Precision GS0 (Zero Retention) Grinder Review

PRECISION GS0 (Zero Retention) Grinder

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• Set a single or double dose or manual grind
• Stepless grind adjustment
• Easy to use touchpad
• 60mm espresso burrs (conical)
• Comes with both 250g hopper and single dose pump action hopper
• 58mm Dosing Cup and Cleaning Brush included
• 300W DC motor
• Dimensions (mm): 135 / 225 / 410mm (width)
• Weight 8kg

Initial Impressions
The grinder from Precision appeared in my Instagram feed a little over a month ago and I immediately reached out to the Dipacci Coffee Company to see if I could have one to review. Only a week or so later it arrived at my door and I was super excited to put it to the test in the way a Home Barista would use it in their daily routine. As I removed the grinder from the box I could feel the weight which is well distributed to keep the machine stable during grinding. The other thing that struck my straight away was the plastic body and what I would call a dinky little hopper. Once on the bench I could see the machine was well finished with no visible imperfections on the body. The one major thing that left a lasting impression was the feel of the worm drive for adjusting the grind setting. It just feels cheap, light and wobbly (not smooth).
My plan to evaluate the grinder was not to conduct a science experiment but rather to use it in the daily preparation of espresso, French press and pour overs to be able to provide feedback on how it might work in a home setting.

When placed next to the Mazzer Mini you can see they are of similar size and dimensions, although the Mazzer is approx. 2kg heavier.

Build Quality
This is the area I take issue with for this grinder which has an RRP of $1249 AUD (sold for $999 at Alternative Brewing and Dipacci). I could not get past the feel of the grinder which has a full plastic body. I have no issue with plastic and have used some grinders which have plastic parts and still retain a solid feel. The Precision GS0 for me has a thinner, cheaper feel that is difficult to articulate.





The other areas of build quality I made note of are the worm drive on the left which feels like a very light cast metal which would likely deteriorate with extended use. This is very difficult to qualify other than to say it is inferior to those with similar worm drives such as those found on the Profitec T64, Ceado E37 or Compak F8. Similarly, the small paddle which pushes the ground coffee out of the chamber, seen on the right, has the same feel of a lightweight cast metal. Although this part has a light or even cheap feel it is manufactured to fit very well inside the grinding chamber and as such is responsible for the good performance in the retention area.

It must be said that although the feel is lighter and thinner than I would have liked to see the finishing is very good. There are no issues with joins or the finish of the body itself.

The single dosing funnel is a real positive in the GS0, as it was when I purchased the smaller GS2 espresso grinder late last year. It comes in a polished black finish and had a very solid feel. This is a nice accessory to add to any grinder that you want to use for single dosing. You can see below however, that the way it fits into the top of the grinder provided some issues as the small retention ball was so stiff it scratched the inside collar of the grinder. The retention pin does retract but was very stiff and difficult to move, and as such made a small gouge in the collar.




Features
The grinder has all the features you would expect for what is intended to be a premium machine. The electronic interface is simple and easy to use in order to program two different doses by time. There is also the option to grind on demand using the switch on the lower right-hand side as you would do for a grinder like the Niche.

Grind Adjustment. Although the worm drive does not feel well made the adjustment method is easy to use with a numbered sticker on the collar to keep track of your grind setting.

Burr Set. 60mm conical burr set which were nice and sharp when inspected during cleaning. The burrs appear well made and very solid in line with other similarly priced grinders. The bur set has no visible branding. Without proper tools like the Kruve Sifter I cannot provide comment on the burr performance other than through visual inspection and taste. The drinks I made were using a bean and method I am familiar with and found the taste similar to those prepared using my Mazzer Min E. Visual inspection shows consistent grind size with no obvious deviations in size.



58mm Dosing Cup. Nice little addition. Well made, lightweight cup. Fits into IMS, Pesado and Pullman precision baskets and will be suitable for all other 58mm baskets.

Hopper. 250g plastic hopper with sit on top lid. I would have preferred to see a better fitting lid with a snug fit and possibly a hopper with a larger capacity. Although marketed as a zero-retention single dosing grinder a larger hopper provides more versatility considering the price.

Portafilter Rest. This is a nice touch for those of us who like to protect the finish on our portafilters. The steel portafilter rest has a nice soft rubber coating. Fits standard 58mm portafilters.

Dosing Button. The dosing button sits underneath the portafilter holder and would usually be activated by pushing the portafilter spout onto the button. As you can see in the picture this is a frustrating feature if you are a bottomless portafilter fan.

Pump Action Blower. This rubber baffle/pump allows the user to blow out remaining grounds from the grinder chamber. In principle it works, although would be more effective if it was slightly larger. In testing it would push out on average 0.2g of ground coffee.

Retention
To sum this up, the GS0 is a very good performer in terms of grind retention. My intention was to see how it performed when used as a daily grinder, rather than to precisely test the retention claims by cleaning after each dose. That said, I did use the grinder four times post cleaning and it had an average retention of 0.3g. This was grinding twice for filter and twice for espresso.
The main test was to grind eight single doses of 20g to assess performance for a user who doses for several drinks consecutively (how I would normally use a grinder). I have posted a video to the Home Barista Coach Instagram showing how I weigh each container (piccolo glasses) then the 20g of a medium espresso roast, grinding and checking the output.

All weighing was done on the Brewista Smart Scales with output results as follows:

1. 19.6g
2. 19.8g
3. 20.2g
4. 20.0g
5. 19.8g
6. 20.1g
7. 20.0g
8. 20.1g

The retention is low when compared to other grinders I have used both at home and as a barista in multiple coffee shops. As an example, my Mazzer Mini used as a single dosing grinder would average around 2-2.5g of retention per dose. It was highlighted to me through Instagram that my test was not valid as I did not clean the grinder after each use, collecting and weighing the ground coffee left in the grinders chamber. Although this is a very valid argument my intent was to test the grinder as a ‘user’ and as such in a manner which replicates real life use. What you can derive from the outputs listed above is that if you do grind a single dose then do not use the grinder for a period of hours you will have a tiny bit of retained coffee in the grinder chamber which may negatively impact flavour.

Cleaning
As someone who is experienced pulling grinders apart, I found this grinder relatively easy to disassemble, clean and reassemble. The whole process took about ten minutes and showed just how little coffee grounds were left in the chamber as you can see in the photos below. Removing the worm drive was a slightly fiddly process but the rest was very straight forward.
You will need a phillips head screwdriver and a 9mm socket to remove all of the internal components for cleaning.


Summary
The Precision GS0 delivers as a very low retention grinder. There are quite a few areas where this grinder cold be improved in the build quality as discussed above and there are a number of key features which let it down. Overall, I would recommend this grinder for home use if you only intent to use one grinder and change brew method or beans often which requires single dosing capability. I would also be waiting for it to come on sale. In terms of value for money if I was intending to spend around the $1k mark I would be inclined to favour the Niche grinder at an additional $400 AUD given its reputation for quality and proven performance as a super low retention grinder.