Cormorant Squeaking and Grinding - Page 3

Discuss roast levels and profiles for espresso, equipment for roasting coffee.
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mkane
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#21: Post by mkane »

More grease won't help in fact it may do more damage than not enough. The balls need to roll not slide through the grease.

ShotClock (original poster)
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#22: Post by ShotClock (original poster) »

Have you contacted Johan? I'd be interested to hear his thoughts, he was very responsive when i reached out via email.

Milligan

#23: Post by Milligan »

mkane wrote:More grease won't help in fact it may do more damage than not enough. The balls need to roll not slide through the grease.
There wasn't any grease to begin with. I'm not going to pack them like wheel hubs on a car, but they need some lubricant that will stick around. Mineral oil certainly is heat stable but it doesn't seem to stay put. Both bearings were bone dry. The one I applied mineral oil to 20 roasts ago was dry as well. The food safe Super Lube has a range 43F-450F which puts it at the edge of temps the roaster sees on the ET probe.

Another option is to add oiling the bearings with mineral oil every 10 roasts or so, but that seems a bit needy. The front bearing is very easy, but it is messy to lube the bearings in place as it is set up.

I have 10 bearings to play with when they come in.
ShotClock wrote:Have you contacted Johan? I'd be interested to hear his thoughts, he was very responsive when i reached out via email.
I haven't about this issue. He has been great in the past. I took a video to send him, but since I tracked down the culprit I decided to wait on sending it. Bearings are wear items, in this case it seems a bit premature, but if they simply weren't oiled/greased well from the factory then that could be the issue. 10 bearings were $10 from Amazon. If they end up not being adequate then I'll get in touch with Johan to see what brand he uses or simply track down a NSK/Timken version. I may spend some time finding a version that is more servicable from the outside. They could be shielded on the roaster side but open on the exterior for easy lubrication/greasing.

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mkane
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#24: Post by mkane »

I'm going on the hunt for a pillow block bearing with grease fitting.

We try and stay on top of bearing maintenance. Wouldn't want a seizure and have the shaft spin, making a mess of things.


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JohnB.
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#25: Post by JohnB. »

I would think that packing the bearings with a high temp grease would solve the problem. If the grease isn't breaking down there would be no need to be constantly relubing them. Loctite LB8034 https://www.amazon.com/Loctite-ViperLub ... 534&sr=8-7 is a food safe synthetic bearing grease that's rated to over 600°F. I haven't had this issue yet with my 4 year old Cormorant but when I do I'll see how well the LB 8034 works.
LMWDP 267

Milligan

#26: Post by Milligan »

Squeaking is not resolved with new bearings and grease even though the original bearings were dry and crunchy. So I tore into it again and dug deeper. I tore it all the way down to the motor housing and gear set which is the last thing that could be squeaking other than the drum rubbing on something on the inside of the body, which doesn't seem to be the case from the testing I've done.

I found another likely culprit. There are three bushings used on the gear drive shaft. The one closest to the gear set had substantial wear while the other two had moderate wear. The most worn bushing had deep grooves in its surface. There was some graphite powder used to lubricate that bushing but it was flaking.

I sent an email to Johan to see what he would recommend. I'm thinking I can find some brass bushings of similar size at the hardware store and regrease it all. That would likely fix the issue (hopefully.)

Damaged bushings. They seem to be zinc coated steel and rode against cast metal.


The section the most damaged bushing rode against. Flaking graphite/grease rests at the bottom.


The gear set that it sits against. Looks to be some slight grooving of the gear.


I'll update with Johan's recommendations. Hope this helps someone else in the future.

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hankua
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#27: Post by hankua »

Loctite LB8034 https://www.amazon.com/Loctite-ViperLub ... 534&sr=8-7 is a food safe synthetic bearing grease that's rated to over 600°F. I haven't had this issue yet with my 4 year old Cormorant but when I do I'll see how well the LB 8034 works
I've been using this grease for several years in my roaster without issue.

Milligan

#28: Post by Milligan »

Johan responded swiftly:
I tracked down the squealing / friction to the shaft and sleeve of the motor, just as you have it in your pictures.
I use a high heat copper based lube that I apply to the shaft, this normally solves the problem.
Normally the 3 washers do not take any pressure, they mostly wont rotate. I would take one out and only replace 2.
So he recommends using a copper based lubricant for the gear set internals (not in contact with the coffee.) I plan to use brass instead of the steel for the bushings.

ShotClock (original poster)
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#29: Post by ShotClock (original poster) »

Quick update from my end - just oil on the faces has quietened things down a lot, so that I'm not going to be taking it apart just yet. Thanks to Tim for documenting the process, I'm sure that will be handy at some point.

Milligan

#30: Post by Milligan »

I may as well give a quick update too. I found copper based lubricant like Johan recommended but it was labeled not for use with rotating assemblies. It was mainly used for an anti-seize compound. I ended up with a high temperature grease rated for use in bearings and rotation. I also packed the new bearing with Super Lube and it is quiet as a mouse for now. I've gotten about 10 roasts on it since I reassembled and it is doing fine. That fixed the problem.

The good part is, the Cormorant is very easy to take apart and put back together. It can be done in an evening. The last time I did it was under 1 hour, but I know what to expect now.