On Wed, 2009-05-20 at 04:44 -0500, Ray Henry wrote: ... snip > I dropped in on the folk at Synergy the other evening and they demoed > gear design for me. Answer a few questions like number of teeth and so > forth and it draws it up and then writes the g-code depending on your > cutter. > > They don't have a rack gear routine (yet) but we played with that a bit > and it looked like the sides of the teeth are flat faced where the exact > angle and distance between are a product of the nature of the gear > running in them. The rack's tooth profile is certainly not a simple > negative of the involute tooth of the gear that runs in it. > > It was an interesting thought and drafting experiment but I stayed well > short of the real math to make 'em. > > Rayh
The rack tooth form is the basis for involute gears, everything else comes from this. The rack form is described in Machinery's handbook and here: http://www.sdp-si.com/d785/html1/D785T007_2.html The straight sides are at the pressure angle (20 or 14.5 degrees usually). This trapezoidal shape, as a hob, fly cutter, or standard #8 gear cutter, can be used with an A axis to cut all of the gear diameter sizes with the corresponding pitch. The other key feature, is the base circle which is derived from the pressure angle lines placed with their intersection on the pitch circle. http://www.sdp-si.com/d785/html1/D785T018_1.html The diagram shows one pressure angle line, the other is just a mirror of it. The point(s) of contact are on this line and since the line and contact point can be thought of as an unwinding string, the sum of the contact points forms an involute of the base circle. I have Synergy, but I am trying to come up with an open-source gear utility. I have a way to go. -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA ------------------------------------------------------------------------------ Crystal Reports - New Free Runtime and 30 Day Trial Check out the new simplified licensing option that enables unlimited royalty-free distribution of the report engine for externally facing server and web deployment. http://p.sf.net/sfu/businessobjects _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
