On Sat, 20 Apr 2019 at 22:03, Leonardo Marsaglia <[email protected]> wrote:
> I'll try to answer both messages into one because I lack the quoting > function here in gmail. If you click the three dots that appear at the bottom of the reply then you can edit, post inline, copy between messages etc (I use Gmail pretty much exclusively) > I plan to reduce the servos of the Y axis about 10 to 1 at least. I would > love to use timing belts and pulleys but I preffer to avoid all the trouble > of making the steps for the reduction. The servos I plan to use are 750 W > and 3000 RPM. You don't have to run the servos at peak speed. It might be worth working out what force you get at the gantry with the rack pinions directly mounted on the servo. > In case of using a screw that long I guess is a > must to have a rotating nut and that's not a simple task too (at least not > as simple as the planetary reducer). Rotating nuts are not a lot more difficult than rotating screws. Both need bearings with adjustable end-float to work properly. You just need a bigger hole through the bearings with a rotating nut. That said, servo + reducer + pinion needs almost no engineering so I can see the attraction. As an alternative to the racks, look at the Bell-Everman "Servobelt" arrangement. That's a really clever way to have low backlash but with much reduced belt stretch. (And, usefully for a wood router, the belts are closed to dust ingress except where the drive pinion is) -- 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, 1916 _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
