Growing increasingly unhappy with my ability to get even roasts from my SC/TO, I decided to explore alternative options.

Convinced after a few controlled trial runs that my problem is with improper agitation of the beans, I thought a drum roaster would be the best way to ensure as even as an agitation as I could get.
I needed a roaster to keep up with my coffee intake, so something around the 14oz to 1 lb range would be ideal. I attempted to find a replacement Behmor drum but they seemed to be out of stock everywhere so I wound up "risking" a mini (coffee and nut roasting) drum from Asia. I was actually surprised and impressed with the build quality.

I then gathered some other materials:
I found a 10" diameter canning pot from Goodwill
Ice cream maker from Goodwill (for a low rpm / high torque motor)
1/4" bar stock and some other nuts, washers, and bolts from the hardware store
Halogen Convection (Turbo Oven) from my previous SC/TO set-up.
Thermocouple from my previous setup.

And I created this: http://goo.gl/photos/PgCeXJG4JQ1nNFsC9 <-Will post to youtube later
(obviously I still have some work to do as far as the motor mount is concerned)
I loaded her up with 14oz of Brazil Bob O Link and switched her on.

The result was the most even roast I have gotten so far.


Cooling is also easy, I just remove the oven top and point a fan / leaf blower at it with the drum still rolling.

Oddly enough I hadn't seen anyone else with a design like this or I would have skipped the Stir Crazy base altogether.

Sweet Maria's tweeted just today that the Behmor drum is back in stock.

What were the roast timings like for milestones like full yellow, first crack, when you started cooling the bean mass?

[quote="yakster"]Sweet Maria's tweeted just today that the Behmor drum is back in stock.[/quote]

I "knew" that would happen as soon as I got my hands on another drum, oh well.

As for milestone times they were a little out of whack due to me having to experiment with the proper heat settings on the Turbo Oven for the new drum base. I found I have to set it much hotter than before due to all the extra air space. I'm going to roast another 14 Oz (by weight) batch in a couple days and post updates and maybe some better component pictures as well.

Cool build, definitely an upgrade from "traditional" turbo roaster builds. Keep us updated with how the coffee ages. Also, I'm curious its constancy from roast to roast.

I love the inventiveness! The Behmor drum would add the churning effect from the interior fins, improving/adding to consistency of roast.

It looks like it'll be easier to load and dump the beans with the drum you bought. With the Behmor, you've got to pull it out of the roaster because the beans come out the end instead of the side. I'll be interested in hearing any updates on how this works out for you.

Are the beans in the picture provided natural or wet processed? Either way, pretty even roast, I do not think you need to go to the behmor drum and its churning fins.

This is the coffee I used for that "first trial" in the photo: http://www.bobolinkcoffee.com/Coffee.as ... linkCoffee

With regards to the drum, the side hatch style is definitely convenient for loading and dumping, I don't plan on actually removing the drum from the canning pot unless I really need to for some reason. There is one churning fin on that drum, I'm not sure if it does much or not. As long as I continue to get consistent roasts (that taste good of course) I will be happy.

It looks like I'm going to churn through this coffee quicker than I thought, so I will probably post more updates in the next couple days.

Trial #2 on the drum base for the roaster, here are some more in depth pics as to its construction:
1/4" threaded rod with coupling nut "spacers"
Holes drilled into stockpot. Used dremel to grind away threads from touchpoints of bar stock and stock pot.


Coupling nut to 1/4" screw, socket adaptor drill bit jammed into ice cream maker motor.


Drum with 14oz of beans.


The roaster with motor and oven attached.


An attempt at an "action shot" although the halogen light made it near impossible to photo the beans mid roast. In real life the visibility to the beans is a bit better than what this picture represents.


The final roasted product.


So my findings after roast #2: Despite the fact that I put the Turbo Oven to its hottest setting right away and left it there, the roast time is still slow, almost as slow as my very first try. I pulled these beans out after about 22 minutes. They drying phase lasted almost 15 minutes.

I am open to suggestions about getting the roast times down.

With the stir crazy bottom my roasts went between 13 to 16 minutes. My main guess for the increased roasting time is that there is simply so much more space in the stock pot to heat, and it may not be the best insulator.

Possible improvements to try in order of least to most effort would be:
Preheating the roaster: The total "time" would be roughly the same but at least the roast time should decrease by a minimum of 3 or 4 minutes.
Insulating the canning pot: With what?
Diminishing air space within the canning pot: how?

Other possible improvements:
How is the drum rotation speed, should it go slower or faster? I could easily replace this cheap ice cream maker motor with a somewhat more expensive variable speed drill, or a quieter motor.

There is a little bit of a sound problem. With all the agitation of the drum combined with the motor, I can't seem to actually hear first crack or second crack and have to play it by sight and eventually experience. Are the cracks truly audible in other drum roasting setups?

Despite these issues, my roasts are much more even than anything I have pulled out from my stir crazy base, even after trying out a few popular agitator arm designs, and for the first time since starting my own roasting a few months ago I am happy with the evenness of my roasts. The drum seems real hard to mess up in that regard. Even if this last roast was slightly less even from some reason that my first roast, all the beans were in the same ballpark.

I'll post another video tomorrow where I talk briefly about the drum base in its current form and then a few shots of the beans roasting.

Thanks

Im thinkin the heater is just too far away from the beans. Can you put a couple metal paddle thingies in there so the beans get pushed up closer to the heat? Or, perhaps more drastic measure, but rig a frame and invert everything so the heater is under the beans? Or work on the heat source/controls, is it cycling on and off during the roast or staying on?