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Thread: Grinder in Imat Napoletana

  1. #1
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    Grinder in Imat Napoletana

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    I have a couple of questions about the grinder in the IMAT Napoletana that I had started to ask in another thread. So to avoid hijacking the other thread, thought Id start my own.

    Greg, if you see this, your thoughts would be invaluable.

    I know the ultimate test as to whether the grinder is grinding fine enough is in the stopwatch/volume. I also know that unless I fill my basket to jam-packed full, the shots do run way too quick (not sure how much, but maybe 12 - 18 secs). They dont look right at that point either. The grinder doesnt have any lower settings, its as fine as it can get.

    So the questions:
    1. Id like to pull the machine apart to get access to the grinder to find out if I can adjust it somehow / check the burrs etc. The machine appears to be fully pop-riveted together. Do you know how to dissasemble it to get access to the grinder?

    2. Should I have to pack the porta filter basket so full that it makes the portafilter difficult to tighten in the group head?

    Cheers




  2. #2
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    Re: Grinder in Imat Napoletana

    Gday MM,

    Before you rip it to pieces, which tamper are you using? Im not saying this just cos I sell them, but using the built-in tamper its impossible to pack evenly, so youll end up with low pressure areas which will always cause quick and overextracted shots.

    You should be aiming for roughly 60ml of espresso from a double basket into a single cup in about 25 seconds. Its not magic, but use that as your initial goal. 12-18 seconds sounds too slow, so if youre getting those times and it still looks too pale Id suspect the tamp. What do the streams look like from each spout? Are they individual drops of espresso, or drop / stream / drop, or thin streams, or thick streams? What about the colour?

    Ive not tried to remove the grinder before, but Ive had mine for 4 years and have never seen the need to change them. I suspect unless yours has had much heavier use the problem lies elsewhere.

    When I pack so tight its hard to get it in the group, with a correct grind it almost always chokes the machine. I normally use about 2.5 7g spoons of beans in the hopper and grind that into the basket, and once tamped its about 5mm below the top of the basket.

    Greg

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    Re: Grinder in Imat Napoletana

    Using a white polymer tamper which is almost the correct size, though not a piston like fit. Leaves a gap at one side that is maybe 1-1.5mm at the widest point. I know the tamper is probbaly not perfect, and I would eventually like to buy one of yours (maybe out of the next baby bonus payment in, um 6 mths ;D ), but I feel it gets things pretty well packed, nice and level, and I use a fair bit of pressure.

    Its hard to describe the streams - I have gotten so used to having to cram the portafilter full to compensate that I wouldnt be too sure what they look like with a "regular" measured amount of grounds. The way I do it now I get good thick streams of rich red/brown coffee, with a crema that takes quite a while to settle. Getting a good shot out of it is not so much of a problem, as really needing to cram it full of grounds and using the extra compression from the showerscreen against the grounds to make it happen.

    My instinct from everything I have read, everything I have tried and eliminated points to the grind. The size of the grounds looks comparable to, if a little smaller, than regular white sugar.

    5mm below the top of the basket would result in a watery weak shot with a blond crema.

    I could do some measuring, take some pics and maybe a short video and

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    Re: Grinder in Imat Napoletana

    OK sounds like the tamps close enough to not be a problem. From what youve said it does sound like the grind, or too much water pressure. When Mal (I think it was) first got his Junior, the pressure was too low and he was able to adjust it back up to what it should have been. Its possible the opposites happened in your case but I dont know what the adjustment was.

    My grounds are definitely smaller than white sugar. Thats more like the size for dripolators. I think I measured 0.3mm diameter once. As an interim measure, you could try to take your beans to the local supermarket and grind some on their grinder to get the size down and see whether that helps?

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    Re: Grinder in Imat Napoletana

    By the way, although the case is pop-riveted together, the grinder is removable. The case is pop-riveted together first and then the parts are installed from the top. Theres a screw behind the grinder hopper and another in front of the water tank that allows the whole top plate to come off. Check out http://www.coffeetamper.com.au/products/vanilla-installation-guide.html as that shows how to remove that part. If you look closely at some of the big pictures (click on the thumbnails, particularly the second and sixth ones from the top), it looks as though the grinders held in by some large Phillips head screws. Youd also need to remove the assembly at the front of the machine, but thats just one screw too.

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    Re: Grinder in Imat Napoletana

    Thanx Greg, thats been seriously helpful so far. Ive not needed to pull the thing apart before, so always resisted the temptation. Now that I need to, its good to know how to do it.

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    Re: Grinder in Imat Napoletana

    No worries. Understand the reticence to do so but its pretty simple. Just make sure its unplugged first! :o

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    Re: Grinder in Imat Napoletana

    My list of pulled-it-apart-and-it-was-never-quite-the-same-again items was rather long when I was a teenager, so just trying to make sure that doesnt happen anymore. Its great having the internet and watcing other people do it all so I can work out how things work without taking the risks myself.

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    Re: Grinder in Imat Napoletana

    No worries ... uh, grunt, just .... pulling off the ... gnnh ... lid now so ... nnnnnnn.... MM doesnt have to ..... Dzzzzzzzzzzzzzzzzt

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    Re: Grinder in Imat Napoletana

    Ok, I found some interesting stuff when I pulled the machine apart last night.

    I took quite a few photos, but these two of the grinder are the most interesting.

    Theyre not as sharp as I would have liked, but the digital camera had flat batteries and I didnt want to wait for them to charge. *I ended up using the 2mp camera on my phone.

    The top section of the casing came apart fairly easily. *Only the screw behind the hopper needed to be undone, since the other had slipped its head through the center of the fourslotted keyhole looking hole near the water tank. I need to find a stainless washer to remedy this though. *The case section was a tight fit and needed a decent wiggle for it to come out.

    The first photo is taken from where the water tank usually sits. *The second one from above.

    So I found a couple of interesting things:
    - the hopper is a snug fit inside the main gear. *BUT theres nothing in the way of locating pins / slots etc, so it pulls out easily and is not glued or screwed in. *The numbers from one machine to the next way well not mean anything, since the hopper can be positioned anywhere.

    - I know next to nothing about electric motors, but this one is pretty beefy.

    - In the first photo you can see a bright, large phillips head screw about half way down the right side of the photo. *Once the chute was removed from the front of the grinder, the two of these screws bright screws (one on the other side too) would allow the entire grinder assembly to pull out.

    - the two peg/pin looking things on top of the large gear pull out and can be relocated. *They stop the grinder being adjusted too far in either direction - coarse/fine. *I assume they give the numbers on the hopper some meaning. *Leaving just one of these pegs in place gives this gear less than 360o of adjustability, which is no issue. *Fortunately the removal of one of these pegs, and the relocation of the second gave me extra adjustment to grind finer, which is EXACTLY what I need. *I think the pegs may also stop the burrs (conical) from being adjusted so close together that you would get metal filings in the ground coffee. ;) There may be some other mechanism inside the grinder to do this, but I didnt go far enough to check this.

    So all in all, mission accomplished. *I can grind a whole lot finer than I could yesterday.





    Next will be on to other problems that may need attention: *
    - The water is flowing out of the shower screen in a way that is not too dispersed - can leave a very deep indentation in the puck in one spot.
    - The water flow rate out of the group head is 350ml/min. *It seems to be too fast, but there also doesnt appear to be a way to easily remedy this.
    - Water sometimes runs down the steam spout - it seems quite loose, and it looks like an easy fix if I can get the right rubber grommet / washer to go where the spout joins the pipe coming out the top of the boiler.

  11. #11
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    Re: Grinder in Imat Napoletana

    Nice work MM! I might have to steal some of those photos for my site... :P

    I do unofficially sell a diffuser disc to help with water dispersion. It can be seen at the bottom of the backflushing page in the Imat / Quaha tips section of my site. Cant say Ive noticed a difference in the cup quality but it certainly prevents water drilling into the puck.

    Not sure about the flow rate. I wouldnt think thats a problem because when youve got coffee there the flow is much slower. Thats probably just the free running speed which I dont think has any correlation to what happens under load. What matters is the flow rate when its delivering 15bar. Its like putting a car up on jacks, removing both wheels and expecting the acceleration rate you observe to correlate to what happens on the road (not that Id recommend doing that!)

    Steam wand problem is interesting, mines only just started doing that after 4 years. I took the wand out and there is a rubber o-ring at the top but it didnt seem too deteriorated. In the first instance try tightening the nut around the steam wand (15mm open-end spanner, I did this last weekend!), and this seemed to help. Too early to call it fixed though as it would happen sometimes and not other times.

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    Re: Grinder in Imat Napoletana

    Youre more than welcome to the photos Greg. *Over the weekend, Im going to have a good go at the shower screen screw - Im expecting to find it pretty grimy underneath. *If a good clean doesnt fix it, I will most probably get the diffuser disc. *The steam wand better watch out over the weekend too *;D

    Whats the diffuser disc made out of?

    The other thing you might dinf interesting on the other photos is that my machine doesnt have the 3 way solenoid valve.

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    Re: Grinder in Imat Napoletana

    Boiler detail - almost seven years since manufacture.


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    Re: Grinder in Imat Napoletana

    Interesting, Ive not seen inside a Series 1 machine before.

    If you have problems with the showerscreen screw Ive got a photo essay on how to do it. Just have to remember to put it up! Let me know if you have probs, but if you havent removed it before youll probably need a good centre punch and a hammer.

    The diffuser disc is a thin piece of brass. Sits between the group and the showerscreen and spreads the water before it hits the showerscreen.

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    Re: Grinder in Imat Napoletana

    Quote Originally Posted by Greg Pullman link=1163646070/0#10 date=1163716805
    Not sure about the flow rate. I wouldnt think thats a problem because when youve got coffee there the flow is much slower. Thats probably just the free running speed which I dont think has any correlation to what happens under load. What matters is the flow rate when its delivering 15bar.
    Uuummm...You meant 8.5-9bar right Greg? :-? :D :)


    Java "Always under pressure!" phile

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    Re: Grinder in Imat Napoletana

    :) Nominally yes. I was more meaning the 15bar pump running under the pressure its designed for rather than into free space. But the exact figures, youd be the expert! :)

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    Re: Grinder in Imat Napoletana

    Gday Greg & MM,
    I just found this very interesting post of yours.
    Re the steam wand drip: After I fitted a longer wand the nut at the top kept coming loose alowing water to run down the outside. My fix was to use some locktite on the nut and do it up tight. It hasnt leaked since. Although I do have a problem with the tap leaking (if you have any ideas thanks).

    Thomas



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