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1-6 lbs Roaster Build - Nothing Fancy
Thanks Allen,

Yes there will be about 3/4" of space between the front of the drum and any vanes. The spokes will be recessed 3 inches and the front of the reverse vanes are 2 inches from the front of the drum. I'm going to put a small reverse vane on the drum just behind the forward vanes similar to how North/Mill City does it. So there's at least 2 inches for my trier, or 3 if I go closer to the center axis. But, the reverse vanes can be moved, so if during testing it's not quite right I just have to break a tack weld to move them.

I have a needle valve on the burner, which is how I got the lower pressure for the video (about 0.5" WC). One thing I've noticed with the jet burners is that they like to be impinged on something, usually in ring burners it's another burner. Without the impingement the flame isn't very stable.
Behmor 1600+, Fresh Roast Plus 8, Poppery II; Lelit Bianca V2, Eureka Mignon Specialita', V60, Breville SGP
Made some progress on the drum. Split shaft collars mounted to spokes; spokes pounded into place (it's a nice tight fit), and one set tacked to drum.
I found out after the fact that the grooved side of split shaft collars is the perpendicular reference face which is spec'd to be perpendicular to the bore. I doubt it matters here, especially once the heat from welding is added to the equation.
Next up, take it to work and put it on the lathe to square the ends and cut to length. Then comes more welding: 1/8th inch strips of steel to make the air space and finally the outer skin.

I opted to use TIG instead of soldering since I don't feel like spending the money on 'safe' soldering/brazing rod free of elements bad for human health.
UmMerkur attached the following images:
img_20220410_181029.jpg img_20220410_184133.jpg

Behmor 1600+, Fresh Roast Plus 8, Poppery II; Lelit Bianca V2, Eureka Mignon Specialita', V60, Breville SGP
Worked on the drum some more. Stripped the paint and trimmed close to final length, 12.25 inches.
1/8th by 1/2 ring tacked in place along front of drum, this will space the outer skin. Will also be adding axial strips.
UmMerkur attached the following images:
img_20220417_214937.jpg img_20220417_214649.jpg

Behmor 1600+, Fresh Roast Plus 8, Poppery II; Lelit Bianca V2, Eureka Mignon Specialita', V60, Breville SGP
Time for an update me thinks. Haven't had a whole lot of time to work on this, but did get some laser cut parts in and am getting closer to finishing the drum. Worked on squaring the ends today with an angle grinder.
UmMerkur attached the following images:
testfit.png lasercutparts_1.png

Edited by UmMerkur on 06/05/2022 2:12 AM
Behmor 1600+, Fresh Roast Plus 8, Poppery II; Lelit Bianca V2, Eureka Mignon Specialita', V60, Breville SGP
This looks great. Did you come across an ideal occupancy i.e. what % of total volume should the maximum amount batch size, and minimum amount of batch size be? I think this is key and imo and is different for drum vs fluid bed.
There is an 1/6 rule of thumb, valid for almost all machines that roast using hot air.
1/6 should be read as 6 litres of roast chamber volume for 1 kg of greens.
An example is the typical dimensions in the 20x20 cm (8x8 in) ballpark, of the 1 kg machines drum.
Or 160 grams for one litre glass for a FB machine.

Actually, this rule is not so "of thumb"... it has a physical explanation, coming from an equation where you put heat capacity of air and coffee beans, and other constants... but nobody bothered so far to this level, just passed to the next, as coming from horse's mouth Grin
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