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Racks and pinionsSunday, February 22. 2009Wherein your narrator explores ways of upping the milled or printed
content of future Reprap machines.
Some years ago I wrote a script in Java for designing involute profile gears on a dare. Having successfully done that, I went on to do another script for designing racks as a companion for the gear script. While I've tried out the gear script on a number of occasions in the past half-year, I'd yet to try the rack script. Now I have. I wanted to mill fairly fine toothed racks and pinion gears. Attempts to do that revealed some problems in my toolpath calculations which I've got some way towards solving. As well, I had a scaling problem in the Slice and Dice routine that I knew about but hadn't had an occasion to want to fix till now. I chased through the coding and parameterised the scaling factors. Right now I have it scaled to 240x240 mm at 0.102 mm resolution. That let me attempt a 190 mm rack {200 mm milling area}.  There is no practical reason why I can't do a diagonal cut on a 12x12" sheet of HDPE and get several 15" racks.  I could either tilt the axes slightly to get rid of backlash or offset and springload two parallel strips of rack to achieve the same effect. Don't take the product you see here too seriously. I cut it with the brutal Airpax steppers that I just took delivery on in mind. 
After doing this, however, I've reached the conclusion that the diminutive Jameco steppers would be better suited to this approach.  The Airpax steppers I intend to use for a geared linear stepper approach. Trackbacks
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