For at least a cou­ple of years now I’ve been plan­ning to build a vac­uum easel for high-precision bor­der­less print­ing. Way back then I acquired an EG&G regen­er­a­tive blower for this pur­pose. Today I finally built the pro­to­type fixture—a wood and plex­i­glass mockup—to get a fix for the proper hole pitch and diameter.

I drilled 560 holes by hand (ugh!) mea­sur­ing 0.052″ each on a 0.250″ grid. The grid pitch is accept­able, but the flow rate through even a few rows of 0.052″ holes will be unac­cept­ably high con­sid­er­ing that the final ver­sion would have over 2300 holes. Assum­ing mass flux is pro­por­tional to the sur­face area of the holes, I’ll need to go down to the 0.020-0.040″ range, which I’m not excited about.

How­ever, while the pro­to­type uses a 1/8″ acrylic sheet, I was plan­ning to use a 1/4″ alu­minum plate for the fin­ished prod­uct. My ques­tion for you, dear reader, is this: will the increased plate thick­ness (thus increased hole depth) sub­stan­tially alter my dis­charge coef­fi­cient? Any help is appreciated.