Self feeding lap

[Roger B]

I made a simple split bass lap for finishing various parts of my fuel injection systems. It shows an interesting tendency to self feed. If I start it off it continues on its own until I push it in the other direction  This is lapping a 1.5mm part with 5 micron diamond paste and around 800rpm. Is this usual? Any thoughts?

<a href="https://www.youtube.com/watch?v=yJYPh8AALzc" target="_blank">http://www.youtube.com/watch?v=yJYPh8AALzc</a>

[Admiral_dk]

Absolutely a guess - but I suspect that the initial movement created by your fingers, makes miniature helix / thread - that continues afterwards .... 

What puzzles me more is the fact that the Tool doesn't spin with the Part 

Per

[Kim]

I was thinking the same thing as Per.

Per, I believe that the lower part of the handle is hitting the bed of the lathe, keeping it from spinning.

Kim

[RReid]

Quick, file for the patent!