Fusion 360: Sketching a Geometrically Correct Circle Involute to Model a Proper Parametric Gear (1)

[@MihaiAndreiStanimir]

This is cool! Do you happen to have shared the project?

[@steelstone]

Comment updated with a link. You'll get the latest version, so slightly different and probably improved. If you want something more advanced, I suggest you my "screw gear and worm gear" video.

[@MihaiAndreiStanimir]

@@steelstone Awesome! The other video is even awesomer 😁

[@MihaiAndreiStanimir]

@@steelstone I checked the file. The gear you provide overlaps with the one generated by the SpurGear plugin. However, once I change Z to 12, your gear is much fatter than the generated one and it wouldn't mesh with itself at the correct distance of 2*rp. Is this different in your worm gear project?

[@steelstone]

​@@MihaiAndreiStanimir You mean the teeth look "fatter", right ? Actually a profile shift is applied to the gear for tooth numbers 16 and below (at 20° pressure angle). As said, I provided an improved f3d project. It includes profile shift. You can modify the "Xshift" parameter to value 0, then you'll obtain the same behavior as the SpurGear script ("Xshift" is the profile shift coefficient). I suggest reading this document, the best I found that popularize the "profile shift" behavior (center distance is affected, 2*Rp is not anymore correct) : www.tec-science.com/mechanical-power-transmission/involute-gear/profile-shift/

[@MihaiAndreiStanimir]

@@steelstone Thank you! 😃

[@chisomnnamani6200]

hey man, me again lol, how did you determine the formulas you used to calculate those unroll angles and lengths? Also I would actually like to talk more if possible, maybe through email?

[@steelstone]

Those formulas are mathematics applied for Fusion 360 on circle involute definition. I didn't invent anything 😉 I suggest you to look at this video, it's a full screw gear modeling. I give a link to the parameter list in the description. kzbin.info/www/bejne/i6jJZXyomNajiqM A parametric screw gear can be considered as the generic for cylindrical gears, so a helical gear is a particular case of the screw gear (same helix angle for both cylinders), and a spur gear is a particular case of the helical gear (helix angle being 0).

[@kellerblack3856]

How would you add a parameter for backlash? Using this for 3d printer backlash is needed to compensate for the inaccuracies of the printer

[@steelstone]

I suggest you to see one of my most recent videos (helical gear, or screw gear). I share the parameters in the description. The backlash parameter is called bl1, it is used for the calculated parameter Ash1 (for the pinion gear, and bl2 with Ash2 for the crown gear). Then look for it while sketching, here (d77 dimension): kzbin.info/www/bejne/i6jJZXyomNajiqM