elkayem wrote:
elkayem wrote: "I don't have any firm evidence on why the original setup didn't work, but my suspicion is that the corrugated hose that came with the the air pump was slowing down some of the air flow. "

Brewin_Bruin wrote:

One alternative for controlling/reducing airflow that IS cheap and simple came to mind. It's been mentioned by others in the fluidized bed forum: instead of controlling the motor speed you can introduce a variable leak via a Y or T connection between the blower and the heating coil, with a valve that allows you fine control. Since most of the current is going to the heater, you can sacrifice a little electrical efficiency for simplicity and lower equipment cost. Following the "KISS" principle is generally a good design perspective. It might whistle, depending on how things are configured.

Brewin_Bruin wrote:
Be careful with PWM and AC motors, unless you do extra tricks like zero crossing, they don't play nicely together, but with DC motors, it's fine.

elkayem wrote:

CharcoalRoaster, thank you for the pictures! I'm trying to discern how you connect the funnel to the heat tube. It looks like some kind of a rubber tube enclosed in a metal tube with a clamp? Looks clever.

Garageroaster, nice design! I was thinking of some kind of a threaded interface like I see in your photo, but couldn't figure out how to spin the RC with the thermocouple wires. I'll have to check out the Ace hardware kit you mentioned. Also, yours must be the only one with a roast chamber supported on the back of a turtle.

elkayem wrote:

It's been a while since I posted to this thread, so I thought I would take a moment to post an update. My build has been proceeding very slowly, but I'm in the home stretch now. A friend gave me access to his laser cutter, which led to a very nice case. The 12V "Air Pig" pump has more than enough power. I'm getting great bean circulation. Perhaps I'll post a video soon, when I start roasting. The only thing left to add is the heating element. Perhaps I'll make a final push to complete this project, and get it all together this weekend.

Here is a photo:

renatoa wrote:
I can suggest you or others interested into a "next project" to consider the MCP4324 sensor board instead the MAX, is the chip used in TC4, much cheaper, at least same performance class, and 4 channels.

garageroaster wrote:

elkayem, my build was based off of OGH's design also but instead of a cocktail shaker I used a sink drain kit and a 7" drain elbow. By doing this I was able to utilize the nut and threads to secure the roast chamber. When my roast is over I vacuum off the chaff and simply unscrew the base to dump out the beans, it actually works pretty good. I'm still in the prototype phase but am going to be building a box to house and stabilize the unit once I get time. The drain kit was $17 at Ace Hardware. Cheers.

greencardigan wrote:

How do you find the MAX31855 in use? I've been experimenting with them attached to a Raspberry Pi and they dont work with grounded thermocouples. Have you had any issues with that? Is your roast chamber grounded?