air powered egraving handpiece

thingiverse

For years I've been using manual gravers to inscribe plates for printmaking and to make ornamental metal engravings. Since these activities are merely an avocation that makes me no money I could not justify the cost of air powered engraving handpieces and the required air delivery systems. Sadly, joint issues make continuing to use manual gravers for extended periods impossible so I went looking for DIY options to make some pneumatic engravers. I was happy to find a couple different alternatives, one of which (by Rick Alexander) is simple and inexpensive to make with minimal tools and equipment. Unlike many expensive and more complex models, Rick's design relies on a modified 12 volt air compressor that provides pulsed air that alternates pressurized air and a vacuum as the reciprocating compressor piston alternates up and down. The piston in the handpiece has an adjustment spring to help vary the piston stroke and help initiate the return piston stroke during the vacuum cycle. Most people make this design on a metal lathe, but it is possible to make with only a drill press and hand tools. I have both metal and wood lathes and could make metal or Delrin (acetal) versions on either lathe, but I wanted to see if I could design an dead simple, affordable, and workable air engraver for the masses at minimal cost. My goal was to retain the full adjustability and perhaps sacrifice a bit of speed in adjustment in order to attain my other goals. This is the result. This is a 3D printable air powered engraving hand piece that remains fully adjustable via an internal spring compression adjuster. I designed this version to be very simple to print with no supports, to require minimal post-processing, and require no machining of the handpiece components. Just print it out, clean up the bores, drop in a purchased piston and spring and go. Items to be purchased are the piston, which is a 3/8" stainless steel ball bearing, a cheap 12v compressor ($40-50) , and a set of various springs. Oh and quick change tool holders and gravers which can be found cheaply online example: https://www.ottofrei.com/GRS-004-806-Traditional-Quick-Change-QC-Graver-Holders-Pack-of-10 In a goal to be almost entirely 3D printed I prototyped some thermoset springs using various filaments wrapped around a mandrel and then heated in my toaster oven, but I dont know if they will be durable enough, and metal springs are dirt cheap so I recommend purchased springs. The spring tension is adjusted from the rear of the tool by removing the end cap and adjusting a hollow-lock set screw inwards or outwards. The end cap is then quickly screwed on to make the handpiece cylinder air tight at the rear where the air line enters.