On Saturday 02 January 2021 01:53:14 John Dammeyer wrote: > After a few days of trials and tribulations it's workable. > > Step 1 was cast a new plate. Then use LinuxCNC to surface and mill > the appropriate holes and slots. Note to self. Don't tell the CNC > program you are using a 6.35mm carbide cutter when you actually use a > 6mm one. The holes and slots turn out a bit small. Putting it all > back and lining it up without a corner reference surface was not easy. > ROTFLMAO! Been there, done that John, enough times I should know better. :)
> Anyway, the next issue was that no matter how I tried, making a 12T > pulley to fit on a 19mm shaft with a 6mm key just doesn't work. With > a big hub the pulley stuck out too far. So I created a 15T pulley > with a narrow hub. Second note to self. Verify that the CAD > simulation has the right space between parts so that it really does > line up properly. My inability to measure that accurately meant some rework in the shaft coupling and the motor mounts for the motorized bS-1. But its all working a treat now. Overall gear ratio is slower than I thought it would be though. Need to set a windup eliminating max speed. And it searches for home really slow due to the windup causing it to coast past the home switch. Fine tuning stuff yet to be fine tuned. Get rid of the windup and I can speed it up abut 4 or 5x. I can't hear the servo running over the psu fans. > Finally I set up the Bergerda drive to move 5 encoder edges for each > step pulse with the motor effectively configured it like the > MicroStepping drive. The ratio from motor to knee shaft was now 3.2 > or 6400 steps per 0.25" of knee motion. > > Rather than muck with INI and HAL files to make sure I got it right it > was easier to use my ELS, set 6400 steps/rev and a pitch of 0.25". > Then with the jog buttons I verified things were moving the right > distance and with a step rate of 20,000 steps/second the Knee really > moves fast. Really fast. > > So now one step back to move 2 steps forwards. Do some rewiring. > Configure the HAL and INI files. And that awful whine from > replacement stepper driver will be gone. That's worthwhile, John. With the 3 phase stepper servo's I just put on the Sheldon, it moves like Casper the ghost, at 100+ ipm. I did have that 1600oz I put on Z, hammering tools off onto the floor with its growk as it moved. A 3NM rated nema-23 is MUCH quieter, and the 3 phase driver is about half the volume of a 2M542. I think it uses only enough motor drive to keep the encoder happy because they both run dead cold while running the lathe-pawn code cutting air. There is no dip switch to set motor current on them, just the microsteps. > I have noticed the 3D > printed pulleys are noisier than the metal ones. But the noisy grind > of the stepper motor is also gone. That's also worthwhile. I've also found the downloadable pulley making code, like from thingiverse, generates pretty sloppy pulleys. Bound to be noisy when the tooth fill is only 25%. But I don't know how to fix the src code for those parametric composers. So after about 6 passes at making pulleys, I ordered alu ones. > More when it's wired up to LinuxCNC. > John Take care and stay safe. And I hope 2021 is better than 2020. 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
