Drum issues - door opening & clunking sounds

[jonas]

I want to address a very strange issue we have had on a few Bullet R2.
It affects around 5% of the machines we have shipped, and mostly goes away after some use, but not always.

It’s been 5 strange weeks trying to get to the bottom of the problem with the doors opening on the R2s. We have had our quality engineer, mechanical engineers, and also the manufacturing engineers work together to try to find the root cause

Things we have looked at include: General tolerances and tolerance stack ups, surface finishes, heat expansion and deformation. Static and dynamic forces on the door.
It has been the strangest mechanical problem to date, and there are still things we don’t understand. However, we do believe that we have a solution.

First of all, the R2 drum is exactly the same as the R1 drum. The door and stainless steel insert on the front plate are also similar in dimensions, even though the R2 insert is held in place with additional screws.
Secondly, the door opening during roasting does not have to be related to the clunking or banging sound that is sometimes heard, these are mostly two separate events.
We have experienced the banging on the R1 in the past, but it would usually go away after the drum is run in, but this time it’s taking a lot longer before it goes away

Door Opening can be caused by:

1. Drum not shimmed to the proper distance. (Distance between drum edge and front plate should be around 1mm)
2. Drum wall inside edge too sharp or with buurs.
3. Drum vane edge too sharp. (The vane that is closest to the front of the drum)
4. Drum vane edge too close to the front plate.
5. Drum not seasoned enough.
6. Freak cases where the beans stack up just right to push the door open.

Fix: If you have done lots of roasting and it only happened once, you can try to soften the inside drum edge, and the front vane edge. Use a fine file to first round the edge, then use fine (600+) sand paper. You want the edge to be rounded and smooth. If it happens on a more regular basis, we will need to replace the drum.

Note: The drums that have this problem are all within spec, so why it happens on some and not others is still a mystery. The location of this vane and the edge quality does play a part, so we will modify this from now on as it solves the problem. Bean size also plays a part.

Clunking or banging:

1. Shims on the drum shaft touching the bearing seal and not on the inner ring (inner race). Especially the back shim that is resting on the spring. These shims are stamped, and are not completely flat.
2. Drum not seasoned enough.

Fix: Turn the shims as shown in the reference below.

To mitigate this from happening again, we will move the front vanes 2mm backwards, and make sure the shims are turned in the right direction.
The problems with the shims could be because the tool to make them is bending them more than previously. This could be because of the material or a worn tool. We will check this as we want the shims to work in both directions. We might also just make them smaller (OD) so that they will not be able to touch the bearing seal.

If you have any issues, please contact us on support, or the place you bought your Bullet.

Jonas

[ryantulleris.D94j]

Hey there thanks for the post I was going to message you all that I’m having this issue.

Some things I’ve tried on my R2 that seemed to improve it sometimes:

1. Keep drum speed at D9 (especially for 1kg roasts)
2. Fan speed 3-4 range

My door has still opened on these settings but I feel like it happens less frequently.

Thanks Aillio team!

[frankc12.quGC]

So I filed and sandpapered the 3 vanes near the door, and reconfirmed that the shims were in the proper orientation.
Tried a 150g sample roast (I’ve lost too many beans at this point to do a test with a full roast), without the 2lb weight I used earlier on the door handle. After charging it immediately bumped the door open and started expelling beans. Luckily I could stop the roast in time to save the beans. I tried again with the weight in place and everything worked great. I then did a second roast without issues. There are sporatic occasional thumps against the door. But the weight kept the door down.

[glcprkusa.Y7MT]

Can you perhaps make a video explaining all this? thanks

[ltocoffee]

I’m having this issue as well. The beans are getting trapped and pushing the door open. The gap is 1mm. The illustration is not very clear. I too would love to see a video on YouTube or on your site as to the filing down or sanding you speak of. Not really comfortable with that solution.

[cash0612]

@jonas on our new R2, we are having this issue during our third back to back roast. Are the shims expanding a bit after getting heated up and pushing the drum back a bit, thereby increasing the gap in front and letting the beans fall out?

We even had the drum stall a few days back. This is causing an issue with out workflow as of now.

[dmarkoulakis.K6KM]

Door handle extension hack

I extended the door handle by 2 1/2 inches. [image] I used some high temp RTV to glue the magnets the bean inlet chute to hold the door open. [image] [image] [image] The extended door handle does not interfere with the trier. I ordered some M5 x 250mm threaded rod from Amazon [image] and some aluminum tubing [image] [image] i cut the tubing to ~2 1/2 inches long [image] I cut the M5 threaded rod to 3 1/8 long (with a hacksaw) [image] [image] Screw one end of the threaded …

I had a couple of roasts early on where the beans were opening the door on my R1. This mod made that problem go away.

I switched back to the regular handle at one point and i didn’t encounter the same problem again. maybe it does just resolve itself after some time. I liked this mod so much I put it back on. It could help on the R2 maybe.

[braca19452f9m]

I can vouch that cleaning the inside of the faceplate wasn’t what caused it, because I always clean it and never have any problems. As for the rest, same here. The beans fell out the in the beginning and stopped doing it after seasoning.

[admin.dUD3]

I’ve been having this issue on my R2. It seems to be happening more in the early part of the roast when the beans are smaller. It almost never happens in the second half of a roast. Of the 11 batches I ran yesterday, it happened 3 times. Currently my solution is wrapping a bungie cord around the handle and connecting the two ends to the legs. I would love to see a more permanent solution.

Just at a glance, it seems like the gap between the door and the drum is too large so smaller beans can wedge in there and bump the door just enough to pop open. I’m curious to see if there is a way to move the drum closer to the door and prevent this.

[braca19452f9m]

I do hope an R2 user will reply, but it seems to me that the back pulley is the same. It might have moved during maintenance, or for some other reason, so just push it back.

Roaster is dropping green beans into cooling tray

Since nobody mentioned it, I will. When you remove the faceplate and then put it back, you’re bound to move the back pulley. Take off the chaff collector and push it forward, hence closing the gap that was created between the drum and the faceplate.

If you’re still having problems maybe you could look at the spacers and the bearing on the front shaft to see if they are in proper position.

[mailmattmorgan.DE16]

I had the same issue with my new R2. Jonas gives troubleshooting steps in his comment above, none of which worked for me, and I ended up getting this resolved by contacting my retailer and Aillio support, who are replacing my drum.

It means I’ll need to install (which they offered to help guide me through, but going to try on my own first) and re-season. Fingers crossed!

[bhroast]

I have an R2, same issue. Tying the handle down with a bungee works great. If I forget to do that, it’s hit or miss.

I think what happens is the beans slam against the front door hard enough early on that the push the door open enough to where they can lodge themselves between the drum and the door. As the roast goes on, the beans expand and push the door open, causing more beans to eject or get stuck between.

The couple times I have forgotten to bungee down the door and this happened, I was able to immediately dump the roast since it occurred at the beginning, extract any beans that got lodged around/under the drum, and then start the roast over. If you don’t dump the roast when this happens then you’ll be stuck with beans being ejected during the remainder of the roast. If you try to bungee the door closed after the beans get stuck between, you’ll jam the drum.

Aillio sent me a new drum, which should be arriving this week. I think they made some modifications to move the vanes back to prevent the bean slamming on door issue.

[micrololin]

R2 Pro

My first 3 roasts went well seasoning with 300g each. My first larger roast of 500g the door opened letting the beans drop into the cooling tray as I was charging. I noticed the door doesn’t fully close on my roaster and needs a slight push to get it closed all the way.

[mailmattmorgan.DE16]

Interesting! That’s definitely not the problem with mine. I have held the door shut in the early part of the roast to prevent this problem, just to have it pop open later.