To Andy's point, it will work, it's just a matter of lots and lots of passes. For instance, see http://neme-s.org/Shaper%20Books/Michael_Moore/shaper%20gear%20cut.pdf for how it can be done on a metal shaper with a rack form tool. There is no need for an undercut. The same basic method could be used for a ball-nose endmill but you'd need to make even more passes because you wouldn't have the correct taper to the sides of the tool or the correct nose radius. There's really no need to reverse if you just complete a full rotation to bring you to wherever you need to start for the next tooth, so that eliminates the backlash problem in your 4th axis. However, I suspect you'd also have a problem with wear on the endmill because of the relatively high RPM and numerous tiny (and slow) passes at a low chip-load required to generate acceptable surface finish. You should be able to do helixes without a problem by adding in the spiral motion, but this would take some thinking.
You could also use a form ground grinding wheel as a slitting saw, as in Dave's method, to finish the gear. It's essentially a single tooth hob with an infinite number of teeth. You could do this post-heat treat if you wanted automotive quality gearing. One form wheel could handle any gear tooth count in the same module/pitch diameter and you can do helixes if you can set your head over at an angle. You can even dress the gear with the CNC machine to ensure that it is of known diameter and accurate form. Obviously I've given this a great deal of thought ... maybe a project I'll attempt someday. Matt ------------------------------------------------------------------------------ This SF.net email is sponsored by Windows: Build for Windows Store. http://p.sf.net/sfu/windows-dev2dev _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
