Soft "Thump" Sound During Preheat


Over the last few roasts, I’ve started hearing a regular “thump” sound as the drum turns during preheat. It’s actually not very loud, but I can feel the vibration of the thump through the table. The drum seems to be spinning fine and during actual roast I don’t notice anything. Should I be concerned? What’s the best way to troubleshoot?


I think I hear this too and I believe I saw others attribute this to beans getting partially trapped between the drum and the door, or the front of the roaster, so that either the door moves slightly or the drum actually moves slightly. While I’m not sure what is specifically causing it, I do know that I ignore it with no ill effect.


Thanks for the response. What I was hearing was more of a very soft “thump” noise during preheat, so there were no beans in the drum. I’m aware of the noises caused by beans near the door.

In any case, I haven’t heard the noise in quite a while so I think it’s ok. It might have been some chaff stuck under the drum or something. If anyone else has run into this though, I’d be interested to hear your theories on what it might have been.


The motor pulley can get loose, which is another thing that can cause the drum to thump. If it’s persistent you can tighten it, Aillio has a pdf somewhere that shows you how. But if it’s just once in a while I wouldn’t mess with it (and I also get those, maybe once every 5-6 roasts).

Edit: just reread your preheat comment. Maybe the motor pulley is a bit tighter when first starting up because of the ambient temperature, and pulls too hard on the drum, but stretches a bit as the roaster warms up and relieves the issue? Just a theory.


Thanks for the ideas. As an update, I’m no longer hearing the thumping noise during preheating. I’m thinking it did have something to do with a cold roaster warming up, thanks for the suggestion @1WithABullet! My exhaust setup allows colder air to float back into the roaster if I don’t block the ducting, and I’m guessing things were just cold those times I was hearing the noise.