Recently I just got a pair of Mythos 1 75mm titanum burrs so I thought I could switch out the stock burrs in my Eureka Drogheria MCD4 85mm. Like in Kran's post, the screw holes fit perfectly, though I found that the Mythos' bottom burr sits lower in the burr carrier than the stock's bottom burr by about 0.5mm - 1mm. Since Eureka's grind adjustment moves the bottom burr (and the motor), the result is that there's a greater minimum distance between the burrs, and now the smallest grind size I can do is about pour-overs.

The reason for this is that the MCD4's bottom burr carrier have a raised groove with a 80mm-85mm diameter which raises the 85mm stock burr higher about 0.5mm - 1mm. With the Mythos I 75mm diameter burrs, it sits in the lower surface of the burr carrier. Does anyone have ideas on shimming the whole bottom burr by 0.5mm - 1mm around the 65mm-75mm band?

Aluminum strips might work to evenly elevate the whole burr, but it would need lot of aluminum layers, and there's also a risk of them flying out during spinning. I've tried to shim with 6 washers evenly spread out underneath the bottom burr and it seems to solidly raise the burrs to the right height, but there's a variance of the height of these washers causing a huge alignment issue. Perhaps there's something else out there that's evenly flat and metal with a 65mm inner and 80mm outer diameter?

Having pour-overs with the Mythos 75mm burrs, I could taste more bright notes than the stock burrs, and visually I see a lower amount of fines, so if we could figure out how to shim it, this grinder could be a $850 Mythos killer one day

P.S. I do not think the Mythos II 85mm burrs will fit on this grinder because of the screw hole distance is different than the Mythos I burrs.

I never had this issue. I was able to align the 75mm mythos burrs in the MCD4 85 using the marker wipe method and always calibrated the "0" to the point of burr chirp.

You may want to see if you have full movement with stock burrs and then try the 75's again.

With the stock 85mm burrs I was able to reach the chirp point, although the grind adjustment becomes very annoyingly hard to turn in that turkish/espresso area. Maybe I should open up the grinder from the bottom to see any issues with the mechanism.

With the Mythos 75mm burrs, I turned the grind dial past the stock burrs's chirp point until when the dial could not turn anymore, so that let me to believe the burr carrier has reached its highest point.

Also, I do think my Drogheria is an older generation than Kran's, perhaps there are slight differences in the parts.

I can confirm I went to the finest grind setting and still far from chirp point.

I have a photo here showing the 85mm bottom burr carrier has the ring that lines up with the raised groove of the 85mm stock burr, but is too large for the 75mm Mythos burrs.



This photo here shows the ring raises the 85mm burr set by about 0.1mm-0.5mm.

I've done the comparison. The Mythos2 85mm burr won't fit.

Do you think it's still worth it to drill & tap the burr carrier? Since the Mythos 2 is 85mm, it'll align nicely in the burr carrier.

Personally I guess the issue of mismatch (M1 75mm) here would not make a huge difference for home users. The slight deformation of the burrs could be neglected if we only grind several cups a day. Of course it might be a different case in the business environments due to the heavy load and accumulation of heat. I have installed the M1 75mm burrs in my MCD4 and I love the taste a lot, though I confess that this is not a serious comparison.

BTW, the gain we might have by installing the M2 85mm burrs is not substantive. The grinding surface of M2 85mm is about 33cm2 and that of M1 75 is about 31cm2. This improvement of the in-cup quality might also be marginal.

I absolutely have no clue if this could help or hurt but I saw this YouTube video in which he had an issue with grind size adjustment mechanism, maybe knowing about the general mechanism could help you (~16min):

I did mess with the spring load mechanism's screw a little but it still didn't help the burrs get any closer, since I already adjusted the dial to the hard stopping point i.e. the finest grind setting that the motor housing allows. If the bottom burr were to raise any higher, the sweep arms would almost start touching the top burr carrier.

With this gap under the lower M1 75mm burr, I decided to buy a 75mm diameter 0.3mm shim from aliexpress. I'll report later to see if this is actually any good at shimming the burr or cause any alignment issues.

Cartmarn wrote: BTW, the gain we might have by installing the M2 85mm burrs is not substantive. The grinding surface of M2 85mm is about 33cm2 and that of M1 75 is about 31cm2. This improvement of the in-cup quality might also be marginal.

For me it was initially more the geometry of the burrs. the 85mm stock burrs are very different then the mythos or 65mm eureka burrs. I've moved on from the 85 simply because the noise and workflow aren't for me.

In terms of not being able to use the 75's, I can offer the following but I'm uncertain how much help it'll be:

The grind adjustment is similar but also different from the other Eureka grinders. The hard stop seems to be a function of the top of the threaded rod running out of thread. Actually a threaded cap that is attached to the rod that the adjuster screws on to. The way to see it is to remove the top plate and then screw on the adjuster until it bottoms out. You'll be able to better see how it the mechanism works.

On my grinder if I remove the rotating burr and then re-assemble everything I have 10.25 full rotations of the adjustment knob before it locks. At this point if I rotate the bottom burr carrier using my fingers to turn the bolt it slightly binds, I assume this is the wipers touching the upper plate.

With top and bottom 85mm burrs installed i reach burr rub at 8 full rotations. So that's roughly 2 full rotations to account for the lip on the lower burr carrier if you're using the 75s.

Again, without being able to experience the issue myself it's hard to diagnose.