As you wind a bolt in the knurled section expands to grip the material you inserted it in.
You can also drill the hole for them slightly under size and push them in with a soldering iron so that the plastic melts locally into the knurled section if you’re so inclined
As you wind a bolt in the knurled section expands to grip the material you inserted it in.
You can also drill the hole for them slightly under size and push them in with a soldering iron so that the plastic melts locally into the knurled section if you’re so inclined