G-Iota DF64 / Solo / Turin Review

Introduction

The G-Iota DF64, also known as The Solo (on Bella-Barista) or The Turin (on EspressoOutlet), is a single dose, extra low retention, flat burr coffee grinder with stepless adjustments. It is manufactured in China and sold by different suppliers, all across the globe (depending on the supplier, you might have the choice between more or less colour options). It is equipped with a 58mm portafilter fork and comes with a plastic dosing cup which can be fitted on the fork. The grinder is sold with Italmill burrs (titanium-coated or not) but some suppliers offer the option to fit SSP red speed coated burrs (both, High-uniformity SSP and Unimodal-espresso).

Availability and price:

· Alibaba for about $420 USD+ little over $100 USD for shipping to North America. This is the manufacturer. They also offer it with titanium burr. You can order in bulk and have access to even more interesting prices.

· The Gluons for $375 USD in Singapore. Contact David through Facebook and Instagram) (this is what I did, +$100 USD for shipping to Canada))

· Bella-barista in England for £399

· Homebarista in Belgium for €399 (will fit and align either SSP burrs for you for €250 or the titanium burrs for €180)

· bohnendealer for €399 on the German and Austrian market

· EspressoOutlet for $599 USD in America (will fit and align either SSP burrs for you for $189 USD). With the pre-order discount Joe is giving everyone, the price is around $400 USD. Even if $599 might seem high, keep in mind that Joe had to import the grinder, so he covered shipping and customs fees which basically add up to match the discrepancy compared to other suppliers. If you decide, like me, to buy your grinder from elsewhere and import it yourself, you’ll also have to deal with it if you need to use the warranty (shipping a 7kg grinder back to China from North America doesn’t come cheap!). If you are located in North America, give a serious thought to EspressoOutlet, and if you can score a pre-order, don’t hesitate! At the time of my purchase, they simply were not offering it yet.

· BPlus for $440 USD in Taiwan

· Frekko in Holland for €399 or €659 with SSP (they carry the 3 SSP burrs: Unimodal/Brew Burr, Unimodal-Espresso/Multipurpose and High-Uniformity Espresso). Lots of colours available.

· Probably more and more places will be selling it, some will add additional brandings so don’t be surprise if it comes up with a different name, price point, minor modifications, different burrs…

First impressions:

Simple design (it reminds me of the Lagom P64), well built, heavy, pretty much 100% metal (die cast aluminum alloy). Large adjustment ring, top funnel to receive beans, rubber bellows included (puffer for additional capacity, to minimize retention and increase dose consistency), plastic dosing cup included as well. Single illuminated on/off button located bellows the 58mm portafilter fork. The grinder comes well-packaged with enough protection to travel without risk. The 4 rubber feet hold it safely in place and thanks to the heavy weight of the device, once it is placed on your counter, it should not move at all. There is over 1.5 meters (5ft) of power cord which should fit most users setup.

General information:

-Motor: Single phase 250W, fitted inside the body tube but fully separated from the top of the grinder, preventing grounds from interfering with the electronics. 45 seconds shut off.

-Size: 22.5 cm (8.9 in) length, 30 cm (11.8 in) height, 13 cm (5.1 in) width

-Weight: 7kg (15 lbs)

-Manufacturer warranty: “1 year from the date of receiving the product”: “repair of faulty machines and replacement of faulty parts (except burr)”. Classic exceptions will void the warranty such as “issues caused by dismantling the machine” etc…

-Burrs: The grinder stock burrs are the 64mm Italmill flat burrs. They can be bought coated with titanium for increased longevity. The grinder will also fit both SSP 64mm flat burrs (Unimodal-Espresso aka Multi-purpose and High-Uniformity). To find out more about what to expect with different SSP burr set, read the very informative Lagom FAQ from Option-O.

Italmill 64mm flat burr (stock burr, non-coated)

In my experience, the burrs need seasoning (grind a few lbs of coffee beans) before to achieve a great particle size consistency over time. You can still drink the coffee made while seasoning the burrs, just be aware that you might notice differences in extraction during the process so don’t judge your grinder too quickly, give it 3–4 weeks depending on your usage. An experiment I have read suggests burrs can take up to 20 lbs of coffee to achieve consistency. If burrs are coated, such as the SSP red speed, it can take longer than with the classic Italmill which are not coated. They will also last much longer (graded for 250kg of coffee for uncoated vs 5000kg for coated → as per SSP website)

-Speed: 1400 rpm (Non-adjustable)

-Capacity: ~40g (+ capacity of bellows: ~50g)

-Grind size adjustment: Large dial offering a good resistance making it easy to change setting while not risking to accidentally change it. Each mark on the ring corresponds to 12.5 microns (according to Dave Corbey, a very knowledgable coffee appliance developer/researcher/reviewer), but keep in mind that it is stepless so one can easily adjust endlessly by setting it between 2 marks.

Original packaging of the grinder

Performance:

-Retention: ~1g  This is the total amount of grounds retained within the grinder after several uses. If you fail to clean it for an extensive period of time, this number might increase slightly. This notion can create confusion, it is not to be mistaken with exchange and/or dose consistency. This is my attempt to describe the ~1g retention of this grinder: After grinding several doses of coffee beans (e.g. 18g double-shot), some grounds will find their way into places where they will remain (around screw holes, o-ring, burr fitting…). It will be especially felt the first time you use your grinder or just after thoroughly cleaning it. After a few grams have be ran through the grinder, most of these areas will have accumulated enough grounds to prevent more from getting stuck as well, giving you a better dose consistency.

-Dose Consistency: 0.1–0.2g (with the bellows)  This value is the difference between the amount of coffee beans in and the coffee grounds out. For example, if I put 18.2g of beans in, I can expect 18.0–18.1g of grounds. On average, I find I am much closer to 0.1g (even under a lot of the time) than I am from 0.2g.

-Exchange: This is the dose of coffee grounds that will remain in the grinder after you use it and that will be transferred into the next dose. This is not easy to precisely estimate, but I have found the exchange to be low enough to not need to purge the grinder between setting adjustment: changes in the grind setting are immediately felt during extraction and consistent after that. Dave Corbey estimates the exchange at <0.3g (which is pretty much on par with his findings of the Niche Zero). This figure is probably the most important to me since I am after an efficient single dose grinder. With a standard grinder, when changing grind setting, it is necessary to grind a few grams of coffee (“purge”) at the new setting to remove all previous grounds from the grinder, therefore ensuring that the next dose will only be made of the new grind size (I have seen some cafés requiring a full 18g dose to be ran and discarded between each change of setting). However, when changing brew method, I recommend cleaning your grinder (which is very easy and very fast to do), I’ll explain more further down.

-Time to grind:

  • Espresso: 18g out in 13 seconds (add to this a few puffs with the bellows, roughly another 4–5 seconds)
  • Pour over: 18g out in 8 seconds (same thing, add a few seconds for the bellows)

-Decibels: ~65 DB (about 20cm from the grinder)

-Burr alignment: For the most part, the grinder comes well aligned, and if you have bought yours with SSP burrs, chances are your supplier will take care of everything for you and ensure it is perfectly aligned before they ship it out to you. Before I go further, I want to say that the differences before and after aligning the stock burrs might not even be enough for you to taste the difference, so don’t feel like this is an absolute necessary step. However, in our obsessive pursuit of perfection, some people (myself included) have taken this task upon themselves. First of all, I have to say that my grinder is different as it was part of the manufacturer samples (it doesn’t have a serial number etc…). To sum things up, I was having issues trying to perfectly align my burrs, I eventually switched the top and bottom burr and it fixed my issue. I haven’t found a single other owner with a similar experience and all the ones who aligned their grinder and shared their experience online haven’t had any issue. After figuring this out, my marker test came out great. I just needed one shim on the bottom burr and three on the top one.

A few things are worthy to note here: The top burr carrier can be placed in 3 different orientations and there is no mark anywhere on it that will help you remember which you have been using so I definitely recommend you make a small mark with a permanent marker once you have found out which has the best alignment. To find this out, you can go two different ways (it is easy to lose track of which orientation you are measuring so make sure to mark them as you go):

  • Method 1: Do the marker test on each of the 3 orientations and compare the results, picking the one that has the least amount of ink remaining: using a dry erase marker, paint the outer flat areas of the top burr, then place the carrier back and tightened the adjustment ring almost all the way. Now, slowly tighten it further rotating the bottom burr with your fingers by spinning the central bolt. When you first hear gentle friction, stop moving the adjustment ring and just spin the burr a few times around. The goal of this is to erase the marker at the point of contact, therefore determining the burr alignment. Now, fully remove the adjustment ring to release the carrier and observe the results, take a picture if needed. Repeat the operation for the 2 other orientations and set your grinder with the one achieving the best result. Using this technique, you can also align the burr by placing aluminum shims under the burr to raise the area that is not touching. I recommend following Thomas Greene tutorial if you are not familiar with the process. If you decide to do this, be aware you could very easily make things worse (which is why a lot of people would recommend you not to touch it). I have personally added one folded aluminum shim under 2 of the 3 available areas (small areas right behind the screws, which are levelled with the holding ring going all around the carrier).
  • Method 2: Dave recommends to “clean your grinder, find the first glide point that you can feel (note which mark on the dial it’s on), then move to the loose point and move the burrs backwards and forwards tightening down the adjuster until you feel the second rub. Note the mark you’re at now. How many marks difference between them? Then repeat the above for the other 2 different positions of the top burr carrier and choose the position with the smallest difference. Mark the carrier, so you don’t forget.”

The top burr is not necessarily ideal for alignment tweak as its carrier only has 3 raised flat areas where shims can be applied (as opposed to the whole surface under the burr like you find under the bottom one), right on top of the screws. Still, many people, myself included, have done it successfully. Also, one must be careful when doing the marker test not to push the upper carrier down while rubbing the burrs on eachother as it will make things very frustrating and inefficient.

Highlighted areas show where to place shims when aligning the top burr. Picture also shows empty space behind the top burr where some of the retention occurs.
Once you have found which orientation of the top burr carrier is best aligned, make sure to mark it!

-Clumping: almost none with the stock burrs, the grounds come out very fluffy so the anti-clumping plate does a great job. I must say I only use light and medium roasted beans. Dark roast could potentially be a bit more difficult so you can always try RDT (Ross Droplet Technique: apply a couple of water sprays on your beans prior to grinding). No matter what grinder you use, I am an advocate for WDT, which means stirring the grounds in your portafilter for even distribution and levelling as well as breaking down any potential clump. You can easily make yourself a WDT tool by planting some acupuncture needles or 3D printer cleaning needles into a wine cork (for example, these from Amazon). Flexible needles are best: John from Decent recommends either 0.35mm or 0.4mm needles, not less or they won’t do anything and not more or they will create craters in your puck).

18g in at setting 9 (espresso range)
DF64 Extraction on Flair Pro
Grounds at espresso range with stock burrs
DIY WDT tool

-Burr touching point: As far as I know, no DF64 touching point (grind setting on the adjustment ring at which the upper and bottom burr first make contact) is actually at 0. Also, each orientation of the top burr carrier end up having different touching point location, so once again, make sure to check which orientation is best and mark it so you never forget it. If you assume that your touching point is at the 0 mark on the adjustment disc, you might not be able to grind fine enough for espresso. Follow the video tutorial below to find your own touching point (unplug your grinder before to attempt this).For example, someone I was talking to, while grinding at 2, still had too coarse of a grind but was afraid of going finer as to prevent burr damage. After finding out that her touching point was around -4, she has been able to dial in perfectly her espresso. On my grinder, I found that the touching point is around -5 (right on the “t” of “Do not adjust past 0…” warning message from the manufacturer. I highly recommend marking this point on the adjustment ring to give you the peace of mind of grinding finer than 0 if needed without being scared of causing any damage. What this means, in my particular case, is that I actually have roughly another 60 microns of available burr movement past 0 (5 x 12 microns= 60). Different burrs have varying thickness, so if you change your burrs (or add shims under them), your burr touching point will most likely be different, so make sure to check for it and change your mark if needed.

How to find your burr touching point (I recommend to unplug your grinder first)
My touching point is roughly -5

-Burr change/replacement: Since access to both burr carriers is very easy, changing the burrs can quickly be done by unscrewing the 3 holding screws and swapping the burrs with new ones. Just make sure your burr is well centred before to fully tighten the screws.

-Cleaning: Simply unscrew and remove the adjustment ring to free the upper burr carrier and use a brush and a vacuum to clean all grounds. If you notice some grounds that are stuck before the exit chute I, once again, recommend you be extremely careful when/if trying to remove them, to prevent any damage to the silicone rubber clumping plates.

How to access the burrs to clean and/or replace them

Accessories:

-Bellows: it is necessary to get the full dose out. A few pumps with it push the grounds against the anti-clumping plate, then it all comes out at once and pretty much “nothing” is left after that. Make sure to have either a funnel around the portafilter or that you are using a recipient deep enough and close enough from the chute to prevent any mess. Only use the bellows after the grinder has finished grinding the beans but while keeping the motor on (pushing the bellows can potentially affect burr alignment since the upper burr carrier is held in place by 3 springs on the bottom). The lid of the bellows is made of metal and can be placed directly on top the grinder funnel if one doesn’t desire to use the bellows.

-Dosing cup: The grinder comes with a plastic, 58mm dosing cup. A lot of people like it as remaining grounds can easily be spotted. I personally find myself using a metal dosing cup that I hold against the chute, resulting in a much more controlled mess and less grounds stuck to the inside of the cup when transferring into a portafilter (less static).

Notes:

  • If you want to improve your extraction, distribution is key. Yes this grinder does a great job in terms of clumping and grind uniformity, yet I prefer to grind into a dosing cup, giving it a few shakes before transferring the grounds into my portafilter. I then spend some time applying WDT and carefully tamp to create an even and flat surface.
  • If you wish to change the look of the grinder, as per Bella-Barista: “After attempting to remove the carbon wrap and polishing the aluminium, we have discovered this would require a great deal of time and effort and recommend not removing the wrap at all. The easiest option-to change the look is to apply a wrap over the original one.”
  • If you wish to reduce the amount of “wasted” space in the burr chamber, the user “Gampiero” on HB came up with a cheap DIY mod. He found it particularly useful with dark roasted beans. Personally, I did not feel the need for it while using light/medium roast.
  • Some users have had issues with popcorning (very common with single dose grinder: once most of the beans have been ground, there is no mass pushing the rest of them down so the last ones struggle to get caught by the burrs). Personally I haven’t found this to be much of an issue but I talked to the manufacturer and they said they are working on a mod (post #109 here shows an early design): some kind of paddle that would be located below the main bolt and that would push the beans towards the burrs. At the time of this review they were still at the early stages of testing but I wouldn’t be surprised to see the future orders being shipped with it fairly soon, and I assume the mod could be added to the previously shipped units such as mine. Other mod I have came across was posted on a Polish forum, you can see it here on post #523. Also, if you have access to a 3D printer, @Ben-030 from Home-Barista forum has designed and shared these 2 different mods: Option 1 and Option 2. Both works very well to reduce popcorning as well as slowing down the bean feeding rate. Both need to be placed inside of the bellow. (as always, people like Ben share for free their designs for the community, it is not to be used for personal financial gain). Because of the high speed (1400 rpm) of the grinder, a disc mod such as the one we have seen on the Niche Zero doesn’t make sense to me as I can’t imagine any bean would find its way through the hole at that speed, and I think it would also reduce the efficiency of the bellows.
  • On a similar note, if you find you are having inconsistencies in your grind size (for the same reason as explained above, this is common to single dose grinders), you can try to control the rate at which you feed the beans in the hopper. Once again, the same mod designed by @Ben_030 will help you with that endeavour.
  • The retention/dose consistency/exchange of this grinder are all really good, but as always there is room for improvement. After brainstorming from several owners that I have read on different platforms, it seems that so far, Ben_030 has found and designed an easy solution. It will however require you to open up the grinder completely, probably voiding your warranty in most cases so think about it twice before to go ahead. This mod implies removing the two silicone anti-clumping plates and replacing them with the Mythos One clump crusher (I linked HomeBarista Belgium but you can easily find this anywhere, Google is your friend). Because the thickness varies, you’ll need to 3D print this spacer or make one yourself, fairly easily from pretty much anything you can cut to the desired size.
  • If you find the chute is getting too messy and you don’t have a funnel or don’t want to hold a cup right underneath it, @Ben_030 has once again done the work for you and designed a portafilter fork that can be switched with the original one and that will bring your portafilter closer to the exit chute. Same thing here, he lets you 3D print it for free a long as you don’t try to make money with it!
  • Depending on which burrs and which roast you are using, you might be prone to more or less static. Once again, on my side, with light/medium roast and stock burrs, I have not noticed much at all. If you do, try RDT.
  • Because I have only tested the stock burrs, I cannot speak to the efficiency of others, but I believe it is important to note that each of them will bring a different set of pros and cons and I recommend you to inform yourself about what they might be if you are going to purchase them, as they don’t come cheap. More and more users are sharing their findings on forums and social media.
  • I have designed a basic adjustment ring that has markings all around if you wish to print it on a sticker or a vinyl (if transparent you’ll need to change the colour of the markings or you will not be able to see them on the black collar). Here are the .jpeg and .ai file.
Adjustment ring with uninterrupted markings

Pros:

  • Price / Value: getting a 64mm flat burr, single dose, low retention grinder at this price point is unheard of.
  • Extremely low retention, great dose consistency and very low exchange
  • Efficiency / Quality: great results, both with espresso and pour over.
  • Easy to clean: accessing the burrs so easily is highly enjoyable. There is no need for any tools and the whole process can be done within a couple of minutes
  • Simple design and easy to use
  • Well built: all metal, very sturdy; it doesn’t feel cheap at all
  • Great customer service (I speak for Alibaba and The Gluons, but I’m sure the rest of the suppliers are just as good, I simply have not dealt with them)
  • Option to upgrade the burrs to SSP for different particle distribution, longevity, speed... Different burr geometry can open up new flavour profiles and change the body of your brewed beverage, they can achieve different efficiency with different degree of roast etc…

Cons:

  • Exit chute gets partially obstructed at the anti-clump plate when grinding at very fine setting (for espresso). It is completely fine as long as you remain in the same range of setting, as once that “dam” is in place, it doesn’t go anywhere so it doesn’t affect exchange or dose consistency much at all. But when going from espresso to filter range, if I don’t clean the grinder or purge enough beans through it at the new setting, the larger coffee particles, on their way out, cause this “dam” to collapse and therefore come out of the chute, ending up with more coffee out than I put in, and obviously having an excess amount of fines in my pour-over-dose which greatly affects the evenness of the extraction. I wouldn’t recommend to completely open up the grinder (which is the only way to access the 2 silicone rubber clumping plates) as you would be voiding the warranty. Also, try not to stick anything up the chute as you might end up damaging the plates.
  • Wasted space: The retention and dose consistency are both excellent, but if I had to be picky, I would say that some areas offer a lot of potential for grounds to get trapped. One of these areas is behind the top burr ( see picture under “burr alignment” section). Instead of a flat circular area, the top burr is attached to the carrier through 3 individual raised flat areas, leaving a large gap behind it. Since this burr is stationary, one could try to fill up this space or to restrict the major entry point of grounds by reducing the gap between the inner part of the burr and the carrier, for example with some aluminum foil wrapped around the inner part of the carrier.
  • Grind setting indicator not easily visible. On my grinder, the indicator (which is a coffee bean) , is the same colour as the grinder body, making it hard to see. In addition, it is located under the adjustment ring, making it a little awkward to see what setting you are on. You may want to draw a line or a dot on the metal part of the top burr carrier to make it more visible. Once again, I got used to this very quickly and it hasn’t bothered me at all since then. However, you can either purchase this mod from PortaKeeper for $12 or, 3D print it yourself from free designs shared by some owners; If you are interested, check out the mods from GregoryJ (HomeBarista), Strudlez (Home-Barista) and AnthonyTD (Coffeeforums - As per his request, I want to add that he has been generous enough to make these designs public and they are not to be manufactured and sold for personal gain).
  • Adjustment ring isn’t marked all the way and stops at 90. This is a problem because you can quickly end up in an unmarked area to dial in, making it hard to go back to if needed. Same thing happens the other way as the burr touching point is more often than not before 0 with the stock burrs, so if for some reason you need to go extremely fine, you’ll also end up setting the ring in an unmarked area. Finally, when switching burrs, because the SSP are much thicker, your touching point might move to 25 or even more, so when going into coarse setting, you’ll definitely be in an unmarked area. As explained in the last point of the “Notes” section, I have designed a basic file that you can download, modify and print as you wish to counter this issue.

Conclusion:

I really like my DF64, once the burrs have been seasoned enough, the consistency and quality of the grind have been excellent. It will be interesting to try some SSP burrs when I can get my hands on the Unimodal-Espresso in Canada but so far I’m extremely happy with the quality of the coffee I am able to brew and do not feel the “need” to upgrade: I can make a fantastic espresso just as I can brew a delicious pour over.

The few cons I have noted here haven’t bothered me much at all once I got used to them. If they are too much for you, you can try to use some of the mods I have listed throughout the review.

The DF64 definitely is a prosumer grinder (PROfessional grade equipment designed for conSUMER use). At this price point I cannot think of a better option as the value and efficiency packed in it are pretty remarkable.

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