David Lesher wrote:
A quiz:

If you are a brand-name (say like "Barbie-less") for a previously large
chain store... one where America previously shopped; and you sell
dishwashers....

And said dishwasher has a center twirling arm to spray water around...
and the arm is secured with a large plastic screw with big shoulder.

Take plastic screw into shop. Turn new stainless screw out of bar stock.
In stainless screw install a nylon insert OR cut shoulder so that a star
style lock washer can be used.

Second approach. Pull the bottom arm and ream out the threads, press in
a new insert with the opposite threads. Then make a new screw with the
proper threads.

Third approach. Turn a stud with the proper thread and a shoulder. Cut
threads on top in the opposite thread. Use good locktite to install the
stud. Then install the proper nut on top.


Now, you can put the jets on the arm two ways: one rotates the arm so
that the screw, if anything, tightens itself...

And the other so the screw LOOSENS itself....so it backs out, falls out,
as does the arm....

So which way would you design it to rotate? Why?

Justify your response. 10 points. Responses quoting Feynman get extra
credit.

Question 2: Suppose your firm choose badly. How would solve it in the
field?

a) Epoxy screw into place

b) Throw arm away, with screw; tell customer it's an upgrade.

c) Figure out how to get screw to stop doing that.




--
Steve W.