Mythos One constantly changing

Hey all,

I’ve recently started work as the head barista at a newly opened coffee shop. When we first opened we didn’t experience many issues with the Mythos One, but recently we have started going through 4kg of coffee a day. My issue is that during the day the extraction times are constantly changing, sometimes quite drastically. In the morning I set it to 19.5 g in, 40 g out, 25 sec. During service, sometimes even after the first shot, this will creep down to 22 seconds, and later shoot up to 30 seconds. During service, I’m constantly battling the grinder and changing the setting slightly to ensure the extraction time I want.
I am constantly weighing the amount of ground coffee, this also does tend to fluctuate quite a bit.
I understand that that despite the heating element, the burrs and the fines can heat up during rush or cool down in between.

My question is whether it’s normal to constantly change the settings as I’m pulling the shots or whether there’s a better way to go about it. Perhaps there’s even an issue with the grinder.

I think that you have run into one of the inherent problems with any grinder that lifts the armature and lower burr rather than adjusting the burr gap by changing the location of the upper stationary burr. I suspect that you are seeing the armature or stator grow in length as the motor is heated from use. This reduces or increases the gap between the burrs if the expansion of the two motor parts are not uniform. The later Mythos has fans and a heater to try and stabilize the grinder temperature. If the duty cycle on the grinder is not consistent you will continue to have issues. I have mentioned to users of the ClimaPro to leave the grinder on over night to allow the grinder to stay up to temperature from the heater in the upper burr mount.
jpboyt