Java Master 2002 Coffee Roaster

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Java Master 2002 Coffee Roaster
Owner/Loaner Theo Tetzlaff
Serial Number 2736
Make/Model Java Master 2002
Arrival Date June 2022
Usability yes
Contact Theo Tetzlaff
Where Kitchen
Authorization Needed yes
Hackable no
Estimated Value $7,500
Host Area Kitchen

Java Master 2002 Coffee Roaster Theo Tetzlaff Area: Kitchen


This is a Java Master 2002 fluid bed coffee roaster, capable of roasting up to 3.5 lbs green beans per batch.

Loaned Tool

This is an official loaned tool with an active agreement on file accepted by a board member May 8th 2023.

Roast Profile

Roasting Profiles refer broadly to important parameters and conditions of the roasting process. The roasting process is a process of caramelization and carbonization called a Maillard Reaction. Some important roast parameters include:

  • Temperature at beginning of roast
  • Temperature at ending of roast
  • Total Duration of roast
  • Rate of Rise in temperature over total duration and specific periods of roast
  • ‘Development’ of roast at specific temperatures during specific sequences of the roast
  • Degree of ‘crack’ achieved in the bean (i.e. First, Second)
  • Color achieved
  • Speed of air cooling of beans (this part is a significant contributor to ‘sweetness’ in the cup)

In general, coffee sugars are made accessible by roasting, but the caramelization process also reduces perceptual sweetness over roast time at a similar degree of roast. Additionally caffeine content lowers over time with off-gassing from longer roasts. Acidity also tends to lessen over time past City+ and into Full City/Second Crack, until carbonic acidity eventually raises in the darkest roasts. Roasters aim for a consistent rate of rise over time, just as with making caramel, so that the caramelization process does not stop and start haltingly, which will reduce perceptual sweetness as well and lead to uneven bean development.

Roasting on the Java Master

Roasting on the Java Master is determined by two separate controlled parameters: hot air temperature and bean temperature. Hot air temperature is set on the left PID controller. It should be adjusted based on the bean weight to be roasted and the desired speed of roast, and is the temperature of the air entering the roast chamber. More beans require more heat to roast at the same speed. Target bean temperature is set on the right PID controller, and corresponds to the temperature of the air exiting the chamber. When this temperature is reached, the machine begins its cool down cycle. Note that this number is a significant underestimate of the actual bean temperature, but it provides an easily measured parameter for when to end the roast. This temperature can also be adjusted while the roast is in progress to prolong or end the roast earlier, but note that the PID controller takes several seconds to recognize the change.

Suggested roasting parameters:

Hot air temperature range is 530-575 F on the controller. For 1-2 lbs, it should be set close to 530 F. For 2-3.5 lbs, it should be set between 540-560.

Target bean temperature can be set between 370-445 F. This parameter determines the darkness of the roast. Suggested starting points for experimentation:

  • City (first crack complete) - 375 F.
  • City+ (significant development beyond first crack) - 380 F to 390 F.
  • Full City (right before second crack) - 400 F (may be higher.)
  • Full City+ (some but not all beans have gone through second crack - 415 F.
  • Second crack complete - 420 F.
  • French roast - 425 F?

Additional efforts are being made for us to be able to ‘log’ roasts as temperature over time graphs, in order to compare roast profiles for individual beans and measure outcomes.

Operation Checklist

  • Get stuff ready:
    • Get hopper, funnel, bags from Kitchen
    • Weigh beans (Kitchen has a scale)
  • Turn Power on
  • Turn Heat on
  • Check (and, if necessary, empty) chaff collector
  • Turn on exhaust fan (switch on wall to the right of the machine)
  • Set air and bean temperatures
  • Put hopper in place over the blower vents
  • Pour in beans
  • Make certain the top cap is in place
  • Press the Run button
  • Hot air heats up beans, eventually beans reach set Bean temperature
  • Machine turns off heat, cooling water starts, machine continues to blow air to cool down beans
  • Wait for bean temp to drop below 370 F, at which point yellow Reset lamp lights
  • The operator can dump the beans now, or continue to cool the beans in the chamber. To dump:
    • Press the Stop button.
    • Pull the handle to dispense beans into hopper immediately after the beans stop moving. (Leaving them sit still too long is a fire risk.)
    • Give the beans a sideways shake in the hopper and let the air vents under the hopper cool the beans.
  • Bag the beans
  • Turn off Heat and Power switches
  • Turn off exhaust fan
  • Return hopper, funnel, and supplies


  • Never run a roast unattended! (Please!)
  • Do not roast anything other than green coffee beans.
  • Roasting beans that already have been roasted is a fire hazard.
  • Minimum and maximum load are 1 - 3.5 lbs green beans.
  • Make sure the chaff collector has adequate space. Empty it regularly.
  • Do not operate without water (this is permanently installed now so it should be fine.)
  • Do not operate without the exhaust blower turned on.
  • Beans above 300 F, without cooling air flow or not in motion in the roaster, can catch fire. Stopping the roast is therefore bad. A power outage during a roast is also bad. The roast should be allowed to complete.
  • The roast can safely be stopped once bean temperature reaches the target, the cooling cycle engages, and the beans drop to 370 F. When this happens, the yellow Reset light will illuminate. Beans can be allowed to cool in the chamber, or the roast stopped with the Stop button and the beans then immediately dumped into the cooling hopper by using the lever. Fans on the tabletop in front of the roaster will blow cooling air over the roast beans. Beans will cool in the hopper via cooling fans within about 3-4 minutes after roast.
  • A manual valve is located on the left side of the machine, which will trigger a water sprayer to flood the chamber. Use this only in case of a bean fire in the chamber.
  • Should temperature rise in the chamber uncontrollably, the system will automatically engage the water sprayer. Disable, when any fire is put out, with the Reset button.
  • No roast should take more than 15 minutes. A timer will halt a roast after 15 minutes. Larger quantities of beans roasted darker may need higher air temperature to ensure the target is reached before 15 minutes.
  • The front external parts of the roaster may get very hot in operation, especially continuous operation. Do not touch hot metal. Please.
  • Do not use the roaster for high volume commercial production. This is expensive and on loan. Let’s not PS1 it, okay?

List of Currently Authorized Users

Qualified Member Trained By Date
Theo Tetzlaff Owner/Why would I do this to myself?
Riley Pierce Danger Committee/Manager/Trainer/BAMF
Carl Karsten Riley Pierce 11/9/22
Ron Olson Riley Pierce 11/16/22
Dan Wells Riley Pierce 11/16/22
James Lamken Riley Pierce 11/16/22
Claire Fiorino Theo Tetzlaff 11/20/22
Ian Sampson Theo Tetzlaff 11/20/22
Joseph Staffa Riley Pierce 12/14/22
Andrew Wingate Riley Pierce 1/3/23
Elizabeth Koprucki Riley Pierce 1/4/23
William Shehan Riley Pierce 1/5/23
Laura Sparks Riley Pierce 1/5/23
Patrick Mahon Theo Tetzlaff 1/18/23
Ryan Mata Riley Pierce 2/8/23
Dan Walsh Riley Pierce 3/1/23
Ryan Helsing Riley Pierce 3/29/23
David Earl Theo Tetzlaff

Riley Pierce (refresher 9/8/23)

Jordan Kessel Theo Tetzlaff 4/16/23
Aaron VerDow Theo Tetzlaff 4/16/23
Jonathan Bisson Theo Tetzlaff 5/3/23
Lucas Alvarez Theo Tetzlaff 5/3/23
Bryan Sills Theo Tetzlaff 5/3/23
Adam Stafford Riley Pierce 5/17/23
James Nowell Riley Pierce 6/7/23
Paulina Hubli Riley Pierce 7/1/23
David Henderson Riley Pierce 7/23/23
Jim Leonardson Riley Pierce 9/13/23
Elizabeth Braun Riley Pierce 9/13/23
Matthew Gaffney Riley Pierce 9/13/23
Tam Ragatz Riley Pierce 9/13/23
Stephen Metzel Riley Pierce 9/27/23
Scott Yoder Riley Pierce 9/27/23
Paul Johnson Riley Pierce 11/13/23
John Jegerski Riley Pierce 11/13/23
Nathan Dietz Riley Pierce 11/13/23
Dan Tan Riley Pierce 11/13/23
Burton Kent Riley Pierce 12/9/23
Brent Myers Riley Pierce 1/10/24
Molly Williford Riley Pierce 1/10/24
Thomas Repasky Riley Pierce 1/10/24
Saad Ali Riley Pierce 1/10/24
Cris Sievenpiper Riley Pierce 1/10/24

Green Coffee Bean Suppliers

Please note, of these, I really can’t stress enough how generally superior and much more transparent + informative I find Sweet Maria’s compared to everywhere else. -Theo

Sweet Maria’s is great for the beginning roaster because they provide highly detailed cupping notes, suggestions on what level of roast to use, and their opinion on whether something would make good espresso. But the quality of the beans is a function of the grower, not the importer, and a big part of this adventure is discovery and experimentation. So I’d suggest eventually branching out and trying other importers once you have some experience under your belt. -Riley’'


Task Date Done by Notes
Clean two exhaust thermocouples 12/30/23 Ron and Riley
07/23/23 Riley and David Henderson
05/27/23 Riley
10/26/22 Ron and Riley
Clean glass chamber 12/30/23 Ron and Riley
07/23/23 Riley and David Henderson
02/20/23 Theo
12/21/22 Riley
10/24/22 Theo and Riley Spot cleaning only
Clean upper duct 12/21/22 Riley Spot cleaning only
10/24/22 Theo and Riley Spot cleaning only
Vacuum clean air intake filter 10/26/22 Riley
Clean lower dump valve 12/21/22 Riley Spot cleaning only
10/24/22 Theo and Riley Spot cleaning only
Replace upper chamber gasket 12/21/22 Riley
Clean hot air thermocouple 10/26/22 Riley

Nota Bene:

  • We have replacement gaskets and seals now for the roast chamber + venting tubes, etc.
  • Chaff collector should be checked regularly, depending on frequency and scale of roasting. Not a big deal, but consider checking chaff collector before a new roasting session and/or after roasting several times in succession with beans that give off more chaff [e.g., ‘washed’ beans].

Technical Details

The roaster uses a Watlow PID controller (on the left) to control air temperature. It outputs a process value (4-20 mA), which an Avatar Instruments power controller uses to change the power to the heater via SCR phase dimming. The Avatar supports 240 V but the heater itself only can handle 208 V. This machine was designed to operate on 208 V but JavaMaster confirms it can operate on 240 V with an adjustment. Originally, JavaMaster suggested we limit the PID to 70% max output power. But that resulted in unexplained oscillations in temperature typically +/- 30 F. The Avatar includes an optional feature to limit output voltage via the V-LIM trim pot. This was adjusted so 100% on the PID corresponds to 208 V as measured by a true RMS voltmeter. If the machine is ever operated at 208 V again, it will require re-adjustment of this trim pot.