Strong variations in quality?

After I cut the first two discs down (which wear out quite, even if that does not sound at all danch reviews), I ordered a third which should be enough slack for the rest of the work to be done, according to previous experiences.

Up to this point, I would have given 4.5 stars loose, though the grinding wheels use somewhat, but this total was under angesichsts of what I've already done all that. For the price definitely hold long enough.

Yesterday I now made the third pot in operation. After nearly 10 seconds, rattling a first time, I was not immediately clear that this was not a pebble. 2-3 seconds later it rattles again, the unit was vibrating more than ever at a time. While I slowly entered the reviews with departing parts in Erninnerung scheppert it 10 seconds later again, the machine shakes like crazy and I can just barely keep still to get away.
Result: After just 30 seconds in service (at the same point made further where the previous disc ran smoothly even after hours) were flown 3 abrasive elements, the quasi complete outer row looked very loose (!). Since it was partly already stuck a toothpick between pure element and disc.

Conclusion: 2 times 4.5 stars and a clear 0, makes 9 star by 3 slices = 3

For this, the warning to beware of departing in eight parts and the grinding pots necessarily after the first few minutes (if they then are still intact) Check at sight if not announce departures. If they hold because they are quite good!