Roasting video:

Thanks John. I've never seen that video before.
It appears to be an older design than mine, but very similar in many ways. The video certainly answers Jim's question by showing the inlet funnel and it's plug-style gate for dropping in the bean load.


And I do appreciate the advice about pulling the roast.....and I'll ask again about ramping bean temperature after first crack has initiated. I've been experimenting with heat settings, but having a hard time to identify what works best for the period after first crack starts until pulling the roast.

Should I shoot for 10°F/minute?

I like 3 to 4 minutes from the start of the first to the end of the roast. If the first starts at 385F, and you are going doing espresso 435F to 440F, you are looking at 13F to 17F per minute. If you are doing a brewing roast at 415F to 420F, then you are looking at 10F per minute. If you want to go to a dark 450 to 455F on a Sumatra or something, you are looking at 18F to 25F a minute.

This is based on my preference for spending roughly the same time on light and dark roasts; so the darker the roast, the steeper the final ramp.

another_jim wrote:...so the darker the roast, the steeper the final ramp.

Somehow, this had escaped me for the 7 seven years I've been roasting at home <slaps forhead>
Now I feel like heading home early and roasting a few batches.....

JonR10 wrote:
And I do appreciate the advice about pulling the roast.....and I'll ask again about ramping bean temperature after first crack has initiated. I've been experimenting with heat settings, but having a hard time to identify what works best for the period after first crack starts until pulling the roast.

Should I shoot for 10°F/minute?

Unless you have some easy way to automate the roasting process, such as with a PID, you are likely to find that there is quite a bit of variation in the rate of temperature rise, both within a roast itself, and among the several or more roasts in a given roast session.

The reasons for this are more or less obvious. Unlike home roasters, a drum roaster such as your new roaster will retain quite a bit of heat, and the drum itself will store progressively more heat as the roast session goes on. This will be especially noticeable among the first 2 or 3 batches vs. later ones and will ultimately reach some sort of equilibrium, if you do enough roasts in a given session.

Also, given all the variables you have to deal with, it is simply too much to ask of a human being to be able to manipulate the things you can manipulate with repeatable precision that will give you a constant temperature rise, all other things being equal, from roast to roast, even within a set part of the roast cycle such as after the onset of 1st crack.

So, what you will probably be forced to do is more or less what I do, which is to use your available thermometry and a stopwatch or minute timer, and to take note of when the various events occur during a given roast, then to make on course corrections on the fly as you find that a given roast is either going too slow, too fast, or in line with what you want to accomplish. This means that if you are shooting for, say, 4 minutes or whatever in between the onset of 1st crack and the end of the roast (at your predetermined final temperature), that the speed of temperature rise will vary within limits so that you can make your desired timing landmarks.

It is possible that you will actually get to the point where you can manually get XXX degrees of temperature rise per minute at some point in the roast cycle. If so, this will indicate that you either have a more controllable finely tunable roaster than I do, that you are more skilled at manual roasting than I am, or that both of these are true.

ken

another_jim wrote:I like 3 to 4 minutes from the start of the first to the end of the roast. If the first starts at 385F, and you are going doing espresso 435F to 440F, you are looking at 13F to 17F per minute. If you are doing a brewing roast at 415F to 420F, then you are looking at 10F per minute. If you want to go to a dark 450 to 455F on a Sumatra or something, you are looking at 18F to 25F a minute.

This is based on my preference for spending roughly the same time on light and dark roasts; so the darker the roast, the steeper the final ramp.

This is the approach I use too. I guess my final dump temp. and start of first and divide the difference by my chosen finish mins. Then I take into account the way my roaster reacts during that part of the roast. The goal being to end up at the right average with my planned finish profile. This is where I like having a live RoR reading. I can see if I'm coming in too fast or slow on approach all things being considered and start to make adjustments as needed. You learn how extreme adjustments can be to avoid stalling or excessive ET. I may not always match my preplanned profile for this final phase but can at least keep it close to the target time and temp.
Jon, Really great looking roaster. What does the fin design look like in the drum? They are usually super well designed in pro. roaster.

Ken Fox wrote:Unless you have some easy way to automate the roasting process, such as with a PID, you are likely to find that there is quite a bit of variation in the rate of temperature rise, both within a roast itself, and among the several or more roasts in a given roast session.

This is true. But if you check the roast every 20 to 30 seconds, you'll know if it is going too fast or too slow. I'm frequently wrong when I reduce the air and heat at the onset of the first crack and I'll have to make several adjustments later in the roast. Ken's roaster is less forgiving than most on this since there's no built in sensors or air, but on Jon's roaster may be easier to "steer."

Congratulations! It is such a great looking roaster with many capabilities.

Ergonomically, it is nice that the controls, trier, and sight glass are on the same side. I keep going back and forth on my Mini 500.

Consider roasting in centigrade, because the rate of change is mentally easier to conceptualize. Aim for about 10C/min before 1st crack, and about 5C/min after 1st crack. Load at ET of 130C, turn off gas. The ET will drop until turning point, then turn on gas. This generally takes about 1:10 to 1:30 min.

For reproducibility, load the first roast about 10C higher. So the first roast of the day may start at 140C. I noticed there appears to be a temperature gauge at the exhaust. For subsequent roasts, open the damper or increase fan speed, until the exhaust temperature AND ET are at the right combination. I usually aim for 90-100C for exhaust temperature, and adjust the damper to achieve same ET, for consistency. For the Mini 500, the ET is controlled by adjusting the damper. It appears for yours, it is adjusted by the fan. Is the fan speed adjustable? Hypothetically, if it adjustable, an RPM gauge can be used for accuracy.

Start increasing heat at about 150C. The marbling will occur at about this temperature. It should be easily observable from beans pulled from the trier. First crack generally occurs at about 188-194C ET. Decrease the gas and increase fan speed about 2 degrees centigrade of anticipated 1st crack. The residual heat from the drum will carry the beans into 1st crack. I use two timers. Once 1st crack starts, I start the second timer to measure 1st crack to finish interval. I also just turn off the gas about 10-20 seconds before anticipated finish time. Again, the residual heat from the drum will finish the roast.

There is a good article at the Ambex website regarding location of the BT. So far I have been using only the ET. Additionally, previously I thought about magnehelic gauge for the exhaust, but now I am thinking about air speed.

One observation from my limited tasting of BBQ drum is the flatness and smokiness. I attributed this to the lack of accurate air flow control in BBQ drum roasting, but not sure if this is the correct assumption. The commercial drum roasters generally have more accurate air flow controls.

Ken,
Thanks very much for the sage advices.

I did not intend to say that I believed it was possible to manually control xxx.xx degress/minute precisely, but rather I was looking for suggested ranges that people shoot for. My previous setup did not allow me to measure bean temperatures, so I relied on experience and whatever data I could measure to roast (and got some pretty decent results if I dare say so).

This roaster allows for a fairly good degree of control, and from the start I have been running roasts with a stopwatch and roasting logsheet (the computer I will use for the datalogger interface just came in tonight). I have been taking readings every 30 seconds so I can observe how the machine behaves at different times with different inputs and so I am getting a pretty good feel for the control.

Tonight I was able to "dial in" last stage ramps varying from 8 to 16 (°F/minute) on different roasts by adjusting the gas burner inlet pressure during the final stages of roast. Tonight I was reading at 15 second intervals after reaching first crack so I could make adjustments "on the fly"....

Her are some pics I snapped tonight:

First, a picture of the burner control. The thumbwheel is for the needle valve and you can dial in the heat input within about ±0.1 psi by watching the gauge. I use 0.25 psi increments.



Here is the datatlogger output, and now that I have a computer to use for it I'll be able to watch the roast profile curve graphically in real time as it progresses and of course I'll be able to output the data for making graphs in Excel.


Here is a better picture of the tryer. I do wish it was a little larger but this works well enough:


And here is the plug-style gate in the funnel for dropping the beans into the drum:



Sorry Ed - I haven't even thought to look inside the drum at the fins yet

chang00 wrote:Congratulations! It is such a great looking roaster with many capabilities.

Thanks very much for the input!!
I'll have to read your post a few times and do some temperature conversions to fully absorb your advice.

My ET is just a gauge on exhaust, and my main measurement is the BT probe readout. I assume it's in a thermowell and there is an offset, so my bean temp reading seem to be off by roughly 15-20 °F (usually reaching first crack reading between 360 and 370 °F and second crack happens at around 400-410°F)

The fan is on a rheostat so the switch position indicates fan speed. I preheat at the lowest fan setting + max burner, then run it higher fan during the drying stage (with a very low burner heat setting), then low fan + higher heat while ramping from drying to first crack, then max fan with lower heat as I approach first crack.

I could post numbers but they will be relative to my measurement offset. I will post graphs when I figure out how later

Thanks again,
Jon