I like #1 also. Use Locktite on the threads? #2 has to much cantelever on the bearing.
#3 isn't bad but looks more complex at first glance and the bearing appears to not be nearly as beefy, however it might be more than adequate. Looks like you are making an actuator of sorts. I could use a source for some of those, but scaled down just a bit. Ball screw actuators seem to be very expensive.. Dave On 12/13/2012 5:11 PM, andy pugh wrote: > 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. > > ------------------------------------------------------------------------------ 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
