Thought I would send you an update along with some pics of the new roaster,
After some research on the web I chose this Broil-Mate unit rated at 44,000 btu with a twin H burner and cast aluminum construction for about $220 delivered at ace hardware online
I then sourced a nice 5″ dial analog thermometer on ebay with a 12″ probe that sits about in the middle of the drum 1/2″ above the top, it seems to adjust rapidly to heat changes and the probe only senses heat at the tip so it works out well
I found a heavy duty 12″ fan that moves 2200 cfm and fashioned a cooling box that could be mounted to the frame and a removable sleeve lined on the bottom with 1/4″ hardware cloth then a window screen mounted in a slot below to catch the chaff, at the bottom the fan blows down to pull air through rather than push the air (and chaff) through
Using your motor I made a box of birch ply with a 1/4″ aluminum plate mounted in front, a 2 gang box is mounted with a switch for the motor on the left and one for the cooling fan on the right
On my first and only roast (so far) I decided to go ahead and try 5lbs. of green beans because this is the load I want to learn the profile for.
I fired up the grill and at about 6 min. it hit 600 degrees, I pulled the drum, loaded the beans as quick as I could and the temp was under 500 when I resumed, I got the temp back to 575 by about 5 or 6 min in and by about 15:30 had heard a few snaps of the first crack, at about 16:45 the first crack was rolling hard and the temp was reduced to about 550, 18:20 sees the end of first crack and 19:30 the second starts with about the 20 min. mark seeing a fast rolling second crack and I turned off the heat, dumped the beans as fast as possible into the cooler and started to stir with the wooden spoon, the cooler worked great with the beans at ambient temp in about 2 min., I have to say that even though I went into the second crack a little fast (I will get it right the next time) this has to be the most evenly roasted coffee I have ever done! My Hottop cannot compare! and at 10 times the batch size this thing is AWESOME! It now gets the coveted spot on the back garage wall NICE!
Next comes the sheet metal mods as my heat is at 60 to 70 percent most of the roast, My only problem now is I have to give away to much coffee because I want to try this thing out again soon!
Hats off to a great product!, Gil Scales