We are enthusiastic about single-dose espresso grinders. That's why our test of the Niche Zero turned out so positive. However, the Niche — not least since Brexit — drains a good €800 from your wallet. We wished for similar performance for less money. And to give you a heads-up: the G-Iota, also offered as DF64 in many places, fills exactly this gap. The DF64 costs half the price of the Niche Zero, but doesn't have to hide when it comes to performance.
To the current test report of the DF64 Generation 2.
In our test report, we examine the grinder from every angle, share a few tips, and even take a first comparison with the 23 other espresso grinders we're currently testing. Here's the comparison with grinders in the same price range.
In the meantime, we've published an upgrade video for the G-Iota. We've tried a lot. Among other things, we installed SSP Multipurpose burrs, which do a really good job. This makes the DF64 even better.
For Austria and Germany, Bohnendealer* is the importer of the G-Iota. Unfortunately, there is no official importer in Switzerland.
Single Dosing or Single Dosing – What is that?
Espresso grinders are experiencing their 2nd evolution today, which has also arrived on the home market. The 1st evolution was the shift from "bean hopper" or "dispenser" to direct grinding or "grind on demand". Instead of pre-grinding larger amounts of coffee and having them in the dispenser, you grind directly into the portafilter. A first step towards more freshness and less oxidized coffee was the result.
Today we are going through the 2nd evolution, with the shift to single-dose grinders. Because still, a large portion of the coffee was exposed to oxygen and light in the bean hopper. The single-dose or single dosing principle is penetrating the market and works like this: a home barista weighs out the desired amount of coffee, puts it in the dosing section at the top, and grinds directly into the portafilter.
This makes it possible to switch between coffees. For guest A, a decaf can simply be brewed, while guest B prefers a fruity espresso. The coffee stays fresher because it's stored in the perfect container. For the home barista, weighing the coffee reveals the connection to the brewing ratio and opens up the possibility of playing with recipes.
This is what a single-dose grinder must be able to do:
The grinder should have no retention and should expel all ground coffee.
The brew recipe should be easily adjustable, and the grind size should produce the same particle distribution when returning to the same marked setting after adjustment.
In short, consistency and precision are important!
The bellows on the DF64 ensure the grinder has no retention.
DF64 as a Single Dosing Grinder
The DF64 meets the necessary criteria for a good single-dose grinder very well. It uses some aids, such as the bellows, but ultimately the grinder achieves its goal.
If the DF64 is used without the bellows, it has a retention of 1.5 grams of coffee. While this is a good result compared to many conventional grinders, it's not acceptable for a single-dose grinder. By using the bellows, however, the retention can be reduced to nearly 0 grams. We recommend that after grinding the main amount of coffee, use a few bellows pumps to remove the remaining coffee powder from the area behind the flapper. Caution: this can result in a powerful burst that may also cause some coffee powder to scatter on the table. With gentle pumps, however, we were usually able to avoid this. This reduces the residue in the grinder (retention or grind retention) and, for example, the 18 grams of coffee input are consistently ground back out.
The grinder also impressed us with its precision. We were able to adjust the grind size and return to the same grind size without difficulty. The grinder does lack a good grind size marking. Creative minds have developed marking indicators for 3D printers that work well and can be ordered on platforms like Etsy*, for example.
A corresponding update could improve the grinder further or make operation easier. However, we had no problems returning the grinder to the same grind setting. In fact, the grinder was more precise when adjusting and returning to the same setting than many other grinders in the test series.
Therefore, we can confirm that the DF64 or G-Iota has everything that makes a good single dosing espresso grinder!
Espresso Performance of the DF64
We really enjoyed the espressos from the DF64. They were balanced and different emphasis could be brought out well. The particle distribution of the grinder was in the solid average range.
Espresso Data (T4):
- X50: 318.30 Micron
- Fine Peak: 20.78%
- Main Peak: 247.58 Micron
Operation of the DF64/G-Iota
We already covered the operation of the DF64 in the chapter on single-dose capability. Basically, the grinder can be adjusted precisely and well. The large grind size adjustment wheel turns very smoothly and allows infinitely variable adjustment. The large diameter provides a sluggish transmission to the effective grind size adjustment. This is very positive, in contrast to grinders like the Eureka Specialità, where the small adjustment wheel often steers past the target point.
The grinder has no other adjustment options. There's an on and off button. That's it.
The alignment of the espresso grinder is not part of the classic "adjustment" and operating range. Some users report that their DF64 was delivered with burrs that don't perfectly align. As a result, the ground coffee has a less precise particle distribution and the burrs dull more quickly. The position of the burrs can be checked and adjusted independently. We will make a video about this. However, there are already several instructions available online under the keyword Grinder Alignment. With our DF64 model, the burrs were perfectly aligned.
When using the bellows, we recommend careful and controlled pressure so that the grind size doesn't shift.
Side view of the G-Iota with transparent dosing cup that fits directly on the portafilter.
Size, Weight, and Appearance
Elegant, narrow, and heavy — that's how the G-Iota stands next to our Decent Espresso. It's available in various color patterns. We bought and tested a black and white model (like all grinders, we also bought these grinders ourselves for testing purposes). The grinder is one of the heavier grinders in the price segment up to €500. The grinder weighs 13 kilograms and stands very firmly and solidly. 30 mm height, 130 mm width, and a depth of 225 mm create a harmonious picture.
The grinder comes with a transparent dosing cup. The dosing cup fits well in the portafilter holder. Our cup got a small crack when tapping out. Benjamin and Michel disagreed on their assessment of the cup. While Michel would replace the cup with a metal one, Benjamin appreciated the transparent design. Especially for learning and training purposes, the transparency is interesting, making it easy to see how the coffee powder is distributed in the portafilter.
Not only the dosing cup fits in the holder, but also all common portafilters from manufacturers like Rocket, La Marzocco, or Slayer. With portafilters that have larger side ridges, there is wear on the rubber hooks. However, these can be easily replaced.
Conclusion on the DF64 - G-Iota
The G-Iota is a really good grinder that impressed us in almost every category in our test. Only in terms of speed does the grinder rank among the slower ones with only 19.1 grams of output in 10 seconds.
The noise level of the grinder at 83.2 decibels is in the middle range. Operation is smooth and very precise. Thanks to the bellows, retention is reduced to 0. This makes the grinder not only excellent as a single dosing grinder.
In terms of value for money, the G-Iota impresses with a purchase price of around €400. As you can also see from our video: we're very taken with the DF64. A really good espresso grinder and a very interesting choice as a single-dose grinder.
And that's not all: if you want to improve the grinder further, switching to 64mm SSP burrs can give you an even better grinding result. Whether that's necessary and whether we can detect the difference in a blind tasting, we'll provide you with the results and video afterwards. We're also planning a direct comparison with the Niche Zero and Eureka Single Dose.
Upgrade Video for the DF64 G-Iota
► SSP Red Speed Burrs at Bohnendealer*
► G-Iota Grind size indicator on Etsy*
► Angled Improved Dosing Cup Holder for DF64, G-IOTA on Etsy*
► G-Iota Dosing Cup Holder 51 mm on Etsy*
*These are affiliate links. If you order through this link, it won't cost you any more. We receive a small commission. This helps us buy more test materials and publish new tests. Thanks in advance! We also refer here to a shop that we know well and from which we know that it provides good service.
