans. Compare the design simplicity to the new Bezzera that's the topic of so much recent discussion, for example. I challenge the first new Strega owner to control temperature with the same ease I did with my Mini...

PC