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Thread: I am confused with what Rocky is doing?

  1. #1
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    I am confused with what Rocky is doing?

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Hi all ...

    I have been having a few problems with getting my grinder (Rocky) set correctly to pull the perfect shot. I have had the scales out to ensure I am giving a consistent tamp, and I have standardised my Sylvia technique - pretty much leaving me only grind to play with.

    I have pulled Rocky apart and cleaned him as per coffeegeeks guide. I ended up with a true zero about +3, and the furtherest it will move to is -7.

    From what I have been reading in various forums I should be ending up with a setting of about 7 points above my true zero for espresso coffee & that I shouldnt be operating below my true zero.

    The only way I seem to be getting a shot that takes close to 25 sec is to set the grinder well below my true zero - yesterday ending up at -4 ... Even at that point while the coffee has a nice crema, it is still a little bitter suggesting to me it is overextracted.

    I did a bit of an exercise late last night, with the grind at +10, +5 and 0 and it did not seem to make a whole lot of difference to the extraction time - which was 11 seconds for 10 and 5, and 13 seconds for 0!!!!

    At the moment I feel a bit like I am going around in circles trying to understand what is happening here! I have pulled Rocky apart twice and cleaned him and each time ended up at around the same point!

    I feel that if I operate with the grinder set at -4 that the coffee is way too fine and I might be operating in an area that will cause damage to the grinder???

    Thanks for any light you can shed on this!




  2. #2
    Senior Member Lovey's Avatar
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    Re: I am confused with what Rocky is doing?

    Quote Originally Posted by Myrtle link=1161559534/0#0 date=1161559534
    Hi all ...

    I have pulled Rocky apart and cleaned him as per coffeegeeks guide. *I ended up with a true zero about +3, and the furtherest it will move to is -7.
    Is this a typo?
    If the true zero point is +3 *(on the dial) there is no way that you could move it to -7. This is 10 steps below where the burrs are touching and should be a physical impossibility, unless the blades are made of flexible material of course *;).
    If you tried operating the machine below the true zero point, the burrs would never turn as they would be locked together.
    It sounds like you mightnt have found the true zero point. I wouldnt worry too much about what the dial is telling you though, theyre never accurate.
    If the espresso is extracting roughly around the 25-35 second mark, you only have to make minor tweaks to the grind setting, ie 1 or 2 notches to bring it to the correct timing.
    If youre extracting roughly within this time, the taste and colouring of the pull is how you should be judging it.
    The other consideration is the beans. How fresh are they? Beans that are stale will taste like crap and it will be hard to examine the tastes properly. On the other hand, beans that are too fresh after a roast will give you big gaseous pours, and tend to extract too quickly.
    Hope this helps.

  3. #3
    Senior Member fatboy_1999's Avatar
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    Re: I am confused with what Rocky is doing?

    Myrtle,

    Im a little confused by the statement you are operating below true zero.

    True zero to me, is where the burrs start to touch, therefore operating under true zero would not be possible.

    My true zero is -2.

    Im currently operating around the 6 mark which makes it true 8.


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    Re: I am confused with what Rocky is doing?

    Ok - sounds like maybe I have my terminology wrong.

    +3 is where the burrs are just touching - making a whispering sound.

    -7 is the finest I can turn the burrs.

    -4 seems to be where I get a 25 second pour, that is still quite bitter.

    I am using beans I have roasted myself - 1 week old (Bali batur) . Beans were taken 20 sec into rolling second crack.

    eta - with some other beans (also roasted by myself), I have had to grind at -7 and been lucky to make a shot that takes as long as 25 sec . I feel I am operating too close to the finest end of the scale - it isnt giving much room to move. Am I worrying about nothing?



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    Senior Member Lovey's Avatar
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    Re: I am confused with what Rocky is doing?

    Quote Originally Posted by Myrtle link=1161559534/0#3 date=1161566268
    Ok - sounds like maybe I have my terminology wrong.

    +3 is where the burrs are just touching - making a whispering sound.

    -7 is the finest I can turn the burrs.
    Are these setting with the grinder running or turned off?
    If the grinder is running and the burrs are just touching at +3 (it will sound like a metallic chirping noise), there is no way you could keep turing the burrs until -7.

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    Re: I am confused with what Rocky is doing?

    This is with the grinder running.

    At +3 the burrs are only just starting to touch - it is still very quiet & the contact is infrequent.

    At -7 the contact is much more frequent and very loud - more than what I would call metal chirping.


  7. #7
    Senior Member Lovey's Avatar
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    Re: I am confused with what Rocky is doing?

    When the grinder is running and you screw the hopper downwards, there will be a point where the burrs just meet, which will sound like a metallic chirp or a chinking noise. You shouldnt be able to move it much more than this without stalling the motor or doing some serious damage to the burrs. Are you able to describe the noise that the grinder is making, everyone perceives things differently.

    At +3, what noise is it making and how frequent is it?
    At -7, what noise is it making and how frequent is it?

    Out of interest, hold old is your grinder?

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    Re: I am confused with what Rocky is doing?

    I will give it a go ...

    At +3 there is the faintest whisper as the burr just contact. There are distinctive clicks (barely audible) as they contact. When you move toward +3 as the hopper goes down, there is a distinctive change in the sound which to me sounds like the burrs just meeting.

    At -7 the clicks are very very frequent - almost like they are constantly in contact. The grinder is making a lot of noise.

    I have had the grinder for about 6 yrs - it has been in retirement for about 3 years - where it was sitting at the bottom of the pantry. I brought him back to life about 2 months ago.


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    Re: I am confused with what Rocky is doing?

    Hi Myrtle,

    Quote "I have been having a few problems with getting my grinder (Rocky) set correctly to pull the perfect shot. I have had the scales out to ensure I am giving a consistent tamp, and I have standardised my Sylvia technique - pretty much leaving me only grind to play with. "

    Lets just for a minute revisit the other factors....

    Assuming you are using the double basket? The single is really hard to make work at all.
    Also there is an alternative double basket available from Coffeeparts that is a bit deeper, holds a bit more coffee which will help your extractions to approach what you seem to be looking for, (I thought they tasted better and timing was a bit better)

    Tamp is consistent,....if you have had the scales out it probably is.
    What about the puck after the pour, are you getting any channelling around the edges? That will affect the timing and taste. Ive found that best results with tamping, as far as reducing chanelling is to tamp lightly, then knock the sides, then tamp firmly once and polish.

    Brew temp can affect the taste, some say a sweeter shot can be poured at slightly higher temp, do you know where you are in the cycle? At very least do some timing from when the temp light goes out, somewhere between 1:30 to 2:30 should be good time to start your pour, (or PM Scoota gal, she has a routine that works for her), next step is to fit a thermoprobe to the boiler and monitor boiler temp with a digital multimeter or similar (from about $30 all up its cheap and works) next step is to go the PID route, but thats a lot dearer

    Frequency of cleaning of Silvia is also important. Water flush and water backflush every day, and chemical clean and backflush, including removal of the grouphead screen, once a week is essential to stop development of unwanted tastes in your shots (you may be doing all this already, Im just shotgunning every thing I can think of).

    Lastly depending on when your Silvia was made it might have the famous OPV valve that is set too high. Recently I have fitted the extra thick teflon gasket from Coffeeparts to reduce the OPV to around 9 bar where it should be, and myself and Rayzurhed who also did the same mod, both thought the shots were a bit sweeter. This part costs about $1:50 I think and any handyperson can fit it if they take their time.

    Now grinding and dosing, updose is the only way to go.
    Grind into the filter basket, tap the sides of basket with your hand firmly grind some more and tap again, grind until nearly full, then (whatever works best for u) I tap the portafilter vertically on the bench twice to settle the grinds into the basket, grind some more until you have a mountain tap portafilter on the bench once or twice, level off, I use a knife,
    by now you could have as much as 18-20g in the basket. Can also updose by using the weight of the tamper to settle the grinds before you add more, but my tamper was probably a bit heavy.
    When changing grind remember there is a few grams of coffee in the chute and blades that need to be pushed out before you are getting the next grind size into the basket. A Click-clack lid (Click-clack containers can be purchased from supermarkets) is great for assisting with blowing out the chute, it has a seal that just fits inside the bean hopper and by pushing down quickly pressurises the hopper, and the chute is the outlet.

    Hope you find something helpful,
    Regards
    Bullitt

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    Re: I am confused with what Rocky is doing?

    It almost sounds to me like one of the burrs is "floating" rather than being held in place....

    It should be almost silent until it touches-- sort of "ching.. ching.. ching" (very quickly) then a bit lower it will make a nasty metallic grinding sound... a bit lower again and the motor will be stalled....

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    Re: I am confused with what Rocky is doing?

    JavaB ... have gone back to Rocky and checked him out. at 0 - I get a distinct "ching ...ching" beyond that I get the nasty metal on metal sound, and I can carry on adjusting down to -7 where that sound just gets worse and worse!!! Not too sure where that leaves me at this point, given that I am grinding in this region to make anywhere near a decent coffee.

    Bullit .... thanks for the shotgun approach. I have read about your OPV mod success .... it brings out the engineer in me!!! I think I still have a fair way to go working on my own technique before I attempt that mod I suspect. I am using the double basket provided with the Rocky. I have also ordered a Pullman Tamper to be sized to a new basket ordered from him. I cant see any evidence of channelling in the puck - it comes out very dry & firmly packed. I probably still have a bit of work to understand the temperature cycle better. I will have to check out the click clack lid - that sounds like a good tip.


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    Re: I am confused with what Rocky is doing?

    Yeah I did also think that you could have a floating bur in there by the way you describe it, but hard to understand how that could happen, as they should be fairly well screwed in.
    (Engineer in me caused me to have a good look in case I was ever going to try to fit new burs, which should be a long time away yet).

    And follks I really arent keen on some of the descriptions of what it sounds like when the burs are touching, I set mine by hand after a good clean and then work back from there to dial in the grind. Just cant bring myself to run it and find where they are touching, Id be afraid of damaging the teeth on the burs, although I am pretty sure the manual says you can do it.
    Maybe you should order some ground coffee from a reputable roaster and try that, if its any better it would point to a problem with your Rocky.

    OPV mod, as noted in another post, only to be attempted by those who are confident they know what they are doing, hope I didnt lead anyone astray here...But it does seem to help reduce the affect of some of the other variables that affect the shots.
    The (in)famous too high setting ex factory can contribute to bitter tasting shots, which is one of the issues you are working to solve.

    The basket that comes with your new tamper should also be a bit bigger and should also help with sweetening the shots a bit.

    Regards
    Bullitt

  13. #13
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    Re: I am confused with what Rocky is doing?

    Re the click clack lid - Big W here in Sydney had a good range of them.
    Unfortunately for me my Macap hopper is between click-clack sizes.

    I got around that though when I saw what Hazel of Coffee Alchemy uses.
    She has a plastic pump like you get for pumping up airbeds.
    Its about 6 inches high and 4 inches in diameter.
    I could only find a shorter one but it works OK.

    We remove the hopper and place the open end of the pump over the hole where the hopper goes.
    A quick pump or two forces the remaining grounds through just like the click-clack lid, maybe even better.

    Mine - (under $3 from junk shop - you remove the hose and a plug from the bottom that holds a spring in place that helps the plastic re-expand. With mine I also had to reverse one of the 2 valves (you can see the red one in the picture) so that instead of the air sucking into the pump through one and out the other, the air sucks in through both and then is forced to go out through the bottom where the grinder is.)


  14. #14
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    Re: I am confused with what Rocky is doing?

    Myrtle, you might want to consider going and getting yourself a LM double basket to go in the Silvias portafiller. Its a little larger than the standard Silvia basket and may help you with improving your shots.

    Coffeeparts has these baskets if youre interested in trying that as well.

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    Re: I am confused with what Rocky is doing?

    Thanks for all the tips everyone. I have learnt a thing or two. My problem has been a combination of things.

    Most importantly - Rocky wasnt as clean as I thought he was :-[ Rather embarrasing!! So am now getting a much better grind.

    My tamping while I was getting a standard pressure, it was uneven in the basket - so one side was higher than the other.

    I have also been focusing on where I am in the temperature cycle & trying to standardise there.

    I am also giving Sylvia a bit longer to warm up - learning a bit of patience here! After my lesson with Rocky, Sylvia is also getting a good regular clean now!

    The upshot is, I am now getting better shots which is proven in the taste. I am not all the way there yet, but am confident I am moving in the right direction.

    I managed to find myself a click-clack lid from Big W - fits perfectly - an excellent tip that one. Works well at clearing the ground coffee from the chute.

    I have a LM double basket on the way, so expect some more improvement there.

    My Pullman tamper is on the way - just need to convince my other half, that waiting till christmas truly would be detrimental to perfecting my craft!!

    My big lesson has been to have some patience, and think a bit more about what I am doing! No need to solve ALL the problems at once.



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    Re: I am confused with what Rocky is doing?

    Well done Myrtle, pleasing to hear some positive feedback :)

    I went through a saga with cleaning Rocky some time ago, and it turns out that he doesnt need to be puilled apart very often at all, and using the click clack lid (or similar) will enable any excess grounds to be blown out, as you have found out.
    Apart from that, removing the hopper occasionally is beneficial to clean out the rest of the grinding chamber (power off of course), but the burs themselves shouldnt need cleaning very often at all (oh and dont try the using the 2 minute rice method that is suggested elswhere, caused me more problems than it solved)

    Regards
    Bullitt

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    Re: I am confused with what Rocky is doing?

    Thanks Bullit...

    I have done some more playing around over the weekend, and I think I have now narrowed the problem down to my tamping practices. While I was managed to tamp to around the 15kg mark, I am not sure how "even" my tamp was.

    I was managing to get anywhere between 17-19g into the basket - need a little work on my technique to reduce the variability here.

    My technique now is half fill basket - tap to even up in basket, fill basket so it forms a small mountain. I also found that if I used my spatula to break up the clumps in this mountain before I tamped that was when I poured the best shot. This seemed to give me exactly 25 secs to get a double shot that tasted great.

    My best so far - its good when it all comes together.



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