Machine Cooling Fan Hum

During my last few roasts, I’ve noticed a distinct humming sound that comes from the back of the Bullet while it’s cooling down. I imagine it’s something with the fan; should I give the machine a deep cleaning and see if that fixes it? Bear in mind I’ve only had it a few months, probably no more than 25 roasts total.

Difficult to say. Unless the fan and housing is really dirty I think you can wait a little bit. What fan speed setting do you use for cool down? Does the humming increase with increased fan setting?

I’ve been able to test this out, and I can confirm that it’s the impeller fan. I believe it’s making a small amount of contact with the metal chaff basket as it turns and I can’t seem to get it to sit perfectly tight and flush. I’ve given the Bullet a deep cleaning and the issue persists. As you mentioned, yes the humming grows louder with increased fan setting.

I’ve actually managed to get the issue on video! You can see the impeller fan dragging the chaff basket in a circle as it spins a little. This seems to happen on and off. What should I do about this?

Did you remove the impeller fan from the motor during your cleaning ? Maybe it’s sitting too far forward on the shaft now and fouling the basket ?

I’ve moved the fan as close to the back wall as I possibly can without it touching and the issue still persists. It almost seems like the chaff basket isn’t sitting snug enough in the rubber part, which is causing the impeller fan to suck it out a little, hence the friction.

I think you’re on to something. My chaff basket is hard to remove from my rubber gasket, I have to hold the gasket down or it comes up with the basket.

If you’re basket isn’t snug when fully seated in the gasket, I’d check to see if you have the gasket properly installed or needed a better fitting pair.

P.s. I wasn’t able to play the video.

I’ve uploaded the video to YouTube this time so it should work.

Sweet Maria’s did a video on this issue where the basket touches the impeller. If the gasket isn’t seated all the way into the groove as well as the basket seated you’ll have this issue. Take another look at how the basket and gasket are seated. That may be the problem.

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You nailed it! I re-seated the gasket and the issue went away completely. Thanks for the tip.

To anyone from Aillio reading this, please look into ways to correct this problem in future iterations of the roaster. It seems too common to be a fluke. Honestly I’m not that stoked about the rubber parts in the machine in general, the flap at the bottom of the chaff collector has a tendency of not sitting quite perfectly either.

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Not sure I’d call it a hum, but whatever the chosen name it seems to be contagious.

After nearly a year of never having a problem with the chaff collector filter it happened to me too. And of course the chaff collector was hot and getting hotter as the chaff filter made more and more contact with the fan impeller. It was odd behavior: when I pressed on the filter while giving it a slight rotation, it would just squirt back out and sag down a bit where it would have made contact again. Once the black rubber got warm, the filter was not going to stay in place. But once cool again, no problem.

After a lunch break I did 3 more roasts without incident.


Edit: Btw, I was roasting beans with a lot of chaff. I think that’s part of the issue.

I had the same issue with my 1 month old bullet. When it arrived, the chaff collector was VERY loose in the gasket. I was quite surprised, because I saw Tom’s video, where the reverse was the case. And then…about a week ago, this horrible noise started, which I immediately traced to the impeller fan. In my case, it was NOT that the rubber gasket was seated improperly. It was the collector itself, that was just sort of hanging in the opening. It took a fair amount of elbow grease, but finally I got the collector seated about 1.5 mm down into the gasket.

If you take the gasket off, it is much easier to see the problem (and the solution…) But be forewarned; you can’t seat the collector in the gasket when it is out of the machine, and then attempt to get the two together back in the machine. You might rip the rubber groove if you attempt this.

So you have to seat the gasket, then work the collector around the opening, little by little, pushing with a fair amount of force, as you go.

I wonder how many units were shipped with the collector loose in the gasket!

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Thanks for this. The outer groove is apparent but I have never spotted the inner groove that the filter basket rim is supposed to fit into… totally missed it.

You’re right that it takes some effort to get the rim to seat. I was tempted to use a pick of some sort but could just picture the edge tearing. Long term this is going to be a pain, but for now I have my mistake corrected. Thank you!