I own a nice Macap M4 stepless with chrome finish.
Friend of mine owning the Mazzer Mini just changed the burrs with the ones from Mazzer SJ and was quite satisfied.
Question is simple :
Will Mazzer burrs fit the Macap? Has anyone tried it?

Macap M4 = 58mm / Mazzer SJ = 64mm

This is really a non-answer, but I offer it at no charge:

The Macap M4 and Mazzer Mini both have 58mm burrs, but I don't know if they have similar hole patterns or cutting surface patterns (i.e., the slant in the cuts may differ between manufacturers to slow/speed the cutting time commensurate with the motor's torque). The thread Installing Mazzer Super Jolly burrs in a standard issue Mini shows how someone modified the Mini's burr carrier to accommodate the Super Jolly's 64mm burrs, but I have no experience with it. So, to non-answer your question, I don't know if the 58mm burrs for Macap and Mazzer grinders are identical. And obviously, as Ian noted, the 64mm burrs of the Super Jolly won't fit in the Macap M4 with modification; if modified as such, the Macap motor might not appreciate the additional strain.

It would have actually been sweet if the 64mm burrs could fit my Macap; I suppose this would not be possible (apart from doing some nice mod as the one described with the Mini Doser).
Btw Mazzer Mini Electronic and Mazzer SJ burrs are both 64mm; most likely this is why SJ burrs fit the Mini Electronic.
Anyway, if anyone has tried 58mm/64mm burrs from Mazzer in a Macap just let me know please.

Burr height is largely irrelevant. 1mm added thickness is 1 upper carrier rotation less on reassembly.
The critical dimension is bolt hole circle diameter.
Some M4 'replacement' sets do not fit because this dimension is slightly off.

To fit 64mm burrs in the M4 :

• with absolute ±.001" accuracy measure bolt hole diameter of 64mm burrs
• remove M4 burrs
• remove lower carrier from M4
• remove 'wipers' from lower carrier, ensuring an absolutely ±0.0005" level 64mm burr fit
• drill & tap lower carrier
• drill & tap upper carrier
• hope 250w motor lasts long enough to recoup investment

a new 64mm grinder is probably a better buy