This evening I was testing my new Bullet’s drum speeds from D-9 to D-1. Reason for doing so is that I read on Scott Rao’s blog about proper drum speeds to correlating roaster sizes.
He recommends about 70-80 RPM’s for 1-2kg machines and less RPM’s the bigger the roaster is. He mentioned that it primarily depends on the drum diameter, in which case there can be a narrow and long 1kg drum, or a wide and short 1kg drum. This made me want to check my roaster’s rpm.
So I went ahead and marked the shaft from midpoint to perimeter and marked the outer bearing race as it’s stationary. Then I proceeded to turn on a 1 minute timer and counted revolutions in 1 minute on all drum speeds(roaster was empty, I don’t know if coffee beans in the drum would make a difference) Here is what I found:
My take on this is, that the rpm is in the correct range as far as I can tell.
However if I had not manually checked the rpm, then I could have potentially thought that I was changing my drum speed going from D-9 to lets say D-6, but that wouldn’t have been the case at all.
Just be aware of this and perhaps check your roaster as it could be different than mine.
I have taken note for myself what my settings correlate to in actual rpm’s.