127T change gear for cutting metric threads on a Harrison L5 lathe

thingiverse

The 127T gear is necessary for cutting metric threads on the imperial Harrison L5 lathe. (12.7mm is precisely ½" so 127T gives an exact conversion). Other gears needed to cover almost the full range of metric thread pitches are 40T,50T, 60T and 63T. I remixed this from my previous Harrison gear code that uses customiser to allow you to dial up the number of teeth you want. I would not recommend running with plastic on plastic but I have run 3D printed gears against steel gears for a while now and they seem to work fine. Update: See my remix of this (http://www.thingiverse.com/thing:1808219) if you already have a 100T gear and never want to use both 100T and 127T at the same time. The remix uses less plastic, is quicker to print and can be printed on a 150mm square bed piece by piece or all at once on a 200mm square bed. Which is easier to make? I'll post another update once I have made the 127T-100T remix. I think the full 127T gear would be more convenient if you want to switch between metric and imperial thread cutting. Print Settings Printer Brand: RepRap Printer: Steelfence Rafts: No Supports: No Post-Printing Superglue the parts together. How I Designed This This remix uses puzzlecut to slice the full gear into 3 pieces to make it compatible with 3D printers with a 200mm square build plate. I would suggest doing a couple of test prints to ensure that they key together OK first. I used my slicer software to trim the height to 3mm for the test prints. There is a kerf variable in the openscad file that can be edited to increase or decrease the spacing between the puzzle pieces. You can comment out all but the desired part in OpenSCAD and compile and save them in turn or you can do as I did and save the STL with all 3 parts in it and manually edit the output STL file with netfabb to split it into three separate files. The -0.05mm kerf that I used was pretty tight - needing a bit of filing and sanding to make it fit. I didn't use any glue - just pressed the parts together with a vise.