Copyright 2004. All rights reserved.
Making a grill based coffee roaster a little more roaster and little less grill.
In January 2003, I built the Five Pound BBQ Grill roaster . The five pound Frontgate drum-based grill roaster has served me well for almost two years. It was time to make some changes that I had been mulling over in my mind to improve the setup, and take it to the next level of roaster proficiency. It needed a ventilation system--a way to vent smoke to the outside of my workshop and away from the beans. The plan was to use the almost 2" opening along the back of the grill top to capture both smoke anc chaff. It was the obvious place, because when roasting, the smoke and chaff poured from that opening.
I bought two 6" ductwork register boxes and pop riveted them together, cutting away most of the ends where they joined to allow heat and smoke to flow through one to the other and up the flue. I cut and formed a top piece and fabricated the other necessary pieces to extend the box out to the side of the roaster so that a flue could be attached without interfering with the grill top as it opens and closes.
A 3" flue pipe seemed to be sufficient to allow smoke to escape without sucking all the heat from the roaster. I couldn't find the necessary 3" triple lined thimble piece that goes through the wall and provides an airspace for fire protection, so I settled for a 4" thimble, and used a connector between the 3" and 4" flue. A length of flexible metal tubing connects the roaster with the fixed flue going through the wall. This allows the grill/roaster to move around a bit without tearing up the flue. The two 6" register boxes catch quite a bit of chaff that falls out the back.
(Click the pictures to enlarge)
The box! The box! A simple box with a couple of chaff cleanouts and a flue/damper.
Here's my roasting setup with the vent to the outside. Cooling tray is to the left of the roaster and the big floor fan helps push smoke out the door when I lift the lid to dump the beans.
Here's a rear view of my little roasting corner in my workshop.
Here's the 4" outside flue through the triple walled thimble.
Here's a closeup of the vent box and twin chaff collectors. One would have been better, but with off the shelf parts, this was easier to do.
The bean thermometer is a 12" dial thermometer stuck into the bean mass through a hole in the grill top and into the open end of my drum. It seems to give me reliable temperatures that correspond to those I would expect at the various roast points.
A clamp on fitting holds the drum shaft upright while I pour beans in using a canning funnel.
I still need to finish my two pound fluid bed roaster, but in the meantime, the bean cooler portion of the project works great for getting five pounds of beans cool in a couple of minutes.
The main thermometer is shielded from direct heat/flame with a 6"x6" terra cotta ceramic tile (cracked on first use, but still works)
I use this little digital timer to keep track of my roasting times. Nothing special, but it has taken quite a licking and keeps on ticking (OK, it doesn't tick, but I couldn't resist)
The cooler portion of my fluid bed roaster project works splendidly to cool the beans in a matter of a couple of minutes. I stir them with a wooden spatula until they are mostly cool.
I love stirring the beans after a successful roast. Kinda like a little Zen garden
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Quote of the day..."Drinking ISH that I paid $22.50 a pound for, roasted in a HotTop
that I paid too much for, brewed in a Solis Master that I paid too much for - but it sure does taste good!"
John Abbott, Sweetmaria's Homeroast List