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.
https://www.trinamic.com/support/eval-kits/details/silentstepstick/ 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 <[email protected]> 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 > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
