I also found a good online method screed by one Ross Korsky, who wrote a helical gear script for Autodesk Fusion – Helical Gear Generator.īut as I say, I was impressed by the FreeCAD ‘Gear Workbench’. SDP/SI 2019, Elements of Metric Gear Technology.īeyond that, Radzevich 2012, Dudley’s Handbook of Practical Gear Design and Manufacture seems to be floating around the web as a pdf (just saying), and Google Books has large parts of Maitra 1994 Handbook of Gear Design, 2nd ed. I did try to follow the theory of helical gears, but I concluded that for me, to really understand it was a deep project that I could not pursue. taking a 2D involute gear profile, copying it say 1-inch above, rotating that top one a bit and lofting the result, won’t make a good meshing gear. If you get into it, the problem is around getting the tooth profile right – it is at the normal to the angle of the tooth. Short answer is, in the end I used the suggestion of above, and modeled my helical gears in FreeCAD, the open-source nurbs modeler. I am not sure that I can comment actually. Meanwhile, we have to accept that other approaches may ‘look the part’ on-screen, but have their inaccuracies. I can’t, because I don’t know SW well enough to do the translation. Maybe someday someone will translate L & K’s SolidWorks approach into Rhino commands. Loganvsky and Khmarova 2016 “3D Model of Geometrically Accurate Helical-Gear Set” Procedia Engineering 150:734-741 ( pdf available on Researchgate) show step-by-step how they produced in SolidWorks a high-tolerance helical gear, and it was not a trivial task. None of these approaches probably give a truly accurate result for manufacture of highly-loaded gears. If it won’t union, make the 2D tooth profile ‘key into’ the body of the gear more, before making the closed polycurve, rotating it and sweeping it. This swept curve is then capped, polar-arrayed and unioned with a cylinder equal to the root diameter. If using the 7-step approach above, and want the tooth profile to be normal to the helix angle (a more realistic shape), I found that you need to create a closed polycurve, and sweep that along the 2 curves as described in step 6. when documenting historical machinery in 3D). The approach I gave above is probably as good as any, and has the advantage that you can control the outside diameter, if that is important (e.g. To see this effect more easily, try the helical gear calculator at Engineer’s Edge. With the FreeCAD add-in and on Rush Gears models, pitch diameter stays constant as you alter the helix angle, but the outside diameter does not: it decreases with increasing helix angle. This approach too requires you input either normal module or normal diametral pitch (not transverse). It does well other than that.Īlternatively, I found that Rush Gears lets you make custom helical gears and download them as STP files, etc. Initially I was confused that it gave an unexpected pitch diameter on the finished gear, but eventually realised you must keep in mind, it is asking for the normal module rather than the tranverse module. I tried FreeCAD, or more specifically loaded the FCGear Workbench add-on and tried that.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |