On Sunday 02 August 2020 12:10:30 Thaddeus Waldner wrote: > I’ll chime in with my 2 bits. > > One issue is whether the motors have enough torque to actually drive > the load at the specified acceleration. You probably knew that. :) > Maybe install the plate and strap a small weight to the glass to > simulate a large print, and test it. Many of these printers use > stepper drivers that are tunable, either via a small pot on the driver > or via software. You might need to bump it up a bit if it loses steps. > Also, if it uses the Pololu StepStick drivers, you can easily swap > those out for something that can handle more current. I recommend > Trinamic SilentStepStick.
I have not uncovered the driver board yet, but assume its some sort of an 8 bit arduino based thing. It apparently senses, somehow, extruder jams as I have to remove the exit guide, feed it thru it and reinstall it to install/replace the PLA spool, as it misses the entrance and doesn't chew up the string by grinding on it, but backs away a mm or so and tries again. It was also set OOTB, to feed about 15mm of pla for a 100mm command, so I wasted half a roll making stuff you could see plumb thru. Its all a new learning experience for an 85 yo ex television station engineer and CET. Who may have to learn freecad to optimize the 3 harmonic drives I have under construction. Thanks, I'll clothpin the glass to the bed, readjust the z home and see how the bearing carriers come out as I still have them to make yet at a slightly oversized scale, either that, or make 3 more of the internal splines at a reduced scale. Neither fits the other well in the design I got from thingiverse, leaving lots of backlash. Thanks Thaddeus. > https://www.trinamic.com/support/eval-kits/details/silentstepstick/ That doesn't appear to be a direct replacement for this one. > Another issue is that with a change in mass you will see more > resonance in the axis motion. This will show up as a wavy texture on > planar faces near sharp corners, such as on a cube. The design of > those printers is pretty smart, IMO, because they placed the large > moving mass near the base of the printer. But they do need high > acceleration to keep the head moving and they are built as cheaply as > possible so ... > > > On Aug 2, 2020, at 9:59 AM, Gene Heskett <ghesk...@shentel.net> > > wrote: > > > > Greetings all; > > > > Several question mark below. > > > > Those glass plates for my ender-3 Pro's build plate use have > > arrived, and I'm somewhat taken aback by the mass of a 230x230mm by > > 4mm piece of glass. This at least doubles, likely more, the weight > > the y motor has to manhandle, in my mind affecting the ballistics of > > its movement. No glass clips or instructions came with it although > > the glass was packed to survive a tactical nuke, So I'll raid the > > laundry room for some spring clothes pins. Plastic, lighter than the > > old wooden ones, but I stuck a couple on the front of the bed and > > the heat isn't bothering them. > > > > The stock Merlin driver has some adjustments for both acceleration > > and jerk. Accel is currently set at 500, sounds pretty instant to me > > and jerk is set at 8 but thats a new term for me and I have no idea > > of how a change to that effects the machine. > > > > Given the increased mass to move, is it even possible to keep the > > working velocities at the currently set values, or is there a way to > > determine what is optimum for this added mass it has to move? > > > > I'm assuming changes in the ballistics would have to be set in the x > > axis at the same time to keep it from bending corners. > > > > Or, would I be better off spending the sheckles for one of the > > improved 32 bit driver boards I see being offered? Power supply > > might come into play too as its only 24 volts now, which will effect > > its accel and ballistics envelope too. > > > > Discussion, educational/reference URL's all welcome. > > > > Thanks all. > > > > 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 > > _______________________________________________ > 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
