|IMO: This is the best modification you can do for a few bucks to eliminate the weak motor of a homemade SC/TO coffee roaster and increase your roast size.|
This modification will make your roasts more even and allow larger roasts up to one pound and more.
I normally roast 1 lb 2 oz at a time (~3 cups) and can easily do 4 lbs/hour without hurting myself. If you want to do smaller roasts, I suggest you play with the stir arms to get good agitation of the beans tumbling them over the stir arms without pushing the beans too much. I put small roll pin sleeves over my stir arms to get it right for my roast size.
|In order to increase the heat to meet my particular basic roasting profile at different times during the roast (in addition to the turbo oven adjustments) I added a 1000volt/50amp diode and SPST switch in series with the heating coil and thermostat of the base. I used 1/4 of a bridge rectifier for the diode. Although the diode is not necessary, using a diode made the heat transfer smoother than without it when switching the base heat on and off. Be sure to use high temperature insulated wire when doing this modification.
If you have any questions, you can contact me at: coffee@[the domain name of this site]
I credit Peter, longtime friend, brother-in-Christ, roaster and green and roasted bean supplier of The Excellent Cup, to getting me started in building a coffee roaster.
My Spin on Coffee Roasting Profiles
Do we really have to cup and develop a profile for every 5 pound batch of beans we buy to get a good roast?
Most of us amateur roasters buy beans at different times and different varietals from different farms. Some of the inconsistencies we face buying beans, even from the same farm, is that farm region has different enviromental seasonal changes each year, different aged plants, usually a mix of varietals, varying processing environments, crops at different altitudes and harvested over different times during their harvest season. All these varying from one batch and shipment to the next.
Then our roasters have consistency issues like thermocouples and placement, bean temp, environment temp, air flow, drum speed, roasting temperture, size of roast and roast times. All this besides the different types of roasters and roasting. I assume that these all vary somewhat in the way and timing you roast from batch to batch.
I've come to the conclusion that no batch of beans is the same, no roaster the same, no grinder grinds the same, no water the same, following the roasting profile is not exactly the same every time, no consistency in brewing and taste buds are not the same every day.
After considering all these inconsistencies, IMO the art and science of roasting has too many variables from one batch to the next to deal with a different profile each time.
As an amateur roaster, I started by studying several expert's award winning roasting profiles and have found there is a common thread to most of their profiles. Dry time (200F - 300F) about 4 minutes, Maillard time to first crack about 4+ minutes, development time is more or less around 3 minutes.
So just like my washing machine, dryer and dishwasher that have many different cycle options, I always use "normal" when using them. Same for roasting coffee. I use the same profile for all my beans (http://www.bobbooks.net/ROR.htm).
I know that many experts might disagree, but I think most are fooling themselves that every bean needs a different profile to get excellent results or maybe even near perfect results. I do understand that you must have good beans to start with.
After roasting several years and having many people doing blind cupping for me scores of times, I have found that EVEN the same roasted batch will give a wide range of cupping results from different people.
I have even given people 2 seperate bags of coffee from the same batch and they gave me different cupping results for each bag! All these differences could be on what type of car the person drives, barometric pressure, weather forecast, moon cycle, local baseball score and sun spot activity. Needless to say, my experience is: "It's a crap shoot" and the only thing that really matters is, "Does the coffee taste good!"
The only basic thing I vary with the roasting profile is the development time to get different roasts from light to city++ and the drying time because I buy my beans directly from a farm in Nicaragua where they only harvest during last of December to spring, so if my beans are getting older I shorten the drying time up a little.
90% of my roasts use the same profile listed here are pulled at the beginning of second crack. I always have excellent results from all who taste my coffee.
That's the fun of being an amateur roaster! Trying different beans, methods and profiles for your roaster to get the best roast possible. The most important and best profile is the profile that will produce a coffee that "tastes good" to you and your friends.
Take my spin for what it's worth as I'm only a novice roaster and still have a lot to learn! I would appreciate any comments positive or negative.
If you are a follower of Scott Reo and his theory of roasting then maybe this chart based on time may be helpful.