Yeah the sides of your flex bearing contact the sides of the spline bearing before it bottoms. See the post I just made for more detailed photos. John
> -----Original Message----- > From: Sam Sokolik [mailto:samco...@gmail.com] > Sent: November-30-21 1:23 PM > To: Enhanced Machine Controller (EMC) > Subject: Re: [Emc-users] Harmonic Drive > > This is the profile I am currently using... > > http://electronicsam.com/images/greenmachine/IMG_20210127_104354.jpg > > > On Tue, Nov 30, 2021, 3:10 PM John Dammeyer <jo...@autoartisans.com> wrote: > > > So nothing as complicated as: > > https://journals.sagepub.com/doi/pdf/10.1177/1687814019850656 > > > > I did detailed measurements on the cup version I printed and there are two > > issues. The worst is the shrinkage of the plastic results in the bearing > > holder being 1mm too small in diameter compared to the drawing. Outside of > > Bearing to Bearing should be 84mm and is 83mm. That leads to the teeth > > not entering the spline gear as deep as they should. > > > > There's also shrinkage across each tooth from the 3D print process so that > > even as they mate they bottom out before the sides contact. And based on > > other reports of 3D printed harmonic gears the thickness behind the teeth > > should be 1mm rather than 1.5mm which ends up being too stiff. > > > > Then end result is this version has backlash but it turns quite nicely. > > The max I can get with this small Size 23 old surplus stepper is 8 seconds > > in one revolution with the 35:1 reduction at 1600 micro-steps/rev. I also > > can't grab the hub and stop it. > > > > Finally, the spline gear and support body must be a lot thicker as it > > moves under load which shows up in the original authors video too. > > > > I'll put together a folder with the photos. > > > > John > > > > > > > -----Original Message----- > > > From: Sam Sokolik [mailto:samco...@gmail.com] > > > Sent: November-30-21 12:46 PM > > > To: Enhanced Machine Controller (EMC) > > > Subject: Re: [Emc-users] Harmonic Drive > > > > > > I will post them later tonight.. To be honest - I took a video of the > > one > > > of the drive mfg and kinda measured the tooth angle. (mine are just > > > triangles..) > > > > > > sam > > > > > > On Tue, Nov 30, 2021 at 2:30 PM John Dammeyer <jo...@autoartisans.com> > > > wrote: > > > > > > > Hi Sam, > > > > Could you share the STEP file for the flex gear? I want to look at the > > > > tooth shape. > > > > Thanks > > > > John > > > > > > > > > > > > > -----Original Message----- > > > > > From: Sam Sokolik [mailto:samco...@gmail.com] > > > > > Sent: November-27-21 8:18 PM > > > > > To: Enhanced Machine Controller (EMC) > > > > > Subject: Re: [Emc-users] Harmonic Drive > > > > > > > > > > I found that a while ago - That was what I initially started to > > build. > > > > > But the cup seems to not handle flexing. Atleast pla (I never > > tried it > > > > > with petg). When Andy mentioned the style with no cup - I went that > > > > > direction. I first made the flex gear out of pla - but it fatigued > > after > > > > > about 6 hours of running full speed (of the stepper). Which might > > be > > > > just > > > > > fine for a hobby 4th axis. Your not running the rotary axis at 100% > > feed > > > > > all the time. I bought a role of petg and printed a flex gear > > with > > > > it. > > > > > As much as I have run this setup (petg flex gear and pla splines) - > > I > > > > have > > > > > not had the petg flex gear fail - even after torque testing it. > > > > (although > > > > > I have not taken it apart) but it still runs and doesn't randomly > > stall. > > > > > > > > > > sam > > > > > > > > > > On Sat, Nov 27, 2021 at 10:05 PM John Dammeyer < > > jo...@autoartisans.com> > > > > > wrote: > > > > > > > > > > > For those who have 3D printed the gear portions of the harmonic > > drive > > > > what > > > > > > plastic did you find worked the best? > > > > > > > > > > > > Thanks > > > > > > John > > > > > > > > > > > > > -----Original Message----- > > > > > > > From: John Dammeyer [mailto:jo...@autoartisans.com] > > > > > > > Sent: November-26-21 11:18 PM > > > > > > > To: Enhanced Machine Controller (EMC) > > > > > > > Subject: [Emc-users] Harmonic Drive > > > > > > > > > > > > > > List has been quiet lately on the harmonic drive subject. I > > > > stumbled on > > > > > > this site. > > > > > > > > > > > > > > > > > > > > > > > > > > https://howtomechatronics.com/how-it-works/what-is-strain-wave-gear-harmonic-drive-a-perfect-gear-set-for-robotics- > > > > > > > applications > > > > > > > > > > > > > > John > > > > > > > > > > > > > > > > > > > > > _______________________________________________ > > > > > > > Emc-users mailing list > > > > > > > Emc-users@lists.sourceforge.net > > > > > > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > > > > > > > > > > > > > > > > > > > > > _______________________________________________ > > > > > > Emc-users mailing list > > > > > > Emc-users@lists.sourceforge.net > > > > > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > > > > > > > > > > > > > _______________________________________________ > > > > > Emc-users mailing list > > > > > Emc-users@lists.sourceforge.net > > > > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > > > > > > > > > > > > > _______________________________________________ > > > > Emc-users mailing list > > > > Emc-users@lists.sourceforge.net > > > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > > > > > > > _______________________________________________ > > > Emc-users mailing list > > > Emc-users@lists.sourceforge.net > > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > > > > > _______________________________________________ > > Emc-users mailing list > > Emc-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
