The Nesco Coffee Roaster is a home roaster I like, and I recommend it with a few conditions. To be exact, I feel it has a couple drawbacks. Dark roasts take a long time (namely, on circuits with voltage below 110v). It has some great features though, especially the catalytic converter that eliminates the bulk of the smoke associated with home roasting. It truly works - this machine produces a lot less roast smoke than any other home machine. The Nesco's longer roast times make it easier to target lighter and medium roasts. Most home roasters (and popcorn poppers) pass rapidly from first to second crack without a significant pause. The hidden benefit of the Nesco's long roast profile is the extra time between 1st and 2nd crack. This gives you extra time to ponder the exact time you want to stop the roast.
Interested to see what other Nesco users say about this machine? Check out the Using Air Roasters section on the Sweet Maria's Forum.
My first impression is that this machine is unique and probably cost the Nesco people a lot to develop and to build. It has two fans driven off the same motor, a belt-pulley system to drive the cast metal auger that agitates the coffee, and a converter to help reduce smoke emissions while roasting. The latter is very effective (granted that smoke released over a long roast cycle is going to be less noticeable than a short cycle. The converter is a heating element and a honeycombed ceramic piece that burns off smoke The auger spins very fast and agitates the coffee very thoroughly during the roast cycle. There is very little airflow through the roast chamber during the roast cycle and not much during the cooling either so expect a lot of chaff mixed in with the coffee while roasting. Even the smallest pieces of chaff do not leave the roast chamber for the chaff collector. While this may not look good, it really doesn't hurt the quality of the roast. Overall the chaff collection is poor and I would recommend that you have a vacuum cleaner handy. You can actually suck the chaff right out of the coffee if you don't hold the nozzle too close, or you can dump the roast into a metal colander after the cooling cycle is complete, and shake out the chaff. You will want to get the roasted coffee out of the roast chamber as soon as the machine stops, because the slight air flow does not completely cool the coffee. I measured the beans at 130 degrees after the Nesco cooling cycle. This is not too bad, but what you really want is rapid cooling in the first minute after the roast cycle terminates. Otherwise, the coffee continues to roast well into the cooling cycle, and indeed you need to learn to stop the roast early to take into account the additional roasting that will occur when the heating element is off. The roaster is really easy to use except for the chaff collector seal at the top of the unit. You need to seat it properly or chaff will leak out and the roast heat will be lost. The best way is to push the chaff collector in the top and work your little finger around the seal to seat it, then seat the entire top onto the roast chamber and base.
Overall, the roaster works well for someone who hasn't been exposed to roasting before. There is a belt drive tensioner in the base of the machine and this needs to be engaged to drive the auger better -the machine may squeal a bit with it engaged but this is better than having the auger jam during the roast. We haven't heard of people receiving defective units or having failures after a few uses, but we did hear of a few units breaking down after extended and heavy use. The main concern that comes up with the Nesco is the cup quality, especially of the darker roasts. For someone that hasn't roasted before, the machine will offer a great improvement over store-bought coffee and will probably match some micro-roasted or gourmet chain coffee too. But we have gone through a considerable amount of coffee and have noticed a dullness in the cup. I think the cause might be the inadequate cooling (not the temperature after the 5 minute cycle, but the fact that the low air flow is inadequate to drop the coffee temperature in the first minute or two. Although I removed the coffee from the roast chamber immediately after the cooling cycle each time, the ideal thing to do is to remove it as soon as the roast cycle ends, dump it in a metal colander and draw air through it with a fan. The incredibly slow finish of the Nesco is off the traditional "slow finish" scale. It's incredibly slow, and what amazes me is that it isn't doesn't seem to be stalling the roast after 1st crack. With a first crack finishing 12.5 minutes into the roast and a second crack starting at 19.5 minutes, the lull between them is exceptionally long (note; this was with a smaller batch size, their "french roast" batch size): this does give you a lot of time to determine the "degree of roast" you want but the cost might be the roast quality. This long roast time starting with the first exothermic reaction is unlike any roaster I have used.
If I could tweak this thing, it would be a burner control to accelerate the roast as the coffee is on the verge of First Crack to prevent a roast stall, then back off a little, then back off a little more as it reaches my target roast temperature. But I think the Nesco is really aimed at someone who isn't going to worry about these things, or look inside the roaster, and hasn't heard of roasting before so they don't have a basis for comparison.
Someone told me this is the roaster they would give their grandmother, and after using this a while, I would think so, or at least for your hobby-addicted uncle. :-) It does work well and the mechanisms inspire confidence. For someone who wants to open it up and play with the heat coil, and find a good place to insert a temperature probe, the Nesco offers some great possibilities. After all, this is mechanically a unique roaster.