On Dec 17, 12:29 pm, Michael Gray wrote:
Could I suggest:

http://www.neme-s.org/Rollie's_Dad's_Method.pdf

Thank you Rollie's Dad.

Mike in BC

That's a good quick trick but it depends on measurement rather than
comparison of equal readings, which is potentially more accurate. It
won't work at all with an indicator like this:
http://contractorstools.com/graphics...ind5series.jpg
because the reading isn't linear.

Jim Wilkins