Due to numerous unexpected expenses, the budget intended for drum roaster build was reduced to almost penny. Needed to start the project on target date with such small funds. It must be broken down to several small sections. Do one at a time as the budget and incidental materials come. Incidental refers to materials scouted from junk shops, friends donations and scraps from broken equipment.
I placed my bet on the drum first. Besides, this is always to first step found in every roaster build demos and tutorials. We sub-contracted the drum, center shaft and front plate. We don’t have yet the equipment to roll bend thick metal plate and weld the middle shaft in almost perfect center. We build the skeleton housing ourselves and borrowed a 3-phase geared motor plus VFD from a generous friend. The drum rotated as intended and seems to mix the beans well after few trials and modifications. Did a first roast with a poorly made housing – thin galvanized iron sheet. It went well.
Time to get a little serious.
I observed so much heat loss on the sides. Not surprising cause we used galvanized iron sheet. The roast process could have used half the energy with the same output.
Perhaps the best insulation popped out of my mind is the clay brick. I already saw several ovens made of bricks. They looks nice and energy efficient. Locally made pizza oven are lined with bricks. They are not so popular I guess. Heavy and fragile blocks require extra cost and care during transport. I may want to ship the frame and bricks separately. Or, rather build all from scratch in point of installation. Then again, change of position will be tedious.
The next in line is asbestos. They are highly toxic however. It may require me more money for safety measures, hazard pay and hospitalization in the end. Let say we installed successfully with great caution. Roasting my commodity immediately next to unsafe thing makes me feel guilty.
Fiberglass is another a good choice but also has safety issues. Just imagine minute glass pieces suspended in air. It may not hurt skin but what if inhaled? An inert and dangerous foreign matter inside the system.
Then I accidentally saw the ceramic fibers. A guy was installing it in his newly made laboratory oven. Ohh! It maybe my best bet for now if not for its high cost and life span of only two years. It become brittle after the period. Easily broken with slight forces. Meaning, it should be securely installed in-between walls. Preventing it from getting into foods once degradation begins.
I think I should take it slow. Like what i usually do. Use roaster and made modifications as excess budget appears.
Marvin is the lead chocolate maker of Ben and Lyn Chocolate Inc. Has strong background in food research and development. Occasionally conducts training and lectures. Lecturer of Cocoa Foundation of the Philippines. Do coaching and consultancy services on his free time.