Precision gearbox have habitually less than 15 arc/min of backlass. More $$ you spend , less backlash you gest, some mfg. have 0 backlash gearbox that are very expensive. I have used gearbox from GEM and from CGI with very good results. With a 15 arc/min backlash, convert in degrees this give a .25 deg of backlash, add a 3" pinion gear to go with a rack, you will get a total backlash of .002", that is good enough for me, list price for a 5/1 nema 34 std. from CGI is 380$.
Hope this help,
Alex
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Alex
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