On Monday 07 September 2020 16:26:56 Leonardo Marsaglia wrote: > Gene, > > Is this printer controlled by LinuxCNC? I know you've been doing a lot > of work making LCNC to work with the Pi but I don't remember if you > were controlling your 3d printer or another machine with that. > I'm making stuff that LCNC will eventually run on a mill or lathe, or that the Stellarium program can run to manage the precise aiming of a star chasing telescope, but all the SW running the 3d printer is the freebie stuff yu can download to work with the printer.
The src code for this, in the form of .stl files came from a thingyverse project, and TBT was not at all optimized to make a good harmonic drive. Schloppy cad work IMO. So much of what I've been doing is tweaking the sizes for closer performance, and finding a suitable material to make each piece out of. PLA is extremely brittle so flexgears last 1 to 10 minutes. TPU has way too much flex, so while it can be made to go thru the motions, the motions are, to be kind, inaccurate like there's a batch of rubber bands running things. Then Hubert donated a spool of PETG, which is fairly rigid, but bendable without sounding like a bag of popcorn in the microwave if held up to your ear and the sides flexed inward a half inch on each side. So thats the flexgear material, but its not a high speed material because it needs 50C hotter nozzles and beds than PLA, and thats a problem for a $400 printer. So the plastic flows slower. But I'm going to make new end-caps where the nema 17 motor that runs these mounts, which as you know, can get hot, too hot for PLA because it will cold flow at those motor temps. This heat also telegraphs up the motor shaft into the bearing carrier that runs inside the flexgear and forces the flexgear into the eliptical shape that does all the magic, destroying its ability to keep a good grip on the motor shaft, so they are being made of PETG because of its higher heat tolerance and may be superglued to the shaft in the final assembly. The rest of the assembly isn't subjected to the motors heat, so can be made of PLA. When making stuff out of plastic in a printer, its laid up a layer at a time. In this case the layers are .12mm thick. Thats quite a bunch of layers if the part is 40mm tall. So the cad design's .stl is fed to a slicer, which makes gcode the printer understands, telling the printer where to move to and how fast as it draws a line of hot plastic by ejecting it thru typically a .4mm nozzle tip as this tip travels over the part flying .12mm above the previous layer. Yeah, its slow, watching paint dry slow. But it also, if all the stars are properly aligned, works. This flexgear.gcode is aboout 40 megabytes. There are several slicers, commercial and freebies, I'm useing UltiMaker's cura-4.7.0, which works fairly well and is a free download from their site as a self contained appimage. The printer runs a gcode interpreter called Marlin, usually on an arduino but it is no comparison to LCNC. Very simple, it doesn't do curves, so the slicer has to break the curves up into short straight lines that if you don't look too close, blend into curves. I am of course a new bee at this, so I am both learning and asking a boatload of questions. Part to build bed adhesion can be a problem. You heard glue or hair spray used and I can testify that when its stuck, it can be stuck tight enough it will take a piece of glass with it. I finally found a small eyebrow of glass missing from one of my two borosilicate plates, stuck to the bottom of a bearing carrier that spent the night in the freezer before it finally came loose. Call it glue, but what it really is, is a film that prevents that solid bonding but which still holds the part as it being built. A kids purple glue stick, smeared around on the glass, then scrubbed into a just noticable haze by a wet paper towel or a toothbrush works well. Probably more than you wanted to learn in one gulp. :) Stay safe and well, Leonardo. > El lun., 7 sept. 2020 a las 17:24, Gene Heskett > (<ghesk...@shentel.net>) > > escribió: > > On Monday 07 September 2020 16:01:05 Gene Heskett wrote: > > > On Monday 07 September 2020 14:57:13 Gene Heskett wrote: > > > > I just noted that when it starts building the splines on the > > > > flexgear, that the color is getting air and hair contaminated, > > > > turning frosty. So since I've got the extra snout installed, I'm > > > > wondering if its cooling too fast, so I did a tune->fan speed > > > > down to 52% to see if the slower cooling gives it time to flow > > > > smooth and restore the color. Report later after its done a few > > > > layers. > > > > > > > > Cheers, Gene Heskett > > > > > > It occured to me that less cooling aimed at the nozzle would also > > > help its ability to supply flow, so I am upping that about 1% a > > > layer, up to 104% so far, with no skip clicks from the extruder > > > drive. Too bad I can't control both at the layer count in cura, I > > > think it might be helpfull. > > > > Another PS, I am up to 106% for flow, and the solid candy red color > > has returned to the splines, 23% for fan speed, I'd guess its > > turning 400 rpms, so no great cooling effect. This is a definite > > improvement in laying solid plastic. > > > > So put this in your trivia basket. > > > > This piece is about done. > > > > 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
