After the egg-plotter, I constructed two successively larger and more complex XY tables. I also experimented with using an engraving tool (Dremel) in place of a pen. I had been using hardware store materials (threaded rods for lead screws, drawer slides for linear rails), and although the precision achievable using these components was amazing, I grew to resent their limitations. I began researching the methods and materials used by industry. What I found was crushing-- the real parts
were enormously expensive-- just one foot of twin rail with carriage and ball-screw could run >$1K. And I wanted to work on a large scale. I started looking for places that might carry surplus mechanical components, praying for
similar bargains to those I'd found in the surplus electronic equipment market. Over several months, and forays into many a warehouse, I found what I was after. In a dirty, machine-oil-stinking back-room, sat two 8 ft. long, 2" diam. hardened steel rods, with carriage and mating linear bearings-- all for $60. I had to replace one of the bearings ($100), but overall, it was a bargain. I found a scrapped 6 foot linear table in a different warehouse, and at long last had the main ingredients for a large-scale XY table. I purchased the most reasonable 6 ft. ball-screws/nuts I could find (new), and after considerable effort getting things mounted and aligned, had a robotic engraver
capable of covering an area of 25 sq.ft., in .001" increments. (1992).