blondica73 wrote:I ran a sample roast using the TC4 and difference in temps grows to as much ast 60F at one point.

Are you saying that the reading between the TC4 and the Omron start off the same but as the roaster warms up the two readings begin to vary from each other eventually by 60f? And you are using an Omega dual thermocouple probe?

*Edit- just saw your BC Automation thread and it seems this is what you described is happening. This behavior sounds to me like you have the thermocouple probe wires reversed to one of your devices. Go to the device which seems like it's off (the omron?) and reverse the thermocouple leads. Also make sure all leads are making good contact/screwed down properly. Also make sure you have the right type of thermocouple selected in both phidgets and the interface program for the TC4 (with phidgets is called phidget control panel, it's separate from artisan and has settings like what type of thermocouple are connected)

Here is the spec for the A/D converter (MCP3424) on the TC4 board.
"With Type K thermocouple, it can measure temperature from 0°C to 1250°C degrees. The full scale output range of the Type K thermocouple is about 50 mV. This provides 40 µV/°C (= 50 mV/1250°C) of measurement resolution."
This could explain the difference as the OMRON controller expects 0-900F while the OMEGA thermocouple is -328 to 2282°F. Based on the OMRON manual I believe I need to change the input type from 6 to 5 to ensure it interfaces properly with the thermocouple. I'll make the change this weekend see what happens.

So after spending a few months with this roaster, gaining experience and performing numerous upgrades I wanted to update this thread. First I would like to revise my initial review of the roaster. I still feel that the roaster has a lot of quality and am happy with the construction as it comes from the manufacturer, however there are a few areas which really need to be refined in order for the roaster to really shine and which probably holds back the roast quality compared to larger/more sophisticated roasters until corrected. I don't think these issues are only with the BC-1, it seems that most other small gas roasters share the same limitations.

1) The airflow control is ridiculously poor. The fact that they even add an airflow control knob makes you think your controlling airflow but you really are not. I added a magnehelic gauge and can tell you any change in the knob from 20% to 100% produces an extremely tiny change in airflow. Below 20% every fraction of an inch you move the knob has a profound and unrepeatable effect on airflow/fan speed. In the newer models they added a damper which should take care of this problem (although I still think a magnehelic would be useful to visualize the air flow changes with damper settings).I upgraded the fan on the roaster with the same dc controllable version that comes with the Mercury (with help from member Hankua, thanks for your considerable help/efforts Hank!) and now have 100% control from 0 - 100% with a 0-5v control signal


2) I feel that these small gas powered single layer drum roasters put too much energy directly into the drum with not enough thought put into the air-path through the roaster. This, I feel, results in too much energy coming from conduction vs convection and the air not heated to a high enough temp. Also these roasters have 2 burners, which provide more than enough btu's but because of their design, put out considerably more heat in the center of the drum where the flames from the two burners overlap. These also have thinner drums then larger roasters, which is necessary so that the thermal mass of the drum doesn't overpower the smaller amount of beans these hold, but also do a poorer job of spreading out the heat resulting in a potentially unevenly heated drum with hotspots. I have combated this problem by installing a copper heat shield between the drum and flame which transverses almost the entire length and width of the roast chamber (with a small gap in front in case chaff falls from the front of the drum) which increases the heating of the airflow, decreases drum temp, evens out drum heating, and consequently increases convection vs conduction energy.

3. The drum has forward mixing vanes but not reverse. Maybe the manufacturer thinks they are not needed on a 1lb roaster but the Huky managed to fit them in and I can't imagine how they wouldn't improve mixing of the coffee in the drum and preventing the beans from staying against the front of the roaster.

I will post the details and pictures of these mods in the next post

Magnehelic:

This was installed in the exhaust stack. Hankua gave me all the part numbers needed so I didn't need to do any research.. Thanks again Hank.



Dwyer Magnehelic 2000-00 0-.25" wc.
1/8 npt male barbed fitting 3/16' Id into hole drilled/tapped to exhaust plenum
3/16" silicone tubing
Dust filter for gauge

Fan:


CY100LBDC24DC-7-V2 24V three wire fan, 24v+, -, 5v+ controll signal. It comes with a simple control circuit for a few bucks. This should also be easily be controlled by artisan with a phidget or arduino, etc.

Heat Shield :








Made from 99.99% copper 101. Held in with:



Which I drilled/tapped and replaced the m4 screws which hold on the outer covering of the roaster with longer ones that protrude into the roaster and screw into this aluminum bar stock

Nice, thoughtful report!

Amazing, that's all I could say!

blondica73 wrote:Here is the spec for the A/D converter (MCP3424) on the TC4 board.
"With Type K thermocouple, it can measure temperature from 0°C to 1250°C degrees. The full scale output range of the Type K thermocouple is about 50 mV. This provides 40 µV/°C (= 50 mV/1250°C) of measurement resolution."
This could explain the difference as the OMRON controller expects 0-900F while the OMEGA thermocouple is -328 to 2282°F. Based on the OMRON manual I believe I need to change the input type from 6 to 5 to ensure it interfaces properly with the thermocouple. I'll make the change this weekend see what happens.

Temperature differences between OMRON and TC4 were fixed, I neeed to ground the TC4 board to the common ground, roaster ground. Now they are wishin 3 F. I inserted an offset in Aritsan and they match now.

Awesome update Josh. As you know I'm investigating a lot of this too and I really appreciate all that you have done and shared.

I'll bet I'm not the only one interested in the magnehelic path too. IF you or Hank would post those parts that would be greatly appreciated too. Also, did you have to filter for chaff/smoke fouling?

Happy Roasts!

Very cool to see an air pressure magnehelic installed on this. Good work! Can you expand on your experience with that a bit more? I've been looking to do the same to my machine.
Did you need a pitot tube?
Did you account for the heat of the air or the dust/pollution?
What typical range do you use for your machine? I'm trying to figure out what pressure range I need so I can maximize the range for the gauge I eventually get.

Thank you!

Madman13 wrote:Magnehelic:

This was installed in the exhaust stack. Hankua gave me all the part numbers needed so I didn't need to do any research.. Thanks again Hank.

<image>

Dwyer Magnehelic 2000-00 0-.25" wc.
1/8 npt male barbed fitting 3/16' Id into hole drilled/tapped to exhaust plenum
3/16" silicone tubing
Dust filter for gauge

Fan:
<image>

CY100LBDC24DC-7-V2 24V three wire fan, 24v+, -, 5v+ controll signal. It comes with a simple control circuit for a few bucks. This should also be easily be controlled by artisan with a phidget or arduino, etc.

Heat Shield :
<image>

<image>

<image>



Made from 99.99% copper 101. Held in with:

<image>

Which I drilled/tapped and replaced the m4 screws which hold on the outer covering of the roaster with longer ones that protrude into the roaster and screw into this aluminum bar stock

Where did you purchase the copper sheet from? I would like to try one of those for my BC-5. Could you post roasts of before and after the copper shield?