…then machined these tubes or “slugs” to drop in the holes. The purpose of the slugs is to prevent the head of the bolt from crushing the top layer of fiberglass as the bolt is tightened. I machined them so that they sit on top of the bottom layer of the floor and just under the top layer, so that when the bolt is tightened it will compress the floor just a bit before bottoming out on the slug.
Here is the finished product – we were wondering whether to paint them, but I think they look pretty sharp the way they are. They are only about 1/8″ off the floor, so they shouldn’t catch feet.
What do you think?