Upgrading Eureka Atom... to 65mm burrs

Grinders are one of the keys to exceptional espresso. Discuss them here.

#1: Post by Kran »

So i've been toying around with upgrading the burrs on my original 60mm Atom for awhile now. This was partially due to the need to tinker and partially the want to upgrade. Couldn't justify going to a Specialty 65 and cost of going to a 75 wasn't worth it since I already had a a grinder that I was content with. Finally got around to doing the conversion and it amazingly worked (small * until I finish off one cosmetic issue). Total time 1-2 hrs depending on how many times you've taken apart the grinder to clean and how comfortable you are with this type of stuff. This isn't meant as a how to article. It's more a proof of principle:

Key parts are the upper burr carrier and of course the 65mm Eureka burrs. If you read the spec on the Eureka burrs they're called 65mm but actually listed as 64mm in the dimensions. This was a key part of the process since the MDX has 64mm burrs and I was able to purchase the carrier online.

The carrier is needed because the upper burr sits in a recessed cavity milled into the underside of the carrier. From pictures in various threads of the upper burr carrier with burr installed (Atom, Spec65, 65E etc) it's hard to see this detail. The fit is very precise so the larger burrs would not fit the original Atom upper carrier.

The only real modification that has to be done before putting the 65mm upper burr into the MDX carrier is to grind down the tab on the top of the carrier. The Atom is on left and MDX is right. You can see how it's pointing up on the MDX carrier.

About 5 min with a dremmel and we're good to go. If you take a look at the image below, here's where the * comes in. More about that below.

Some comparisons of the burrs once I got the originals out. 60mm on left 65mm on right

No Eureka markings on underside of the 65mm burrs. Branding is on side:

Ok, now the lower burr carrier. Happily, no modifications or anything needed. If you look at the carrier with the 60mm burrs removed you can see a raised area between mounting holes and wipers. This is what the 60mm burrs sat on. Radial alignment seems to be exclusively via ID of the burr and the central raised area of the carrier, between mounting holes and center bolt.

I was very excited to see this since it meant that I didn't need to find a way to shim the 65mm burrs or anything for radial alignment. Didn't measure but it seems that ID of the 60mm and 65mm burrs are almost identical. When I put the 65mm burrs in there was little to no radial play, just like with the upper burr carrier.65mm burrs installed:

Ok, everything was put back together and reassembled. Note that I had to go one full rotation or more coarser so the burrs wouldn't touch. I think the 65mm burrs are slightly thicker than the 60mm burrs.

Here's where I ran into one issue. I was so happy about everything fitting together that I didn't realized that the neck on the upper burr carrier from the MDX is taller than the atom:

So cosmetically, the upper lid doesn't fit with the upper carrier installed:

I'm not going to let this stop me though. I'll just 3D print a nice cosmetic solution and everything should be fine. Likely just a gasket to fill the gap and maybe some longer screws to attach the top plate.

That being said, I went ahead and did some testing in a slightly less finished way:

I've only put a little time in after the burr swap but here we go with a few number using 14days post roast Malabar Gold (got 5lbs and decided it wasn't for me, oh well):

Using well broken in 60mm burrs I was getting 16.2g out in a grind time of 8.5s (not single dosing). I pulled a shot of 24g espresso in 25s at a dose of 17.5g right before the burr swap.

Immediately after the burr swap I did a quick dial in to 25g espresso in 25s at a dose of 17.5g. The grind time for this was 20g in 8.5s (again not single dose). So minimally, it does seem to be grinding faster albeit not at the exact same pull parameters. Here's the shot:

After the above shot I ran 2lbs of old beans through that i've been hoarding for burr seasoning. I'll get back at it tomorrow but for now, i'm off to design some 3D printed parts to finish off the burr mod.


#2: Post by Leicaman »

Very impressive stuff. Thanks for posting. Does seem like quite a lot of effort though ;)
Do the 60 and 65 have the same motor btw?

Aida Battle: Indigo Reserve from world renowned Finca Kilimanjaro in El Salvador
Sponsored by Aida Battle

#3: Post by Hide »

SSP Redspeed Burr or Eureka Zenith 65 alignment issue

I have an issue posted above, I'm wondering if you may have some advice since the mechanism is pretty similar?

The top bolt of the top carrier group once screw down, it will cause that side of the burr to touch pre-maturely.

Kran (original poster)

#4: Post by Kran (original poster) »

Leicaman wrote:Very impressive stuff. Thanks for posting. Does seem like quite a lot of effort though ;)
Do the 60 and 65 have the same motor btw?
Less effort than selling the Atom and buying a Specialty 65, at least for me. I think the motor on the 65 is higher power but I haven't had any issues yet (Malabar Gold and an Espresso from Sey coffee that's pretty light roast).
Hide wrote:SSP Redspeed Burr or Eureka Zenith 65 alignment issue

I have an issue posted above, I'm wondering if you may have some advice since the mechanism is pretty similar?

The top bolt of the top carrier group once screw down, it will cause that side of the burr to touch pre-maturely.
Haven't run into any issues. Everything is running with plenty of room for adjustment and error (choke to correct flow is similar to pre-mod but I haven't fully explored the range yet).

Also, here's a picture of the final product with 3D printed gasket. No need for longer screws. The important part here is that there has to be clearance between the black lid and the upper burr carrier so that when you screw down the lid you don't push down on the upper carrier. The way the motor/carrier is mounted there is some give if you torque hard enough which might affect the adjustment mechanism/alignment.

I plan on using it this way for a bit. If/when I jump to the SSP burrs I might cut down the upper carrier so it looks more stock.


#5: Post by Frisbeeist »

Nice mod. Do you have an STL for the gasket? I assume others will be in a similar situation in the near future.

Kran (original poster)

#6: Post by Kran (original poster) »

I could provide the stl files upon request. It's actually 4 files (front, rear, left and right) for the gasket because my printer is kinda small. Can easily adapt to a 1 piece design for those with a larger printer.


#7: Post by mikeTRON »

So how much money did this upgrade cost and was it worth it?

La Marzocco · Home: customized for espresso aficionados
Sponsored by La Marzocco · Home
Kran (original poster)

#8: Post by Kran (original poster) »

$40 for the burrs and $65 for the carrier.

For me worth it in taste is subjective since i can't directly compare taste from a 60 atom and the modded 65 atom. Just like I can't remember taste differences between my PL53-->Preciso-->Quamar M80-->Vario-->Atom 60 because beans were all different over the time I had each grinder.

Personally it was worth it because it pushed off the desire to upgrade for a few more months.


#9: Post by Peti925 »

Hi Kran
Thanks for the idea, I've upgraded my Eureka Atom to 65mm burrs from 60mm as well. It all started, when my Atom got a bit shaky after being posted to Ireland from Hungary. The whole grinder was vibrating after the delivery, so I sent it back to Hungary using a different company now. (By the way, is there some method to ship these grinders more safely? Like putting bubble wrap around the motor, which is held by rubber gaskets in this model or closing the burrs together during shipping?) In Hungary we have a man, who is really experienced when it comes to fixing or modifying espresso grinders. He said though, there was no vibration when it arrived (maybe it got another hit on the way back, that fixed it :lol: ). So I decided to upgrade mine, as he had access to a lathe. First he tried mazzer sj burrs, but the lower burr carrier of the atom60 wouldn't accept the sj burrs, because of their slightly smaller inner diameter. But I remembered your post, so I ordered an original eureka 65mm burrset from the italian Elektros site. It was 25€+12€ for the shipping. However I didn't follow your method for the upper burr carrier, because we used the lathe to make the larger burrs fit in the original upper carrier. He said it is possible to attach the upper carrier part in the lathe. I haven't tried the grinder yet, but it is nice and quiet now and the man, who repaired it said it is working fine. I am very interested to see the results, because the grinder was stellar even with the smaller burrset. I can post some photos if you're interested. Are you still using your modified Atom?

User avatar
Supporter ♡

#10: Post by redbone »

Nice job, I recall Peter_SVK (member in Slovakia) undertaking a similar project with a Fiorenzato F4E Fiorenzato F4E rebuild (take it to another level ...).
Between order and chaos there is espresso.
Semper discens.

LMWDP #549