I've just found a new photo of another Atlas carriage stop. In this one the "bumps" are actually screws. This makes some sense, since it might be intended to adjust for wear/scraping of the ways.
I would hope there is not enough wear from a carriage stop that would ever require recurring adjustment. However, it is important to get the adjustment just right to ensure that the stop has reasonable friction against the ways.
My "ugly" carriage stop has three adjustable bolts for that purpose. I have not touched them for a long, long time.
(I suspect Charles was misled by those bolts and thought they needed to be diddled to move the stop. Nope, just the one socket head clamp screw.)
Gene
