When it comes to flexing and bending, think about the bed too. If the servo motor and pullies are mounted at the tailstock end, then the bed will carry the reaction forces and see exactly the same tension and “twist” force as the screw. But if the motor is mounted at the headstock end the bed sees no net forces.
The twist force on the bad will be the motor’s stall torque times the pulley reduction. Would that be enough to warp a cast iron bad? That depends on the detainees. Also you. want the force of the motor applied to the fixed end near the headstock because none of the mounting points will move as force is applied. In short, think about what bends as force is applied, the motor pushes on the screw one way and the motor mounts in an equal but opposite direction. > On Dec 25, 2023, at 3:37 PM, Linden via Emc-users > <emc-users@lists.sourceforge.net> wrote: > > Hello All, > > In the early stages of converting a 13 x 24 inch manual Chinese lathe to > run with Linux CNC. > > I have 2 questions regarding replacing the Z axis lead screw with a 3205 ball > screw: > > What I am thinking is mounting the fixed end in a pillow block at the head > stock end of the lathe and the floating end in a second pillow block at the > tail stock end of the bed. The question I have is there any reason I > shouldn't drive the ball screw from the floating end? My logic for driving > at the floating (tali stock) end is 1 I have more room for belt reduction at > this end and 2 with the fixed end of the ball screw at the head stock end is > that the ball screw will be in tension when it is pulling the carriage toward > the head stock during cutting and less likely to flex or bend. > > The second question I have is what would be a realistic cutting speed range > for the ball screw in RPM? The servo motor I am using has a top speed of > 3000rpm and I am trying to figure out reduction ratio that is realistic. > > Thanks in advance for any help or suggestions. > > > Linden > > _______________________________________________ > 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
