On Sunday 18 October 2020 18:35:39 John Dammeyer wrote: > Hi Gene, > Just to bring this back to real life here. You have one of these > right? > > https://www.amazon.ca/Semi-Universal-Dividing-Vertical-Horizontal-Inde >xing/dp/B00RMLWNHS
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. > And you want to control it via CNC right? Yes. > 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. I won't know the exact SCALE until I can move it as I have, sitting commented out in the hal file, enough extra code to turn it past the home switch about 105 turns, measureing the encoder counter for 100 turns in the middle of that spin. Divide result by 100 to get SCALE in that gear. Same code I used to determine the spindles SCALE when I put a 1000 line encoder on the rear of the spindle motor, replaceing the hacked up, shop made optical that had so much quantization noise it hammered the gears in the head making it sound like all the ball bearings were filled with square balls busily chewing up their cages. Before, it oscillated with Pgains above 2.5-3, now its happy with Pgains in the 20+ range. But I need to see if I can rig an ammeter because I can no longer hear a slowdown while tapping until I hear the iron in the motor chirp when the Pico pwm-servo I'm using for spindle drive goes into current limit at about 17.5 amps. In the process of doing the gear shifting, theres no meshing ramps on those plastic gears so when the gearshift knob is between gears, the motor is now set to idling at about 20 rpms, saving me the trouble of grabbing the spindle and hand meshing the gears to complete the shift. And the response is so fast with Jon's servo that I can do knob cranks at full song without damaging the gears. But that whole head has a ton of spinning at full song at 3k revs hours on it now, and is about due for fresh gears and bearings. The bearings are all skate wheel bearings except the spindle itself and are getting noisy. Those can be had from VFX for around a 5 dollar bill for a sleeve of 10. But we all know how shitty VFX bearings are. I'll use better than that when the time comes. And metal gears if I can find them. But I got stopped about dinner time tonight as I'm going to have to cut that side spacer plate out in two passes, not enough Y table range to do it in one pass. The cnc kit I used years ago puts the Y motor out front and limits the g09704 Y motion to a couple red hairs above 5" and I need a bit over 6 to do it in one pass. Theres a different kit that puts the Y motor on the rear, which keeps the Y range better, but requires more machining I couldn't do without an even bigger mill. Sigh. This mill has other problems, like a post that leans a bit and cannot be straightened without reaming the bolt holes. Its a BBLB mill at the end of the day. Emphasizing the unbreak-ability of the TANSTAAFL law. ;-) > John Dammeyer > Thanks John D. > > > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) If we desire respect for the law, we must first make the law respectable. - Louis D. Brandeis Genes Web page <http://geneslinuxbox.net:6309/gene> _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
