@marcfoster1 - Glad that you found a way forward. I’ve always felt that connecting an exhaust system directly to the exhaust port on the Bullet could be problematic. I’ve owned several electric drum roasters that had batch sizes large enough to produce enough smoke and odor that it needed to be managed outdoors. On all of them, I used an active (but detached) exhaust system. That means I have a variable speed fan that can push the smoke and odor outdoors, but is not directly connected (contacting) the roaster. I have a setup like that on my Bullet and it has not caused any roasting problems or errors.
I believe that Aillio’s thought with the whole 3D printed adapter was to provide a direct-connect, passive exhaust. But that can invite several problems for the roaster and/or the exhaust line (especially for longer runs). In addition to smoke and odor, the exhaust from drum roasters carries roast dust and moisture. That moisture can collect in the exhaust line if it is not being actively removed.
A direct-connect, long exhaust run (with no active fan to help promote flow for the line) is not helping the roaster or the exhaust line’s function. The Bullet’s exhaust fan isn’t really powerful enough to manage that situation. Even if you look at other professional grade roasters of 1Kg and larger, they incorporate a separate active exhaust design. For anyone that is concerned about an active exhaust system’s impact upon the roaster’s heat performance, installing a Magnehelic (that samples the pressure in the Bullet’s drum exhaust) can tell you if there is a problem (or not).
Glad you are roasting again and I’d suggest modifying your exhaust setup to include a non-connected, active, variable speed fan to manage the smoke, moisture and odor for this particular roaster.
I have a lightweight box that I built that sits just around the rear-end of the Bullet as a pre-collection chamber. The box is positioned just behind the Bullet’s side perforated vents so that it doesn’t block or impair that flow. It has an integrated hood at the top of the chamber that sits a few inches above the Bullet’s open exhaust and then connects to my 4" exhaust line. Half-way down the exhaust line, I have a variable speed fan that has a good range of low speeds to push the exhaust outdoors. There are lots of different ways to do this, but the main concept is not to have the exhaust system connected direct to the Bullet’s exhaust.