Do you know what the hip pocket damage is on one of these, or if they even available in Oz at all?
Here are some pics of the Faema family. It is surprising to see such quality in this relatively unknown machine. It sports a 300 ml brass boiler, adjustable over pressure relief valve, 3-way solenoid, 58 mm commercial portafilter, copper piping and steel braided water lines, a resettable thermal cutout switch.
These are more features than found in a Silvia and on par with the likes of an Isomac Venus (looks nearly identical inside) and the ECM Botticelli II (both $1000 machines).
This model Family has a common rotating steam valve, rather than the sliding steam valve. It is purported that this later model has an aluminium boiler, so beware.
Here are a few pictures to show you what it looks like and whats inside.
[img] * http://i4.photobucket.com/albums/y129/mjfernee/faema%20family/Faemafamily2.jpg[/img]
Heavy 58 mm commercial portafilter
Inside - the top of the boiler
The over pressure valve
The first shot tasted really good...
Do you know what the hip pocket damage is on one of these, or if they even available in Oz at all?
They used to retail for close to $1000, if I recall a few posts correctly. They are no longer in production, although there is a slightly later model available in Canada with a sliding steam valve and side access to the water reservoir. However, it purportedly has an aluminium boiler. Why theyd make such a radical engineering change, I dont know (maybe cost engineering :o). Just beware. The model I have was supposedly in production between 1982 and 1992 or thereabouts.
Heres a link to the model available in Canada:
I got mine on ebay for $187.50... I saw one go a few months ago (same model but white colour) for $260ish so theres a few price points for you.
All is not roses though. Its a pretty errr, well less than aesthetically pleasing machine. Just note that the body is cast aluminium, not plastic. In fact its one tough machine with very little plastic overall.
Worst point so far is the drip tray. Its far too shallow and difficult to remove and empty. Its almost a design afterthought.
Just drill a hole in the bottom, tap it, and run a line out. No more worries about removing the drip tray.
Just a few more notes:
The group heats up really fast, maybe 10 min or thereabouts. The group head temperature cycles between about 91 and 96 deg C and responds to the heating element switching within a few seconds. The wierd thing is that the shot temperature seems to plummet; starting at a GH temp of about 93 deg C, the shot temp dropped quickly to about 88 deg C and fell to 84 deg C by the end of the shot (ristretto). Sure enough, the shot was sour. So this machine is designed to be operated near the top of the heating cycle.
What this seems to indicate is that the machine is designed to mix the cold feed water with the hot boiler water, similar to a HX machine. This is unusual, as boiler machines are usually designed to keep the feed water and brew water separate for as long as possible to maintain temperature stability.
Nevertheless, this machine is perfect for what I have in mind. Ill just have to crack the boiler open to see whats going on.
Im not sure that a 10C drop is weird. This is about what you get with most small boiler machines. We both measured quite sizeable temperture drops of this order with the Silvia I recall. PID will help compensate but taking say 50 - 100mls out of a small 300ml boiler is bound to cause a significant temperture drop I would have thought.
A drop in temperature from boiler *through portafilter will occur during the extraction because of temperatue loss through the cold grounds and because the group will also siphon off some heat. *
A big chunk of brass weighing several kilos as used in E-61 groups (the group on its own weighs as much as some entire cheap machines) will give very stable temperature...whereas at the other end of the scale a thin *aluminium group with small aluminium portafilter will radiate it all away.
Further heat is lost as the coffee leaves the spout and collects in the cup --- the air cools it very rapidly.
While about 95C is an ideal temperature for water to hit the grounds, its most unlikely to stay at that level through the 25" extraction.
No, talking about drop in the boiler temperature as measured at the grouphead.
Small boilers, no matter how well designed always have significant temperature drops as the boiler is emptied and more cold water flows in. The effect can be minimised by good design but not eliminated.
On a standard silvia an 8C temperature drop in the water from the boiler is pretty common and it can go as high as 12C depending on when the shot is pulled.
The only real way around it is to have a bloody big boiler in the first place and that is what the professional single and dual boiler machines do. They all start from about 1400mls.
Thats why I like the ECM Giotto over the other prosumer E-61 based machines as it has a bigger boiler than most (all?) of them.
So, Sparky, that was you who bought that Faema on ebay the other day. Good score! Im the guy who bought the $270 machine a few weeks earlier. Its my first machine apart from an Atomic used to death in the 80s. Im very impressed, but Ive come to be realistic about what it can handle. All Ive had to work with is some pre-roasted beans (grown by the Paoli family in Coffs Harbour) but the espresso is great. If I try to serve too many people and froth etc, the machines just not up to it. But hey, this is my home, not a cafe.
By the way, now Im like the rest of you. In the last few weeks Ive bought a Rocky, a Cona, a Trespade hand-grinder, and Im about to attempt roasting. That Faema created a monster.
Yeah, the Faema is a good machine. But it is an old machine, which has been out of production for maybe 15 years. You can still get parts fro www.coffeeparts.com.au, such as element, boiler o-rings and group seals and thermostats, so short of cracking the boiler, the machine should be repairable.
Ive done some preliminary thermologging and it seems that it is probably more stable than a Gaggia Classic, but shy of a Silvia. So for a sub-$300 machine, it is exceptional value, as long as you can keep it running.
As I mod the machine Ill keep you all updated as to what is possible with such machines.
Ive done some preliminary thermologging of the Faema Family and then got stuck into adding the PID controller. This completes phase 1 of the modifications. Phase 2 is under way, but involves much greater modification. Im not sure when it will be finished, but it will produce a very different machine with greatly improved temperature stability. As for the current machine, it is reasonably stable. With the PID controller it will maintain an intra-shot temperature within 2 deg C.
First, here is a graph showing the thermal cycling of the group head, using a thermocouple pushed up between the grouphead and the porta-filter.
The next graph is an intra-shot temperature profile obtained by placing a thermocouple bead on top of the coffee puck and locking it into the group. So its measuring the temperature of the water as its hitting the puck. It exhibits a thermal profile very reminiscent to the Gaggia Classic (which is another boiler-on-group design). A 60 ml shot was poured using a ristretto grind. It struggles to hold the temperature variation to within 6 deg C. In fact the cold water injection forces the element to switch on near the end of the shot.
Now I have added the PID controller and run a few shots to see how the PID affects teh performance. It reveals a few issues and give you some idea of what improvements a PID controller can affect on these machines. In contrast to the Gaggia Classic, the PID controller gives a dramatic improvement in shot stability, keeping things to about 2 deg C variation.
I brewed 4 shots in succession, giving the boiler time to stabilize between shots (10 - 15 min). The first shot is an anomoly. It looks plain wierd. All the remaining shots exhibit very similar behaviours. For a ristretto, Id cut the shot short at 30 ml, but that doesnt win you anything as the 2 deg C drop occurs during that initial 30 ml period. Then the PID controller fights back and the heating compensates for the cold water injection, keeping the temperature profile reasonably tight.
What I do notice is that the brew temperature successively increases from shot to shot. This I attribute to elements in the brew path that take longer to heat up, notibly the 3-way valve, that is attached as an appendage to the group. So it looks like that even with a PIDed boiler, some flushes will be required before an accurate target temperature can be reached and maintained.
I hope people like Mal will be interested in this data, as this machine has a very similar design to the Mokita.
Thats really great data and is very close to the profile I recorded (manually) for my Mokita. I didnt have the t/c bead inside the PF though, just jammed between the inside wall of the PF and the Basket, and I think this probably introduces an "averaging" effect where my measurements are concerned.
By the way, what do you use as a data logger for these recordings.... seems to be capable of quite respectable resolution? As always, great work Sparky and very valuable data for those of us with a temperature stability fetish. All the best,
Hi again Sparky,I brewed 4 shots in succession, giving the boiler time to stabilize between shots (10 - 15 min). The first shot is an anomoly. It looks plain wierd. All the remaining shots exhibit very similar behaviours.
Regarding that 1st shot anomaly, you didnt have the PID Auto or Fuzzy Logic active during the pour did you? That might be a cause for the odd behaviour prior to the controller collecting relevant setup data..... what do you think?
I use a cheap DMM, Digitech QM1538 with RS232 output. Its $60 from Jaycar. The high resolution was obtained by reading the RS232 output directly using a Matlab routine. The software that it ships with is not too good and it wouldnt work on my computer in any case (well not my laptop, but it worked on my desktop)... anyway, it records in 1 sec intervals. This is wierd as the DMM outputs at 0.4 sec intervals and there is no handshaking at all. So the software must either interpolate or it gets every second data point slightly wrong. So I wrote my own Matlab routine to read the RS232 output, giving me the full 0.4 sec resolution.
As for teh PID controller, the autotune definitely wasnt on. These were 4 shots in succession (10-15 minutes between each) The last shot was a delay of maybe 30 minutes, which is amasing given its closeness to the preceding shot. Thats the sort of repeatability Id like.
The rising temp is most likely due to elements in the brew path that dont passively heat very efficiently, so need a heating flush. This is very common with most machines and you really have to do some very careful engineering to avoid this (like the new La Marzocco home machine for instance). In the Faemas case, its most likely the remote 3-way valve that needs to heat up with some flushes.
Just a few more photos of the Faema. This time totally exposed. This is what she looked like inside. Not too shabby. I drained the boiler and measured the volume at 280ml, just shy of a Silvias 300 ml, but in the same league for sure. As for the internals, they are impeccable. Have a look:
and from the other side, you can see the appendage thats probably causing the thermal problems (well the need to flush to get up to temperature).
This shot shows the group. Im going to swap out the shower screen/water dispersion block for either a Brasilia or Bezzera unit a bit later. They are interchangeable. Another nice thing about this machine.
Just one more, a bit more of the same....
These are for historical purposes only. This is pre-PID mod and also, well, the machine doesnt quite look like this anymore. Ill update soon with the details, but its exciting times for the Faema. Ill be bringing the machine along to the meeting on the 27th of November at Wordsmiths cafe at the Uni of Queensland, if anyone wants to check it out in the bare metal... and taste a ristretto from it. No promises for a god shot though.
Apart from the odd arrangement of the 3-Way Valve attachment, this looks to be quite a nicely engineered little machine. A pity they didnt stay with the original design instead of opting for an Al boiler and the Steam Slide Valve.
Will be very interesting to see what its performance is like after the PID installation :)
Yep, its a very high quality machine. The Silvia will outperform it in stock configuration, due to the offset group design, which prevents the cold feed water from cooling the group. But the Faema has higher quality parts. In the Faema ,with the addition of a PID controller to stabilize the temperature, the controller can compensate for the cold feed water in the latter part of the shot and keep the intra-shot temperature stable to less than 2 deg C. This is Silvia territory. Im not sure about a PIDed Silvia, because Ive never gotten a thermocouple near one, but Id guess it would be no better than 1 deg C stability. Jim Schulman posted an interesting comparison of the thermal stability of different class machines on the Home-barista site. Ill repeat it here (translated to Celcius and rounded a bit):
So going from the Saeco to the Silvia, you go from 5C to 2.5C error on shots for about an extra $250
Going from the Silvia to the least expensive HX, you go from 2.5C error to 1.3C for an extra $625
Going from there to the new technology - dual boiler, PID etc. gets you from 1.3C to 0.5C for an extra $2000.
The last figure was with reference to the new La Marzocco GS3 "home machine", which incidentally is expected to retail for US$4500 or thereabouts.
Heres a second run at the PIDed Faema, showing the sub 2 deg C intra-shot stability. The beans I used were quite stale, so the shot timings vary quite a bit. But for a reasonable shot time, the machine keeps the variation under 2 deg C. I ran the test with a warming flush first to try and heat up the 3-way appendage. That was two shots of 30 ml. But it still required one more shot to stabilize. Then the next two were right on the money. After that there was a 1 hour pause (with the machine running) and then I ran another series of three shots. The first of this bunch was higher than the previous ones, then the next one settled back to the same point. The last one was a very quick shot and went well above the previous shots. Thats not surprising, as the increased flow means that the hotter boiler water doesnt cool down as much enroute to the puck. So even with PID control, its important to keep the grind and tamp constant, to get repeatable shots. But its clearly possible, with amasing accuracy (repeatability) ....
However, not to be content with this level of performance, Im implementing boiler preheating. Id like to achieve 0.5 deg C intra-shot stability using the preheater. Its all plumbed in and hydraulically sound. It just needs the electrics and its away.
For those who ask, why is he doing this? Why not just enjoy the coffee? Well apart from my own scientific curiosity and enjoyment in building something, I am continually frustrated by the coffee at work being consistently better than what I can manage at home. I just cant seem to extract all the flavour they are getting, much to my chagrin. They use a 3 group Wega, which has an E61-type head. And they get it right time and time again. I get it right maybe once... Everyone else likes my coffee, but maybe my standards are higher. The coffees at work are just awesome... >:(
Besides, I do love to tinker. :D
Hi again Sparky,
Very impressive performance stats indeed for this little Faema.
The Wega operators must really know their machine back to front by the sounds of things, to be able to pull such good shots so consistently.... a bit of a rarity too I would imagine. It would have to be an easier proposition to practice on a properly tweaked commercial machine when someone else or the business is paying for the coffee consumption.
I guess weve all done our share of adjust grind, adjust dose, ensure tamp is level and then measure tamping force, pull the shot, taste the result.... and then start all over again. It can take quite a number of shots and adjustments to process variables before we get to the stage where an acceptable level of consistency of shot quality is achieved. I must admit that I find it a bit difficult to go through this sort of process when the end results are indistinguishable from shot to shot.... sure go through a lot of coffee until nirvana looks to be within reach.
Have you ever asked the barista(s) at work if they would let you pull a couple of shots on their Wega? Might be an interesting exercise just to see how your shots compare to theirs? If they can produce such good shots on a consistent basis, maybe a few lessons from their resident guru is a possibility? You never know, and it might prove to be really worth while. Just a thought.....
Anyway Sparky, cant wait to see the results from the next phase of the Faema revamp. Will be very interesting to see how much of a difference the pre-heating boiler makes to the end result. Until then, all the best.....
It all went together, no electrical problems, plug in, turn on,..... 10 minutes later reset the earthleakage trip. SH*T! I forgot to fill the boiler.....
The irony is that all the mods work. I had cracked the boiler and resealed it, with no dramas. It came up to pressure. No leaks.... Just one fried element....
Time to try coffeeparts to see if they really do stock replacement elements....
This sort of thing has been plagueing me at work as well. Two pieces of equipment recently decided to fail at a very crucial time. That time was inevitably just before getting results...
Cest la vie.
Sparky, I think this is but a small hiccup for a fellow of your talents... 8-)
Ive got a couple of questions?
1. How do you reseal a "cracked" boiler...presumeably you need to insert a new element...how do you seal so you have no leaks under pressure?
2. Just what are the perishable parts in this machine as Id like to be able to order a "kit" and replace them in mine.
What I mean by cracked the boiler, is to break the seal, not actually crack the brass. Short of actually doing damag eto the boiler body itself, everything is replaceable. *I will have the replacement element by tomorrow! Talk about service. www.coffeeparts.com.au is amasing. Their policy is to have all items in stock. If they have to back order, then they dont charge postage. They stock all the perishables for the Faema family, including thermostats, switches, boiler element, boiler o-ring, element seals and group seals.Originally Posted by termoli link=1130542649/15#20 date=1132544591
When I asked about the Faema stock, they said they will continue to support this machine. In fact they said that they are in the business of supporting old machines from as far back as the 60s.
I continue to be impressed by this machine. Hopefully the experiment phase 2 can continue and Ill have the new machine on hand this Sunday to try up against the big boys at the monthly meeting of crazed coffee-o-philes. *::)
This time its in Brissie right here at the Uni of Queensland at Wordsmiths cafe (Sun 27th of Nov). 9am start. All welcome. Lots of coffee to taste. Local roasters and bristas all bringing along something different to try.....
Hah ha!!!! Last night, amidst searing flashes of lightning and titaninc peals of thunder, the Kraema was born....
And it worked.... The boiler temperature went up when I hit the brew switch, not down.... Some tweakiing is needed, but I now have extra control over the boiler temperature during the shot.....
Mark, that must have been your maniacal laughter I heard between the flashes of lightning and pounding thunder, seems fair given all the experimentation going on at your place ;)
Damn right - propper moody night Dr Sparkenstein!
Yup, first experiments are in. Some very interesting results, but not what Id expected. Boiler recovery is very rapid with the preheater, but the temperature stratification in the boiler is now affecting the brew temperature. So it can actually be less stable than with the PID alone.
Still very early days yet. So theres no conclusions at the moment. Just some more insight into these boilers.
A postcard from flatland.
Still in testing phase, thats why the temp is low. Ill move the PID setpoint up this week to a proper brewing temp.
hey Mark, Ive been following your saga with interest, once you iron out those .3 *spikes you should be right to go ;) Amazing results dude, its astounding what you can achieve with a phd in qantm physics ;)
Ive gone down a similar path ::), water feed for my dosing chamber is solar heated as it snakes down a sunlit wall from a roof top tank, its slightly restrictive in that it only works on sunny days and the otimum temp this month is ony achieved between 3.45pm and 3.48 pm. Oh well the doctor said I needed to cut back......
btw sorry I couldnt make it to wordsmiths, sounds like it should have been great, hopefully next time!
Using the simupuck, I took the machine for a spin. Its pretty well characterised now and a few interesting things came up. The brew water is totally decoupled from the feed water, even without preheating. This means the stable boiler temp can translate into stable brew temp. After a few hours of investigation I settled on a target brew temperature of 93 deg C and put in some real coffee and let loose. I did happen to log the shot, as well as taste it. Unfortunately the shot was too fast and the temp rose by about 0.5 deg C. And the taste.... well ... I think I need to use a better grind.
I have a mod in the pipe that should fix that rising temp that I get for doubles. A true ristretto would have been much flatter, and may have even tasted better...
Note, the coloured bar is 1 deg C thick
Ive had a chance to play with the new modded boiler pipe. While it fell a bit short of what I was aiming for, it nevertheless made some improvement. The most striking was that all shots are kept within 1 deg C variation and the thermal profile is nearly a rising straight line. I plan to insulate the sides of the boiler, which I expect to reduce this variation even more. The one amasing detail is that there is no need for preheating the brew water. The thermoblock doesnt even get turned on. It passively heats to about 40 deg C and thats where I leave it. I may yet have some effect, but its small. The biggest most striking mod (after PID control) is the removal of the group feed pipe inside the boiler. This completely decouples the feed water from the brew water and you can get a very stable thermal system. This then begs the question; why doesnt someone make a machine with this design and a tightband thermostat? Ive been scouring the net for thermal profiles and this machine is in the league of La Marzocco, and Synesso and the Barista Minore (aka Brewtus). In fact the thermal profiles are strikingly similar to those obtained from the new La Marzocco GS3 (worth US$4500). In contrast my investment is sub$300.
Im planning to add insulation to the sides of the boiler to further stabilize the system. There is also one more boiler pipe mod I have in mind. That will have to wait for next year as time and conferences are closing in on me.
Anyway, for the taste test. A ristretto of some Merlo Private blend. First one brewed at a nominal 91.5 deg C... A touch burnt. Drop by 1 deg C, flush 60 ml (using a simupuck), brew another shot. It comes out at just above 90 deg C. Not too bad given only one flush to shift the group temp. Taste was good. I think the pump pressure was too high though, as the shots were a bit thin. I also need to add a pressure gauge...
These shots stay within 0.8 deg C. So Im getting there. Still aiming for sub 0.5 deg C (consistently)
Well done Mark.
One more update for this year. The machine is essentially thermally stable. At least as stable as anything out there. I ran a couple of ristrettos last night and got the entire profile within 0.5 deg C for both shots. One was within 0.1 deg C for 90% of the shot....
Great, so now to get drinkable espressos from this machine. Both shots were sourish and thin. So I have to dial in the pressure and up the temp a bit. Im really looking forward to getting some coffee nectar from this baby. Theres no use tinkering and still getting below par shots...
Last week a mate made me a ristretto with his BZ35 (same as my machine) and he hit it right on the spot and got thick crema with a full bodied chocolate palate. Thats reinvigorated my quest for espresso. Why cant we drink stuff like that all the time?
The Kraema is meant to address that point.
Hmmm, upped the pressure from 4 bar to 9.5 bar..... :-[ ::)
Ever the the film The China Syndrome Sparky? :o
very interested in this software you wrote please can i get a copy...Originally Posted by Sparky link=1130542649/0#14 date=1131761254
I have a faema erika electonic which has a built in grinder. I have been using it at home for the last 9 months and absolutely loving it. I picked up a faema family at auction last week and very keen to use the commercial portafilter to see what the differences would be with my smaller erika i wired on a plug and turned it on (all appliances bought at auction now have the plug cut off). It all lights up but no heat, steam or water and when a push the coffee button there is a bit of a loud click but no action, the boiler doesnt heat up and no water is pushed through. I am wondering if its as simple as a fuse blown or a major part has died like the pump. I noticed the photos of sparkies faema famly machine which is the same as mine and have done a quick comparison with the insides but didnt notice anything. Thinking maybe i should get a voltmeter and check out the circuits or is it worth taking it someone for an overhaul. Does anyone know a good place in sydney. I dont have much money though and would rather try to do it myself and find out more about the workings of the machine. Any hints?
another post from faemageek a green bean,
When is the next coffee snobs event in sydney?
Originally Posted by faemageek link=1130542649/30#35 date=1138061265
Theres not too much that can go wrong with this machine. Here are a few possibilities that I can think of: The pump may not be working. Check the plug, wiring and then the pump itself. Getting a new pump isnt too difficult. The other potential problem is the element. You may have fried it if you turned it on and there was no water in the boiler. Ive done this to mine and had to get a new element for it. If you can operate a multimeter and know your way around basic circuits, you could check both the pump and element. In the case of the pump, check the wires are connected properly and that the coil in the pump isnt open circuit. For the element, check for an earth leakage from the element to the body of the boiler. That means your element is fried. Otherwise it may be one of the switches or a faulty thermostat. All these parts are replaceable. Check www.coffeeparts.com.au They have all the replacement parts that you need to get a Faema family up and running again. They are in the Faema sectiion, page 24.
Otherwise, any reasonable coffee machine repairer should be able to get it up and running again.
Cheers mate, will give that a go and if I fail with that then head to the professionals. I have a contact at coffee works express in south sydney that should do the trick. Thanks for your time.
On: 12. Nov 2005 at 13:07 you mentioned using a Digitech QM1538 DMM with RS232 output. Im also trying to read the RS232 output of a QM1538, and would be grateful for any info you can help me with regarding the format of the output.
Im sitting in an airport, so this will be quick for now. The output is in 0.4 sec intervals and consists of 14 byes. Each pair of bytes encodes either a digit on the display or some of the other indicators. The code can be found by searching the jaycar web site in the forums. Just search for QM1538 and you should find it. Otherwise PM me your email and Ill send the details of the format.Originally Posted by kiwi_roaster link=1130542649/30#39 date=1139818908
Cheers, mate! *The Jaycar site entry for the QM1538 had a downloadable PDF than gives the full story on the RS232 protocol. *Many thanks, & happy brewing.
Ill be updating this project very shortly. Ive just installed another mod that may well produce some interesting insight into this and similar machines. But then again it might not. Well just have to wait and see. The latest mod is a first step to where I ultimately want to take it. Unfortunately taking it further might get expensive, unless fleabay can toss me some more goodies. For example the latest bit has a RRP of over $400, but I landed it for less than $50 (new).
The machine now only bares a vague resemblance to its former self. It looks more like some wierd Dr Who monster now. Im still holding out to one day get a decent espresso from it though.
Just make sure it doesnt turn into a Dalek Sparky.
Exterminate! Exterminate! Exterminate!
OK, the new mod is working and I have given the machine an initial spin.
Ive just attached a pressure transducer to the steam pipe using a compression T fitting. I had a little trouble with the compression seals, so a bit of silver solder was employed. The result is a pressure tight addition that gives me an electronic pressure readout. The pressure transducer is the expensive bit. The cheapest one I could find here in oz was over $300. The one I sourced is much higher quality, rated for operation up to 125 deg C with an accuracy of less than 1% with linearity, hysteresis and bidirectional repeatability of 0.05%. I got a 60 bar unit. I would have preferred a 20 bar unit, but beggars cant be choosers.
This gives me the opportunity to do painless pressure logging while making a shot. Ive never seen anyone submit a pressure profile to the various forums before (apart from a recent thread in home-barista where a pressure trnasducer was attached to a portafilter to monitor the pressure ramp up for three different machines), so this is an opportunity to test some commonly held beliefs.
My main motivation is to be able to use this sensor as a means of controlling the brew pressure. Thats the long term plan. I also have a shorter term plan to develop a simple electronic preinfusion control box for use with vibe pumps. This transducer will help me test the unit.
So to start off, there has been numerous discussions of the merits of the two main types of pump used in coffee machines. The vibratory pump used in small home machines and the rotary pump found in commercial plumbed machines. The rotary pumps have a huge capacity compared to vibe pumps and with the addition of a by-pass valve, can provide a stable brew pressure for multiple groups. In contrast the simple vibe pump is operating right near its capacity for just a single group. Im always a bit nervous when a piece of equipment is operated near the extremes of its performance specs. So now to test it... (caveat: As I dont have a rotary pump, I am unable to compare the two at this moment).
The first set of curves show the repeatability of the stalled pressure obtained for a particular setting of the OPV (Over Pressure Valve). I am using a Fluid-o-tech 70 W vibe pump with Fluid-o-tech OPV attached to the front of the pump.
Not too shabby. It hits the target pressure with a precision of less than 0.1 bar.
Next to compare the brew pressure to the stalled pressure (obtained using a blank filter basket)
Hmm, in this machine the pressure buildup is still quite rapid, taking about 3 sec with the blank filter basket and about 4 sec with a real shot (double basket).
Now lets have a closer look at the stalled vs brew pressure:
You can see that there is a 0.3 bar drop in pressure when actually brewing a shot. That is probably due to the fact that the OPV is right next to the pump, while the transducer is attached to the boiler with an intervening thermoblock in the way. So that drop is due to the resistence of the brew path at a brewing flow rate. Note, that there are no gicleurs or flow jets in this machine, so the two pressures are pretty close together. You can also see that as the shot progresses, the pressure drops. This was my best shot and it still drops. Others dropped by up to 0.4 bar during the shot. Some of it is due, no doubt, to channelling, but otherwise, its probably a natural effect of extracting the coffee oils, which progressively reduces the resistence of the puck.
One of the things I will take away from this is that the brew pressure wont be fixed. For a double, which has twice the flow rate, the drop in pressure should be greater again. Ill test this some time later. Also, for doubles, the vibe pump is operating close to its limit where the OPV can no longer regulate the brew pressure. So things might conceivably be worse still.
At the end of the day, Im having a bit of fun with the machine and trying to learn a bit in the process. Im still not drinking the espresso from this machine. I tasted it last night, but found it rather sour, so its a temperature adjustment as well. But I used beans that always seem to produce a sourish taste from any machine Ive used (at least 4 others including HX machines). They make great cappas but not good espresso. So Ill go looking for a good espresso blend to try out now the machine is working and the pressure dialled.
The machine is coming closer to being commisioned. Mainly a few alterations to go, but no functional mods. Ive swapped the pressure transducer for the pressure gauge from the portafilter to check its calibration. It seems to be pretty good. So Im brewing close to 9 bar and the temp profile is nearly flat and constant (to less than 0.5 C). With the preheater, the boiler recovery is pretty quick (no more than 5 min, but pulling an immediate second shouldnt be a drama).
I decided to use the naked PF to eliminate contributions from the old PF I was using and Im using reverse osmosis water to prevent galvanic corrosion of the thermoblock and not introduce extra tastes into the brew. Now for the taste test...
Wow, the naked PF shot just oozes out like honey. Thick and creamy. Taste was pretty good as well. At least my grind, distribution and tamp seem to be spot on. No sign of channelling, very even extraction and ... pretty good taste.
Next up the temp by 0.5 C and try again. This time the crema was noticeably darker and the result... well I made it into a cappa without tasting it. Im trying to get that chocolate flavour that they manage at the cafe at work. Still not there. But I dont think its the machine to blame this time. This blend seems to favour a fast extraction (the cafe uses 17 sec), so Im thinking its really in the shot parameters. They also brew at a lower temperature (with lighter crema).
The upshot of all this is that the machine is ready for action with some different beans to try and find espresso nirvana. The fist stop is to revisit the Dom Republic Soliman that gave me my first taste to nirvana and see if I can revisit it.
Ill try and get some piccies of the naked PF action with the machine soon.
I read through your Faema Family thread with some interest. I picked up one of these nearly a year ago with the Faema grinder to boot for the grand sum of $135. MIne is white with a black and white two tone grinder ! I had to replace the group head seal but apart from that everything was operational. Now the element has started to trip out the circuit breakers (so probably a good run for something that is 17 years old. I have one of these one order as well some new seals.
Since I have the thing stripped down I have though about PIDing it. Did you manage to fit this internally? Its a pretty homely machine anyhow so a black box hanging on th side wont improve things. What I can gather you also took out the boiler tube ? Is that still out and something you would recommend doing ? And finally I noticed on your picture of the three way valve the free tube has been tied off. Mine isnt and I can say the three way effect only works sometimes - wet grounds on many occasions. Any thoughts ?
Thanks in advance for any advice you can spare,
Hi Rick, welcome to CS.
The PID controller is external, but the SSR is internal. Im about to change that though, as the heat inside is killing the SSR, so it will also go into the controller box with an external heat sink. I had to drill a hole in the side of the case to get the wires out.
The 3-way pipe is attached to a Y-junction with one end closed off. The other end is open and feeds into the drip tray. This is the way my machine came. My 3-way is working fine. If youre is dodgy, then you could probably just get a new coil or entire new assembly for about $80.
As you might have read, I already installed a new element and got the machine back up after inadvertantly frying the original one. All in the name of science I guess.
The PID controller is the first major mod. Itll stabilize the boiler temperature down to less than 0.1 C (on the outside). However there will still be internal temperature gradients. The next big mod is to remove the brew pipe. That prevents the cold feed-water from mixing with the brew water. That gets the temperature stable to less than 1 deg C during a shot. Thats better than most commercial machines can manage. So you get temperature set-ability and stability with those two mods. The last thing would be to set the brew pressure with the OPV. Then the machine is about as good as it can get.
I hope that helps. These are great machines and are worth keeping running. Worst thing is the sad drip tray. Looks are pretty retor as well.
Heres a photo-update of the machine and a shot using the naked PF.
The ugly-duckling itself... Not really ready to go out in public, but working nonetheless.
Whats lurking behind? A thermoblock and a new pump/OPV. Note: the SSR will be moved.
And last the pressure transducer Ted into the steam line and insulated boiler.
And heres what come out the business end. This one was pretty thick. Brew temp was too hot though.
Whats good about this setup is that the machine is no longer a major factor in determining what goes in the cup. It brews at 9 bar (easily adjustable) and the temp can easily be set with 0.5 C precision. That leaves the hard stuff: Grind, dose and tamp. Still enough to keep me busy. ;)
Thanks for your advice and your Coffee Snobs welcome. I am still waiting on my spare parts to come but they should be here tomorrow courtesy of Coffee Parts. Great company I agree.
I just saw your latest photos - what a beast ! but it certainly looks like it is doing the business if that bottomless portafilter shot is anything to go by. I will be putting mine back together without the boiler pipe as soon as I get the parts. The PID will come in a later date. I can only see some really expensive Australian available ones so its time to hit ebay.