Pitch Lap Calculator (for spin polishing, see below)

Mel Bartels

Number of stars
Tool to mirror size ratio
MOT TOT   pressure

Straight stroke   length offset spin
W stroke   overhang

Presets full contact petal lap reverse petal lap

Notes

Pitch lap top view (black is pitch)

Relative polishing action on the mirror - side view

Relative polishing action on the mirror - top view

Tool spinning on rotating mirror section

First, find tool rotation rate than zeros out the net rotational vector. This is the tool's free spinning rate.
Do this by minimizing the net direction value below the graphic. Then inspect the polishing action.

Rotational vector inspector

Green CW rotational vector, red CCW rotational vector.
For example, with mirror rotating at a fixed rate, what is
the rotation rate of a freely rotating tool (Net direction = 0)?

Tool to mirror size ratio
Mirror rotation rate
Tool rotation rate
Tool offset
Use pitch lap contact pattern from above?

Relative polishing action on the mirror - side view

Relative polishing action on the mirror - top view

Consider these three examples with the tool centered on the mirror. The tool matches the mirror's rotation in the first example, netting zero rotational action. In the second example the tool does not rotate at all, causing the mirror to generate a clockwise rotational vector. In the third example the tool spins faster than the mirror, causing counter-clockwise action.

Here's how I work out the rotational vector (distinct from the polishing action:

Created 2017, last updated Jan 29, 2024