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Thread: Mazzer Robur uneven grinds?

  1. #1
    Senior Member skidquinn's Avatar
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    Mazzer Robur uneven grinds?

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Hi all
    Relatively new here and hoping for some advice regarding a Mazzer Robur E and an issue I seem to be having with uneven grinds. I picked up the Robur through my brother a number of months ago for a price that was too good to resist. It had been used in a commercial environment and has ~ 7000 on the counter. I think year of manufacture is 2010. When I purchased it, it had a sticker on it indicating that the burrs were changed in May 2013.
    My previous grinder was a Gino Rossi RR45 (which I believe appear rebranded as numerous other brands) and at first, the Robur seemed to produce much better coffee in the cup than I could manage with the Gino Rossi.
    Over the last few weeks I think I've noticed that there are very very small bits or chunks after grinding through the Robur. The quality of the espresso has been pretty ordinary as well and I can't seem to get a shot on the bottomless portafilter that doesn't shoot everywhere at first, and then blonde far too quickly.
    To make sure I wasn't going mad, I've fired up the Gino Rossi again to compare and have no such issues. The coffee is great.
    I am using home roasted beans which are no more than a week old, so should be no issue there.

    My guess is that I need to replace the burrs, but have read that Robur burrs should last anywhere up to 800kgs of beans? The counter suggests (unless its been round the clock completely...... maybe multiple times??), that it hasn't had that volume through it? Should I just replace them anyway? Are burrs from 2013 considered old?
    Are there any other reasons why this would happen? And why its only happened since I bought it?
    I have pulled it apart again and given it a good clean (burrs and all) but this hasn't helped.
    Realise its hard to make a call without knowing volumes through it though.....

    Any thoughts?
    On a side note, it is such a beast of a thing, I'm still deciding whether I will keep it long term. My wife thinks I'm completely mad, but has been surprisingly tolerant with my new obsession!!

    Thanks

  2. #2
    Senior Member chokkidog's Avatar
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    A café with a Robur-e is likely ( but not, of course, certain) to go through 20kgs + per week.

    Burrs would need replacing every 10 months at that rate. Proportionately less for higher coffee consumption.

    And at 80kgs/week..... do the sums.

    The shot counter only goes to 9999.

    It tells the truth...... but only if you know the lie! ;-)
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    Senior Member skidquinn's Avatar
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    Thanks chokkidog! As I suspected..... Makes you wonder why they don't add another digit or two to the counter to make it actually useful.
    Will order some new burrs!!!
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    yep sounds like new burrs are in order,,,,, maybe too , you ground a stone etc that was in the beans ? who knows

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    Senior Member skidquinn's Avatar
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    Quick update. New burrs installed, but am still having issues.
    I had read that Robus burrs can take a period of 'breaking in' so I kept a look out for the finish on the burrs before installing...... Even to the naked eye I could see the rough finish.....
    Anyway, installed burrs and its grinding super slow (for a Robur) and still pulling pretty ordinary shots.

    Anyone tried the white rice through the grinder to break these in? If I had to do that with coffee beans, it would take me years.

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    TC
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    Don't grind rice.

    It will settle once you see about 2k shots...
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    Senior Member chokkidog's Avatar
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    What is 'super slow (for a Robur)' in actual time? And for how much grinds?

    The issue with the new burrs is one of those things you get with a commercial grinder in a domestic situation.
    Last edited by chokkidog; 30th March 2016 at 03:50 PM. Reason: punctuation
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    Senior Member Gavisconi007's Avatar
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    Quote Originally Posted by skidquinn View Post
    Hi all
    Relatively new here and hoping for some advice regarding a Mazzer Robur E and an issue I seem to be having with uneven grinds. I picked up the Robur through my brother a number of months ago for a price that was too good to resist. It had been used in a commercial environment and has ~ 7000 on the counter. I think year of manufacture is 2010. When I purchased it, it had a sticker on it indicating that the burrs were changed in May 2013.
    My previous grinder was a Gino Rossi RR45 (which I believe appear rebranded as numerous other brands) and at first, the Robur seemed to produce much better coffee in the cup than I could manage with the Gino Rossi.
    Over the last few weeks I think I've noticed that there are very very small bits or chunks after grinding through the Robur. The quality of the espresso has been pretty ordinary as well and I can't seem to get a shot on the bottomless portafilter that doesn't shoot everywhere at first, and then blonde far too quickly.
    To make sure I wasn't going mad, I've fired up the Gino Rossi again to compare and have no such issues. The coffee is great.
    I am using home roasted beans which are no more than a week old, so should be no issue there.

    My guess is that I need to replace the burrs, but have read that Robur burrs should last anywhere up to 800kgs of beans? The counter suggests (unless its been round the clock completely...... maybe multiple times??), that it hasn't had that volume through it? Should I just replace them anyway? Are burrs from 2013 considered old?
    Are there any other reasons why this would happen? And why its only happened since I bought it?
    I have pulled it apart again and given it a good clean (burrs and all) but this hasn't helped.
    Realise its hard to make a call without knowing volumes through it though.....

    Any thoughts?
    On a side note, it is such a beast of a thing, I'm still deciding whether I will keep it long term. My wife thinks I'm completely mad, but has been surprisingly tolerant with my new obsession!!

    Thanks

    How full is the hopper when you are experiencing these issues? I have read elsewhere that the Robur needs to have a decent surcharge of around a quarter to a half of the hopper being full of beans in order to create sufficient down-pressure onto the grind chamber to ensure consistent grinding. Perhaps this is part of the equation?

  9. #9
    Senior Member skidquinn's Avatar
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    Quote Originally Posted by Talk_Coffee View Post
    Don't grind rice.

    It will settle once you see about 2k shots...
    Far out..... 2k shots is about a year at the rate I use it....... haha. Will take your advice on the rice though. Thanks!

    Quote Originally Posted by chokkidog View Post
    What is 'super slow (for a Robur)' in actual time? And for how much grinds?

    The issue with the new burrs is one of those things you get with a commercial grinder in a domestic situation.
    I haven't timed it exactly, but I reckon somewhere between 12-15 seconds for ~ 20 grams. Compared to the old burrs that were well under half of that.

    Quote Originally Posted by Gavisconi007 View Post
    How full is the hopper when you are experiencing these issues? I have read elsewhere that the Robur needs to have a decent surcharge of around a quarter to a half of the hopper being full of beans in order to create sufficient down-pressure onto the grind chamber to ensure consistent grinding. Perhaps this is part of the equation?
    Have tried both with my usual single dose and with ~ quarter hopper full of beans. Same result unfortunately. I think the auger is supposed to assist with this.

    I guess the recurring theme here is that these beasts are simply not designed to be used domestically.......... Makes keeping this thing just a little harder. Thanks for your help guys!!

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    Senior Member Gavisconi007's Avatar
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    Quote Originally Posted by skidquinn View Post
    Far out..... 2k shots is about a year at the rate I use it....... haha. Will take your advice on the rice though. Thanks!



    I haven't timed it exactly, but I reckon somewhere between 12-15 seconds for ~ 20 grams. Compared to the old burrs that were well under half of that.



    Have tried both with my usual single dose and with ~ quarter hopper full of beans. Same result unfortunately. I think the auger is supposed to assist with this.

    I guess the recurring theme here is that these beasts are simply not designed to be used domestically.......... Makes keeping this thing just a little harder. Thanks for your help guys!!

    I wouldn't give up!

    Why don't you take it in to a good coffee tech (or get them to come to you). It could be a simple adjustment. Another thought- if you see my photos of my Nino which I posted last night, you will see I have fitted a glass vertical hopper. This definitely makes the grind more consistent when using small quantities of beans like in a domestic environment. You could try a temporary system such as a PVC pipe or similar. Put a tamper on top of the beans to keep a constant down pressure. If it works, then go for the glass custom-made version like mine- others have used perspex- could be a bit cheaper than glass- I prefer glass because it doesn't scratch and looks the part. Worth a try before dispensing with such a beautiful machine.

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    Senior Member skidquinn's Avatar
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    Quote Originally Posted by Gavisconi007 View Post
    I wouldn't give up!

    Why don't you take it in to a good coffee tech (or get them to come to you). It could be a simple adjustment. Another thought- if you see my photos of my Nino which I posted last night, you will see I have fitted a glass vertical hopper. This definitely makes the grind more consistent when using small quantities of beans like in a domestic environment. You could try a temporary system such as a PVC pipe or similar. Put a tamper on top of the beans to keep a constant down pressure. If it works, then go for the glass custom-made version like mine- others have used perspex- could be a bit cheaper than glass- I prefer glass because it doesn't scratch and looks the part. Worth a try before dispensing with such a beautiful machine.
    I saw that - the glass hopper looks epic. Yep, had some good plans for this grinder...... A nice repaint and some sort of custom hopper. Just wanted to make sure I was happy with how it was grinding first. I'll have a bit more of a play and see if I can get any improvement. I'm just not sure I love it enough to bother with sending it to a tech or having one out.

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    Hi, it is just remotely possible that the motor shaft is not true. It may be possible to check this by removing the top burr and placing a piece of paper over the lower burr then ever so slowly replace the top burr and screw it down until it just touches the lower burr then winding it off to see if the touch is all the way around. It can be done with two pieces of aperture will carbon paper between. It should leave a mark all the way round.

  13. #13
    Senior Member chokkidog's Avatar
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    Well, to be fair, if you're going to pass it on you should sort the issue first, otherwise it's gonna be a fire sale! :-D

    Who wants a Robur grinding at Super Jolly speed? Something is definitely up.

    Might pay to pm or email Rick @ Coffee Machinist (site sponsor) and see if he can throw some light on it.

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    Can you post a picture of how your grind looks like?

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    Senior Member skidquinn's Avatar
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    Hi all - just to update on this one for anyone that may run into the same problem down the track and find themselves here.
    Seems like the burrs on the Robur have already started to settle. I've put about 1kg of beans through in the last week or so (both to drink and play/dial in) and the quality of the grinds (and resultant) has improved drastically.
    I am back to using this as my grinder of choice.

    By the sounds of the advice received here, it seems it should improve even more over time as well, so am glad I changed burrs. Also glad to have this website as a sounding board for all things coffee related. thanks guys

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    Is it still taking 12 seconds to grind 20grams of coffee?

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    Senior Member skidquinn's Avatar
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    Quote Originally Posted by rackxp View Post
    Is it still taking 12 seconds to grind 20grams of coffee?
    Timing has improved as well, but is not where it should be yet. At a guess I'd say closer to 8-10 seconds for 20 grams. However, I have only been single dosing the grinder, which causes it to grind slower than with a hopper & beans above it. Might test this tonight.

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    Did you buy genuine burrs? Are you grinding to fine? That's still too long in my experience. Should be around 4 seconds with new burrs.

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    Senior Member skidquinn's Avatar
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    Quote Originally Posted by rackxp View Post
    Did you buy genuine burrs? Are you grinding to fine? That's still too long in my experience. Should be around 4 seconds with new burrs.
    Yep and my grind is only as find as it needs to be to produce good shots from the Silvia.
    I'll check the grind speed tonight when the hopper on it and report back

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    Could you take a photo of the ground coffee? Could you weigh out a double shot and tell us how long it pours for?

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    I am single dosing too and it takes around 10 sec to grind as well (can measure it properly if you like). With hopper it took around 4 sec (3.x) indeed.

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    Senior Member skidquinn's Avatar
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    Quote Originally Posted by samuellaw178 View Post
    I am single dosing too and it takes around 10 sec to grind as well (can measure it properly if you like). With hopper it took around 4 sec (3.x) indeed.
    This is good to know. At least I'm somewhere in the ballpark

  23. #23
    Senior Member skidquinn's Avatar
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    Quote Originally Posted by rackxp View Post
    Could you take a photo of the ground coffee? Could you weigh out a double shot and tell us how long it pours for?
    Certainly can. I'll report back with the details tomorrow (hopefully!)

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    Life-long Learner DesigningByCoffee's Avatar
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    Quote Originally Posted by rackxp View Post
    Did you buy genuine burrs? Are you grinding to fine? That's still too long in my experience. Should be around 4 seconds with new burrs.
    I agree - with new burrs there is still something that doesn't sound quite right. I have mine set at around 3.8secs for a 25g triple basket…

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    Commercial grinders for domestic use may have problems initially. My brand new Kony-e took at least a year before it ground completely clumpless grinds. But now it is perfect and has been so for ~5 years

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    If your still not having any success. I'm happy to come over and try and help you.
    (I travel to Brisbane three or four times a week for work)

  27. #27
    Senior Member skidquinn's Avatar
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    Didn't get a chance to test last night, so only had a chance for a quick test this morning before work. Will do some more checking tonight.
    But so far found..... Time to grind 20grams single dosed was 9 seconds. Made my second coffee of the morning shortly after with the hopper on but only about 150 grams of beans in the hopper (I'm also new to the home roasting and haven't quite worked out my timing of when to roast yet!!). The grind time with beans in the hopper was just under 7 seconds for the same volume. So slightly quicker. I think this would probably be even quicker with more grinds in the hopper??
    First photo is a shot of the grinds and second photo shows ~ 30ml espresso which poured in 26 seconds. The beans are only 4 or 5 days old so I think I'm using them sooner than I should.

    One thing I've just realised as I type this, is that after single dosing, I always remove the electronic doser chute lid and with a small brush, brush out any grounds I can reach and then purge the grinder. I do this because there seems to be a fair amount of grounds that are in there. I haven't actually tested whether I can taste a difference between doing this or simply leaving the grounds for the next coffee? Any advice on this? I also assume this then plays with the timing of the next shot as there aren't the grounds at the front of the grind path that there would be if I didn't sweep them out?
    Hope this makes sense.....
    Anyway, let me know thoughts or if I'm doing anything particularly wrong.
    Thanks
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    I think if you try using it without single dosing, sweeping or purging - your grind times will come within spec.

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    Looks fine to me. My dose is 15g for 30-40s extraction.

    Just measured my timing this morning - my grind time is about 9-11s before I hear the sound starts changing - indication of 95% grind was done. There is normally a bean or two worth of chunks not going through due to popcorning. So at that point, I stop pressing the button and then pulse again (I don't use the single/double button). 100% of the beans will go through then - rather than holding the button for 15-20s continuously in one go.

    To be honest, it's not worth loading the hopper with 1 kg worth of bean just to get it down to sub 4s grind time - too much wastage. I'm pretty sure if you load more beans, it will get close to 5s, and less when the burrs are broken in further. The Robur is so much quieter compared to ANY grinder I've owned in the past, so it's not really a problem.

  30. #30
    Senior Member skidquinn's Avatar
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    Quote Originally Posted by samuellaw178 View Post
    Looks fine to me. My dose is 15g for 30-40s extraction.

    Just measured my timing this morning - my grind time is about 9-11s before I hear the sound starts changing - indication of 95% grind was done. There is normally a bean or two worth of chunks not going through due to popcorning. So at that point, I stop pressing the button and then pulse again (I don't use the single/double button). 100% of the beans will go through then - rather than holding the button for 15-20s continuously in one go.

    To be honest, it's not worth loading the hopper with 1 kg worth of bean just to get it down to sub 4s grind time - too much wastage. I'm pretty sure if you load more beans, it will get close to 5s, and less when the burrs are broken in further. The Robur is so much quieter compared to ANY grinder I've owned in the past, so it's not really a problem.
    Thanks mate. I too only use the manual grind button. Also gives me a chance to lightly tap the portafilter to settle 80% of grounds before grinding the rest in. I found using the preset timer I'd end up with grinds all over the bench.

    Agreed. I was not planning on leaves beans in the hopper ongoing, rather wanted to ensure my grind speed and quality is on par with other Roburs.
    Thanks for your input.
    GQ

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    No worries! Glad to know I'm not the only insane one for single dosing Robur-E at home

    Another question : do you use a bottomless portafilter? I discover that the grind needs to be mixed to pull evenly under a naked portafilter. So because of that, I grind into a stainless steel dosing cup, give it a quick shake/stir, and then pour into the basket. I don't dose directly into the portafilter from the grinder. Slightly more hassle but the results are spot on every time and worth the extra effort for me.

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    Life-long Learner DesigningByCoffee's Avatar
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    Quote Originally Posted by skidquinn View Post
    One thing I've just realised as I type this, is that after single dosing, I always remove the electronic doser chute lid and with a small brush, brush out any grounds I can reach and then purge the grinder?
    Ahhhh that makes more sense

    I don't single dose, but when I do completely flush the system (after grinding a bag of plunger for a friend for eg) it does take 4-5 secs for a good flow of grounds to start coming out again, then 3-4 secs more to fill. So sounds like your machine may be fine - it's just not really being used as it was intended

    The whole question of retained grinds is another one of 'those' questions around here - you'll bring out all sorts! FWIW I've left the screen in mine and don't flush out after each grind. This is fine, with little impact on the taste IMHO if you are doing 2-3 doubles/triples a day so refreshing regularly - less than this and it starts to be an issue. But it is a commercial grinder designed for high turnover…
    Just my 2 bobs

    Cheers Matt
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  33. #33
    Senior Member skidquinn's Avatar
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    From time to time I do use a bottomless portafilter, however most I make are split for me and the wife. So doesn't get as much use as I'd like.
    However, when I've used it I haven't found issues with uneven shots grinding straight into the portafilter.
    I'll give that a go now that I've got new burrs and report back.

  34. #34
    Senior Member skidquinn's Avatar
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    Quote Originally Posted by DesigningByCoffee View Post
    Ahhhh that makes more sense

    I don't single dose, but when I do completely flush the system (after grinding a bag of plunger for a friend for eg) it does take 4-5 secs for a good flow of grounds to start coming out again, then 3-4 secs more to fill. So sounds like your machine may be fine - it's just not really being used as it was intended

    The whole question of retained grinds is another one of 'those' questions around here - you'll bring out all sorts! FWIW I've left the screen in mine and don't flush out after each grind. This is fine, with little impact on the taste IMHO if you are doing 2-3 doubles/triples a day so refreshing regularly - less than this and it starts to be an issue. But it is a commercial grinder designed for high turnover…
    Just my 2 bobs

    Cheers Matt
    Good to hear. Thanks Matt.
    Interesting point re. retained grinds. I might also give this a go and see if I can actually taste a difference.
    One of the other big reasons I single dose is I like changing around beans.
    Certainly agree with you on the commercial grinder point.... but I was offered this one at a price that I simply couldn't refuse. Plus they are awesome. haha

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    Quote Originally Posted by DesigningByCoffee View Post
    Ahhhh that makes more sense

    I don't single dose, but when I do completely flush the system (after grinding a bag of plunger for a friend for eg) it does take 4-5 secs for a good flow of grounds to start coming out again, then 3-4 secs more to fill. So sounds like your machine may be fine - it's just not really being used as it was intended

    The whole question of retained grinds is another one of 'those' questions around here - you'll bring out all sorts! FWIW I've left the screen in mine and don't flush out after each grind. This is fine, with little impact on the taste IMHO if you are doing 2-3 doubles/triples a day so refreshing regularly - less than this and it starts to be an issue. But it is a commercial grinder designed for high turnover…
    Just my 2 bobs

    Cheers Matt
    I agree Matt - that is exactly what I've found with my Kony-e. I just load the hopper with the day's worth of beans in the morning (100g +/-) and grind away. I might dump the first double worth, but no purging between shots and my screen is intact.
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    Life-long Learner DesigningByCoffee's Avatar
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    Quote Originally Posted by pcf1978 View Post
    I agree Matt - that is exactly what I've found with my Kony-e. I just load the hopper with the day's worth of beans in the morning (100g +/-) and grind away. I might dump the first double worth, but no purging between shots and my screen is intact.
    Yep. I only have 120-150g in my micro-hopper - might purge 5-10g before a grind. There might be a slight difference overnight after a late morning brew the day before, but with my super freshly roasted beans (I often end up with them in the machine the same day when people turn up wanting some right now!) I tend to find it can help to settle to pour - really fresh through can be a little bright, but a few hours helps to rest them in the chute!

    I must be a bad, bad, bad snob

    And I tried removing the screen once - a coffee flew out of the bottom of the spout all over the bench and virtually none in the p/f - so out went that idea! Is there for a reason I guess!
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