While loading bobbins for her next quilt project, Mary found another one that just wouldn’t fit on the winder:
Knocking the rock out of the bore required a pin punch and more than a gentle tap, but it eventually left without damage. The little stick in the slot looked organic, although it vanished without a trace during the operation.
I originally thought the bobbin factory’s final vibratory polisher used walnut shells, but the evidence certainly suggests ordinary gravel!
The Smell of Molten Projects in the Morning 