krld Senior Member Joined: 1 Jul 2012 Posts: 6 Location: Sydney Expertise: I live coffee
Espresso: Sunbeam 4800c Grinder: Kyocera Hand Grinder Roaster: Popcorn popper
Posted Sun Jul 1, 2012, 8:07pm Subject: OPV valve and pressure gauge fitted to sunbeam 4800C
I'm a coffee lover and getting right into the art of coffee making since my wife bought me a sunbeam 4800c. The 4800c took me a long time to figure out how to get descent shots of espresso from it. My journey so far...
I started off with ground coffee beans from the supermarket (yuch!). Then bought a Kyocera hand grinder for $70 online and I think it's pretty good at grinding, I know there is a lot of discussions about paying big bucks for a good grinder and admmitedly I haven't tried an expensive grinder yet, however I recommend the Kyocera that I'm using and think it works very well.
After a fair bit of searching and advice from this website from other people trying to get good coffee from their machine, I purchased a descent tamper (the plastic one that comes with the 4800c is fairly useless) and an unpressurised basket (also recommend). I also bought espresso shot glasses so I could easily measure the extraction volume within the 25-30 seconds
The biggest thing I noticed was getting freshly roasted coffee beans from Newtown and the taste was so good as compared to the store bought beans. Then I was given a Tempo popcorn maker as a present and found out about roasted coffee beans with them at home. Bought green coffee beans so cheap and wow!, for anyone not roasting at home, please do - it has made the biggest difference to my home coffee's!!
Now, i make pretty decent enough shots but found my machine wasn't consistent as it relied on my tamping pressure to adjust the pressure at the brew head. One coffee would be nice, then I would maybe not press slightly as much and the next shot would not be as nice. It frustrated me so much I nearly gave up on it. I think the sunbeam 6910 is the same on it's extraction functioning, then I found info about OPV valves.
I decided to buy a Vibiemme Domobar bypass valve and also a gauge so I knew what pressures I was adjusting to, and piped them in after the pump and before the Thermoblock (the thread was the same). I have now set the pressure to 10 bar and so far, the bitterness is gone and the shots are consistent and very nice. It costs only about $60 odd bucks to upgrade and makes a big difference. Also, the pressure drops immediately after extraction and stops spurting out when removing the portafilter (must be the valve letting air in?). I made an access hole at the side where the valve is and i can easily slide a screwdriver in and can now adjust the pressure without stripping down the machine again.
Many people seem to go for name brand machines and say to save up to get a Silvia, but I cannot afford to pay that much for a coffee machine for starters and on a technical level, it's a machine that has valves pump etc so can be modified to at least get better shots. I'm not saying my machine pulls shots like a silvia or anything but I'm happy with the results and am posting this to show other cheap model espresso machine owners that this is a cheap, easy mod that can make a big difference to their machine. I was so fed up with getting inconsistent shots that were always slightly bitter due to the high pressures from my machine but am now very happy with the results. I haven't really found anyone modifying cheapish machines and recommend this.
If anyone wants any more info please ask and here are some pictures of it fitted to my 4800c. Also, if anyone has an advice for me on bettering my coffee making, please let me know !! Back to top
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