arriflex wrote:
Regarding drum/pot shape, your early posts on choosing higher speed agitation were inspiring to me. So much so that I've even considered a pot that tapers slightly inward at the top like a Turkish shape might. Anyway, I'll leave further discussion to the "dynamics" thread.

arri

I'd be careful not to have too much taper or it could effect the air circulation if you use a similar fan and element design as a TO top where the fan blades blow air out sideways passed the surrounding element and then down the sides

The fan on this thing is about 4.5" diameter. I haven't powered it up yet, but in spinning it by hand I suspect it moves a pretty fair amount of air. There is a fair amount of KISS I wouldn't mind maintaining, so it's fine to stick with a straight sided pot for simplicity.

I would imagine the blade design on that fan are similar to a TO top. It draws into the middle and blows towards the side. Different than a typical exhaust or window fan. You can always hold a little smoke by it and see where it goes. On a TO the perforated plate bring flow up and in and shoots out the open sides going past the surrounding 2 layer element. A rather nicely designed heat producer.

You are correct, it is a centrifigal fan without a housing and will draw air from the center and throw it across the heater element. Mine is an AC fan so speed control will be limited to something like a router speed controller and torque will go way down with voltage. There have been previous mentions of a desire to control the speed of the fan, I assume this affects primarily the convective action in the roast. When and or why would one want to increase or decrease the convective role? Would it be in tandem with changing the rate of radiant element?

Arri

You just have to be concerned with fan speed and chaff movement getting sucked up in the heating system. I found the best speed for my design and don't adjust it. We're OT. You should either start a thread on your roaster build or send me a PM.
farm

Thanks Ed, I just ran across a number of threads that I hadn't previously seen that seem to have a lot of concepts that will help me. When I start my build, I'll get a new thread going. For now, I'm inspired by numerous topics that have led me to believe that I just need to get my feet wet and see how it goes. Then start thinking about improvements.

Harvest season is upon us in California and I will not have time to start a build until fall. Plenty of time to continue reading.

Jim, I'd like to clarify the basic setup of a Catuai TC4 combination as you described applied to my prospective rig:

2 Thermocouples placed one in the bean mass and one for environment monitoring. Type K seems to be most compatible with the libraries written thus far for the TC4 recognizing that they were written modularly so that other TC types will be supported eventually.

An Arduino and a TC4 shield with the thermocouples connected directly to it. If I understand correctly, some consideration for the project box and location of the TC4 should be made for measuring environmental temp at the TC connection to it. I assume that by directly connecting the TC to the TC4, this is self corrective.

Load the Arduino with the aCatuai.pde sketch you linked to earlier in this thread. Is this instead of aBourbon? The readme for pBourbon says

As of release 2.20 of pBourbon, you may also
use the aCatuai.pde sketch on the remote.

which sort of implies to me they might both be loaded simultaneously although I'm pretty sure that would not be good

On a computer, I need to download Processing and run pBourbon in that IDE according to one of your posts at Homeroasters.org pBourbon will pull the data streaming from the Arduino running Catuai and do pretty things to it, but does not send anything back to the Arduino.

All controls are hard wired to the Arduino and TC4? 10k Potentiometers for analog input to control pwm/ssr outputs and buttons for creating markers. Do I have to have the 16x2 display for aCatuai or aBourbon to work or will they work without it?

I feel like I'm re-writing a FAQ, but I couldn't find one anywhere so I'm sorry if this is repetitive.

It would be really cool, and really challenging, to have a taxonomy and feature chart of the numerous TC4 family members.

arri

arriflex wrote:Jim, I'd like to clarify the basic setup of a Catuai TC4 combination as you described applied to my prospective rig:

2 Thermocouples placed one in the bean mass and one for environment monitoring. Type K seems to be most compatible with the libraries written thus far for the TC4 recognizing that they were written modularly so that other TC types will be supported eventually.

Correct. The currently released software expects type K. There is, however, a newly added library that supports K, T, and J. It requires only a very simple edit to either aBourbon.pde or aCataui.pde to use J or T.

arriflex wrote:An Arduino and a TC4 shield with the thermocouples connected directly to it. If I understand correctly, some consideration for the project box and location of the TC4 should be made for measuring environmental temp at the TC connection to it. I assume that by directly connecting the TC to the TC4, this is self corrective.

A nice, permanent installation would include a project box and two thermocouple panel jacks (available from Omega.com). As long as you use thermocouple wire between the panel jacks and the terminals on the TC4 board, then any differences in temperature between the inside and outside of the project box are compensated.

Short of this, then running the thermocouple leads all the way to the TC4 terminals is the most accurate method of connection.

arriflex wrote:Load the Arduino with the aCatuai.pde sketch you linked to earlier in this thread. Is this instead of aBourbon? The readme for pBourbon says which sort of implies to me they might both be loaded simultaneously although I'm pretty sure that would not be good

You can load only one sketch at a time into the Arduino.

If you wish to simply monitor/log your roast, then load aBourbon.pde.

If you wish to monitor, log, and manually control your roaster using potentiometer dials, then load aCataui.pde instead (not in addition).

Zip files with the current releases of Catuai and Bourbon can be found here:
http://code.google.com/p/tc4-shield/downloads/list

arriflex wrote:On a computer, I need to download Processing and run pBourbon in that IDE according to one of your posts at Homeroasters.org pBourbon will pull the data streaming from the Arduino running Catuai and do pretty things to it, but does not send anything back to the Arduino.

Yes, download Processing and use its IDE to load and run pBourbon.pde (edit the COM port ID in pBourbon.cfg first). If you have any trouble with this step, let me know and I will create an executable distribution of pBourbon and post it on the project site.

Aside from a bit of 2-way communication to synchronize timestamps, with pBourbon the stream of data is strictly from the Arduino to the PC.

arriflex wrote:All controls are hard wired to the Arduino and TC4? 10k Potentiometers for analog input to control pwm/ssr outputs and buttons for creating markers. Do I have to have the 16x2 display for aCatuai or aBourbon to work or will they work without it?

Not sure what you mean by hard wired? The potentiometers connect to standard 3-pin headers on the TC4 (+5V, swipe, GND). The pots are required only if you wish to monitor and control your roaster using aCatuai.pde. (EDIT: on my setup, the two potentiometers are panel mounted, with 3 lead wires each. I put Molex KK crimp connectors on the ends of the leads, and they slide on/off the pin headers. There are also many other choices for connectors that will attach to the standard 100 mil spacing pin headers on the TC4. The leads could also be soldered directly to the board).

Neither the 16 x2 display nor the buttons are required -- strictly optional. But if you do decide to hook them up, using the project's custom I2C port expander PCB (LCDapter board) makes it much easier.

arriflex wrote:I feel like I'm re-writing a FAQ, but I couldn't find one anywhere so I'm sorry if this is repetitive.

It would be really cool, and really challenging, to have a taxonomy and feature chart of the numerous TC4 family members.

Agreed. All that is needed is a volunteer

Jim

Thank you, Jim, very much. When I start getting the gear together and get some real hands on with it I'll try and write up a guide.

arri

arriflex wrote:Thank you, Jim, very much. When I start getting the gear together and get some real hands on with it I'll try and write up a guide.

If you end up having time to do this, I think it would be of great benefit. Thanks.

Jim