What do you think is the smallest workable size for printed gears? I am starting work on a design and due to various constraints, it would require a pinion with 8 teeth and a module of 1.2, giving the gear a pitch diameter of 9.6mm. I know I can accurately print it that small, but would it be too fragile or have other problems? I read something which suggested 9 teeth was about the limit (at a 25 degree pressure angle)
top of page
bottom of page
Thanks, that's good to know! I did some test prints today (with a lot of switching between the CAD program and the slicer, just as you say), and the results look OK, but I have yet to try them in a train. I'll try modifying them the deepen the dedendums if they don't work well.
I tried some experiments a while ago to see how small the gears could be printed. I was able to print module 0.7 gears with 8 teeth using a 14.5 degree pressure angle. The gears were modified in CAD to deepen the dedendums and narrow the main gear teeth to a 40% tooth width. Here is the CAD showing the original gear in black and the modified gear in black.
Here are the slicer results at mod 0.7.
And the slicer results when scaled to mod 1.2. It would print better if the pinions were made wider so the small gap fill becomes internal perimeter. A 20 degree pressure angle would be a better starting point than 14.5 degrees. The main gear could be made narrower to close the small gap and eliminate the gap fill.
Small gears can be done. The trick is to go back and forth between the gear generator program, CAD, and the slicer to see what it will print like. I find that the default from the gear generator may be optimal for a metal gear, but it always needs modification to print cleanly. I use the radial copy command a lot.