You can, and the result will be poor for the same reason a blade grinder is poor: nothing is cutting to a size.
What happens
Blades smash beans until you stop. Some particles get hit many times and become dust; others get hit rarely and stay as chunks. The output is a random distribution rather than a grind.
Dust over-extracts almost instantly and turns bitter. Chunks barely extract and taste sour. Both arrive in the same cup, which is why blade-ground coffee tastes muddy and harsh.
If you have no alternative today
Use a forgiving brewer. Immersion — French press or AeroPress with a long steep — averages the mess out better than a pour-over will.
Pulse rather than run continuously, and shake the container between pulses.
Sift if you are desperate. A kitchen sieve will remove the worst of the dust.
Aim coarse. With a wide distribution you want the average on the coarse side, so the fines are less over-extracted.
The honest recommendation
A seventy-euro hand grinder will transform your coffee more than any other purchase, including the machine. If you are grinding in a blender and buying good beans, you are paying for quality you are then destroying.
Mortar and pestle, incidentally, is better than a blender for a moka pot — crushing produces fewer fines than smashing.
Last reviewed 8 August 2026