round clip mount revised

This is designed for use with a power wheelchair castor. It is a customized version of Jhack's Customizable Round Clip (https://www.thingiverse.com/thing:65816) using threading and the bolt from johann517's G-Clamp (https://www.thingiverse.com/thing:1673030).

This is designed to work with yyh1002's Modular Mounting System (https://www.thingiverse.com/thing:2194278).

Print at 35-50% for clip strength with support.