Photo 1 shows the bolt used by Bealle with the slotted head that can eat up a piece/bottom. Photo 2 shows the installation of flat head"elevator" bolt using double nut to allow tightening the installation nut. Photo 2 shows the flat head of elevator bolt after installation less likely to do damage in made contact with piece. Photo 4 shows the worn down 6"D wheel being replaced with new 8"D. Of course, the 6" wheel will still be used for pieces between 6 and 8"D interior or larger.
Tripoli Buff 1.JPGTripoli Buff 2.JPGTripoli Buff 3.JPGTripoli Buff 4.JPG

I do miss Don Pencil. He used the flat head bolt initially. FYI - I did have to drill a couple of small holes in face to use pins and bar to remove a wheel once that had become jammed against shaft and was not anchored tight to loosen wheel.