Behmor roaster - wire drum damage

[StillShaving]

Had a problem roasting coffee this weekend. I loaded the wire mesh drum with beans in preparation for roasting in my Behmor 1600. I usually give it a vigorous shake and few rotations by hand to coax out any of the small beans (imperfections) before inserting into the roaster. Usually a couple of beans/particles shake loose, but this time I was surprised to see dozens of beans flying around. Upon close inspection I saw that one of the agitating fins had broken away from the wire mesh and was folded into the drum. Rather than stop and repair it, I just folded back into shape and went ahead with the roast. Only lost 10-20 beans during the roast, so that aspect of the day turned out okay.

A few pictures of the damage. Might be difficult to see clearly, especially if you are not a Behmor user.


Same picture angle as above, this time with a white piece of paper inserted behind the fin to highlight the failure:


View from the top. Can see the hole on the right side along with the dangling fin:

[StillShaving]

Okay so how did this happen? I don't blame Behmor or the manufacturing of this unit, at least not directly. Even though I did not notice when this happened, thinking back I believe it was my own doing that it happened right now, but I also believe it was bound to happen in the future without any assistance on my part. The root problem is that occasionally a small bean fragment gets caught in the open wire mesh or under the edge of these fins. (I will try to capture a photo of one at some point and add to this thread). Either a small bean that should not have escaped the grading process, or more often a small bean fragment that has more to do with imperfections of nature and how not every fruit/seed is properly developed.

As coffee roasters know, cleaning up after a roast is a messy exercise. With the behmor I clean chaff out of the drum with the brush that was shipped with the unit, it is soft but still strong enough to dislodge any chaff from the wire mesh. Small beans that get caught directly in the mesh take more force or a different tool, but are easily removed without much fear of damaging the drum.

That leaves the small coffee bits which get caught under the edge of the fins, they get firmly wedged in place and are hard to remove, even if pushing the bean out from the opposite direction it entered. Removal can take a good bit of force, more than the wire mesh can handle IMO, leading to its failure. But other than leave these bits in place to be burned off during the next roast, I don't have any idea how to safely remove them. And much like water expanding into ice can generate damaging force, I believe the same process is occurring here which leads to inevitable failure. Over time I have noticed more and more of these coffee bits getting caught under the fins. Part of my stock of green coffee beans is getting old so that could be contributing to the increase in coffee bits, but also I think each time this happens the fin gap is made slightly larger, making it slightly easier for the next one to enter. This almost never happened the first 10-20 roasts, but I have seen it a lot more recently.

[gearchow]

Wish I could help David, but I can't even pretend to understand what happens in a coffee roaster composed of more then 2 parts. Could it be repaired by brazing or TIG welding?

-jim

[life2short1971]

David if you have had the roaster for a long period of time I believe Behmor offers a smaller mesh drum now and was an option in the beginning. I know I have the latest myself but i still don't think the mesh should have melted. Have you contacted the seller or Behmor directly? I have not had any beans fall through mine yet and I have done at least 25-30 roasts or more. I don't count. Would you like me to measure the mesh size to see if smaller mesh is available.?

[StillShaving]

... Could it be repaired by brazing or TIG welding?

-jim

That was my next question for the forum, to solicit ideas for repairing the drum.

I think brazing or welding would be the best way to fix but I don't have the equipment and have done neither before. I have done some soldering, even using a gas torch (one of those hand held cylinders) so I should be able to braze it if I got the right equipment. Since this is not something that needs to look good or otherwise serve as a critical repair it would be a good experiment for me to try. Or I may just look for a local welding shop to fix it up properly.

If the cost of a proper repair looks high relative to buying a new drum, I may try a low budget fix like getting some steel wire (fishing equipment department) and inter-weave a few extra strands to close the gap in the mesh. Stabilizing the agitating fin will be more difficult, I think a half dozen wire wraps around each end might hold it in place, but that may just look ugly or be unstable and create new gaps to trap roasting beans.

....Have you contacted the seller or Behmor directly? I have not had any beans fall through mine yet and I have done at least 25-30 roasts or more. I don't count. Would you like me to measure the mesh size to see if smaller mesh is available.?

Thanks for the offer Scott. But I am fairly certain I have the smaller mesh, as it was available when I purchased my Behmor and advertised as a nice new feature. My problem is with the mesh failing and creating a hole 4 times bigger than normal. I would encourage other Behmor owners to inspect their drums to see if any small gaps are present behind the fins or not. I have not contacted Behmor to ask about the failure or see if he has seen similar problems with other customer's drums. If my theory is correct he may want to take extra steps in their manufacture to insure their longevity.

[life2short1971]

I hope they assist you.

[benvh]

I would send a note to Joe at Behmor. He is very responsive. My motor burned out when I lived in San Diego. They sent a replacement free of charge and Joe offered to come over and help me install it.

Ben

[StillShaving]

I would send a note to Joe at Behmor. He is very responsive. My motor burned out when I lived in San Diego. They sent a replacement free of charge and Joe offered to come over and help me install it.

Ben

I do plan to contact Joe. I don't tweet, but I have been following him on twitter for a little while and see that he is nice guy on top of trying to provide home roasters with an affordable product. I am still debating in my own mind whether this is a manufacturing defect or something I caused by trying to push out stuck beans. Either way the product engineer should be alerted.

[StillShaving]

Upon closer inspection I found another agitating fin with some damage. It is still functioning properly, but I think its just a matter of time before it is also popped off by an expanding coffee bean. Below is a photo showing some damage to the weld points, but more importantly that there is a dime sized gap for the next coffee bean to get trapped and expand.


I point this out as precaution to other Behmor users to inspect their drums.

[dan25]

What's happened with your wire mesh drum?

[NJBob]

+1 on contacting Joe. His customer service and follow up is fantastic. I had an air-flow problem early on and Joe sent me a replacement part and walked me through its installation step by step.

I used the roaster for ~ 5 years and hundreds of roasts (before upgrading to a Sonofresco) with no beans or fragments sticking behind the fins. My guess would be that your drum was defective from the start.

[StillShaving]

I contacted Behmor tech support using their formal channel on the web. I am not a disgruntled owner and did not try to act like one in my web support (email) request. To help describe what happened, I pointed them to this B&B thread. I briefly described the problem with the help of this thread and basically told them at first I thought I caused the problem by casually clearing out stuck beans wedged underneath the fins, but that on second thought the beans should not be getting caught there to begin with, and did they see similar problems with other customer's drums? I wrapped up my post saying I am going to try a simple repair and get back to roasting.

I got a somewhat tepid email response from Bob at their "tech" email address. Saying they appreciated the feedback and are always looking to improve the product, and that sometimes beans get caught in the wire mesh (which is true, but a different issue), but not directly commenting on the fin attachment issue, or gaps between the fin and drum. That he hoped I would be successful in my repair. (A few small beans do often get caught in the wire mesh, but they appear harmless and have not caused any damage to the drum).

So my response from behmor.com was inline with my damage report/request, but I did not find out if this was a common problem or not. My roaster is out of warranty and a new drum is not expensive, so I did not want to make demands. Also I thought I had come up with a simpler DIY fix than my original thought of interweaving a few strands of wire thread, or taking it someplace for brazing/welding. That I would screw some short sheet metal screws through the fin, placing a washer on the outside of the mesh and using the fin to clamp back down against the inside of mesh, to support the fin while also closing the hole.

This past weekend I got out my variable speed drill and best drill bits, but tapping into the metal was more difficult than I imagined. I held the drum in my lap and tried to hold the fin but the drill bit wondered around too much and I did not want to press the issue. I realized I needed to remove the fin completely to clamp it down to a stable surface before drilling, otherwise I may injure myself. So I stopped and am rethinking this approach.

After closer inspection, I do think there is some subtle manufacturing design defect. In that the fin is attached at an angle relative to the wire grid. The wire grid is interwoven so that there are small peaks and valleys along its surface. If the edge of the fin overhangs a valley instead of being butted against the next ridge there will be a small gap for a bean tip to enter and act as a wedge. Since there are lots of peaks & valleys along the edge and the fin sits at on an angle, it is difficult to close them all down with a few simple tack welds, that the amount fused material should be more substantial IMO, to fill in any potential gaps near the edges.

[gearchow]

good luck with the drilling and for pete's sake, safety first. in addition to having the work mechanically held in place (clamped), wear glasses. Drilling holes in wood is one thing (and should be wearing glasses there too), but metal is a whole nother. Also (and I don't know if this is even possible), think pop rivets. A pop rivet tool with various sizes of rivets is a wonderful item to have around.

-jim

[nff]

cut pop cans into small squares and screw/rivet them together

[benvh]

Is that the large or small grid drum? If it's the large, I have an extra you can have. I only use the small now.

Ben

[StillShaving]

good luck with the drilling and for pete's sake, safety first. in addition to having the work mechanically held in place (clamped), wear glasses. Drilling holes in wood is one thing (and should be wearing glasses there too), but metal is a whole nother. Also (and I don't know if this is even possible), think pop rivets. A pop rivet tool with various sizes of rivets is a wonderful item to have around.

-jim

I like this idea of using pop rivets. I think a rivet tool would fit deep enough into the drum to address the fin I am having issue with, but I am concerned about getting a washer or something similar behind it to hold against the hole in the wire mesh.

cut pop cans into small squares and screw/rivet them together

I probably misunderstand your idea, but it did make me imagine cutting a soda can with tin snips to fashion some new fins. Or find some thin sheet metal. Either of which would make it easier to tap with a drill and screw onto the side of the wire drum to replace the original Behmor fins with ones which are more malleable and easier to work with.

Is that the large or small grid drum? If it's the large, I have an extra you can have. I only use the small now.

Ben

Thanks for that, it is very kind of you to offer up your drum. I have the small grid drum and did manage to fix it this weekend. I will include some pictures in the next post.

[StillShaving]

I went to my local Lowe's hardware store in search of some materials to repair the drum, or at least keep it limping along. Sweet Maria's sells a new drum for $20 so that set an upper limit on any repair I would attempt. Except SM or other retailers don't have any drums in stock until late October. Worse case, I expected to get some small stiff wire to interweave and close off any holes, and leave the fin flapping in the breeze. I came across a small assortment of cotter pins and thought they could work. So with a bit of unconventional engineering (insert a more colorful term here if you would like to use) used them to clamp the fin back down in place.

The cotter pins I used were 1/16 x 1 inch size and were at the limits of being workable. Longer pins would have been better, as well as something with a thinner size like 3/64 or 1/32. It took a good bit of force to get the pins to interweave into the existing grid and I feared the bending forces might break the wire mesh but it held up. At least for one roast.

Cotter pins clamping down on the Fins:




A view after the roast:

[StillShaving]

Not very exciting, but here is a 44 second video of the post-fix drum roasting some Vietnamese Robusta, where you can hear the roast entering 1st crack. Roasting 14oz of coffee on the P1 profile at maximum time (20:30 I believe) and no roaster pre-heating. These beans are rounder than Arabica so they posed no problem with wanting to get stuck in the drum.

[nff]

what light was that?

[Sullybob]

what light was that?

The Behmor has a light inside the roasting chamber.