bought a second 5# bag of it. I probably should have used my Uganda Bugisu '03, since I've still got about 10# of it, but I just roasted some Friday. I had trouble keeping control of the temperature. Even though the New Braunfels thermometer showed that I was running about 25-40 degrees over target, first and second cracks were at the late end of the target windows. The final roast was an unintentional melange. (I'm going to add the 57 RPM motor) I chewed on a bean and it was yummy! I let the coffee rest until morning; after all, it was late afternoon and that's caffeinated stuff.
My Charbroil experience getting there were not good, though. I bought the $99 Charbroil from Lowe's and the Charbroil "universal rotisserie" I found there. I had a few problems initially...
First, the big one: I really regret buying the $20 Charbroil universal rotisserie. It wasn't worth that price. The motor had trouble turning my RK Drum, hesitating at a repeating part of the rotation. The Charbroil motor did not fit the Charbroil grill well, with the electrical cord and the on-off switch interfering with the grill's shelf. Further, the rod is two pieces that screw together. It broke easily when I tried to straighten it. The rod appears to be cast metal that is threaded on one end. Then, I tried to find a 5/16" rod to replace it. Not an easy thing to do on a holiday weekend. The only hardware store that told me they had 5/16" square rod in 36" size was wrong -- they had 36" round, but only 12" in square. Neither Lowe's nor Home Depot had any either.
THE FIX: I had to go back to Lowe's for some more painting caulk (for an unrelated project), so I checked out their other rotisserie items. Sure enough, there was also a $32 Charbroil universal rotisserie called the "Premium Electric Rotisserie". This had a one-piece rotisserie spit rod instead of the two-piece. The motor was labelled "heavy duty" and was bigger, heavier, and with the cord and switch were well-placed. There was also a wooden handle for the spit rod. All the Lowes' boxes were in bad shape and I decided not to buy one. I went by Home Depot on my way home, and bought the same unit there at a competitive price.
Second, a minor problem -- I had to bend the ends of the grill's flame shield ("vaporizer bar") upwards so that the center would be lower. This was so that the drum wouldn't touch the flame shield. Slight bends with a 10# hammer solved this issue.
Third, another minor problem with my Charbroil setup: temperature control was horrible. Perhaps that's a function of where I placed my thermometer, which was 1" below the CharBroil logo in the front of the cover. This puts it close to the exit for all heated air from the grill. As a test, though, I pulled out my digital thermocouple that I used with my Hottop. I ran it through a hole in the side of the grill's hood and found it read anywhere from 35-50 degrees higher than the New Braunfels thermometer. Not what I expected, since the indicated roasting temperature was already well above the targets -- and I had trouble or couldn't get low enough for the target temps. That, and the fact that my 1st and 2nd cracks were towards the end of the acceptable time ranges, made me think that the thermometer was reading way high. Hummm...
Finally, another problem with the $99 CharBroil -- ignition. This has the only burner I've ever seen which has the gas holes on the top of the side seam. Couple this with the standard boxy igniter, screwed to the top of the burner so the box hangs BELOW the gas holes. Since the purpose of the box is to capture some gas to ignite, the lighting is awfully difficult. It's easier to light it with a butane starter.
Roasting was the fun part. I could watch the temps rise up, fall, twiddle the gas valves for more or less gas, and listen, listen, listen. When it was finished, I dumped the beans into a metal mesh colander on top of a 10" box fan and stirred the beans and chaff. Note: I didn't want a 10" box fan, I wanted a 20" but that's hard to find in September. I finally found one and bought it, because the 10" didn't push enough air.
If I was starting over, I would: 1) buy the Brinkman grill at $200 or the Charbroil "commercial" at $300 from Lowe's 2) buy the "premium" rotisserie, or at least buy one that had a full-size spit rod 3) get a high-rpm motor BEFORE the first roast. 4) find a 20" box fan and not settle for a smaller size.
I'm now using my digital thermometer with thermocouple in addition to the large analog thermometer. This gives me a quick-response indicator of temperature changes, while the analog one responds more slowly. After a few roasts where I just stuck the thermocouple about 4 inches into the grill body through one of the 1/4" holes in the side of the top, I pulled out my 1/4" copper tubing and tubing cutter. By running the thermocouple through the copper tubing, I have a way to place the thermocouple's bead (the actual sensing mechanism) where I want it. If you zoom the pictures above, you can see the copper tubing entering the grill lid from the left side.
(If you can't zoom the pictures, then try Firefox or Opera. I think you'll like them more than Internet Explorer. OK, OK, I decided to have mercy on the I.E. users! I made the pictures into links that will open larger versions of the same pictures)
It looks like my Hottop coffee roaster is going into retirement. I guess I will hold onto it for a while. I'll probably sell the Hottop in a couple months.
Roasting with the RK Drum is fun!
The more I use my RK Drum & gas grill, the more control I am getting over my roasts. I've managed to reduce the roast times to Ron's suggested time range by increasing the gas significantly during the first few minutes of the roast. I'm not sure this is the right approach, as Ron Kyle tells me that early application of too much heat is a good way to get a melange roast. That's what I got with 9oz of Sweet Maria's Donkey Blend this yesterday. I carried this well into second crack and got a blend of Vienna roast and Full City +. I expect it to be very good.
Ron has made a design change to the internals since I got my drum. He notes that it enables the user to get a more consistent roast at the normal rotisserie speed of 6 RPM. Many folks have upgraded to 57 RPM gear motors to run their rotisserie for coffee roasting. Ron also sold a pre-built 57 RPM motor assembly for the RK Drum at his site.
I've gotten my motor, some aluminum angle bar (1.5"x1.5"x1/8"x4'), mounting screws for the motor, a switch, a mounting box for the switch, strain-relief plugs for the box, the clamps to clamp the assembly to the grill, and power wiring to go to the extension cord. Tomorrow, I hope to put this together into a motor assembly (hope, hope...). The Dremel and electric drill (both battery powered) are charged and ready to go.
[a day passes]
I assembled the base plate for my motor assembly, but it's not pretty. The angle iron was the key to putting it together.
First, I cut a piece of the aluminum tread sheet, about 12" x 6". This would be the vertical support for the gear motor. I used a mallet and a vise to bend this to a right angle.
The next step was to cut the vertical slots for mounting the motor. To do this, I started by drilling the corners of the slots and then enlarged them using a saw bit. Boy, was this the hard way to do something, especially with the hardened aluminum sheet.
I cut a 18" length of the 1.5"x1.5" aluminum "angle iron." This would be the visible edge of the motor assembly as well as supporting both the base and the vertical sections. I glued the bent faceplate to the angle piece using "JB Weld" hot temperature epoxy. Then I cut another piece of the aluminum treaded sheet at about 18" by 6" to be the visible base plate, and glued that to the previous assembly.
Mounting the gear motor was no biggie. I bought some brass machine screws at my local hardware store for the mounting holes and used split washers to make sure they held.
I used a small plastic project box , a mini toggle switch, a strain-relief plug (package of assorted sizes, and insulated male/female quick connectors from Radio Shack and a length of extension cord to provide power to the motor.
I gave up on the concept of using clamps to hold the motor in place on the grill. My more simple solution was to (1) cut two short dowels, (2) drill through them, (3) insert some metal loops from an old swag lamp's chain into the dowels to use as "stops", (4) and drill two matching holes through the base plate and the grill shelf. Now, I just set the motor on the grill shelf, line up the holes, push in the dowel plugs, hook up the power, start the grill and go...
Roasting with an RK Drum, part 5
Digital Thermometer & Thermocouple
Temperature control is one of the important features of using a gas grill-based roaster, as it is for any type of roaster.
The gas grill, though, is especially susceptable to temperature variations because of wind. The large exposed shell can also cause you to have significant temperature differences, season to season, for any selected gas flow.
If you're roasting your own coffee, you are likely to be using "the good stuff," too -- not cheap green coffee but green coffee that costs significantly more per pound than the standard coffee brands.
I use two thermometers when I roast. I have a large New Braunfels Smoker analog dial thermometer mounted in the front of the grill (see my RK Drum #1 page).
I also use a digital thermometer with thermocouple to be able to monitor the temperature changes more quickly.
You can find the digital thermometer/thermocouple set at Sweet Maria's Home Coffee Roasting Supplies on their Home Roasting Accessories page.
In this first picture, you can see the left side of my grill, with the digital thermometer standing in a small wooden block (I used a dado blade to cut an angle slot in a piece of 2x4 for a stand). The thermocouple wire snakes around to the 1/4" brass tubing compression coupling.
I had this coupling fitting on hand. It makes a nice "stop" so that the wire can go through the copper tubing and the tubing won't fall into the roaster (see my RK Drum #1 page for the original -- which was a long piece of tubing stuck through the side).
The next picture shows the inside of the drum. Notice that the copper tubing simply sticks through the side of the grill. The compression fitting keeps it from falling in. The tubing is free to swivel with gravity.
The tubing is bent into an elongaged S shape. When the grill is closed, the end of the thermocouple is horizontal, level with the rotisserie shaft and about one inch to the front of the shaft.
The last picture is a closeup of the thermocouple mounting assembly (isn't that a nice word for this?). You can see the thermocouple wire sticking into the brass fitting and the thermocouple bead sticking out the end.
You might wonder why the thermocouple wiring is so dark — black and brown.
This is the same thermocouple that I was using in my Hottop coffee roaster.
