This doser works! Almost no grounds left after "clicking" your dose out. Click to enlarge.

Bottom of the doser shows the simplicity and, well, plastic-ness. Click to enlarge.

Stray grinds from gaps, after about 4 doubles ground. Click to enlarge.

The Ascaso grinders are available in several different varieties, configurations and optional setups. You can order three different colors, two different burr types, and two different "grinds delivery" models. In addition, there is an optional automatic activation feature that may become available for some models.

CoffeeGeek only tested the doser models, a conical burr version and a flat burr version. We cannot offer up any concrete opinions or details on the doserless models or the automated features, other than what we were told by the distributor. In short, the doserless models are designed to dispense directly into a portafilter or receptacle while the grinder is activated. If there is enough demand for it, an optional automatic activator might become available in the future. This optional feature will turn the grinder on automatically when you place the portafilter near the chute.

Notes on both models

The doser on both our test models raised initial concerns about quality, something I stated on the previous page. Just looking at the doser assembly, it seems a cheap afterthought, akin to the Rocky's doser.

Initial looks were, for the most part, deceiving: the doser assembly on the Innova grinder has some very good design aesthetics and construction qualities that impressed everyone who used the test units. There are some negative aspects to this doser, but overall, we were very happy with it and its performance.

The doser assembly does use what appears to be middle or low grade plastic for some of the parts. There are gaps between the exit chute in the grinder and the doser which allows stray grinds to spray out of the assembly, slowly piling up on the base, the fork, and your counter. A better fit would have been nice - far too many doser grinders allow grinds to fly here and there. There's only one doser model grinder I've tried that has a superior fit and finish between the doser assembly and the body of the grinder - the Mazzer Mini. That grinder is an example of all that is right with creating exacting tolerances in design and fit. The Innova could take some lessons from Mazzers in this regard.

One thing that impressed the heck out of me on both my doser models is how the doser completely dishes out grinds - after clicking away, the doser is almost entirely grind free - I'm guessing there are scant milligrams of grinds left over. The vanes do a very complete job of brushing out everything into your portafilter. By comparison, the Rocky's doser leaves behind as much as a gram of grinds, and even the Mazzer mini leaves a shallow layer of stray grinds behind. The Innova does not.

I wish I could say the same about the grind exit chute (the tunnel between the burr set and the doser). This horizontal path is fairly long (1.75 inches) and almost completely clogs up with grinds. After filling up, the grinds start compacting in the tunnel. This is more noticeable on the flat burr model than the conical burr unit, mainly because of the flat burr model's slower RPMs and smaller burr cutting area end up delivering a lower volume of grinds per second.

1.75 inches is the pathway between burrs and doser. Click to enlarge.

As much as 6 grams of coffee is left in the chute between uses. Click to enlarge

Grinds can compact in the chute, leaving more stale grounds between uses. Click to enlarge.

This clogging can lead to as much as 6 grams or more of coffee grinds that must be scooped out manually in order to ensure fresh grinds for each shot. This is a major issue with the grinder, and I'm not quite sure how Ascaso can fix this, other than moving the burr group a lot closer to the doser chamber, modifying the trajectory path of the grinds, or incorporating some sort of double-geared "sub vane" beneath the grinding burrs that will shoot out the grinds faster.

Ascaso is aware of this concern. They claimed they will be attempting to polish this chute to remove friction points. I have not yet heard if this has been done on shipping models, nor have I heard from anyone who has actually tested on of these polished models. I also have my doubts this will make any appreciable difference.

The fork on both models is a very simple affair. It is also positioned too close to the doser - I can barely fit my Pasquini portafilter under there, and a Pavoni Professional piston portafilter has to be wedged in. I made the suggestion to Ascaso that they either lower the fork, or alter the mounting plate so that if you loosened the screws, it could be slid up or down, then tightened in the new position. Ascaso agreed, and will be addressing this issue.

Flat Burr doser model

This is the model that initially impressed everyone around here the most. The burr assembly is very beefed up with the top burr set mounted on a big, heavy brass mounting. This mounting also has a gear as part of its design, which engages a screw (or worm) drive assembly, offering up the stepless grind selection ability that is a big selling point for these units.  The burrs themselves look like slightly smaller versions of the Mazzer Mini and Rossi RR45 burr set - not much money was spared here. An intricate tooth pattern in the burrs suggests very precise grinding control, something proven one you actually use the grinders for real. The burrs measure 49mm across.

The bottom mount of the flat burr set is equally impressive: it is housed in a strong and secure metal base that holds the entire assembly tightly (absolutely no play). The threading for the top burr mount is very shallow, which means a lot of revolutions are required to lower the top burr onto the lower burr. This is a huge bonus - the shallower the thread, the better the grind selection ability.

The only non-metal portion in the burr assembly is the resin mount used for the worm drive attachment. There have been some questions as to the durability or even the flexibility of this mount, but none exist in my mind. It's a thick piece of resin that, when screwed into the base, is extremely secure. The fact that the grind knob on my flat burr model broke off in shipping, yet this mount stayed perfect is testament to how tough this mount is.

One issue I have with the flat burr model is that the motor spins too slowly. Common convention in espresso grinders is that flat burr models need to spin at faster RPMs than conical burr models because they have a less surface area when compared to conical burrs. This smaller surface cutting areas require higher RPMs to pump out the same volume of grinds, second by second.

The flat burr Innova has a motor that spins at about 700 RPMs (claimed) under no load. It loses some of its RPMs under load (ie, while grinding beans) but not much. This speed is far below the conical burr's rated 1200 rpm spinning speed. When I first read these numbers, I thought they were switched by accident. They weren't.

I'll discuss this implication further in the performance section. For now, I'll state that if they end up using a faster motor, combined with a better gearing system that provides higher RPMs while maintaining good torque, they could significantly reduce the amount of time it takes to grind for a double shot. These modifications could also potentially solve the clogging issue in the chute - spinning faster will send the grinds out faster, and possibly prevent serious clogging.

Conical Burr doser model
When compared to the flat burr model, the conical burr Innova has less of a chute clogging problem, mainly because of the higher RPMs this model has. I have no complaints about the speed of this grinder, and how fast it can do a double shot dose of grinds.

I do have my concerns about Ascaso's choice of motor and gearing system for this grinder. They have opted for a 140W motor doing 1200 RPMs under no load (the flat burr model is a 250W motor doing 700RPMs - better torque conditions). Under no load, the conical burrs spin at about 1200 RPMs. Add beans and it reduces greatly - by as much as 200, 300 or more RPMs. It also varies the RPMs by a noticeable amount while under load - my best guess is maybe 50 to 75 RPMs speeding up or slowing down. A variance in grinding speed purportedly affects overall grind consistency.

I asked a couple of folks with engineering backgrounds to evaluate this motor and the sounds (and RPM changes), and the responses I got back were similar - they were not positive if this variance and load stress would shorten the life of the motor, but they did all say that a better gearing system is needed to reduce the obvious torque deficiency of the grinder. If it's dropping 200, 300 or more RPMs when load is introduced, the gearing system should be set up so it initially spins at 200 (or more) RPMs slower than it does when under no load. As beans are introduced, the gearing system would kick in and maintain torque, only dropping the RPMs by 50 to 100 under load.

Top (or bottom, depending on your perspective) view of the resin mount. Click to enlarge.

Bottom view of the resin conical burr mount. What are the holes for? Weight savings? :) Click to enlarge.

The Solis Maestro gear system features this kind of excellent gear reduction, and Ascaso would benefit greatly from studying that product's implementation of torque control methods. They may also want to switch it to the same motor used in the Innova flat burr model while they're at it - a 250W, 700 raw RPM motor would make a good candidate for a quality gear reduction system for a conical burr. All of this was the consensus of mechanical and industrial engineers I consulted with regarding the motor, including one directly involved in the coffee and espresso equipment business.

I can understand this theorizing, except for one thing - the grind quality from the conical burr model was absolutely amazing and consistent. In fact, I was beginning to notice within a week or two of testing that the conical burr model was slightly ahead of the flat burr model in terms of espresso shot quality. I was seriously impressed with the output of the conical model.

Inside the conical burr model, the housing for the burrs is quite different from the flat burr model. The worm drive mount was resin just like the other test model, but the rest of the burr mounts were the same dark gray plastic resin material as the mount, which is a departure from the brass used in the flat burr assembly.

This is not that the grind quality really showed any difference. I can see the concerns from people regarding the use of plastics over metals, but in a month of testing, quality of grind was not one of them. Longevity is a possible issue, but a few years of testing will be required before this becomes apparent.

The conical burrs are much more beefy and defined that the standard conical burrs found in grinders in the $80 to $140 range. The tooth pattern is very intricate and extremely precise. These burrs provide a heap of surface cutting area for slicing through your beans. I was impressed with them, even though the plastic resin housing was a bit of a letdown.

However, there is a roughly $80 price difference between the conical and flat burr models, and this is where the savings come from.

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