[Bruceb]

I believe your modification of the rod by grinding of the threads is illegal by R73.
<R73> Items specifically PROHIBITED from use on the ROBOT include:
A. Any pneumatic part or component rated for less than 125psi.
B. Any pneumatic part or component that has been altered, modified, machined, coated, or changed from its original “out of the box” condition, except as required for normal assembly with other components. The only acceptable modifications are:
• Tubing may be cut.
• Wiring for pneumatic devices may be modified to interface with the control system.
• Assembling and connecting pneumatic components using the pre-existing threads, mounting brackets, quick-connect fittings, etc.
• Removing the mounting pin from a pneumatic cylinder, provided the cylinder itself is not modified.
• Labeling applied to indicate device purpose, connectivity, functional performance, etc.