Imex CR-100/Cafe Rosto owners, need your experience

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Imex CR-100/Cafe Rosto owners, need your experience

Postby bobo » Thu Jun 27, 2013 4:33 pm

Hello.
I own a new CR-100 as my first roaster for about six months and have a quite mixed impressions aboit it.
I've never had problems with low heat and long roast as the current at my place is realy high. Counterwise, I've always been confused with too brief roast my Imex tended to perform - 6-8min.
I realy don't remember how good were my first tries on roasting. Not really good I think. Then I started to roast outside with ambient temperature about 3 to 5.C. The results were just fantastic! So I decided to use a voltage regulator with my roaster to lower roast temperature like I did on my "winter" roast sesions.
I did so - aded voltage regulator. Now I can lower current from 235V to 185V.
I tried 5 or 10 roasts. Started ar 235 and lowered to 205, 195, 185 on 3-4min of roast until coffee beans were of desire color. What can i say, my results varied from mediocre to awfull! My english is too weak to describe the "flavours", but what I can say for sure is all my coffees had coffee color, had a flavour of something roasted, had weak body and any different coffies tasted similarly bad - flat, tasteless, etc.


So please, if somebody using the same roaster please share with me your experience on using it - roast profiles, timings, temperatures. I'm going to try my IR-thermometer to control roasting, hopefully, it will help.

Other model air-roaster users, your suggestiong are also highly appreciated.

Thanks a lot!
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Postby GreenBean » Thu Jun 27, 2013 5:13 pm

Hi bobo, welcome to TMC. :D I have no experience at all with the CR-100. I think I understand the basic operation of the roaster but I do not have any information on any controls it may have to allow you to control the roast. Hopefully someone with experience will be along to give you much better advice than I can.

I am not sure that reducing the supply voltage is a good idea. Reducing the supply voltage will reduce the fan speed and hence the airflow as well as reducing the heater power. The fan will have been designed to provide sufficient air flow to fluidise the bed of beans reducing the voltage by more than a little will probably defeat that. If you really want to experiment with reducing the heater power then I would suggest you separate the power supply to the heater and reduce the voltage to the heater only.

An IR thermometer will not measure the bean temperature if any glass or other material is between the beans and the thermometer.
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Izzo Alex Duetto | Gaggia XD 2 Group | Mazzer Super Jolly | La Cimbali Max | Solis 166 | Dalian 1 kg roaster | Hottop P | Hottop B | French Press (several) | Kettle modded, no really, added digital thermometer |
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Postby bruceb » Thu Jun 27, 2013 8:05 pm

Image.

My first roaster was a hot-air machine (Hearthware Precision) that gave me good results. It was very similar to your roaster. I decided to try reducing the voltage, too, but understood, (as GreenBean noted above) that the fan must continue to run at full speed and only the voltage to the heating element must be reduced. I opened it up and found the leads going to the heating element, pulled off the connectors and attached wires to the element and ran the wires out through a hole in the bottom of the roaster. I put a plug on the wires and plugged them into a variac with a voltmeter. If you do this it is very important to turn on the machine FIRST before switching on the power to the heating element. Otherwise you will burn out the heating element very quickly. Once you have the fan on and the voltage to the heating element adjusted you can then add the beans and start timing. I did this for about 6 months, but was never sure whether the results were worth the effort. It's worth a try, though.

To measure the temperature at all accurately you will need an electronic thermometer with a thin wire lead that you can slip in past the lid. The thermocouple should be very small and should be in the bean mass. Nothing else will work.

I hope you know not to try modifying the roaster if you are not comfortable with working with electric current. A 50 Hz shock of more than 100 volts can be dangerous or even lethal.
Three Francesconi (CMA) espresso machines - Rossi, San Marco, LaCimbali, Faema and 2 Mazzer Major grinders- CoffeeTech Maggionlino, Hottop, Alpenröst and HW Precision roasters.
I decided I needed a bit of a change so I roasted some Monsooned Malabar. That was a change!
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Postby bobo » Fri Jun 28, 2013 7:01 am

Thanks bruceb & GreenBean!

My voltage mod does't affect fan but only heater, I had to say it in my post.

Besides, i've found convenient way to measure been temperature
Image

so now I only need your roasting leads :)

Thank you
bobo
 
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Postby GreenBean » Fri Jun 28, 2013 9:22 am

You really need advice from users of this roaster. Have you seen the Sweet Maria's tip sheet on this roaster? If not click here.
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Izzo Alex Duetto | Gaggia XD 2 Group | Mazzer Super Jolly | La Cimbali Max | Solis 166 | Dalian 1 kg roaster | Hottop P | Hottop B | French Press (several) | Kettle modded, no really, added digital thermometer |
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Postby bruceb » Fri Jun 28, 2013 11:29 am

I see the same problem here as in so many roaster mod discussions, namely, there are no objective criteria that apply to the results. Personal taste is so ambiguous and unreliable (for most of us, perhaps not for professional roasters or those with "perfect taste"). I know that after roasting a specific coffee and thinking how wonderful it is, the next day or even the same afternoon I may find myself wondering what I thought was so great about it. If one had a "100% taste comparison" that one could always rely upon (and not just a memory thereof) one could compare. I don't have such a coffee and never have had.

The result of this is ambiguity when changing roasting parameters. The changes in results are usually subtle (otherwise they are usually disastrous) and one is often unsure whether there is an improvement, or even a difference.

One thing I know for certain about this is that espresso and espresso-based drinks are not a good medium for testing, even if that is the way the coffee is too be consumed. Most people's taste buds are either numbed or shocked by espresso and results are even more unreliable. A simple cupping table is far better to detect subtle difference in roasts.

Big roasters solve this problem by having a "board of tasters." One or two people can easily mislead themselves or be uncertain, but 6 independent testers can probably be relied upon. Most of us don't have this luxury when it comes to deciding whether a change is for the better or not.
Three Francesconi (CMA) espresso machines - Rossi, San Marco, LaCimbali, Faema and 2 Mazzer Major grinders- CoffeeTech Maggionlino, Hottop, Alpenröst and HW Precision roasters.
I decided I needed a bit of a change so I roasted some Monsooned Malabar. That was a change!
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Postby bobo » Sat Jun 29, 2013 9:06 am

Thank you, bruceb!

You are absolutely right saying "The changes in results are usually subtle (otherwise they are usually disastrous)".
If you happen to make a good batch of roasted coffe, it can vary in nuances but it still will be a good coffee. But if you screw it, nothing would save it and this is mostly my situation.

Maybe I just need basic principles of roasting: what temps, when to add heat, when to reduce it, etc.

I like Capuccino, espresso and aeropress coffe. The last one gives a clearest answer if a rost good or bad.

I've found some profiling leads here http://www.home-barista.com/home-roasting/roasting-profiles-for-espresso-t3115-10.html#wrap. Hopefully, they will help.

GreenBean
Sure I've been there! Nothing helpfull, unfortunately. I buy greens there, by the way.
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