I made a video of the sound: Bullet r1 grinding noise - YouTube.
It sounds sketchy to me, so I’m waiting until I figure it out to proceed with things like seasoning. I tried pulling the drum forward like the manual said, and it didn’t seem to budge. If someone can point me to a guide (extra points for a video) that would help me with next steps, I’d be very grateful. Thanks!
-Andrew
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That sounds completely normal to me. It is coming from the gearbox when the drum is not loaded with beans.
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Same exact sound I was hearing. I took a couple videos just like you. Sweet Marias said that the sound will go away and to not worry about it. However, if you ever so slightly push against the motor towards the center of the roaster it goes right away (you have to remove that other cover). I did not want to void my warranty so I did not do anything permanent, just took these videos and asked.
It has to be the spring that has been installed that provides the tension. It wasn’t present on older version of the Bullet and is now - and those old versions don’t make this sound.
The instructions are written in a way to make people like you and me stop before seasoning when we hear that noise, it says any grinding noise and stop. Thus why I was complaining to Sweet Marias.
I think Aillio should make a fix, some sort of reverse pressure to make that go away, its disconcerting to hear it.
and then me finding out how to fix it:
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If you apply too much reverse pressure then the belt it not tight anymore, so it is a trade off.
All bullets have this sound, even the older ones when the belt was tightened.
The sounds comes from when the shaft is loaded with a radial force and there is not much we can do about it except from maybe documenting the sound.
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Thanks for answering! I hope that there is some sort of manufacturing improvement that can be made in the future, as the machine is super quiet except for that noise.
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There is and we are working on something 
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My Bullet also makes this sound, and it is getting worse, to the point where it’s hard to hear first crack. I think it is coming from the drum motor. There appears to be too much side load on it. In March you said you were working on a fix - any progress?
FYI this sound has been coming from the Bullets since the beginning. If you start loading the drum with beans it is normally much less.
The early Bullets did not have a spring, and the belt would come loose over time, so later we added a spring to tension the belt and this is what is causing the side load and noise from the gearbox.
Some bullets are less noisy than others. There are a few things you can try if you find this noise annoying:
- Rotate the motor bracket to compress the spring excessively so it permanently deforms just enough to apply less pressure on the bracket. Be careful you don’t damage the spring.
- Someone had luck in rotating the gearbox relative to the bracket. This requires you to remove the gearbox from the bracket (2xM3 screws) and then rotate it 90 degrees, re-assemble and listen again if the sound is worse or better. Continue this rotation until the noise is less.
I have not tried solution 2 myself but I think it would work.
Jacob( or anyone that may have an idea about this) , I have a very nasty new sound occurring after 150+ roasts. I sent a message and video/sound clip to Aillio about 2 weeks ago but no response at all. The Bullet runs and sounds completely normally during preheat but when beans are loaded a loud sort of rat-a-tat-tat noise occurs and continues throughout the roast. Initially the sound only occurred for a minute or so in to the roast and would then disappear, however it now occurs 100% of the roast’s duration. A video/sound link is here: IMG 4153 - YouTube
Appreciate any insight… wonder if I’m doing any damage running it like this. If it was an automobile making this noise i wouldn’t be driving it. Thanks
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@larz - Your video link is showing as “unavailable” on my end. But the noise you are describing could be a slipping drive belt which is known to make a noise like that one. It would be logical to expect that if the belt is on the edge of being properly tightened that it could start making noise when the beans are loaded.
On this video that Tom Owen made at Sweet Marias at ~ the 2:32 mark, you will briefly hear the sound of a slipping belt. Tom inadvertently causes the belt noise for a moment when he manually turns the drum too quickly.
Hey PapasCup, thanks for pointing out that the link wasn’t working…I corrected it and would appreciate you trying again. Also, thanks for sending the link to Tom’s video. That issue I am familiar with but its not what I am experiencing as you will ascertain if you try that video/audio link again. However, I think you are right about the drive belt being responsible; logical…what else could it be I’m thinking too. There is in fact more slack than I would expect. I haven’t researched or torn it apart to see if there is an obvious adjusting mechanism/method as I was hoping to hear from Aillio with some specific instructions, but since none are apparently forthcoming (which is another issue itself) I will dig into it further and report. Thanks again.
Update: yes, there is an excessive amount of play in the drive belt so that is likely the problem. Getting at the drive to see if an adjustment can be made appears to be no small issue for several reasons. If anyone has attempted that it would be great to hear from them. If these belts routinely require either replacement of adjustment over time, it seems like they will have to introduce a little more accessibility to that area of the machine…unless I am missing something. I have reached out to Aillio again with a more compete description of the problem.
@Larz - Listening to the video is sounds like it could be belt noise or possibly some other object back there that is hitting something. Maybe also check the Exhaust Fan to make sure there isn’t anything in there that could be contacting the blower fan assy.
While I have not done any belt adjustments on my Bullet, I have removed that plastic Cover that shrouds the rear area to allow access to the drive motor area. If you haven’t removed the Cover yet, it is easy to remove.
Using the Aillio H3.0x60 Tool (or equivalent hex-head wrench), just remove the (4) screws that are accessed through the holes I have indicated in red-circles (attached image). If you are careful in pulling the Tool back out through the screw access holes, the screw will stay on the end of the tool so that you don’t have to go “fishing”.
On my Bullet (which is a ver 1.5), the drive motor looks to have (2) basic mounts to the chassis. The lower mounting screw appears to be fixed and the upper mounting screw has a slotted mount that appears to allow tension adjustment on the belt. I’m no expert on adjusting the Belt (yet) because I’ve had no reason to tinker with it. Maybe just first observe the motor (in-use) to see what the Belt is doing when the motor is driving the Drum. Good luck.
Thanks once again… especially for the reassurance that those 4 hex machine screws that I was fearful about removing, won’t be forever lost in the bowels of the beast. I did get a quick response to my second message to Aillio (apparently my first message attachment was too large and never arrived their server) . They too indicated that it was almost certainly the drive belt and reminded me that that specific problem was identified and a solution provided on page 24 or 25 of the online manual and that performing this adjustment wouldn’t affect the warranty.
Even if you were to drop one of those (4) screws to remove the Motor-area shroud, they would likely drop down into bottom of that plastic shroud. Just be sure the Bullet is unplugged from power because there is a small (fused) circuit board on that same side that could short-out if a screw lodged in the right place. But, the screws really do stay pretty snug on the head of the hex tool during removal.
Pages 24 & 25 of the manual have more to do with a Drum that isn’t turning at all than a Belt adjustment. It would be good if Aillio also added some points/tips about properly adjusting the belt tension. Something like belt-deflection distance or some method of checking tension that they use. It is very difficult (if not impossible) to even get a finger into that belt area.
I’d probably use a thin rod or dowel to press on the belt to feel the tension, but that is still more feel or guesswork than proper tension. Aillio knows that too much tension adds to motor noise. That is why many 1.5 owners (myself included) have heard a slight grinding sound since day-one with our Bullets.
Adjusting the tension is probably something you will just have to play with to get right and likely not all that difficult. If you know/see that it is too loose, then I’d loosen the bottom motor assy mounting bolt to allow the motor to swivel. Then slightly loosen the top bolt to allow moving the motor to increase belt tension. I’d also watch for the belt alignment across both the motor and drum drive gears so that it is laying properly across those gears.
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Thanks. Yes, I see after removing and reinstalling the 4 hex screws, just how simple it is… hard to know until until one opens the thing. As far as the manual’s instructions re tightening the belt, they are actually very specific to this issue (see below) and pretty clear and simple… the entire process, disassembly and reassembly included, took 10 minutes. There was a huge amount of belt deflection that needed to be corrected…and although I’m still preheating to begin a roast to test the results, I’m pretty darn sure this is it. The passage below is from near the bottom of page 24 of the online manual:
Symptom: A loud (da da da da da da) noise is heard when the drum starts turning:
Cause: The belt is loose. (On Bullets without motor spring)
Tools Needed: Hex Key 3&4mm
Solution: Unmount the chaff collector and take off the right back cover by unscrewing the 4 hex screws that are in the same location as the alignment pins on the chaff collector. After the cover is off, loosen the two bolts that hold the drum motor. Pull the drum motor bracket to the right (when looking at the R1 from behind) and tighten the top screw first, then tighten the bottom screw. When you feel the two screws cannot be tightened further, stop. Reattach the cover by using a hex screwdriver with a straight head. Round-headed drivers are very hard to use.
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Good for you and hope that adjustment solves the whole problem. Also good to hear that you saw an issue with belt deflection.
I have a PDF of that same online manual. The page you are referencing is page 22 on my copy, so I didn’t go back that far. If the adjustment worked for you and gets you to a good result, then victory. 
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Roast completed, worked perfectly…back in the game. Thanks again for your help.
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I know this is an old topic but I’m hoping someone can provide some insight. I’m hearing the drive belt slip but it ONLY slips when the machine is first powered up. I can also reproduce the sound by manually rotating the drug (audible in the send part of the video). It’s a V2 and has the belt tensioner. I’ve tried to add additional tension when tightening the 2 motor mount screws but didn’t see any improvement. Here’s a video -DZ9A5365
What is your serial number?
Does the motor and drum work fine once you start it up?