> > 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)
Ok, I just had to copy and set the copied text as "quote" because I can't do it the easy way as you sugest Andy. I miss the select and reply feature I had until a couple of years. 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. Well, that's the next step I need to take. I'm eyeballing my gantry will weight around 250 kg but that's not for sure. Anyway I was trying to reduce the most I can the speed of the servos so they can move the gantry comfortably. 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) I really like that approach. The only concern of mine is always the reduction, because with that system I have the same behavior as a direct pinion driven by the servo but a lot quieter and also without the backlash. Do you think two 2.4 Nm motors with almost non reduction can handle the inertia the 250 kg gantry will generate? I ask this because all the other machines I put servos onto are screw driven and this is the first time I work with a gantry and linear ball bearings, and may be I'm oversizing all of this. The thing is, since servos can rev really high I was thinking about trying to reduce as much speed as I can to gain torque and stability. Thanks a lot as always for your help and knowledge! El sáb., 20 abr. 2019 a las 18:59, andy pugh (<[email protected]>) escribió: > 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 > _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
