Hello. I am pretty new to the espresso world and would like to share a creation that I have been building in my home machine shop. This device started life as a Krups FND-1 that I picked up at Sears for $40 (on sale). I bought it without knowing much about espresso, but quickly learned that serious espresso drinkers consider this machine to be total junk. As I understand it, there are a couple problems: First, since the machine relies on steam to pressurize the water, the temperature of the water is necessarily too hot at 212*F or higher (under pressure). Second, the total amount of pressure created is too low -- about 20 psi or less. To address these problems I have outfitted the machine with some parts I had around the shop, and turned it into quite a beast!
The temperature of the water is controlled by a programmable meat thermometer. The exact desired temperature and actual temperature is shown on a large LCD display. There is a small amount of proportional control to this system: As the water temperature climbs within 10*F of the set point, the heater is switched off and on at %50 duty cycle.
The pressure of the water is controlled by an air pump that came out of a 12V battery jumper box for cars. These portable devices are used to jump-start cars and often include accessories like flashlights, compressors, etc. The battery in mine had died, and I took the still-working compressor out of the unit. Even though this is an air-only pump, it directly controls the water pressure by pumping air into the top of the boiler. The water is taken from the bottom of the boiler, so no hot air escapes, only water. There is no control circuit -- only a switch for the compressor and a gauge to monitor pressure. The machine can easily pump up to 140 psi (over 9 bar).
The whole system works very well (as near as I can tell with my limited espresso experience). Please feel free to ask me questions. Thanks -Ben
Beezer Senior Member Joined: 17 Oct 2006 Posts: 457 Location: Fresno, CA Expertise: I love coffee
Espresso: Quickmill Anita Grinder: La Cimbali Max Hybrid
Posted Mon Mar 26, 2007, 9:31am Subject: Re: Heavily modified Krups espresso machine: $50 + spare junk parts = crema
Very creative. However, I have to agree that the movie of your shot looks like it's still way too hot, and the shot pulls way too fast. Watch how a shot from a good quality espresso machine pours. It barely oozes out of the portfilter spouts like honey. Your shot blasts out like it was fired out of a cannon, complete with steam. The crema appears to be more from the turbulence of the coffee hitting the cup than from CO2 being released under pressure. Maybe your machine needs a way to regulate pressure better, like an overpressure valve.
bkraz Senior Member Joined: 25 Mar 2007 Posts: 5 Location: Sunnyvale, CA Expertise: I like coffee
Posted Mon Mar 26, 2007, 4:58pm Subject: Re: Heavily modified Krups espresso machine: $50 + spare junk parts = crema
Hey guys, thanks for the comments. As I mentioned, I really have very little knowledge about making espresso -- I didn't know it was supposed to drip out slowly. I figured the steam and froth were just extra fun parts of the process. If you are interested, I re-tooled the machine and made another video:
I noticed that the Krups machine has a little hole in a passageway that aspirates the hot water as it exits the boiler and enters the portafilter. This must be their idea of a crema-making device. As you point out, I was getting lots and lots of froth. I plugged the hole, and now only get hot water into the top of the portafilter. There is still crema, but I guess it looks a little more normal now.
Posted Mon Mar 26, 2007, 8:52pm Subject: Re: Heavily modified Krups espresso machine: $50 + spare junk parts = crema
You didn't say what you are using for a grinder. I have to believe that your creation will give a decient shot with a good grinder.
I didn't think of it until Brad brought it up but high pressure air is more scary than high pressure liquid as it will expand. I recomend that you come up with some sort of "scatter shield" to place between yourself and the machine as you pull the shot.
moneymanager Senior Member Joined: 28 Feb 2006 Posts: 161 Location: Indiana Expertise: I live coffee
Espresso: Silvia Grinder: Tranquilo Drip: FP & pour over Roaster: RK Drum
Posted Tue Mar 27, 2007, 5:26am Subject: Re: Heavily modified Krups espresso machine: $50 + spare junk parts = crema
Excellent work Ben. Now please apply that ingenuity to a real machine and things will be very interesting. You're sadly limited by the machine so the resulting shot is somewhat irrelevant. I think you realize you won't get "real" espresso out of that machine unless you turn it into a real espresso machine.
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