# Re: Sean's methodology again.

On Jul 5, 12:27 pm, richardalanforr...@xxxxxxxxxxxxxx wrote:

If we have a 500x500mm block, the distance of the faces of that block
from a plane running through the middle is 250mm.
If the tolerance on the flatness of the block is 3 of 4 microns,
that's 0.0012% to 0.0016%, which exceeds your parameters.
If the tolerance on the parallelism of the block is 5 microns, you
just meet your criterion of 0.001% for parallelism only.

The tolerance % of one surface point compared with the opposing point
as measured from the center is a fraction of the *total* distance -
not half the distance. The tolerance is a comparison between opposing
surface points, not between one surface point and the distance to the
center.

However, unless there is *NO* tolerance on flatness, your criterion
cannot be met, as deviations in flatness will reduce the "reflective
symmetry".

So these blocks do *NOT* meet your criteria.

Try again.

You're reaching for straws now. But, if it will make you feel
better, I'll reduce the tolerance level by 10 fold to 0.01% for my
criteria - just so there will be a few more real true positives that
actually exist for which not even you can possibly argue otherwise
(Yes, I do know that's a stretch of faith given your history is what
it is). It doesn't make a hill of beans difference as far as the
point I'm trying to make here. Each increase in tolerance
requirements only increases the positive predictive value of this
particular ID test. The pattern is obvious well before we get even
*remotely* close to these degrees of tolerance. That's the whole
point. But, of course, this simple concept flies right over your head
- as usual.

< snip >

RF

Sean Pitman
www.DetectingDesign.com

.

## Relevant Pages

• Re: Seans "methodology"
... within the range of 3 to 4 microns and parallelism of opposite faces ... measuring the distance of opposing points from that plane. ... If the tolerance on the parallelism of the block is 5 microns, ... But the blocks do not reach the criteria of "reflective symmetry" ...
(talk.origins)
• Re: Seans "methodology"
... The tolerance on the 200mm cube is 2.8 microns. ... with respect to flatness and parallelism: ...
(talk.origins)
• Re: ON topic- Flycutting ALuminium
... If it were me (and with that flatness tolerance), I'd not touch the flat surfaces, but I'd rough out your perimeter, all your features & large holes, then send it out to be blanchard ground - then when you get it back, finish your perimeter, features, and holes. ... When you relieve that stress by removing material on one side, the part bows. ...
(alt.machines.cnc)
• Re: Granite, Symmetry, and ID - Summary
... that various forms of symmetry, such as reflective symmetry, can be ... with an excellent true positive and low false positive rate. ... The angle cannot be "rounded" off to less than the degree of tolerance ... The distance of each surface point on one ...
(talk.origins)
• Re: Granite, Symmetry, and ID - Summary
... The % tolerance is still the same regardless of units. ... center of the stone and compared to the distance to the exact opposite ... rounded off shapes do not qualify as "irregularities". ... above parameters are met the prediction of deliberate artifact carries ...
(talk.origins)