Improving Coarse Adjustment on Polaris

Getting the Losmandy mount properly aligned no True North was possible but not easy.  The field of view in the Polar Alignment Scope is a bit narrow.  Someone on Cloudy nights.com suggested that I put a laser pointer in the polar axis use the beam to get a coarse aim at Polaris.  This would get the Polar Alignment Scope close enough for fine adjustment.

Fine idea so I machined an adapter to hold the laser pointer centered in the polar axis where the Polar Alignment Scope (PAS) normally sits.  That tube is 22mm diameter so I found some scrap aluminum that I could turn down to 22mm.  It is not a tight fit but then again I do not want friction impairing the fit of the PAS in the polar axis.

The laser pointer barrel is 16.6mm.  My largest twist drill that does not look like a prop from the 1960s terrible Land of the Giants series is a 1/2" bit.  My boring but is not long enough to bore out the needed length.  Yes, I came up with a clever workaround a week or so ago.  But better was to find a 17mm twist drill.  If one exists that is not made in the PRC, I could not find it.  Fortunately I found an American-made 9/16" bit which is about 17.2mm.  Close enough.  I do not want a press fit.

The steady-rest served its function as I drilled the 1/2" hole large enough for the laser pointer to easily slip in place.  My original plan was to put the laser pointer in the hole butt-end first but to get the on button to a useful position required enough cutting to take a different approach.  I put the business end into the 17.2mm hole turned the laser up to 1 MW and bored out a hole in the other end.  No, really I drilled a .157" hole in the far end so the beam goes out.  It slides into the base of the PAS bore and I can press the on button.  

The laser pointer will still fall out of the adapter and both fall out of the bore.  Tomorrow, I will drill and tap a 1/4"-20 hole in the side of the adapter and use a set screw to keep the laser pointer in position.  (This should not push the laser pointer too far out of center.  Even .6mm offset should be fine.,). I will put some masking tape on the outside of the adapter so it sticks in place at least approximately.