by BenJackson » Sat May 28, 2011 12:32 am
After assembling my gantry as described (endplates on a flat surface) and then leveling the short V-rails that the gantry rides on I discovered that only 3 wheels were touching because the V-wheels were not coplanar. Also, the long rail itself sloped significantly down towards the front edge. I was able to adjust all of this out by loosening the wheels and adjusting them to level the rail and remove any twist. As a quick first step you can just loosen all the wheels and as you tighten each one make sure it is pushed toward the top or bottom of the hole in the plate. My plates were assembled freehand so each wheel started with a slightly different location within the punched hole.
I'm still pondering whether the geometry of the final mirror would let you make a vertical beam without a perfectly horizontal carriage. I guess not since the lens is going to be coplanar with the carriage.