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Exploring the Huky 500 Part 3:
This is the final part of the review that covers roaster operation of the Huky 500, along with a discussion of roasting results and some roast profile examples to go along with it. I also included a list of annoyances and final recommendations.
- 1. Setup and Warm-up:
I start by placing the roaster with the metal feet resting on the cooking grate of the burner. Luckily, the grate is designed in such a way that all the feet contact the grate in the centers in a sturdy way (note, this is specific to my setup. YMMV). If this weren't the case then I would have probably needed to construct larger feet or put some kind of wire mesh on the grate. Next, I connect the DC power supply (works on 110V/220V) to the motor, switch it on, then open the diffuser shutter and the crank on the burner at full power to warm the roaster quickly.
During warm up, I connect the BT and ET probes to the digital thermometer (I use an Omega 802U) and attach the thermometer via the USB cable to my Macbook Pro running Artisan.
I then connect the fan to a plugged-in portable light dimmer (see below). The light dimmer is used to control fan speed and ventilation to a greater degree than using the damper. Besides, the fan is incredibly powerful (so much so that it seems it just might levitate off the range ☺) and the dimmer can provide an upper end to ventilation flow when the damper is fully open.
Next, I take the exhaust pipe and connect it to the roaster chimney and then down to the inverted funnel sitting inside the bean tray that is atop the fan. The damper is fully open at this time. I then turn down the dimmer to low so the fan operates at a steady slower speed - the intention here is to provide some active ventilation as the roaster approaches the end of the warm up phase. My current thoughts with this process is that the when the roaster reaches drop temperature, the entire apparatus is active at this temperature under active ventilation, with both heat entering and exiting the roaster pretty much the same way both before and after the drop. Although technically ventilation isn't required during the drying phase, I do feel I can move roasting times along with large bean charges. Besides, there is plenty of BTUs to spare on my stove. I suspect I'll revisit this approach as I gain more roasting experience with the Huky.
2. Drop phase
I then reduce the burner level significantly (P2 on a scale of 1-to-10) when it approaches drop temperature, otherwise I would overshoot the target temperature quickly and it will take some time to bring the roaster back down to equilibrium.
When the roaster reaches drop temperature, I pull the exhaust pipe out of the chimney replace it with the bean funnel. I start the recording of the roast cycle on the Artisan program and then drop a pound of green beans into the funnel and all beans then drop into the drum (well almost).
In what I consider to be minor design flaw, the chimney has a 90-degree elbow bend, so after the drop, some beans remain in the chimney at the horizontal bend. To remedy this, I quickly rock the roaster back on two feet lightly to knock the rest of the beans into the drum. I then remove the funnel and replace the exhaust pipe back onto the roaster.
Right after drop, I quickly turn up to at least P6. Dropping a pound of beans into a hot stove-top roaster of this size (compared to Kilo-sized roasters) produces a significant impulse of heat exchange from the drum to the bean mass, even for the heavy 2.5mm thick drum of the Huky. I feel this impulse is best offset by quickly applying an impulse of compensating heat to keep drum MET stabilized (more on MET later). Here again, this is where having a high-BTU/Hr gas burner comes in handy; to quickly apply heat (and then withdraw it) as needed without the hysteresis lag of an electrical heating element. Using this approach I keep my turn-around times for 1-pound batches to about 1.5 minutes.
3. Drying Phase
During the drying phase, I usually reduce the heat back down to about P3/P4 to achieve phase exit at about 4-4.5min. Both the diffuser shutter and damper are still fully open at this stage and the fan is low (F2) to carry the moister out of the roaster to assist in drying. The site glass on the roaster door is ovalized and large enough to clearly see the beans during drying and the grass smell of the beans are clearly sensed due to the active ventilation exhaust. The site glass is also self-cleaning since the beans continually rub against the surface (much like the Quest and very much unlike the HotTop).
4. Ramp Phase
At the start of the ramp phase I close the diffuser shutter since I will be applying more consistent heat to the roaster and upping up convective heat. During the ramp phase, I usually adjust the burner to between P3-P6 to achieve a ramp to first crack at about the 8.5-minute mark. I also bump up the fan to about F5 at this point to impart a fair amount of convection heat to the bean mass. What's interesting is that ET jumps markedly with this fan speed increase, even when burner power is held constant, which seems counter-intuitive since more heat is exiting the roaster (i.e. more heat leaving the system). However, I wouldn't be surprised if the air suction from the fan increases the burning efficiency open flame burner, compounding the radiant drum heat with elevated convective heat to kick up the ET. I'd curious if other people have seen this phenomenon with their active ventilated drum roasters.
5. FC Phase
When first crack is reached, I obviously reduce the burner flame back down to a lower level (P2/P3) to extend the 1st crack phase, per the roasting profiling convention most adopted in this forum. With an open-flame burner, ET seems to respond quickly to the flame reduction (closed diffuser may also assist here), so I've yet to have any issues with accidentally stalling the roast. Increasing fan speed is optional at this time, and I haven't yet fully worked out taste-wise the affect it has on the roast, but I try to see this as a way of imparting a more air-roasted convective heat to this phase.
The thing to keep in mind is that fan speed should high enough for chaff removal. And keeping the damper fully open definitely helps in this matter: although the damper is well-made, it unfortunately is in the path between the roaster and the tray where chaff collection occurs. So if the damper is closed down, or even partially open, chaff can actually collect in the exhaust pipe and limit airflow. This is largely why I use a dimmer to control ventilation instead of the damper. The other reason is that I've just developed a better feel for ventilation by directly controlling the fan. Perhaps at some point I'll return to modulation of airflow with the damper (i.e. give it another chance).
6. Ramp to SC
As 1st crack is ending, I take different courses of action depending on the target roast leveI, most of which is common knowledge to viewers of the forum, namely ending roasts at different timings and applying the appropriate temperature ramp. I normally apply more heat (P4/P6) and fan (F6/F7) to advance the ramp to SC and to ensure good chaff removal. If I want to impart more of an air-roast profile, I'll push fan further (F8/F9), but this seems to also have the affect of contracting roast times. I expect that this has an affect similar to heat gun, since increasing fan speed also seems to increase drum temperature.
At this point I make good use of the tryer, which is large enough to clearly see the roast development of the beans. I must say having one is a big step up from the HotTop, as I can clearly see the texture of the beans as well as color. Watching roast development is phase is important, especially for roasts in the City-to-Full City bands, when you don't yet have the sounds of SC to indicate the appropriate time to end the roast.
However, there is a manageable design flaw in the operation of tryer: with large bean charges, some beans will spill out of the receptacle if you fully remove the tryer from the roaster, mainly because where it is located and because of its horizontal orientation. The good news is that the tryer is long enough that there really isn't a need to fully remove it (and lose heat in the process) - you can fully view and even dump the tryer without having to remove it.
7. Dump Phase
I most commonly roast for espresso, so I usually take the roast into at least to the first cracks of Second. At this point, concentration is heightened (listening for SC, smell of the roast, visual queues from the window and tryer, etc.) to know when to dump the beans. However, the Huky design imposes a series of maneuvers before the beans are dumped, and it happens at the most inopportune time (i.e. at the very end of the roast). At this point the bean tray contains all the collected chaff and this needs removal before the beans can be dumped into the tray. The maneuver requires that the exhaust pipe be raised/removed from the roaster so the funnel and tray (which must be removed together else a plume of chaff will ensue) can be removed from the top of the fan. I then dump the chaff in the trash and sweep the screen by hand to get the excess out and then put the empty tray back on the fan. While this is happening, the roast is not actively ventilated (i.e. pipe disconnected) so this maneuver must occur quickly and also be completed at the precise time to complete the roast and dump the beans: if too soon, you would need to reattach exhaust pipe to resume active ventilation till the roast complete; if too late, then your roast goes past your target.
The good news is that there is a very simple workaround to all of this: I bought an extra bean tray. I use one tray for chaff collection, and the other to cool the dumped beans. With the extra tray, I simply remove the exhaust pipe and chaff tray (with funnel on top, which keeps the chaff trapped in the try) at the very end of the roast, drop in the empty bean tray and then finally dump the beans (about a 5 second process). This small upgrade is highly recommended as it takes the stress out of this final step.
Once the beans are dumped into the tray, I then up the fan to full speed (F10) and the beans quickly cool in less than 2 minutes without any apparent need for cooling tray agitation (automated or otherwise); the powerful fan more than makes up for any need to stir the beans. When the beans are cooling is the best time clean out the chaff from the extra bean tray. If I want to perform another roast, I reduce the flame back to around P2/P3 and place the funnel back on the chimney and repeat the whole process. Actually, I also have an extra funnel, so I can charge the roaster immediately after dumping the beans and before having the clean out the chaff from the tray. The funnel also does a nice job at dumping the beans from the tray into a storage container.
Roasting Profiles and Results
The are a number of factors I haven't really touched on yet that go into controlling the roast and working a target profile, including such things as drop temperature, batch sizes, MET temperature control, etc. I must admit, after using the Huky for 4 months now, I'm still in the process of learning the nuances of the machine, though control of the roast controls (heat, fan, damper, diffuser) has become second nature now, and my ability to hold profiles have improved. For starters, the Huky is still very much a manual machine, so you must dedicate some "calibration time" with the machine; understanding how much flame will affect the ET/BT temperature and roast times, including the breaking point where too much heat will tip/scorch the beans or too little will extend the roast times.
I chose to keep the usage of the MET probe out of the discussion since most users would not initially have this setup. It was only after about two months when I installed the MET probe. Since then, I do find I have better roast control and which allows me to push the burner output without fear of tipping/charring the roast. This is more important if you want to roast larger batches in the 400+ gram range and also want to target FC in the 8-minute range.
Regarding batch size, I almost always roast in 1-pound increments, so I decided at the onset to calibrate the controls for this target batch size, hence most of my experience is controlling the roaster in this batch range. Recently however, I tried a few batches at the extremes. At the low end I tried 150 grams. Here initial drum temperatures need to be low (200C range) else the beans would dry too quickly from the heat capacity of the thick solid drum. Also, the ET probe is barely immersed into the smaller bean mass, so probe tends to register higher temps and become less precise as a proxy for internal bean temperature (Note - this may not be the case with the stock 50 RPM drum speed). As such, I feel 150g is really about the lower limit of this roaster (at least at a 73 RPM speed).
On the other extreme, I find 500g batches are similar to handling 1-pound batches, except that higher flame levels are required and higher fan speeds needed to ensure an even roast. Also, one may need to skew toward higher drop temperatures to help curb the turn-around temperature from dipping too low during the drying phase (especially if the Huky isn't outfitted with a higher capacity burner).
Of course, there is a limit to how high you can take drop temperature before tipping occurs, but I have found, for reasons not fully understood, that higher drop temperatures into the 285-300C (numbers from my particular MET probe location -YMMV) range can be tolerated without any noticeable tipping. There also seems to be some interplay between MET and drop temperature. If I'm doing back-to-back roasts, I find that a higher drop temperature can be achieved for the same given MET temperature, without creating ashy-ness in the roast. It's an interesting behavior and would like to know if others have seen this kind of effect (including Quest users with MET instrumentation).
For one-pound batches, I can readily target a Turn-Around-Time under 2-minutes; Drying phase under 4.25 minutes; FC under 9.0 minutes, and SC under 13 min. I typically roast to FC+ for espresso, though I'm starting to explore lighter roasts. Here again, the tryer comes in quite handy.
So far, I'm finding excellent roast uniformity with my setup, even in the lighter roasts. This could be due to the solid drum ventilation path, the faster 73 RPM drum speed, and/or the volume of forced air from the strong fan. Furthermore, chaff removal has been excellent - there is simply no chaff left in the roast, which is a far cry from my experience with in the Hottop.
Here are some samples of 1-pound roast profiles I did. The first is 14.5 minute Yemen-Mokha blend I took into Vienna territory. I wanted to keep a consistent RoR during the ramp phase and draw out FC by lowering the flame in half at that stage. Drop temperature was at 240C with a turn-around at 1:40. The resulting roast was chocolaty with fairly even uniformity for even a DP Yemen.
Next up is 1-pound roast of the same Yemen-Mokha blend that I took into the earlier stage of FC+ before I ended the roast at 12.5 minutes. I started with higher drop temperature and found myself coming in with too high of a RoR and so backed off the flame somewhat to get the drying phase in in the 4-minute range and FC at the 8-minute mark. The higher drop temp didn't lend to any tipping/ashy-ness to the roast and the end results were more pronounced with spicy notes that worked well with my vacuum brewer.
Peeves and other Nits
I've already mentioned the tryer and chimney design nits in the previous section. The only other issues I had were related to the drum rubbing against the front faceplate intermittently when roasting, and this became more pronounced when the roaster reached full temperature after thermal expansion. I have to admit this may have been due to my request to Kuanho to have gap tolerances tightened for my unit, which probably sat well at room temperature, but after a number of roasts, the rubbing become more frequent. As such, I expect other owners won't have this issue. I have since filed down the end of the drum slightly so remedy the problem.
Another nit worth mentioning is that the coupling sleeve between the motor shaft and drum shaft often comes loose. The coupling is held down by 4 stainless set screws and I expect thermal expansion/contraction is responsible for this loosening. I have since replaced the set screws with ones of longer length and added nuts to fasten down the screws securely - problem fixed.
And as mentioned on another thread, the stock 50RPM down-geared stepping motor is loud and has an irritating pitch, although over time one does eventually get somewhat more used to it (especially if there are other sounds to drown it out - exhaust fans, the swishing of the beans, etc). The 73 RPM motor I upgraded to does run quieter and smoother, and this is probably due the smaller gear reduction of this motor, but still it's not as quiet as the HotTop. The gearbox that motor is housed in is pretty large, and should be able to accommodate a larger motor with a lower base RPM. I've since asked Kuanho about getting a better motor outfitted for the roaster in the future.
As an early adopter, at least as far as the US market is concerned, I'm happy to say that the Huky 500 is rather capable at handling 1-pound batches while still offering good roast control, and is a good option considering the price-point of other actively ventilated pound+ drum roasters that provide tryers. The operative word with the roaster is flexibility, which is important for a manual roaster: in choice of heat source, direct/indirect heat control, solid/perforated drum, radiation vs. convection control, targeting a drum roast vs. a more air roast characteristic profile, etc. The Huky is not as self-contained as something like the Mini 500 or Quest, and not plug-play like the HotTop, but it still compact in its design can be made flexible for your particular setup. Plus, the aesthetics and build quality are hard to beat.
But with this flexibility comes some uncertainty as to the reasons for success for any one particular Huky setup. In my case, I made more than a share of modifications and integrations for my setup (covered in Part 2 of the review), so I'm not exactly sure what contributed to the successful performance of the roaster. Was it the higher BTU burner of my range burner? Was it due the burner being open flame instead of IR? Was it the faster drum speed? The solid drum and ventilation path? The diffuser?
Early on, I had since been working with fellow participating in the Kaffee-Netz forum, who had the standard Huky 500 configuration with the stock IR burner. In comparing notes, he was far less successful in getting 12-14 minute roast cycles without charring the beans, even when the charges were reduce to less than a pound. Conversely, I was not exactly sure what aspect of the stock setup was the cause of inferior results for him.
However, recent feedback from other early adopters in the US seem to indicate that the main reason the stock Huky configuration doesn't work as well is due the stock portable IR burner. In particular, tekomino has shared some good results with the standard Huky when using a third-party 20K BTU/Hr open-flame portable burner that can be found on Amazon (and the burner is at a comparable height to the stock burner so that the exhaust pipe does not require modification). My hunch is that the higher BTU capacity, combined with the convective aspect of an open flame burner really made the difference in the roast performance. An IR burner primarily heats up the metal drum, whereas an open flame burner heats up the air as well, and this seems to dovetail well with the strong fan ventilation control and airflow path of this roaster. Hopefully, other adopters who employ open-flame burners can post some results on this thread and compare notes.
I would even go so far as to not recommend the Huky unless a strong open-flame burner be used for the setup, whether it is something akin to the Amazon burner or as in my setup, integrated with high BTU open-flame burner on a rangetop. Once this is in place, the Huky 500 comfortably stakes out a place in the tier of high-quality 1-pound manual drum roasters.
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