Gaggia coffee machine repair

Spent some time wondering where this question should go but as it will probably turn into a debate on how to grind beans, then "Tearoom" seemed appropriate...

I have a Gaggia Classic espresso machine, much used. The ground coffee goes into an aluminium cup with a double-layer base with a small gap between the two. The inner base has many fine perforations; the lower has one slightly larger hole. I gather this is to do with the production of "crema" - froth, to the rest of us. This cup sits in the portafilter (the removable bit with a handle) which has a double-ended spout to distribute the coffee into one or two cups. Inside the portafilter is a small plastic plug with a blind hole from the top and a cross-hole near the bottom. Apparently this helps to control coffee flow. It is apparently called the jet swirl emulsifier.

From time to time, the single hole in the cup blocks. I let it sit with some special cleaning powder and run the pump occasionally until, usually, the blockage clears. Today, it did clear, almost explosively, and coffee spayed enthusiastically out of the spout. Turned out that for whatever reason, the plastic plug thing broke into many pieces. Likely to cost best part of a fiver to replace plus postage. Can't 3D print in PLA due to temperature (80C or so). The only plastic rod in the workshop is acetal which is not suited for that temperature either. So, plan is to use an odd scrap of brass - fairly simple bit of turning and cross-drilling.

And so - the question (at last, I hear you say). Anyone have any idea of compatibility (taste, corrosion, etc) between hot coffee and brass? I can't think of any examples of seeing brass and coffee in contact; brass components on the coffee machine all seem to be plated. Thoughts?

Edited By Nealeb on 25/07/2023 15:36:50

Edited By Nealeb on 25/07/2023 15:37:57

You could try a bit of PEEK, a plastic which can stand temperatures up to 220°C and a melting point of 343°C.

I've seen coffee "tooling" made from brass in the middle east.

Robert.

Not sure, but sometghing in the coffe MIGHT attack brass.

Is it fairly straightforward to make?

Stainless woulkd better and safer IMO

Howard

Most of your machine will be brass or copper and then plated but I would guess only on the outside!!

Thanks for the comments. Yes, PEEK would be ideal - but I have none (used my small stock making a hot end for my first 3D printer!) and it's not cheap, would need to wait for online order to arrive, and I want my coffee machine back working again asap! It's on the limit for ABS, looking at Wikipedia data, but I suspect that the original was indeed ABS and, as the Wikipedia article suggested, that it became so brittle after maybe 10 years or more that it shattered into small fragments when hit by a sudden stream of coffee once the dam broke above it. Just picking up some fragments to try to take measurements showed me just how brittle.

I've just spent a little time making a replacement from an odd stub of brass which seems to work fine. I have had to guess dimensions and precise shape from various online outfits that sell this component as a spare part but I doubt that any of it is super-critical. I have also done what I should have done in the first place which is a quick Google search on brass and coffee. Seems that there are some cultures in which coffee is actually brewed in brassware, and there is even a suggestion that the zinc that leaches out in tiny quantities is good for your health. Well, maybe - I was more concerned about the copper leaching out and leading to heavy metal poisoning!

Just to add, the Italians are happy to use copper and its alloys in coffee machines - the piston of my La Pavoni P67 is made of brass (or possibly bronze), as are various of the pipe fittings, gauge glass mountings, etc. The boiler is copper, with a bronze end plate and the heater elements are copper sheathed with bronze mounting plates.

Those small conical Turkish coffee pots that are heated directly over a flame are brass and the coffee they produce is pretty strong, so if that doesn't react I doubt if a 'mere' espresso would.

As memory slowly oozes back into my brain, I recollect that actually, some years ago, I solved a problem with lime scale in the boiler frequently clogging a pressure relief valve in this machine by buying a piece of fine brass gauze from one of our usual ME suppliers and making a sleeve to fit over the internal exit pipe from the boiler. Fixed that problem nicely - but it seems that I wasn't worrying too much about brass in the filter then. In any case, given that I seldom use the thing to generate steam, it only gets to around 80C, less than those Turkish coffee-boiling cups.

What I have subsequently found on moving from a very hard to a very soft water area is that I now no longer get lime scale problems. Instead, there seems to be steady corrosion of the inside of the aluminium boiler which I am sure will go pop one day. There is now a slow build-up of, presumably, something like aluminium oxide in the boiler (which is being retained there by my filter, fortunately). On the plus side, being aluminium, my club boiler inspector is not qualified to look at it and therefore can't condemn it!