There is also this application that will generate gcode for synchronous belt sprockets too: gearotic.com
N. Christopher Perry On Jul 5, 2013, at 10:24, Chris Kelley <[email protected]> wrote: > Gregg, > > I've been playing with doing almost exactly what you are talking about. > I've even cut some proof-of-concept involute gears using only a gcode > program that generates the gear. > > Here's some images of the test part (aluminum): > > http://i.imgur.com/0AYZbpi.jpg > > and > > http://i.imgur.com/LeW10nX.jpg > > Here's the "finished" part: > http://i.imgur.com/tCYRMjJ.jpg > > The gear closest to the end is 18 teeth and the one farthest from the end > is 17 teeth. The cutter was just a 1/8" diameter end mill. The aluminum is > ~2" round stock that I cast from dirty scrap aluminum so there is some > obvious porosity. > > The gcode program is attached to this message. I'm kind of hesitant to post > my code because it's likely difficult to follow (even I have a hell of a > time debugging it, and I wrote it. > > Unlike using a form cutter to generate both sides of a tooth space at the > same time, my program uses a straight sided end mill and forms one side of > the tooth space at a time. With a form cutter you move the cutter only in a > horizontal plane (or vertical in the case of a fly cutter) while rotating > the gear under it. My program moves the cutter at an angle from the > horizontal that is equivalent to the pressure angle. > > While my program generates involute gears, they are not even close to > standard DP of modules, but gears made with the same parameters but with > different number of teeth will mesh correctly. With my code you specify > what I call the root width (the width of the flat on top of the equivalent > rack teeth, which is also assumed to be the diameter of the cutter), the > tooth height (the height of the gear rack teeth), the pressure angle > (anything positive and non-zero should work), number of teeth, and the > "quality" (number of passes for each side of the tooth, bigger numbers take > longer, but make more accurate forms, especially on forms with undercut). > > Things I would like do add (once I get one of those elusive round tuits) > are the ability to make actual standard DP and Module sizes, as well > helical and knuckle gears. > > -Chris > > P.S. My 4th axis may or may not rotate the right (standard) direction, so > you may have to change a few signs to make the gcode work. > > > > On Thu, Jul 4, 2013 at 8:12 AM, Matthew Herd <[email protected]> wrote: > >> 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.pdffor >> 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 > <gearcutB.ngc> > ------------------------------------------------------------------------------ > 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 ------------------------------------------------------------------------------ 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
