Home-built roasting drum

[Bardo]

My friend (who is a metal worker) and I have finished the first prototype of the BBQ roasting drum. It is what you might call heavy duty, being made of 1/4 aluminum. Weighs about 7 lbs I think. Next step, getting grill and rotisserie pieces pulled together. Great excitement, and thanks to Buzzroaster for his generous guidance.

 

[CoffeeJunky]

I don't see the fin inside of your drum.
You need to have at least 2 fins.

Other then that, it looks great.

When I was making my drum roaster, I went out and got a used bbq grill.

Good Luck

 

[PinkRose]

CoffeeJunky,

You're very observant! I bet a lot of us didn't notice the missing fins.

Rose

 

[Bardo]

There are two fins, 1.5 inches deep each, at 180 degree intervals.

 

[PinkRose]

Thanks for clearing that up, Bardo.

Thanks for sharing your creation with us. Soon you'll actually start roasting with it. I bet you can't wait!

Rose

 

[peterjschmidt]

I'm curious about the size of the holes, and how you'll keep the door/flap closed during roasting.

 

[CoffeeJunky]

those holes are big enough to release smoke so not big of deal. Flaps can be easily secured with spring or little hook so that also would not be too big of deal.

As long as there are small fins to flap the beans around, that would work fine.

Good Work

 

[Bardo]

I am planning on a small hasp to keep it closed, very simple. The holes are 1/4 inch, although we did countersink them on the outside, in the hopes of getting the air moving faster. Not sure that I have a scientific reason for doing that.

 

[BuzzRoaster]

This will definitely get the job done . Very nice work.

Because this drum is made from very thick aluminum, it is going to conduct and hold heat very well. You are going to have to be pretty diligent with your temperature control. It is not going to respond to flame adjustments as quickly as a thinner material. Initially you may have to anticipate the end of first crack and lower your temps sooner, until you get the hang of how this drum will behave. One other thing I would recommend is to play with your preheat temps. Again, because this is pretty thick material if you preheat this drum too much you may find you are getting to first crack too quickly, especially with smaller batches.

Of course all of this is just speculation on my part, just a few things to consider before taking this new drum for a spin (pun intended)

Make sure to log everything until you get used to how your drum behaves.

Nice Job!

 

[Bardo]

Junky, did you have any odor problems with your used grill? Maybe hamburger flavored coffee is the next big thing, but I don't want to be the guy to introduce it. Buzz,
Good thoughts. My goal is to maximize my control over the variables of heat and airflow, base on yours and others input. To that end I will close it up as well as I can, with the exception of intake and exhaust holes, and perhaps go with the idea of a small fan on the exhaust. Also a good electronic thermocouple to track the temp accurately and pretty real time, and some kind of metal cover over the heat element to more smoothly radiate the heat. Other ideas as I search for the grill?

 

[CoffeeJunky]

I actually cleaned the bbq grill very carefully. I washed and washed again.
I didn't get to the bare metal but it was pretty clean and I never had any order problem. Also I had my grill burn for at least 15 mins before I roast my beans. That also take care of other things left behind.

 

[peterjschmidt]

Just a thought, and this is sort of a moot point as you've built the drum already... on a commercial roaster, the drum is usually solid, with perforations on the back of the drum, so that when air is drawn out of the roaster it has to pass through the drum. Your airflow will be different as air going from an intake to an exhaust will have less resistance flowing around the drum, and so the beans will roast slightly differently.

 

[Bardo]

Yes, roasting using a BBQ grill as the heat source is different than commercial roaster, from all accounts that I hear. But it is a matter of learning the behavior of your particular roaster and being able to control the heat and therefore the roasting profile. After all, coffee has been roasted in frying pans with great success for centuries!

 

[peterjschmidt]

You are correct, sir.

I'm unsure what the effects of airflow through a drum really are anyway... I did two roasts on Thurs of the same bean, trying to hit the same time/temp profile, but had the airflow completely closed on the first batch and completely open on the second. Hopefully, that will teach me something when I cup to the two.

I guess my thoughts are simply that you will be using airflow as a means of controlling the temp/environment in the drum, less so than using airflow to draw out certain flavors. Please don't interpret that as saying your method is any less viable than mine.

 

[BuzzRoaster]

Too much airflow can greatly effect the moisture content of your roast. Too much moisture loss results in a flat tasting cup.