Sherman wrote:(Original reply, composed 6/5/09)
Ken,
I had gone over your post in this thread (as well as in other threads) before I replied, and had hoped to elicit some more specific detail with my question - for the vague, inexact nature of my original query, I apologize.
Let me try to be more specific:
Your mention of "roast temperatures", speaks to the earlier notion of the types of temperatures that can be measured: ET, BT, and exhaust. What are your thoughts on this? Do you concur with this idea? Having lurked on H-B for a while before I started posting, I'm vaguely familiar with some of the equipment that you have (the Hottop, the El Salvadorean POS, and the mucho expensivo sample roaster IIRC). Do you have specific measurement types and locations for each? Do they correlate with the Ambex article?
Hello Sherman,
The El Salvadorean POS is not a real roaster, so I won't comment further on it since I don't intend to ever use it as a roaster in the future. As to the Hottop, I hacked in a TC along the lines of what Randy Glass has previously published, in fact inspired by what he has published. Since I don't use that roaster very much I don't have anything else to say about it other than that the location is very much more reflective of actual roast/bean temps then the location where Hottop itself puts the included digital thermometer. My sample roaster is actually not that expensive of a roaster. It cost about $2500 when I bought it however with modifications it has now cost me closer to $5K, although these added expenditures took place over a period of several years.
I don't pay any attention to the list of supposedly acceptable locations for putting a bean probe, and did not do so when I debated, for over a year, where to put the probe in my sample roaster. To me this is in the realm of "mental masturbation." If you are looking at putting a probe into a roaster you own, the question really is, "where can I put a probe that will give me a repeatable indication of what is going on during the roast, something I can follow and adjust my heat inputs by?" That is the important question. You can call it bean temp, you can call it exhaust temp, you can call it anything you want, but in the end it only needs to be a representative temperature that will be consistent across a wide range of roasting conditions. Wherever it is located, you can adjust your roasting inputs to it as long as the location is reliable and consistent.
Sherman wrote:What monitoring equipment do you use/prefer? It seems that the type-K wire thermocouples/themometers seem to be the instrument of choice due to their accuracy, resolution, generally hands-free operation and relative variety of placement options.
I got a K-type TC made for me by Omega of a certain length that I measured before I ordered it, to try to be in the middle of the swirling bean mass in my roaster.
Sherman wrote:You bring up a good point in mentioning the desire for an easily controllable heat source, and that is one area where prebuilt consumer-level roasters can fall short (sans modification).
All said and done, I'm starting to believe more and more strongly that there are certain pillars upon which successful roasting are built. They are:
Accurate, consistent temperature monitoring
Easily adjustable heat source (all other things being equal, more controllable = better)
The extent to which your roasting method supports these pillars will directly correlate to the ability you have to control any profile.
More to come,
-s.
I can't disagree with any of this. The only thing I can disagree with is people who over simplify the difficulty involved in doing a good job at roasting, and who believe that some cheap device can do the job for them in other than a mediocre way. There
are automated ways of doing this roasting thing at a high level of precision, unfortunately they require either a whole lot of effort (like programming and installing your own PID) or they cost a lot. The cheap, off-the-shelf options are not going to give a discriminating consumer the sort of results he or she would like to get.
ken