Machining

 I am making a set of what ScopeRollers would have been if I was making them for a captive audience with an unlimited budget: more precision than anyone can afford.

I needed a tigh fit inside a .990" inside square tube.  So I machined a piec e of 1.01" xquare aluminum tube to just fit.

The machining stripes are cosmetic.  They are ridges caused by using a 1/2" diameter end mill at 1/4" intervals.  They are so close to flat that I cannot feel them, so likely less than .003" high or deep (I am not sure which).  Ordinarily, you remove them by using a flycutter, which runs a cutting tool in a circle acros the entire surface.  Sanding works well, too, although taking some material with it.

Here it is taking .005" slices off.

I wanted something between an interference fit, which requires tapping it into square tube, and a clearance fit.  That describes, it takes finger pressure to get into the tube, so it will stay while I drill and tap a hole to hold it in place.  I wish I could have done a better job getting my hand out of the way.

The next step is cutting that square block into three segments with 30 degree angles for the threaded stem casters.