Hey all, I just roasted my 4th Salvadoran. To re-cap; #1 was the San Fran that Tom carried - excellent, #2 was okay, but a little hollow and sharp hot, just fine cooler, #3 was like the S.F at all temps, but none of the citrus flavor that made the S.F. so good. This is proving to be such an interesting journey I'm going to say with it until the last salvadoran is roasted. What does a PID have to do with this. I PID'ed my roaster so that I could see what different profiles did to the coffee. I now find that it has the additional benefit of being able to repeat the same roast, with different coffees. No question that I didn't follow the same profile. BTW, you can tell I'm not a cupper by my descriptions. Ben |
If there is any interest in this topic let me know, or i'll stop posting about it. Ben Treichel wrote: <Snip> -- Ben Treichel Program Manager S.E Michigan SwRI 248-232-7365 (o) 248-935-6845 (m) |
Ben, Is there a place where the technology is in a diagram form for this PID roasting. I've sort of been following the posts about it for a couple of weeks when it's mentioned but there are some holes in my understanding of the specifics, or probably I should say... basics. Cost, program, program that supports program, OS required etc. And the acronym is for? I'm quite impressed and could get into this down the road. How about kit form and I'll screw it on to my own board? Thanks Rob |
Keep the posts coming Ben. It IS coffee AND roasting related! Kona Konnaisseur miKe mcKoffee URL to Rosto mods, FrankenFormer etc.http://mdmint.home.comcast.net/coffee/Rosto_mod.htm |
I'm interested! Bob Yellin <Snip> <Snip> |
Rob, Here are the basics on PID's. (Sorry if its over simplified) The simple explanation is this. If you place an on/off switch in your heater coil line you can decrease the amount of heat going into the roaster. Since heat translates to a specific temperature based upon a bunch of things, by turning the switch on & off you could control the temperature. Now since you really want a specific temperature, you would want a thermometer to read the temperature. Based upon the readings, you would decide when to turn the switch on and off to achieve the temperature you wanted. This would allow you to 'profile' your roast. i.e. @ 10 minutes 400, 11 minutes 410, etc. Now, since you are watching and setting a desired temperature based upon time you are ramping the temperature. Which is why we talk about PID's that can ramp. Also, since you are controlling on temperature (temp being the feedback, heater on time being the input) you are not required to care how hear translates to a specific temperature. This varies from using a variac since with a variac you are reducing the amount of heat that goes into the roaster, instead of turning the heater on and off. However, if you would multiply the time a variac is on, by the number of watts it produces during that time, and do the same to a PID over time you would achieve the same result. ( i.e. 1000 watts * 60 seconds = 1200 watts * 50 seconds + 0 watts for 10 seconds). However, this equality breaks down in the end if the 'cycle time' of the PID is too long. Cycle time is how often the PID checks to see if it should be on. For a more complete explanation see the link below.http://www.tcnj.edu/~rgraham/PID-tuning.htmlRob Stewart wrote: <Snip> -- Ben Treichel Program Manager S.E Michigan SwRI 248-232-7365 (o) 248-935-6845 (m) |
I'm also interested. I understand something about PID's on conceptual = basis, but have no experience in attempting to use one. I, for one, would like to have some idea where to start. That is to say, = what should I look for in a PID for roasting and what sort of other = stuff (that's a technical term, isn't it :o) I need to make it all work = with a roaster. (In my case a P1.) I can imagine there are many = questions that I don't even know enough to ask at this point. Dave Lowe |
Hi, In addition to Ben's excellent explanation, I'd like to add this: Most SCAA roasters use sample roasters that do not roast at the same speed or profile as their production roasters. This means they can use the sample roasts to determine the quality of the greens samples they get; but they can't use it to establish the best roast time/degree for their production roaster. They have to produce several, perhaps not so good, 5 to 50 pound batches to figure that out. The big boys can buy Neuhaus-Neotec lab roasters at about $15,000 a pop to roast 200 gram samples at any profile they please in order to come up with the best profile for their production roasters. These little Fujis, along with a gas valve solenoid that can pop the burner between, say, 1/3 and full, would do the same for a standard 1/2 to 1 pound sample roaster at a cost of around $200. One could even forgo the relatively expensive sample roasters, and pick up a dozen throw away poppers at a thrift store to take care of a years worth of asmple roasts. Hooked up to the PID, and fan variac, they work just like the fancy NN -- they blow adjustable amounts of hot air ;) Jim On 12 Feb 2004 at 9:26, Ben Treichel wrote: <Snip> |