Cunill/Bunn burr removal

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billm3
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Postby billm3 » Wed Feb 04, 2009 9:49 pm

I purchased a used Bunn "Espress" which is a rebadged Cunill Columbia/CT2, from what I can tell from Google. I want to change the burrs, but the bottom burr is held in place with a 4-sided acorn type nut and a washer that I can't budge.

Has anybody ever changed the burrs in a machine like this? I have not been able to find any results from Google or searching HB.

From the information I have found, most Cunill's have this same burr set-up. The top burr is held by 3 screws, but the bottom is held on by some type of nut. I tried to loosen the nut by placing a screwdriver into the coffee-thrower vanes to hold it in place, but I just started to bend the vanes.

Suggestions?

Thanks-
Bill

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Postby djmonkeyhater » Wed Feb 04, 2009 11:02 pm

Is the bolt reverse threaded?

You can also try some heat although you'll need to be careful with any large sources (torch) for obvious reasons. It worked on my Bregant which was NOT reverse threaded.

I have a Cunill Tauro that I replaced the burrs on but I forget now if it was reverse. For sure San Marco grinders have a reverse threaded bolt at the top because I broke it. It wasn't even tight, just being operated improperly. I twisted out the broken part with my finger and a string of profanity.

WES

billm3
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Postby billm3 » Wed Feb 04, 2009 11:24 pm

Is the bolt reverse threaded?


I tried the reverse.... still no go.

Here is a pic (Dan's request) :wink: that I should have put in the original post:

Image

Image


I placed a screwdriver through the grounds chute to keep the vanes in place (picture 2) but the force just started to bend them (clockwise and counter).

I did have to do a MAJOR cleaning on this thing. It was supposedly used in a church cafe and it looked like it had never been cleaned. It smelled like nasty rotten coffee too. The nut may just be stuck, but hopefully somebody has some experience with this type of thing. At least the price was right!

Thanks in advance for any more suggestions.
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dmorrown
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Postby dmorrown » Fri Feb 20, 2009 3:12 am

Did you ever get that bottom burr removed? I also picked up a used Bunn ES-1G and am having the same problem. I noticed from your pictures that you had not removed the upper burr carrier. If you remove the four bolts, it should come off and you will have better access to the lower burr. I found that I could wedge a piece of wood between a vane and the outlet chute and put a fair amount of pressure on a wrench without bending the vane, but I couldn't move the acorn nut. Did you find out whether it was left-hand threaded?

Thanks for any suggestions.

Dave Morrow

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Postby HB » Fri Feb 20, 2009 8:23 am

dmorrown wrote:Did you find out whether it was left-hand threaded?

It should tighten the opposite direction that the motor turns and vice-versa.
Dan Kehn

billm3
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Postby billm3 » Fri Feb 20, 2009 11:46 am

dmorrown wrote:Did you ever get that bottom burr removed? I also picked up a used Bunn ES-1G and am having the same problem. I noticed from your pictures that you had not removed the upper burr carrier. If you remove the four bolts, it should come off and you will have better access to the lower burr. I found that I could wedge a piece of wood between a vane and the outlet chute and put a fair amount of pressure on a wrench without bending the vane, but I couldn't move the acorn nut. Did you find out whether it was left-hand threaded?

Thanks for any suggestions.

Dave Morrow



I had another person tell me that it is definitely a "righty-loosey" thread (opposite of lefty-loosey), but I still have not been able to move the nut.

I removed the top burr carrier, it is a large plastic outer ring with a metal interior that holds and adjusts the top stationary burr. The piece in the picture with the screws is the top threads for the top burr. I tried to remove that, but it is fastened or welded or glued in place in addition to the screws. I tried prying, hammering, heating, etc, and it did not budge. You'd think that the screws would be enough to hold it....

I need to find some kind of 4-sided socket to fit the acorn nut. My channel-lock attempt just can't get enough torque. If I ever get this thing off, I will probably need new vanes because they seem to be taking the brunt of the punishment while I use them to stop this thing from turning.

-Bill

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Postby djmonkeyhater » Fri Feb 20, 2009 12:34 pm

Before you wreck the burr carrier (brass thing with vanes) I would try some heat and penetrating oil. I have a propane torch for brazing copper pipe that I use. That burr carrier might cost near what you have into the grinder to replace!!

Since it's an acorn nut, put the grinder on it's side, heat the nut up and squirt it with some Liquid Wrench or WD-40. Let it cool and do it again. Try turning it again.

I'd also recommend using an open-end box wrench on that nut instead of channel-locks.

(If some of this is new or frightening to you, you might seek out a machine shop, trustworthy mechanic or someone else that does this kind of stuff daily.)

WES

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billm3
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Postby billm3 » Fri Feb 20, 2009 1:08 pm

djmonkeyhater wrote:If some of this is new or frightening to you, you might seek out a machine shop, trustworthy mechanic or someone else that does this kind of stuff daily.

WES


Thanks for the concern, but I am familiar with this stuff. :? I am a little hesitant to put WD-40 or penetrating oil in a place that will have my coffee coming into contact with it.

From the parts diagram I found, the vanes are a separate replaceable part that slides over the shaft where the burr and nut are fastened. It shouldn't affect anything using the vanes to pry against, unless I get really rough with it. I just have to add the vanes on to my replacement parts list.

I have re-arranged and replaced some of the outer parts. I got the grinder for $100 and replaced the bean hopper and doser with the Cunill Tranquillo hopper and doserless funnel. Total investment $170. I also shortened the outer casing by removing the one of the plastic rings and re-arranging the internal electrics. The burrs are not really bad, but they are used. I am using this grinder at work with a Pavoni lever so it is not a high-volume grinder. The result is that I have a decent commercial grinder that was huge and have made it a manageable and user friendly home model, but with the commercial guts in place. If needed, the whole thing is reversible back to the huge monster-grinder size.

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Postby dmorrown » Fri Feb 20, 2009 5:59 pm

Bill,

You should be able to remove that threaded burr carrier with the four bolts. (The parts list on the Cunill website calls it a "Grindwheel Housing Support.") Mine was only held on by some sticky coffee residue and came off fairly easily after removing the bolts. If your grind chamber is like mine, it will need cleaning, and it can only be accessed by removing the burr carrier. Also, after removing the burr carrier, you can get a wrench on the acorn nut perpendicular to the shaft, which you can't do with the burr carrier on. Finally, you won't be able to replace the sweeper with the vanes without removing the burr carrier.

Perhaps a coffee cleaner like JoeGlo or CleanCaf would dissolve the gunk and loosen it up. I have seen other people use these to clean grinders, and as long as you dry off the parts when you finish, there shouldn't be a problem.

All of the places that sell Cunill burrs describe them as "left." I assume this means that the motor and the moving lower burr rotates counter-clockwise to grind the beans. It seems to me that you would turn the nut clockwise to loosen it, but I read Dan's post to say the opposite. I don't have new burrs yet, so I didn't try too hard to remove my old burrs. Given the problems I have had in attempting to dial in the grinder, I think I will be buying new burrs soon. Once I know for sure which way to turn the nut, I will try to use a little penetrating oil and heat if needed to remove it. I think I will be able to wipe the oil off the shaft once the burr is removed.

Dave Morrow

billm3
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Postby billm3 » Fri Feb 20, 2009 6:48 pm

dmorrown wrote:You should be able to remove that threaded burr carrier with the four bolts... Mine was only held on by some sticky coffee residue and came off fairly easily after removing the bolts.


I tried...... I really did. The bolts came off easy enough, but NOTHING worked trying to get the housing off.

dmorrown wrote:If your grind chamber is like mine, it will need cleaning, and it can only be accessed by removing the burr carrier... Perhaps a coffee cleaner like JoeGlo or CleanCaf would dissolve the gunk and loosen it up. I have seen other people use these to clean grinders, and as long as you dry off the parts when you finish, there shouldn't be a problem.


I vacuumed out the chamber and ran a large dose of "Grindz" through it. It got rid of most of the stale coffee smell and it is pretty clean now. I'll consider the CleanCaf and/or WD-40/penetrating oil to help remove the carrier nut if nothing else works.

dmorrown wrote:All of the places that sell Cunill burrs describe them as "left." I assume this means that the motor and the moving lower burr rotates counter-clockwise to grind the beans. It seems to me that you would turn the nut clockwise to loosen it, but I read Dan's post to say the opposite. I don't have new burrs yet, so I didn't try too hard to remove my old burrs.
Dave Morrow


The burr does turn counter-clockwise, at least on my model. I have tried moving the nut both CW and CCW without any luck. Without being able to remove the top carrier housing I can't get the correct angle as you stated. I'll try the CleanCaf and/or oil on this part too next time.

I think for the time being that I am just going to use the grinder as-is and try replacing the burrs if/when the grinds get really inconsistent...... Or until I feel like tackling this project again. It seems to be working fine for now, I just wanted to replace the burrs because I have done it on my Mazzer Mini and it was sooooo easy. It is also a cheap "piece of mind" project on a used grinder. Until then, thanks for all of the advice from everyone

Bill.