Noise similar to a jackhammer when roasting

When roasting 700g of Natural Santos, after 3.5 minutes at IBTS 170°C, an extremely loud noise occurred, similar to a jackhammer.
I immediately started the cooling mode and unloaded the beans from the drum. The noise then disappeared.
At the moment I don’t dare start the Bullet again.
Does anyone have an explanation for this?

Start by having a look at: Brand new v2 making da da da da noise

Hi John
Thank you very much for your valuable hint, I already suspected something like this and will now look into it more closely.

I had this problem as well. After going through tech support at SM and replacing the motor, it continued intermittently. I was then told to speak with the folks at Aillio in Taiwan. Due to the time difference and our schedules, it was going to take a while. In the mean time I needed to roast some coffee. I moved the Bullet away from the roasting area and roasted with my old roaster. When it was time to speak w/ Aillio, I returned the Bullet to its spot and took the call. Upon turning on the roaster and starting a roast, I found the problem was gone but there were a few beans that fell out of the machine. The issue was beans rubbing against the drum. In moving the roaster, they became dislodged and problem solved. After many roasts, it has yet to return.

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The drum was probably jammed causing the cog belt to slip on the drum shaft or the motor. It can be alignment of the belt on the drum shaft or it could be that the drum was jammed. If beans dropped out you probably have the answer. But you probably ought not assume those were the only beans causing the issue. It might be worth it to check that there are no more hidden ‘gems’ interfering with drum rotation.

Search here on R.W for folks who have removed the drum and adjusted the belt pulley position afterward.

Also if beans did jam the drum, odds are that the clearance between the front of the drum and the face plate is not adjusted as close as it needs to be. You adjust that clearance by removing/adding spacers from the front of the drum. There are at least 2 thicknesses of spacers used and you ought to have a couple spares in the plastic bag in the tool kit. I have the clearance on my Bullet set to the minimum without any scraping. Beans slipping between the face plate and the front edge of the drum is very unlikely with that setting (though once in awhile a ‘runt’ or even a broken bean will defy the odds).


ps- I’ve had good luck using e-Mail to talk to Aillio techs. They’re really very good and have a library of support documents to help guide you with the usual problems.