I don't think so. But have dreams of machining a big 300mm cycloidal drive myself. Large Dia to increase rigidity and accuracy
After a point if you put any value on your time it just makes sense to go buy a second hand cycloidal gearbox On Sat, May 16, 2020, 6:54 PM John Dammeyer <jo...@autoartisans.com> wrote: > Hi Dave, > I think the question being raised is whether it's possible to create a > zero backlash 4th or 5th axis with COTS hardware for less money than a > harmonic drive or the cycloidal gearboxes. > > John > > > > -----Original Message----- > > From: David Berndt [mailto:ber...@uberwin.com] > > Sent: May-15-20 11:19 PM > > To: Enhanced Machine Controller (EMC); Roland Jollivet > > Subject: Re: [Emc-users] Cheaper than normal FHA-25B > > > > Why are you particularly worried about that? Cyclodial gear boxes and > > harmonic drives are both basically 0 backlash, with potentially some lost > > motion. Most are repeatable well under 1 arc minute, which compared to a > > lot of rotary tables already out there. And that's something like a > .0017" > > displacement on a 12" radius. Angular transmission accuracy would seem to > > be almost as big an issue that you'd have to start to think about if > > you're concerned about those levels of backlash. Also overall mechanical > > stiffness. > > > > -Dave > > > > > > On Sat, 16 May 2020 01:49:58 -0400, Roland Jollivet > > <roland.jolli...@gmail.com> wrote: > > > > > I've been thinking about 4th axes; > > > While motorised reduction drives are readily available, the issue is > > > obviously backlash. > > > > > > One way to make a zero backlash drive is to use two identical > > > gearbox/drives. Place them at opposite ends of the axis, and pit them > > > against each other by a few encoder counts. > > > So they will track and retain the zero-backlash. > > > > > > Of course, the total power available is now less than one drive motor, > > > but > > > it is an option to use almost any pair of reduction drives that can be > > > got. > > > But there is also the cost of the second servo amp. > > > > > > > > > On Fri, 15 May 2020 at 14:11, andy pugh <bodge...@gmail.com> wrote: > > > > > >> The normally appear on eBay at up to 6x this price. > > >> https://www.ebay.co.uk/itm/233587431605 > > >> > > >> The B versions have conventional incremental encoders and hall > > >> sensors, so are easy to integrate. Lots of torque, zero backlash and a > > >> very strong and fancy big crossed-roller bearing make them an > > >> almost-complete 4th or 5th axis just needing a bracket and a drive. > > >> > > >> I have no connection with the vendor, if you order one and receive > > >> dolls-house furniture instead don't blame me. > > >> > > >> -- > > >> atp > > >> "A motorcycle is a bicycle with a pandemonium attachment and is > > >> designed for the especial use of mechanical geniuses, daredevils and > > >> lunatics." > > >> � George Fitch, Atlanta Constitution Newspaper, 1912 > > >> > > >> > > >> _______________________________________________ > > >> 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
