Hi Gene, > From: Gene Heskett [mailto:ghesk...@shentel.net] > On Sunday 18 October 2020 18:35:39 John Dammeyer wrote: > > Yes, one of those clones in BS-1 size. Almost too big for a g0704 due to > its height. But the g0704 seems to handle the weight just fine, which > without the motor is still 88 Kg. So I had to rig an electric hoist to > place it. > > > Given the torque multiplication with the worm gear why aren't you just > > using a stepper motor and step/dir interface? Seems like buying audio > > amps and DC motor drivers etc is all making what is fundamentally > > simple very complicated and expensive. > > Worms require lots of torque to move them under cutting loads, which you > have to do to cut spiral gears. Which I intend to do. This motor is > also a right angle worm drive, and has about a 100 line quadrature > encoder on the motor shaft. The worm in the BS-1 clone has more backlash > than this motor has. Very poorly made, not even a bearing ball on the > end-play adjuster, nor is the bolt ground flat, right out of the box. > Making this plate will also give me a good excuse to install some > adjuster screws on the mesh adjuster.
When I sized a stepper motor for my 1942 South Bend Heavy 10L Lathe I made this adaptor for a socket. http://www.autoartisans.com/southbend/TorqueTestAdaptor.jpg I then used a torque wrench to measure what it took to move the carriage. That turned out to not work well because the torque wrench wasn't sensitive enough. So then I hung a 3/8" flex handle on the socket and turned the leadscrew until it was horizontal. After that I hung weight on it at the 12" point until the carriage moved. The weight needed to do that was the torque to overcome static friction. I multiplied that by 2 and then used that value compared against stepper motor torque reduction verses speed charts and chose a 300 oz-in motor with 2:1 belt drive. http://www.autoartisans.com/southbend/Z-AxisMotorMount.jpg It's been more than adequate within the speed specifications chosen. Would I like a faster slew rate to move the carriage out of the way? Yes. But the lathe is old and the half nut and leadscrew were never designed for those types of speeds. So unless I replace the leadscrew with a ball screw what I have works. So again I question whether the you need a work drive motor coupled to a worm drive dividing head. Nowadays stepper drivers are so cheap (as are the motors) overall if you want the unit operating this year it might be easier to go stepper motor. John Dammeyer _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
