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Faema E98 S1 pump conversion from vibe too gear

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  • #16
    Guys,

    I thought as a bloke, I would automatically have good spatial conceptional skills. Maybe not air traffic controller grade, but at least enough to fit stuff into spaces without having to think too hard. Then I met the brass and copper jungle known as the back of an E98. There's tube, fittings, rounded boiler bottoms, slants under the water tank, wiring looms, and they are all in the wrong place. In the end I had to make up a cardboard template, and scribble all over it just to get my head around it all.

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    The plan was to mount the parts on a base, which would then be mounted on the four gel anti-vibration mounts. It didn't matter where I put the bits, something fouled, or didn't line up, or got in the way of the mounting holes. Eventually I sussed it out, and this morning I made a base out of 10mm aluminium. It has four counterbored holes for the vibration mounts, and 4mm deep recess where the pump motor sits. It is as compact as I can get it, while still allowing easy access to the mounts to install it in the machine. Phew!

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    I've got a bit slack lately, and I've started using those push-lock fittings for the 6mm teflon pipe. I'm also plan to take the easy way out and glue the pump and brass manifold to the base with 3M VHB tape - I have no shame.

    So far, so good, Stavros

    PS. I jury-rigged the pump up to one of my old Rancilio Audreys the other day, and made a few test shots. Compared with a vibe' pump, it was just bizarre. To pull a shot, I threw the Audrey pump switch, which now only actuates the solenoid valve to connect the brew head to the boiler. To get flow to the group head, I had to separately increase the speed of the gear pump and wait for a visible flow from the portafilter.

    At a slow pump speed, it takes forever to get even a dribble from the portafilter, and you have to wind up the speed to get what looks like a normal shot. As Audrey doesn't have a pressure gauge, so I was playing it by ear, and by watching for a flow from the OPV to know when I got to nine bar. In the end I got a couple of decent shots out of it, but when you introduce another variable like pump speed/pressure you start to doubt whether you have right grind setting.

    One thing that struck me was that when the solenoid valve to connect the brew head to the boiler, (without the pump on), there is probably one bar of pressure in the boiler pushing water into the coffee grounds, like a poor man's pre-infusion. However, that wasn't enough pressure to get the water through the grounds and into the cup - go figure.
    Last edited by Stavros; 25 October 2021, 05:30 PM.

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    • #17
      I watched the movie 'Kelly's Heroes' on the weekend for the 1093rd time. Classic!
      So begs the question ....... As 'Oddball' said to 'CrapGame'....
      "Hey Stav baby, What is it with you!..... and all these negative waves in the morning?"
      How about some goodness and light and some positive waves ! lol Woof Woof !

      Can I suggest you return said Audrey to stock block std and use it as a test bed.
      Get all your ducks in a row.
      Pull some shots and notate all the important variables.
      Of course taste is all that matters! But I believe the shot metrics is lke a UBD/Melways/Sydways etc.
      Important to keep all the preshot puck prep tight so no variables.
      Write down like everything. P.I./total shot duration /flowrate begining and end/total Grams out.

      Then swap in or out as required.

      Im thinking from your posts that the pump may require more 'juice/revs/etc' to get it to where you want the flow, pressure etc. to be.

      Are you doing a controller (arduino) to control variables?

      Here's a list I thought pertinent -
      Keep the Boiler / HX
      Mount a new smaller brew boiler fed from the HX tube, with a temp sensor inline prior to Brew Boiler.
      Flow sensor at pump outlet to new brew flow path.
      Temp sensor in Service Boiler, Brew Boiler, Near to G/head,
      Heater cartridge into E61 grouhead.
      Sensor on on pump controlling speed
      Manually mount E61 gicleur with manual flow control (needle)

      Short of a saturated (wethead) grouphead, this machine would rock !

      Comment


      • #18
        Are you doing a controller (arduino) to control variables?

        Arduino? No, nope, nooope. Nnnyoope! Not going there. Too old. New concepts - brain hurts too much. I’ll leave that to the young people. Anyway, coffee is mission critical, it’s too important to use some home-made, led-flashing, yum-cha calculator full of buggy code to make a decent shot. How can I put this? In an old-school E98, analogue is best.

        So the control of the pump - I think you could have a separate 30 page thread just on that subject alone. My plan was to replace my vibe’ pump with a rotary pump, and as it is variable speed, manually control it with a potentiometer to tweak my shots. Pretty straightforward, and if it helps me with some of the lighter roast beans, then all well and good. I’m not planning on anything else. (And it’s just a coincidence that I included an extra threaded port which could possibly accept, I don't know, maybe a pressure transducer?)

        If, after running it manually for a few months, I start to see a trend where a certain profile produces a superior shot, then I may look at automating the timing and pump speed. What appeals to me is something basic, like a couple of time delay relays and trim pots to set the time and pump pressure. It wouldn’t do ramp up or down, but it would be repeatable. I could mount them under the drip tray, and tweak the pre-infusion and shot times and pressures - with a screwdriver.

        Having said that, while trawling the internet for information on variable speed pumps in espresso machines, I jagged a thread where I guy was using a industrial controller and pressure transducer to control the pump speed. I thought it was quite clever, as he was using the ramp/soak functions in a Fuji PXG4 temperature controller to control the pressure and profile of a shot. I should have bookmarked it, as I can’t find it now.

        But credit where it's due, I'm impressive to see the lengths some people have gone to automate the control of the pump, using a variety of flow and pressure sensors, microcontrollers, and even graphical displays. One engineer gets way down in the weeds with his pump stuff. About a paragraph in, I’m lost, it’s over my head, but impressive nevertheless.


        I've got to be careful, as I don't want any scope creep with this project

        Cheers, Stavros.
        Last edited by Stavros; 28 October 2021, 01:54 PM.

        Comment


        • #19
          Originally posted by EspressoAdventurer View Post
          Sensor on on pump controlling speed
          Manually mount E61 gicleur with manual flow control (needle)

          That's not a very good idea IMO: the pump and the needle valve will both be trying to do the same job so they will just fight one another.

          Much better to have just one of them do the job it was designed for: in this case the gear pump can control flow rate and pressure all by itself.

          Comment


          • #20
            Originally posted by Stavros View Post

            Having said that, while trawling the internet for information on variable speed pumps in espresso machines, I jagged a thread where I guy was using a industrial controller and pressure transducer to control the pump speed. I thought it was quite clever, as he was using the ramp/soak functions in a Fuji PXG4 temperature controller to control the pressure and profile of a shot. I should have bookmarked it, as I can’t find it now.

            But credit where it's due, I'm impressive to see the lengths some people have gone to automate the control of the pump, using a variety of flow and pressure sensors, microcontrollers, and even graphical displays. One engineer gets way down in the weeds with his pump stuff. About a paragraph in, I’m lost, it’s over my head, but impressive nevertheless.



            Cheers, Stavros.
            No need for a digital controller to achieve that: the slope in the pump curves you posted is due to the current demand of the windings reducing the available drive voltage. You can completely flatten the curve with a simple I x R controller which will feed pump current forward to the voltage control. This will give you a constant flow rate for a given potentimeter position no matter what the back pressure is so you can draw a flow curve with the potentiometer settings.

            If you want to pressure profile you change the feedforward to feedback and you end up with pressure contol.

            All of this can be done with simple and robust analogue controls.

            Comment


            • #21
              Evening Guys,

              Firstly, thanks to everyone for all the advice on the motor control and suitable circuits. I'm slowly taking it on board, and will look at it further once I've sorted out the plumbing and mechanics. I've also sent off an email to Fluid-O-Tech asking them if the electronic driver used with the FG304 gear pump has a built-in compensation circuit, to maintain the speed of the pump as the load increases.

              My vibration mounts finally arrived, (hooray), so I made some 30mm aluminium feet for them, and installed the pump in the E98. (Yep, you guessed it - double-sided tape again.) I ran into a couple of problems along the way. The flexible hose was too short, putting tension on the pump, skewing the base against the flexible mounts. To get the extra length, I made a 70mm long 1/8" BSP fitting out of some 12mm diameter brass. The other issue was that the 24VDC power supply was a bit too big to fit in the spot under the water tank, so I'm now considering mounting the power supply and other electrics under the base of the machine. Probably not a bad spot, as it is away from the heat inside the machine, and would be easier to access for maintenance or modifications. I better put some sort of cover to protect me from the mains voltage wiring too.

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              And finally, it looks like I have a problems with the three-way solenoid valve on the grouphead. What I thought was a intermittently noisy vibe pump or OPV chattering, turns out to be coil on the solenoid. Now that the pump is so quiet, it's easy to pinpoint the source of the noise, and a bit of googling indicates that it could be a faulty shading coil on the 240VAC coil.

              Cheers, Stavros.

              PS. I bodgied up a few things, warmed the machine up, and made a shot. It worked, but was nothing to write home about. I think it will take a bit of playing around before I work out the new pump.

              Comment


              • TailorCoffee
                TailorCoffee commented
                Editing a comment
                looking good!

              • Stavros
                Stavros commented
                Editing a comment
                Just a quick update. I replaced the dodgy solenoid coil, and now I can appreciate how good the serenity is with the new pump.

                Sheer bliss - "Click, rrrrrrrr, widdle widdle widdle, rrrrrr, click". Measured with the sound meter app on the phone - 46 dBA on startup, and as the speed and pressure is increased 50.5 dBA. Then the Sirai pressurestat kicks in - " CLANK, SPRONGgGgGg, CLICK, POINGgGgGgGg ".

              • level3ninja
                level3ninja commented
                Editing a comment
                It's like I'm in the room!

            • #22
              Guys,

              Fired up the machine in anger this morning, to make my usual morning double-shot flat whites. I warned the wife that there would be a leaning curve with the new pump, and to expect some mediocre coffees for a week or so. To be honest, I was expecting all sorts of teething problems.

              To keep the transition simple, I used exactly the same setup I used the day before with the vibe' pump - a 15g VST basket dosed with 16.5g of dark roast. It normally takes about seven seconds before you see the first few drips in the bottomless portafilter, and then you get a textbook looking nine Bar extraction for 40g in 35 seconds. These shots have been consistently good with no problems provided I pay attention to the distribution and tamping of the grounds.

              Based on what I've read online, the plan was to start the shot with the pump at a low speed, (a couple of Bar), to allow a slow or pre-infusion, and then kick it up to nine Bar for the rest of the shot. The first shot initially looked OK, but I only managed to get the pressure up to four Bar before the flow was way too fast, almost a gusher, resulting in a nasty tasting coffee. I had to reduce the grind three times to a setting lower than I've ever used, before I got a normal speed shot. In the end, by watching the flow rather than the pressure gauge, and watching for it to blonde-out, I managed to pull three very decent 42 to 45g shots with 12 seconds of pre-infusion, and total time of 40 to 45 seconds. It didn't seem to matter if you use six or nine bar - they were good looking and tasting shots.

              So, overall, I'm both pleased, and confused. It's like the gear pump is more effective than the old pump. I don't know if this is the effect of the slow pre-infusion, or a characteristic of a gear pump. It's bizarre - a way smaller grind for a similar flow and decent shot, even at a lower pressure. Man, here we go again, down the rabbit hole of multiple variables.

              Cheers, Stavros.

              PS. In the end, I didn't install a separate bleed or bypass valve in the pump plumbing to reduce the minimum flow. It looks like it is not needed, as at minimum speed, the flow is very manageable.

              Comment


              • #23
                Originally posted by Stavros View Post
                Guys.....
                I warned the wife that there would be a leaning curve with the new......
                To keep the transition simple, ......
                Cheers, Stavros.

                Hey Stavros forget the techy blah blah blah....you know as well as I and the rest of us here......
                That What Matters is.....
                What She says about your new found shots ??

                Comment


                • Stavros
                  Stavros commented
                  Editing a comment
                  "That's fairly strong, but not bitter at all". There you go, dammed by faint praise - the story of my life. Mind you, the beans were roasted five weeks ago , , , ,

                • EspressoAdventurer
                  EspressoAdventurer commented
                  Editing a comment
                  Stav you should know by now its in their DNA not to give up too much praise to their menfolk.
                  You mark my words .........
                  Tmrw or next few days there'll be a ....
                  "So Are we having a coffee..... soon?"

              • #24
                Now that we got the touchy feely stuff out of the way...back to the Techy stuff that matters.
                I commend you on the build to this point.
                Im clearly not a Rckt Scientist but wasnt 100% with you on the flow rate over pressure vs bleeding off.
                But had nothing of substance to submit.

                So why not get you hands (or build one up) a Scace 2 device and measure at the GH pressure, temp and that might allow you to mark up or notate some base settings.

                Comment


                • Dimal
                  Dimal commented
                  Editing a comment
                  Excellent idea 'EA'...

                • Stavros
                  Stavros commented
                  Editing a comment
                  EA, in hindsight, my comment on the bleed valve could have been clearer. It was related to an earlier post where I mentioned that I had read that other people who have been messing around with flow and pressure control, have found that the flow from rotary pumps, (including the FG304), can still be a bit excessive. They have fitted either a needle valve or a fixed orifice to the pressure line to allow them to bleed some of the flow back to the tank, reducing the flow to the group at the lower speeds. I tried this on my test rig, and I was able to bleed some flow off, but today I found out that it isn't necessary, as the pump can run slow enough for a slow pre-infusion.

              • #25
                Chaps,

                I've had a good play with the machine over the past few days, and overall, I would say that the mod' is a winner. I'm very pleased with the gear pump, and the ability to vary the speed/pressure on the fly.

                I have continued to reduce the grind to the point where I can get a full 9 Bar shot, but it taste pretty harsh. Strangely enough, I've had much more success with a coarser grind and an extraction between 4 to 6 Bar. So much so, I've reset the OPV to 6 Bar, as the higher pressures seem pointless. I've also noticed that at the lower shot pressures, the machine is very forgiving of lazy distribution and tamping practices. I've been quite cavalier the last few days, and still haven't seen a sign of uneven extraction, or channeling, or those crazy jets which miss the cup completely.

                The only issue I've run into is that the Faema has always been a bit fickle on the temperature side, requiring attention to the preheat/flushing routine, to get a relatively consistent brew temperature. I've noticed in the past that a change in grind can vary the initial flow through the puck, and this shows up in the temperature range in the shot. If you change the grind - be prepared to fudge the brew temperature by altering the length of the little cooling flushes between shots. So, the slow initial infusion has resulted in a couple of degrees increase in temperature of the shots, until I started doing a longer flush before every shot. If I'm careful, during the majority of a 40 seconds shot it's now relatively stable, varying by less than a degree.

                So far, so good. I'm going to keep playing, and check in every couple of weeks to let you know how it is going.

                Cheers, Stavros.

                Comment


                • WhatEverBeansNecessary
                  WhatEverBeansNecessary commented
                  Editing a comment
                  James Hoffman did an interesting piece on why 9Bar was the 'standard' pressure as part of the understanding espresso series. 9 bar appears to be the highest flow point, over that seems compress the puck too much.
                  Maybe that is why the lower shot pressure is more forgiving for tamping and puck prep? interesting that you are getting better flavours at much lower pressures though.

                • Stavros
                  Stavros commented
                  Editing a comment
                  Thanks very much for that comment about Hoffman, I found his video on YouTube, and it all made sense. I've never taken much notice of his stuff, as I thought it was a bit over-the-top, but now I'm going to have to watch his other videos as well. (https://www.youtube.com/watch?v=po3oGIicu-8)

                • WhatEverBeansNecessary
                  WhatEverBeansNecessary commented
                  Editing a comment
                  I think his videos can be both. Sometimes over the top with too much high end information and sometimes too basic to really be useful. But there are a few that are worth watching and the understanding espresso series is interesting while a good portion is not groundbreaking.

              • #26
                Guys,

                I know I said I was going to stay away for a couple of weeks, but just so you can be as confused as me, below is a link to a video of a two Bar shot!! They are a medium roast bean, about 10 days old, more nutty and fruity than my usual dark roast chocolate beans. The grind was insanely fine, but you wouldn't think so by the flow in the last half of the shot. (Those clicks and clacks in the background about midway through the shot are just the pressurestat doing it's thing, not me controlling the pump.)

                Once I started looking, there is a lot of information and opinions on the net about variable pressure profiling, slow infusion, and lower pressure extraction. Some of the issues I've encountered, especially using a finer grind have been identified and well explained, so it is starting to make sense. While a number of people have used a 6 Bar pressure, I've got some really nice shots at 3.5 to 4 Bar. They are not textbook perfect, and I've had to stop a few early, but they taste very nice, and that's what counts to me. So much so, I've had way too much coffee today.

                Of interest was one comment that "Perhaps counter-intuitively, a gentle pressure ramp tends to yield a faster flow rate later in the shot, whereas a swift pressure ramp tends to yield a tightly restricted flow during the last 2/3 of the shot.” That's a trend I've noticed, and may explain the flow in the below 2 Bar shot - a lack of pressure to compress and stabilise the puck.

                So, plenty more experimenting and practice required before I get a handle on this.

                http://www.users.on.net/~m27373/E98/...Bar%20Shot.mp4

                Cheers, Stavros.
                Last edited by Stavros; 10 November 2021, 01:44 PM.

                Comment


                • #27
                  There are just so many variables contributing to the final result in the cup, the mind is well and truly boggled...

                  Mal.

                  Comment


                  • Stavros
                    Stavros commented
                    Editing a comment
                    Yep, It's like I let the Genie out of the bottle, and I can't jam them back in again.

                • #28
                  Stav good stuff much admiration for your achievements with this to date.
                  I didn't see anything in that shot that wouldn't have made me super keen to taste it.
                  Tho the only times Ive run a 14sec P.I. has been when Ive mistaken / mixed up my puck prep.
                  My only thought with that is that 'old skool' italian espresso 'rooles' was don't leave the handle prepped and in the GH for too long a time as the grounds may 'burn' from the heat.
                  As I said old skool, as your running low pressure, low flow rate water P.I. and of course running a higher dose weight I assume than trad Italian espresso.
                  If I was able to be there Id be super keen to try many variables - Taste, Taste, Taste - particularly in overall shot time vs shot ratio (g). Meaning variances to the flow rate and I spose in the later half of the shot. Also variable P.I. times and saturation levels.

                  I found as with others here that 'light' roasts improve over a longer settling time - up towards 20 days - than the longer darker roasts.

                  Please post up the dose weight / shot ratio and a pic of the shot to see the depth of the crema.
                  Also whats the amount of 'space' above the puck in your setup at present?

                  Be prepared for a few who may likely post up ....wtf , ????, knickers all knotted over any mention of mm's, grams, secs and % ratio's etc.
                  Mind you I didn't see an almighty blaze over the 'Esoteric Voodooo Espresso' reference earlier !

                  Edit: PS not referring here to you of course Mal !

                  Comment


                  • Stavros
                    Stavros commented
                    Editing a comment
                    EA, yes 2 bar is definitely a bit low for a shot. I didn't expect it to do that, with the fine grind, I thought the flow would just slow and stop half way through. It's bizarre, it's like the slow pre infusion has changed the rules, and I need to relearn them.

                    The E98 seems to have a lot of headspace, and I need to dose a couple of grams higher than the basket size before I get a puck which makes contact with the screen on extraction, and doesn't come out like mud. With a dark roast, that is about 16.5 grams, and with a lighter roast about 16.8 grams. This gives me a nice firm dry puck which nearly drops out of the basket when you shake the portafilter. I don't know if this is a 'key performance indicator', but it's something I like to see.

                    I have always aimed for the typical 40 grams in the cup in 30 seconds, but I'm happy with a few grams either way, provided that it's still drinkable. I've never considered ratios, or volumes, or anything, just 40 grams. Even when I've changed baskets and doses, I still aim for 40 grams. Except for those rare occasions when you seem to fluke a really nice looking shot which taste great when you stop it early at 30 to 32 grams. Maybe I accidental strayed into ristretto territory - who knows.

                    Anyway, I don't have an espresso shot glass, but in the next few days I may pull a shot into a vegemite jar and see what it looks like.

                    Nah, I'm not expecting any criticism, as the people on this forum have been really good - they seem pretty casual and down to earth about this whole coffee game. It's not like that "other Esoteric Voodooo Espresso forum", (say it like you would whisper " the other woman", who is somewhat exotic, but very high maintenance), who take it wayyyyy too seriously.
                    Last edited by Stavros; 10 November 2021, 04:08 PM.

                • #29
                  Originally posted by EspressoAdventurer View Post

                  Please post up the dose weight / shot ratio and a pic of the shot to see the depth of the crema.
                  OK, this is the first time I've ever bothered to check out the crema - it makes me feel a little, , , um, , , kinky.

                  This is a 17 gram 32 second, 6 bar shot of the medium roast, (ONA Aspen), beans. It ended up with 42 grams in the glass. It still looked a bit fast to me, despite reducing the grind, , again. However, it achieved the main KPI - it got the tick of approval from the wife. Fairly happy with the puck too - if you are into puck appreciation, , ,

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                  Cheers, Stavros.

                  Comment


                  • EspressoAdventurer
                    EspressoAdventurer commented
                    Editing a comment
                    Hmmm ......Kinky Boots ? maybe Stav....

                • #30
                  Nice looking shot Stav. Thick layer of crema in proportion to espresso (liquor).
                  I can only relate what I (seem to know) works for me.
                  So when I get a gusher or an underextracted shot I often look at the crema and see pale insipid thinness - Biege as I call it.

                  Now your shot above - even tho Im not looking down on it from above - has (to me) flecks of hazelnut and a deepness of colour that reflects a well crafted shot with higher % of extraction yields than the biege shot I erroneously referred to.

                  Your shot is typical of what I aim for and call a well setup shot.

                  Stav Id encourage you to try some further variations such as shot yields around the 1:2 shot ratio such as a 17g dose - 34-36g out in 34-38 se.
                  i.e. a flow rate of 1g : 1sec overall. Try see what it gives. Then try some variables on the P.I. side.

                  Stav now that I got you gazing into your crema , whats it gonna take to get you to measure the headspace in your basket at a 17g dose??

                  PS I wish you nothing but peace and happiness Stav...... As we know its a woman's world nowadays, and the good Lord knows and accepts my betrothed for instance is a very hard marker .......but your being held to KPI's by your other half for her morning coffee! ... Oh my Stav I wish you the best.

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