Home Roaster

[Alan]

Hello all,

I'm tired of the lack of accuracy and control that goes along with roasting in my oven--a very old one--at home. I would love to have an indoor small-batch coffee roaster like this:

www.sweetmarias.com/prod.hottop.shtml

...that holds more than 9 oz. Is there such a thing?

Also, John, I'm assuming that you might know this, does this particular roaster mentioned above have temperature controls that go all the way down to 200 F, or do they start high?

Are there any other options that any of you can think of aside from buying a gas grill /rotisserie setup with a drum roaster?

I would rather have a stand-alone unit that I could use inside.

Alan

[Alchemist]

Being a home roaster (of coffee) myself, I can tell you there is nothing on the market that does what we need. The Hottop does not control that low as it is based for coffee. There are coming out with a new model that is more controllable, and I expect you could do up to a pound in it.

I am looking into some custom drums to easily fit into a simple homemade roaster, maybe with open fronts to allow sampling and thermocouples.

The one I mention in the other thread consists of cementboard backed by aluminum sheeting held together with screws along L aluminum corners. Heating is a table top grill element controlled by a variac. Very simple really to build with a minimum of tools.

I use this one inside as cocoa does not emit fumes as you know and the electric element has no byproducts either.

[Alan]

John,

I have some thoughts on a small batch cocoa roaster for indoor use. I'll post them tomorrow along with some images.

Alan

[Alchemist]

OK, I finally have what I want my next cocoa roaster to be and I might as well document the process here, let people chime in on the design, build along with me, etc.

I should say that I am not very mechanically inclined, but I can do the basics. One of the BIG lessons I have learned from building some of my own equipment is KISS (keep it seriously simple - yes I changed it) and use as good of a tool as you can afford, and if you can't afford the right tool, you may well save yourself the hassle, trouble, expense, agony and frustration of buying and using the wrong tool and just don't take on the project. That said, I tend to design around simple but good tools. For this project, this is what I will use.

• Jig saw - good metal blades.
  
• Circular saw - as cheap of a blade as you can find (you WILL kill even a good blade in this so go cheap)
  
• Drill and moderate metal bits
  
• speed square. Really - $5 - LOADS of problems solved
  
• various screwdrivers
  
• optional rivet gun
  
• tape measure
  
• hammer
  

I can't be sure, but that might be every thing. No welding equipment, lathes, brakes, or anything like that. Basic equipment IMO

What are we going to build. Well, a cocoa drum roaster ;D He is a quick summary.

The roasting drum will be made rectangular, solid or preforated as you see fit. Angle aluminum for the stirring vanes and corners, sheet metal for the sides and door. It will have a latchable front door.

The heating will consist of either nichrome wire or a table top grill element - builders choice. The element is easier to work with, but the control is not as quick. For cocoa (and 3 years experience), I find either will work.

The roasting chamber will consist of a sandwiched assembly of aluminum sheeting on the inside and outside, with 1/4" hardibacker (cement board) on the inside. They will be assembled and attached to angle aluminum at the corners.

The drum will be permanently mounted in the roaster, access via a pair of doors in the front. It will be rotated via a motor mounted in the back.

Heat control will be via a Variac (variable voltage transformer) or variable thermostat, builders choice.

If manual control is chosen, a thermocouple will be mounted in the chamber for temperature monitoring.

It will vaguely resemble my current roaster except it will be turned 90 degrees and not have the windows.

The whole cost will probably be in the$200-300 range for materials and most of that is the controls (variac, thermocouple or variable thermostat). Building materials will be sub $100 and should roast 2-4 lbs (depending on your desgin) of cocoa at a time. Up to 5lb should easily be feasible.

So, who is game?

[Alan]

John,

I'm certainly interested, but I'm not going to have much time to look into this in the next few weeks due to other projects.

A Question:

Am I understanding correctly that the roasting "drum" will be rectangular?


Thanks,

C-L

[Alchemist]

apatric said:

A Question:

Am I understanding correctly that the roasting "drum" will be rectangular?

Thanks,

Alan

That is the plan. Individually may wish to pursue traditional round cylinders, but from looking and experimenting quite a bit, I have yet to find a good way to make a round durable drum without a brake.

I have expermented with a retangular mock up and mixing is fine as long as you are 40 - 60 rpm. Slower than that and you get hot spots, but at the higher speeds, the beans are airborn more than in contact with the drum. And construction is way easier. Angle iron (aluminum actually ) for the edges, sheet metal for the sides, screws or rivits to hold it together. Quite simple.

static.flickr.com/41/84355453_719bf5bbac.jpg?v=0 [/img]

[Alchemist]

Well, I am going to just use this as my own sounding board, work out my calculations, etc. Jump in if you want, offer opinions and suggestions, ask why I am doing this certain way or just sit back and enjoy the ride.

My goal in this is two fold.

1) I want a 5 lb capacity roaster.
2) I want to build it in an afternoon.

On to the first item. 5lbs of cocoa beans take up approximately 300 cubic inches, or a 10" x 10" x 3" space. You want the drum only 1/4-1/3 full. I know from experience, you can push cocoa roasting to actually 1/2 full with fine results, but I am going to go with "optimum". So for my 5 lbs, I need a drum of 300 x 3 or 900 cubic inches (in3 from now on). 9" x 9" x 11" gives me 891 in3 which is fully close enough for me. This means I need four panels of 9" x 11" so a 36" x 12" panel of perforated (I am going to shoot for perf for air flow) should work nicely. I am going to go with solid ends, so that will go with other solid aluminum sheets calculation wise.

Some people may find this a little large, or just not ever plan to roast that much cocoa at a time. I will happily crunch some numbers here for other capacities, but I think the calculation is pretty straight forward.

How much do people want to roast?

[Brad]

Hmmmm....

This may be a stupid observation/question...

I could very well have overlooked some thread somewhere earlier, but why would someone go through all that trouble and expense, to build a machine that roasts just 5lb?

I'm currently roasting about 10lb per hour in my home oven (5lb every 30 minutes), and making as one very experienced chocolatier put it "Home Run" 70% dark chocolate.

Even if I decided to start a small commercial operation, it wouldn't be unreasonable to roast as much as 100lb of beans each day in a regular oven.

If I had a convection oven, I could do even more!

That being said, why re-invent the wheel??? Why not just go to a second hand store, buy a cheap stove for $50, drill a hole in the side and build a wire basket around a barbeque rotisserie and go to town with that? Temperature can easily be controlled using bricks.

Even better... drill a hole in one side of your existing stove and cover it with aluminum tape when you're not using it.

Sorry for the cynical tone to this email, but to me, all that effort doesn't make sense.

Brad.

[Brad]

Addendum:

What I didn't say in my previous post, was that I don't use baking dishes or cookie sheets to roast my beans. Restaraunt equipment supply stores sell mesh-like cookie sheets that allow the heat through, but not the beans. I also spread the beans very evenly around on the trays. This way the beans are exposed to air almost all the way around, roast evenly, and don't require turning every few minutes. I just stir the beans once every 15 minutes, and it seems to work just fine.

[Alan]

I have to say that since I figured out the bread stone temperature equilibrium trick, I am not nearly as much in a rush to have a mini drum roaster. Add to that the idea of the mesh cookie sheets, that Brad just mentioned, and I think that I may even be happier. I'm actually going to head over to the local restaurant supply place right now to see if I can find something like that as I'll be roasting more cacao tomorrow.

Perhaps with the combination of the mesh sheets and the bread stone, I'll actually be satisfied with my oven as a roaster.

We'll see. It certainly is a lot easier than building something new.

C-L

[Sebastian]

Benefits to an enclosed rotary drum type roaster will include greater flexibility in terms of what you add during roasting, if anything, as well as an increased chance of higher micro kill. If i were going commercial, i'd give this a great deal of thought...

[Alchemist]

Another reason is reproducibility of roasts. With a small enclosure, control is easier to maintain. I find even with a stone in my oven, I don't have the fine 2-3 F degree control I have with my variable voltage control with TC drum roaster. Ovens have a lot of thermal mass and without constant stirring, heat gradients can be pretty large. With my current set up I can hit any temperatue profile I desire - I can't do that with an oven. The controls are just not that fine.

I do agree with the oven idea though - punching a hole in a used oven and making a roasting drum. I have thought of this same idea. The trick is space. Most every one can find room for a small foot print table top roaster, not everyone can find room for another oven.

On the same note, I am all for the attitude of if it is not broke, don't fix it. If you are happy with your roasts, then there is no need to change.

Some people asked about building a drum roaster - I am trying to oblige.

[benvt]

I just found someone who makes just the round drums on ebay. ( cgi.ebay.com/coffee-roaster_W0QQitemZ170000255025QQcategoryZ67155QQrdZ1QQcmdZViewItem ) . They're a fair price. I'm thinking about combining one of these with a heat source.

[Brad]

Hey...

I just checked it out!

Now THERE'S a good idea and price!

Good call ref!

[Alchemist]

I had not seen those before. I do kind of wonder how he can sell them so cheaply. The raw materials are close to what he is selling for (if not more).

What I do note is that it is a bit long a narrow. You are going to be able to roast about 2 lbs in that, if that. I say if that as I have experimented with another drum (RK drum - a bit more pricey) and even at 8", the vanes as they were too close to the center shaft and there was mixing problems - just not enough clearance. Great for coffee, but cocoa is more bulky.

BTW, they are not on the site, but if anyone has an interest in a cocoa rk drum, contact me. I had Ron (R of RK) make a few for me with shorter vanes and they mix well.

Finally, in question to your semi-rhetorical (?) question Brad, why would someone build a roaster? For me I enjoy designing and building them. Sometimes it is not the destination that is the goal, but the journey.