John R. Carroll wrote:
Winston wrote:
John R. Carroll wrote:

(...)

Those are stress cracks that result from the molding process,
plasticizer migration and shrinkage over time.

Thanks! This plastic stuff is complicated.
Clearly I will have to turn that design task
over to a specialist.

Apparently not too much time is required
for the cracks to develop.

I shot the photo about 10 minutes after taking the grinder
out of the box for the first time. I never even turned it on.

I didn't realize it was new.
Sheesh.
The part has probably cracked at the knit lines.

'Knit Lines'. That is a new one on me.
http://www.protomold.com/Design_Tips/UnitedStates/2004/2004-08_designtips/

Poor knitting has a number of causes but chief among them is improper resin
processing or low mold temperatures.
IOW, somebody screwed up either when they designed the gates/runner system
or when running the mold.

Ah Ha! So it passed final inspection while hot but
grew the cracks in the Amazon warehouse? Wow!

Thanks again.

--Winston