Page 3 of 6 FirstFirst 1 2 3 4 5 ... LastLast
Results 101 to 150 of 279
Like Tree1Likes

Thread: Upgraditis: 2-group Grimac Commercial

  1. #101
    Senior Member
    Join Date
    Apr 2005
    Posts
    1,176

    Re: Upgraditis: 2-group Grimac Commercial

    Mal, there are some things that are not worth the time and effort. These pumps (as Im sure youre aware) have to be put together with high tolerences. There are three bearings inside, only one of which is a standard type sealed bearing. The other two I havent seen before and are probably made by Procon for the task as they also seal the rotor chamber and obviously have to withstand 15bar or more. Bottom line is it looks like hard work to me, especially without the correct tools for the job.

    Besides I have the new pump fitted and running smoothly without any squeaks. It has much less bearing resistance than the other pump. But I must also fess up that when I removed the offending pump I found that I hadnt tightened the clamp ring properly... Oops. That was most likely the cause of the motor stalling, as the pump and motor were misaligned. After removing the pump I found it still turned and didnt seem to have a seized bearing. However, this pump is a very high capacity pump, about twice the capacity usually fitted to coffee machines. Therefore the tightness of the bearing is may be related to this higher capacity (eg. larger seal contact area). As the motor in the Pav is only a small 100 W variety, it is better to run a pump with a lower capacity. The larger 160 W motors can handle the larger capacity pump without a problem and I have a few of them kicking around. So that leaves me with two dead pumps. I will investigate the option of getting them refurbed sometime later..... when I can afford it.

    Thanks anyway Mal.

    Cheers,

    Mark.

  2. #102
    Mal Dimal's Avatar
    Join Date
    Oct 2004
    Location
    Warwick, QLD
    Posts
    15,503

    Re: Upgraditis: 2-group Grimac Commercial

    Ahh, sorry Mark....

    I thought you had a pretty full-on workshop at your disposal. I wasnt really intimating that you should repair the pump for the job in hand now but rather that you could maybe refurb one or two pumps for future backup and gain practical experience at the same time.

    Yep, youve got to be careful matching pump capacity to motor output..... its very easy to get it wrong if you dont have pump curves handy and then could also lead to burning out an otherwise good motor. Anyway, its good to see that youre back in action again, thats the main thing ;)

    Mal.

  3. #103
    Senior Member
    Join Date
    Feb 2005
    Posts
    2,574

    Re: Upgraditis: 2-group Grimac Commercial

    I mentioned earlier on that Mrs Robusto had eyed the Grimac cup warmer and instead saw a plate warmer there waiting to be used.

    Well, I came home from work tonight, and there they were among the assorted latte, espresso and cappuccino cups -- three large plates, already warm. And the machine had only been on for about 15 minutes.

    At this rate, Ill come home to find a whole three-course meal there keeping warm to be eaten (and finished off with a nice double espresso, of course, as a nod to the machines raison detre).

    --Robusto

  4. #104
    Sleep is overrated Thundergod's Avatar
    Join Date
    Jul 2006
    Location
    Sydney
    Posts
    10,494

    Re: Upgraditis: 2-group Grimac Commercial

    Can you up the boiler temp and cook the meal as well?

  5. #105
    Senior Member
    Join Date
    Feb 2005
    Posts
    2,574

    Re: Upgraditis: 2-group Grimac Commercial

    Thundergod, youre giving her ideas.

    --Robusto

  6. #106
    Sleep is overrated Thundergod's Avatar
    Join Date
    Jul 2006
    Location
    Sydney
    Posts
    10,494

    Re: Upgraditis: 2-group Grimac Commercial

    Moi? Mais non?

  7. #107
    Senior Member
    Join Date
    Feb 2005
    Posts
    2,574

    Re: Upgraditis: 2-group Grimac Commercial

    Just for peace of mind, this morning I dismantled the big Sirai pressurestat to check the membrane and contacts, mainly.

    The membrane appeared to be in pristine, excellent condition. No sign of hardening.

    The contacts, I cleaned of any surface carbon, and they didnt appear pitted. (I was looking for similarities to spark plug pitting)

    Also removed and cleaned the vacuum break valve.

    And the dipstick for water level. The final 15 mm or so looked dirty, rusty, and I sanded it clean so water makes a better contact and turns off the pump.

    Everything back together and working well.

    Im not certain whether the pump pressure gauge oscillation is normal.

    When brewing, it oscillates within a 1 mm range, which translates to about 0.2 bar.


    -Robusto


  8. #108
    Senior Member
    Join Date
    Jul 2006
    Posts
    3,495

    Re: Upgraditis: 2-group Grimac Commercial

    Robusto

    Generally oscillation of the pump pressure is a sign that the pump is on the way out...... probably only good for a few thousand more coffees..... ;)

    I wouldnt worry about it at the moment - just keep an eye on it and if it starts to get a lot worse, you might have to look at a replacement.

  9. #109
    Senior Member
    Join Date
    Feb 2005
    Posts
    2,574

    Re: Upgraditis: 2-group Grimac Commercial

    1. So the pointer should be absolutely still during pours, then?

    2. The brew cycle confuses me (its volumetric). Its as though its trying to mimick lever-style pre-infusion.

    First, the pump comes on for a second at around 6.0 bar. The 3-way valve kicks in and some water is flushed into the drip tray.

    Then the pump comes on again, and gently ramps up to 8 bar and out pours the coffee.

    Any ideas?

    --Robusto

  10. #110
    Senior Member
    Join Date
    Jul 2006
    Posts
    3,495

    Re: Upgraditis: 2-group Grimac Commercial

    Robusto....

    1. Yep, on a site where I collected info on testing potential commercial machine purchases.... that was one of the "tests"......and mine does remain stationary.

    2. Mmmmmm that seem strange! Normally preinfusion is provided by the solenoid opening which allows mains pressure to build up in the PF. The pump also starts but the flow is restricted by the group jet (mine is 0.8mm)..... and that causes the pressure to increase slowly from mains to the 9 Bar.

    The 3 way venting water to the drip tray sounds unusual......

  11. #111
    Senior Member
    Join Date
    Feb 2005
    Posts
    2,574

    Re: Upgraditis: 2-group Grimac Commercial

    Gulp. A thousnad coffees left. Pump is good for only another 7 months then! *I dont know about rotary procons supposed to be whisper quiet, either.

    Mine *emits an audible "hum"-like noise when operating. * Not a metallic rumble or anything, just what Id expect a pump to sound like.

    --Robusto

  12. #112
    Senior Member
    Join Date
    Apr 2005
    Posts
    1,176

    Re: Upgraditis: 2-group Grimac Commercial

    Robusto,

    Yep, pump pressure should be rock steady.

    Your preinfusion sounds wierd. Id expect a pump spurt to say 4 bar (or that area, then a pause to let the puck expand and then on again for the duration of the shot. But I would not like the 3-way to exhaust during the process as this can damage the surface of the puck resulting in channelling... This pump pulse pre-infusion is common to a few machines including the new La Marzocco GS3 superhero home machine. None of them involve exhausting the 3-way during the process.

    Oh and my new pump is whisper quiet. It actually goes Shhhhh if theres too much noise in the room ;)

    Cheers,

    Mark.



  13. #113
    Senior Member
    Join Date
    Feb 2005
    Posts
    2,574

    Re: Upgraditis: 2-group Grimac Commercial

    The opening of the 3-way valve into the drip tray happens when I use the volumetric buttons. If I use the emergency rocker switch or non-volumetric button it doesnt happen.

    --Robusto

  14. #114
    Senior Member
    Join Date
    Jul 2006
    Posts
    3,495

    Re: Upgraditis: 2-group Grimac Commercial

    I agree with Mark, releasing the pressure on the puck at that point would not be good for its uniformity...... and I cant think of any good reason why it would be designed that way......

    Maybe the program in the volumetric computer is a little scrambled.... and operates the three way when it shouldnt be.

    I dont know your particular machine at all, and each manufacturers machine has its little differences in operation.... which the designers believe makes it work that little bit better than the others - but I cant see opening the 3 way at that point having any positive effect.

  15. #115
    Senior Member
    Join Date
    Apr 2005
    Posts
    1,176

    Re: Upgraditis: 2-group Grimac Commercial


    Id be using the emergency rocket switch...

    Does the pump pulse during manual operation?

    Youve heard of explosive decompression in a space-craft. Just imagine how your puck feels under the same circumstances. Maybe its a natural selection procedure where only the strong pucks survive?


  16. #116
    Senior Member
    Join Date
    Jul 2006
    Posts
    3,495

    Re: Upgraditis: 2-group Grimac Commercial

    Quote Originally Posted by Sparky link=1173088713/105#114 date=1174445812
    Id be using the emergency rocket switch...
    rocket switch?

    5,4,3,2,1 - fire!

    coffee machine entering orbit in 30 seconds ;) ;D ;D ;D

  17. #117
    Senior Member
    Join Date
    Feb 2005
    Posts
    2,574

    Re: Upgraditis: 2-group Grimac Commercial

    Theres no pulsing of the pump. Its just an audible hum. The pointer on the gauge doesnt do wild oscilations, but very tiny, almost invisible ones. Could also be due to my jury rigged fix inside it.


    Ill have to observe whether the explosive decompression into the drip-tray is clear water or from the puck.

    May be it is some odd by-pass thing within the group, where water already inside it is forced out without affecting pressure on the puck.

    --Robusto


  18. #118
    Senior Member
    Join Date
    Feb 2005
    Posts
    2,574

    Re: Upgraditis: 2-group Grimac Commercial

    Quote Originally Posted by JavaB link=1173088713/105#115 date=1174450031
    Quote Originally Posted by Sparky link=1173088713/105#114 date=1174445812
    Id be using the emergency rocket switch...
    rocket switch?

    5,4,3,2,1 - fire!

    coffee machine entering orbit in 30 seconds ;) ;D ;D ;D
    ....For a taste sensation thats truly, "out of this world"

    --Robusto

  19. #119
    Senior Member
    Join Date
    Feb 2005
    Posts
    2,574

    Re: Upgraditis: 2-group Grimac Commercial

    The mystery deepens.

    Ive pulled a double espresso, and observed the colour of the water from the 3-way-valve into the drip tray. It was very clear.

    With the exhausted puck still in the group, I emulated a backflush routine as though the blind basket was in. Water emerged very clean and clear each time, no sign of having mixed with the grounds.

    Im ...er...baffled.

    --Robusto

  20. #120
    Senior Member
    Join Date
    Jul 2006
    Posts
    3,495

    Re: Upgraditis: 2-group Grimac Commercial

    Robusto....

    That is strange indeed....

    The 3 way is also a pressure relief valve (which normally releases supply water into the drip tray at 15 Bar)..... I wonder if it is malfunctioning.... and releasing at pump pressure.

    Do both groups do exactly the same?

  21. #121
    Senior Member
    Join Date
    Feb 2005
    Posts
    2,574

    Re: Upgraditis: 2-group Grimac Commercial

    Yes, very strange. JavaB. Ive just done a backflush with coffeecleaner, and....everything worked the way if should. Foamy coffeecleaner was delivered into the drip tray.

    Can you tell me what your pump pressure reading is just running water through the group --i.e., without a puck. This may help "calibrate" my own gauge.

    Maybe my pump pressure is too low? I dont know.

    -Robusto

  22. #122
    Senior Member
    Join Date
    Jul 2006
    Posts
    3,495

    Re: Upgraditis: 2-group Grimac Commercial

    The pressure going from idle, then just one group extracting to both groups running flat out (no PFs installed) and the hot water spout delivering at the same time - barely drops from 9 bar (probably 0.1 to 0.2 Bar drop with everything operating......) and thats how it should be.

  23. #123
    Senior Member
    Join Date
    Feb 2005
    Posts
    2,574

    Re: Upgraditis: 2-group Grimac Commercial

    Thanks JavaB. I think I might be in that ballpark --- Ill check a little later.

    --Robusto

  24. #124
    Senior Member
    Join Date
    Feb 2005
    Posts
    2,574

    Re: Upgraditis: 2-group Grimac Commercial

    Water debit and pressure:

    JB: Pump pressure with one group operating reads 8 bar. With two groups at once, it drops to 5 bar.

    That would indicate either the pump is defective, or the pressure needs increasing.

    --Robusto


  25. #125
    Senior Member
    Join Date
    Jul 2006
    Posts
    3,495

    Re: Upgraditis: 2-group Grimac Commercial

    Robusto,

    Id say the pump pressure setting is correct..... (although it could be increased a little to 9 Bar) it simply opens at the correct pressure differential and allows excess output water to flow back to the supply.

    IMHO the more likely causes are....

    1. The pump was never designed to supply both groups "wide open " - unlikely
    2. The pump is old and tired - and cant supply the volume - possible.
    3. Your pump, just like the La Cimbali, is designed to run with mains pressure on the supply side and therefore only needs to ( read is only capable of) raise the pressure by about 4 Bars to provide the required 9 Bars..... and that would be my guess and is also the likely reason for the fluctuations.....

    The La Cimbali pump is a massive 250 L/Hr version..... but requires at least 3 Bar of supply pressure...... and my guess is that your pump (unlike the Procon) also requires supply pressure. The Procon - and some others - will happily draw water from a reservoir. Try yours "plumbed in" and see how it goes.

  26. #126
    Senior Member
    Join Date
    Apr 2005
    Posts
    1,176

    Re: Upgraditis: 2-group Grimac Commercial


    A massive 250 l/hr huh. My replacement is rated at 200 l/pr, but the original "squeaky" pump is rated at over 400 l/hr. Thats probably enough capacity for an 8 group machine...

    I got that particular pump from the US where they like to do things big!


  27. #127
    Senior Member
    Join Date
    Jul 2006
    Posts
    3,495

    Re: Upgraditis: 2-group Grimac Commercial

    Quote Originally Posted by Sparky link=1173088713/120#125 date=1174462692
    A massive 250 l/hr huh. My replacement is rated at 200 l/pr, but the original "squeaky" pump is rated at over 400 l/hr. Thats probably enough capacity for an 8 group machine...

    I got that particular pump from the US where they like to do things big!
    400L/hr - now that IS impressive..... especially when you look at many (most?) two groups which have a 150L/hr pump or less....

    And I thought 250 was massive (but having checked the price of a "genuine" replacement - at least that aspect of the pump is truly massive!!!!)...... The next pump (assuming I need to replace it sometime) will be a procon- and probably the same as yours - ex CoffeeParts.

  28. #128
    Senior Member
    Join Date
    Feb 2005
    Posts
    2,574

    Re: Upgraditis: 2-group Grimac Commercial

    Your analyses sounds highly plausible (as always ;)) JavaB.

    For the moment, though, Im reduced to a single -group!! Every time I press a volumeric button for the right hand one, the earth-leakage safety switch trips and shuts off power to the whole house.

    I dont know what caused that. It happened during my experimentation having both groups going at once. Ill remove the panel and computer tomorrow to see whether they got steamed up today. Or perhaps the problem will go away as the machine heats up.

    --Robusto

  29. #129
    Senior Member
    Join Date
    Jul 2006
    Posts
    3,495

    Re: Upgraditis: 2-group Grimac Commercial

    Quote Originally Posted by robusto link=1173088713/120#127 date=1174464316
    For the moment, though, Im reduced to a single -group!! Every time I press a volumeric button for the right hand one, the earth-leakage safety switch trips and shuts off power to the whole house.
    --Robusto
    Mmmmm.... if the 3 way is operated by 240V (mine are 24V) then I suspect the coil is faulty and is leaking to earth (and tripping the breaker).

    Try unplugging the solenoid (normally 2 spade connectors which just pull off - turn the power off first!!) and see how it goes- the group wont work but it shouldnt trip the breaker if that is the cause.

  30. #130
    Senior Member
    Join Date
    Feb 2005
    Posts
    2,574

    Re: Upgraditis: 2-group Grimac Commercial

    Thanks JavaB.

    Looks like the right group solenoid is the culprit. I swapped ribbon connectors so that the left siwtch panel operated the right group and vice versa.

    The "suspect" right panel operated the left group no porblems.

    But the power went off when I tried to run the faulty right group. It did get wet today. Ill wait overnight to see whether it dries out, but this could be the end of the coil.

    --Robusto

  31. #131
    Senior Member
    Join Date
    Apr 2005
    Posts
    1,176

    Re: Upgraditis: 2-group Grimac Commercial


    Robusto, the good news is that coils are cheap and readily available from coffeeparts Unless yours arent Parker units. Then you may need an entire 3-way unit (about $80 I believe).

    JavaB, I wasnt going for oneupmanship. I got that pump relatively cheap and only noticed the huge flow rating after I won it. While I got the pump really cheap (US$22 for a new pump), the shipping was more than twice the price of the pump. So it wasnt as cheap as Id intended. Cest la vie.

    Ahhh that lovely clunk of the Sirai as I type this....

    Cheers,

    Mark.

  32. #132
    Senior Member
    Join Date
    Feb 2005
    Posts
    2,574

    Re: Upgraditis: 2-group Grimac Commercial

    Sparky, it is a 240V Parker. I dont suppose theres any hope it will dry out and self-fix, is there?

    --Robusto

  33. #133
    Senior Member
    Join Date
    Apr 2005
    Posts
    1,176

    Re: Upgraditis: 2-group Grimac Commercial


    Robusto, whats left when all hope is gone?

    Anyway youre laughing with a Parker unit. The coils are pretty cheap.
    Like part # 700179-22 Parker 220V 50/60Hz coil $27 plush GST and shipping, so all up just under $40. Thats much less than $220 for a new pump....

    ahhh that lovely Sirai clunk once more....

  34. #134
    Senior Member
    Join Date
    Jul 2006
    Posts
    3,495

    Re: Upgraditis: 2-group Grimac Commercial

    Quote Originally Posted by robusto link=1173088713/120#129 date=1174467999
    Looks like the right group solenoid is the culprit. I swapped ribbon connectors so that the left siwtch panel operated the right group and vice versa.
    --Robusto
    Robusto,

    When you say "swapped ribbon connectors" are you talking about the ones going to the solenoid or those from the touch panel to the controller....

    If it was the cables from the touch panel it would have swapped the groups but would not have isolated the problem to either the controller board output (probably a relay) and the solenoid itself. Basically all you would test that way is the two touch panels (which are low voltage units and wouldnt cause your problem).

    The best way to test that is to remove either the wires from the solenoid or where those wires plug in to the controller board.

    If it still trips the breaker - problem on the controller board.
    If it doesnt drop the breaker then the problem is with the solenoid itself (if you disconnected at the solenoid) or the cable to the solenoid or the solenoid (if you disconnected at the controller end).

    On my machine I had a pinched lead (due to faulty previous maintenance) which fortunately was the neutral leg.... so a fault on the line from the controller to the solenoid is also possible.

  35. #135
    Senior Member
    Join Date
    Feb 2005
    Posts
    2,574

    Re: Upgraditis: 2-group Grimac Commercial

    Thanks, Sparky. Looks like Ill have to order one tomorrow, unless something else is at fault. Ah, that Sirai CLUNK. Every 230". Awakens the dead.

    JavaB, I swapped the ribbon connectors from the touch panels into the computer. It just proved to me that the panels themselves were OK.

    So it isolated the problem to the solenoid, whether it be a wet coil (most likely) or pinched wires (will have to have a closer look in daylight). And with a cold machine.

    Its been 30 here today and Ive sweated over a hot boiler enough for one day! ....The forecast is even hotter tomorrow.

    --Robusto




  36. #136
    Senior Member
    Join Date
    Jul 2006
    Posts
    3,495

    Re: Upgraditis: 2-group Grimac Commercial

    Quote Originally Posted by robusto link=1173088713/120#134 date=1174477456
    JavaB, I swapped the ribbon connectors from the touch panels into the computer. It just proved to me that the panels themselves were OK.

    So it isolated the problem to the solenoid, whether it be a wet coil (most likely) or pinched wires (will have to have a closer look in daylight). And with a cold machine.

    Its been 30 here today and Ive sweated over a hot boiler enough for one day! ....The forecast is even hotter tomorrow.

    --Robusto

    Well it is VERY unlikely the panel has caused the problem - it is just low voltage contacts.... so all you have determined is that they are both OK. They couldnt set off an earth leakage breaker - the current and voltage is just way too low. The problem - i.e. the same group is causing the breaker to trip - still exists. It could be the main controller board (mega expensive) which has lots of tracks, the relay which switches the group solenoid and lots of 240V circuits.... and that is a strong possibility, then the connector on that board going to the solenoid, the cable from the connector and lastly the solenoid.

    The problem is either the controller board (moisture across tracks, corrosion of terminals causing shorts etc) or the solenoid itself.... the problem has to be where 240V lives and works (and is now escaping to earth) :(

    And to isolate that you have to unplug the solenoid.... or you will end up ordering a replacement.... and still have the same problem - you will then just be a few dollars lighter in the pocket and no closer to the solution!!

    So following the good old "half split principle" for isolating faults.... the best procedure would be:

    Unplug the solenoid at the controller board ...
    still faulty - controller problem (pray its corrosion or moisture on the board)
    works OK - cable to solenoid or solenoid faulty (go to steps below)

    If cable/solenoid faulty - replace cable at controller board and unplug at solenoid
    Still faulty - cable problem (trace cable looking for damaged insulation etc)
    works OK - solenoid problem (buy new solenoid)

    Waiting with bated breath - youll just have to sweat for your passion ;)



  37. #137
    Senior Member
    Join Date
    Feb 2005
    Posts
    2,574

    Re: Upgraditis: 2-group Grimac Commercial

    I held my own breath this morning, after leaving the machine on all night to dry out any moisture in the electronics.

    Everything seems to be working fine.

    Thanks for your advice, JavaB and Sparky ---Ill hold onto it in case the problem arises again.

    Yesterday while trying to fathom why the solenoid opens the 3-way-valve BEFORE brewing, I removed the blank plug on the side of the group where presumably the lever would go in non-volumetric models.

    Water cascaded down the group and onto the solenoid.

    Since its a 240V unit, the moisture could have caused tracking somewhere inside....

    Of water could have sprayed elsewhere when I bled air from the pressure gauge line to prime the pump.

    Hopefully, its dried out. Without permanent damage.

    But solenoids are only $30. And I need a new pressure gauge. So one more dysfunctiion and Ill order both.

    Thanks again.

    --Robusto


  38. #138
    Senior Member Dennis's Avatar
    Join Date
    Feb 2007
    Posts
    4,512

    Re: Upgraditis: 2-group Grimac Commercial

    Quote Originally Posted by robusto link=1173088713/135#136 date=1174515616
    I held *my own breath this morning, after leaving the machine on all night to dry out any moisture in the electronics.

    Everything seems to be working fine. *

    Thanks for your advice, JavaB and Sparky ---Ill hold onto it in case the problem arises again. *

    Yesterday while trying to fathom why the solenoid opens the 3-way-valve BEFORE brewing, I removed the blank plug on the side of the group where presumably the lever would go in non-volumetric models.

    Water cascaded down the group and onto the solenoid.

    Since its a 240V *unit, the moisture could have caused tracking somewhere inside....

    Of water could have sprayed elsewhere when I bled air from the pressure gauge line to prime the pump.

    Hopefully, its dried out. Without permanent damage.

    But solenoids are only $30. *And I need a new pressure gauge. *So one more dysfunctiion and Ill order both.

    Thanks again.

    --Robusto
    You know Robusto, I have pulled apart the entire engine of a 750cc motorcycle and rebuilt it to factory specifications (blue-printed) and I dont think it was as complicated/complex as your crusade for the godshot! ;)

  39. #139
    Senior Member
    Join Date
    Jul 2006
    Posts
    3,495

    Re: Upgraditis: 2-group Grimac Commercial

    Quote Originally Posted by Dennis link=1173088713/135#137 date=1174516618
    You know Robusto, I have pulled apart the entire engine of a 750cc motorcycle and rebuilt it to factory specifications (blue-printed) and I dont think it was as complicated/complex as your crusade for the godshot! ;)
    Dennis,

    There is no doubt restoration of a commercial coffee machine (especially an automatic) is one of the hardest DIY projects. :(

    There is a combination of plumbing, water and steam under pressure, lots of high power 240V electricals (often requiring conversion from 3 phase) and solid state (microprocessor) controller logic.... and water and steam are the enemy of the control logic.

    It makes for some "interesting" times. A far simpler (but still complex) restoration is that on a semi automatic. They dont have the control logic - just switches and solenoids!

    An automatic coffee machine is a bit like installing your computer in an oven inside a sauna with possibly leaking water pipes...... and all the bits may have had little and or dodgy maintenance.... and you are trying to get it all to work reliably - quite a challenge! :-/ :-/

  40. #140
    Senior Member
    Join Date
    Feb 2005
    Posts
    2,574

    Re: Upgraditis: 2-group Grimac Commercial

    Quite a challenge indeed, JavaB -- especially without a workshop manual.

    Something better attempted in winter too --- When the 120 radiated from the boiler is more welcome than nuisance.

    Ive dismantled, de-glazed and put new rings and bearings on a car engine, and do my own servicing on the family fleet. No, Im not a mechanic. At least with the coffee machine I dont have to buy degreaser. ;D But a trolley jack would be handy. ;D


    -Robusto

  41. #141
    Senior Member Dennis's Avatar
    Join Date
    Feb 2007
    Posts
    4,512

    Re: Upgraditis: 2-group Grimac Commercial

    Quote Originally Posted by robusto link=1173088713/135#139 date=1174520732
    Quite a challenge indeed, JavaB -- especially without a workshop manual.
    -Robusto
    Theres an idea - I imagine youre taking plenty of digital photos, notes etc. and if the project ever ends ;) youll have the definitive 2-group Grimac commercial workshop manual :)...good stuff!

  42. #142
    Senior Member
    Join Date
    Feb 2005
    Posts
    2,574

    Re: Upgraditis: 2-group Grimac Commercial

    Good idea, Dennis, but I dont think it woud be in the top ten seller list.

    --Robusto

  43. #143
    Senior Member
    Join Date
    Feb 2005
    Posts
    2,574

    Re: Upgraditis: 2-group Grimac Commercial

    Quote Originally Posted by robusto link=1173088713/105#108 date=1174438517
    *

    2. The brew cycle confuses me (its volumetric). *Its as though its trying to mimick lever-style pre-infusion.

    First, the pump comes on for a second at around *6.0 *bar. The 3-way valve kicks in and some water is flushed into the drip tray.

    Then the pump comes on again, and gently ramps up to 8 bar and out pours the coffee.

    Any ideas?

    --Robusto
    Ive spoken to a Grimac technician about this, and he assures me that it is normal, that it IS the electronically-controlled machines method of preinfusion. *

    It all happens without disturbance of the puck, and the release of water from the bottom of the group into the drip tray is excess water not used in the preinfusion.

    Ive also ordered a new solenoid coil and 2-hole steam wand tip from Coffeeparts, should arrive tomorrow. *While the old coil shorting to earth fixed itself up for several days, it did it again last night during some backflushing. It tripped the household safety switch.

    I measured resistance with a DVM and confirmed some ohms between the two poles and earth, instead of infinite resistance. *Its intermittent, and dangerous, so out it goes.

    --Robusto

  44. #144
    Senior Member
    Join Date
    Apr 2005
    Posts
    1,176

    Re: Upgraditis: 2-group Grimac Commercial

    So the Robusto household will be in coffee nirvana by tomorrow... assuming, that is, that all goes well on the other side of the portafilter.

  45. #145
    Senior Member
    Join Date
    Feb 2005
    Posts
    2,574

    Re: Upgraditis: 2-group Grimac Commercial

    A step to Nirvana will be tonight when I go home and install --hopefully, the new pressure gauge. I say hopefully, because not wanting to spend $200 for a genuine Grimac, I bought a Coffeeparts Rancilio one which, Im told, should slot right in there after a slight mod to the rear hold down bracket.

    I cant wait to see how this new gauge readings compare with the old, suspect ones.

    Im hoping that the reasonable -- and some, even very good -- espressos Ive been making were with the pump way over/under 9 bar, so imagine what theyll be like when I tweak!!

    In fact. the last two shots were almost sweet enough to have without sugar.

    And, ah, its good to have two groups -- when one dies (solenoid) the other still lives on.

    --Robusto

  46. #146
    Senior Member Dennis's Avatar
    Join Date
    Feb 2007
    Posts
    4,512

    Re: Upgraditis: 2-group Grimac Commercial

    Robusto, Ive read only part of your journey with great interest. I think once this instal is complete that you really need to make a video of yourself making a shot and posting it for us all to see! :)

  47. #147
    Senior Member
    Join Date
    Feb 2005
    Posts
    2,574

    Re: Upgraditis: 2-group Grimac Commercial

    Aw, shucks, Dennis, Im too shy for that :-[ But as soon as I have perfected the extraction I will take some photos and post them. I cant complain about lack of crema -- it literally fills the cup during the pour. ;)But the colour could be a tad darker :-/

    The Rancilio pressure gauge-- which costs $75 compared to the Grimacs $200 --- appears to have the same manufacturer. But unfortunately the pipe from the boiler doesnt quite reach. Ill have to either get an extender to cover the extra 6 ml or so, or try to gain extra length from the pipe by straightening it somewhat.

    For now, Ive connected the gauge by positioning its face against the back of the front panel rather than in front, where it should be. That gained me those extra millimetres.

    The pump pressure reads 9 bar -- so I cant improve on that. The boiler pressure reads 1.1, so Ive backed off the pressurestat to 0.8 bar.

    Ill give it a road test with a loaded basket in half an hour or so.

    --Robusto


  48. #148
    Senior Member Dennis's Avatar
    Join Date
    Feb 2007
    Posts
    4,512

    Re: Upgraditis: 2-group Grimac Commercial

    ot - how do you roast your beans robusto?

  49. #149
    Senior Member
    Join Date
    Feb 2005
    Posts
    2,574

    Re: Upgraditis: 2-group Grimac Commercial

    I have a home-made barbecue rotisserie drum set up. Ive been doing 450 gram batches lately and they dont last long with all the fine tuning Ive been doing.

    --Robusto.

  50. #150
    Senior Member
    Join Date
    Jul 2006
    Posts
    3,495

    Re: Upgraditis: 2-group Grimac Commercial

    Robusto,

    What does the pump pressure look like now? Is it stable at 9 Bar or does it still fluctuate?

    I assume the pressure will still vary with the second solenoid (when you have a chance to fit it)... if so you might have to look at plumbing it in.

    That pre infusion is most unusual.... but must work I guess. Just seems to me releasing the pressure would disturb the puck leading to channelling. I was wondering if the three way is some special type which doesnt actually release the pressure on the puck - just the pressure from the pump.

Page 3 of 6 FirstFirst 1 2 3 4 5 ... LastLast

Similar Threads

  1. Grimac 2 Group machine
    By Journeyman in forum Brewing Equipment - Midrange ($500-$1500)
    Replies: 6
    Last Post: 3rd March 2013, 08:05 PM
  2. Replies: 2
    Last Post: 4th December 2012, 10:27 PM
  3. Whats the Size of Group Seals for ExpoBar Megacrem 2 Group Commercial?
    By whitie8000@hotmail in forum Brewing Equipment - Extreme Machines ($3000+)
    Replies: 15
    Last Post: 22nd June 2011, 02:16 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •