2012/12/14 andy pugh <bodge...@gmail.com> > I have designed three alternatives. > They all use bearings that I know I can get, rather than bizarre exotica. > The first idea is: > > https://picasaweb.google.com/lh/photo/EqgIdXH-kCH8I90oYKfm2dMTjNZETYmyPJy0liipFm0?feat=directlink > This actually uses a car wheel bearing, which is angular-contact and > has adjustable preload. > The preload is adjusted by the orange threaded collar. The pulley > screws on and in doing so it clamps the outer race. Clearly some means > is needed to stop it unscrewing again. > I am not sure I have the available length for this design, though. > > The next alternative is more conventional, and uses a double-row > angular-contact bearing (3809). This bearing is not adjustable, and > looks like it would be a lot less stiff than the first one. > > https://picasaweb.google.com/lh/photo/DELJ44ystXfa1HavUrYFmtMTjNZETYmyPJy0liipFm0?feat=directlink > This requires a more complex casting shape to get the belt into place, > and a separate end cover. It also puts the bearing a long way from the > belt tension load. > > The third design uses the second bearing again, but in a better place. > > https://picasaweb.google.com/lh/photo/X9ZXwL-oMXpF9cc6wAIbQNMTjNZETYmyPJy0liipFm0?feat=directlink > This design is growing on me, the only problem being that I can't > quite see how to retain the bearing outer race in the casting. It has > a nice direct drive from the belt to the ballnut. > > I think the first option looks like the best, if it can fit. For > reference I have a 40mm OD on the ballnut and a 76mm diameter hole > 90mm deep in the machine bed. This means the protrusion to the left of > the casting in the pictures has to be shorter than 90mm and less than > 75mm dia. > > Andy, you might want to take a look at my design http://img338.imageshack.us/img338/7208/screenshot20121214c.png http://img255.imageshack.us/img255/7208/screenshot20121214c.png The green part is a hollow shaft, there are two angular contact roller bearings, preload is adjusted by two nuts I had to cut the timing pulley on the hollow shaft, and consider many other limitations to keep it small as a part of a joint. But I tried to keep it as simple as possible.
Regards, Andrew -- > atp > If you can't fix it, you don't own it. > http://www.ifixit.com/Manifesto > > > ------------------------------------------------------------------------------ > LogMeIn Rescue: Anywhere, Anytime Remote support for IT. Free Trial > Remotely access PCs and mobile devices and provide instant support > Improve your efficiency, and focus on delivering more value-add services > Discover what IT Professionals Know. Rescue delivers > http://p.sf.net/sfu/logmein_12329d2d > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > ------------------------------------------------------------------------------ LogMeIn Rescue: Anywhere, Anytime Remote support for IT. Free Trial Remotely access PCs and mobile devices and provide instant support Improve your efficiency, and focus on delivering more value-add services Discover what IT Professionals Know. Rescue delivers http://p.sf.net/sfu/logmein_12329d2d _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
