Roasting ball bearings


Super Moderator
Staff member
Aug 14, 2003
Boca Raton
I had a friend call me with an issue. When he roasts he finds 1 to 3 unroasted beans. I told him to get a rubber mallet and tap the down chute when starting his roast. That maybe they are getting stuck bellow the hopper. He spoke to another roaster that suggested putting 1.5 lbs of ball bearing in the drum and turn it on. He says that it knocks all the debris free. I told him that I thought that was a bad idea. If he did do this it could damage the paddles in the drum. I also said that if the beans were trapped in the drum they would come out like charcoal when they popped free. Anyone want to chime in on this?


Aug 7, 2013
Sounds like the beans are getting trapped in the down chute of the hopper. Anything beyond that which has the proximity to fall back into the batch at the end of the roast will show some degree of "heat exposure". Curious thing what some roasters will consider putting into their roaster...ball bearings? Has anyone complained of a ball bearing ruining their grinder?? Yikes!!


New member
May 27, 2014
Ball bearings will also take off some of the seasoning on the drum, which will help more beans to get stuck.
When I drop the roasted beans into the cooling tray, I stand there while they are cooling.
I occasionally stop the mixing arm to manually remove the following:
1. Quakers - those beans that appear under-roasted (but aren't).
2. Over-roasted (dark) bean fragments. They are not whole beans and therefore roast quicker than normal.
3. Stones.
So while a gentle tap on the loading chute could prevent a few beans being caught there, I would still do my quality control while the roast is cooling.
This is why many roasters come equipped with a light pointing at the cooling tray, so you can more easily see this stuff.
I have positioned a much bigger, brighter light to make this job even easier.

Quakers and over-roasted beans dramatically affect the taste in the cup.
Getting a stone in your grinder can be expensive.

Thought for the day:
Anyone else find it difficult to not look at the mixing arm?
Eyes are built to track movement to catch prey or avoid being caught by something higher up the food chain.
I try my hardest to focus on the beans, but as the mixing arm moves by, my eyes want to follow it.