I think your end mill cutter analogy is useful. What I would add is that in order to get good layer adhesion, the actual width of the 3d-printed track needs to be slightly “squashed” by the nozzle as it is placed. A good rule of thumb in my experience is to use somewhere between 2-3 times the nozzle diameter and no less than 1.5 times the nozzle diameter.
My experience might not be universal, since I’m using an old Stratasys with a heated build envelope and print mostly ABS. AND I can’t change out the nozzle. > On Jun 2, 2020, at 3:37 PM, Chris Albertson <albertson.ch...@gmail.com> wrote: > > I just printed a set of 3mm pitch GT3 timing pulleys with my 0.4 mm nozzle. > They came out just fine. > > The final profile of the pulley tooth is not determined by the > nozzle diameter it is limited by the step size on the printer. My pulley > fit the belt well enough that tooth shape is not the limiting factor. On > my case it is runout, not tooth shape that will cause the greatest error. > > Think of an end mill cutter. I can make sharp corners with a 12mm diameter > end mill. What I can't do is make less then a 6mm inside radius. Same > with the nozzle but backwards. A 0.4mm roud nozzle can make at best a 0.2 > radiu corner while the 0.2 nozzle can print a 0.1mm radius. But the > printer steps are that size and introduce a larger error than the nozzle. > In any case what you really care about is error in motion transfer between > the pulleys. Runout matters but a tiny radius error on an outside corner > does not change how the belt sits in the pulley. > > There is a big disadvantage to 0.2 nozzles (1) they clog up and need > cleaning and (2) printing is about a lot slower. > > Your first step before printing pulleys is to print a cube. Use CAD > software so you know the exact dimension you specified, run it trough the > slicer, print and measure all sides and angles. Get those > measurements good enough. > > When designing with plastic, you have to make stuff bigger. Use the > largest pulleys that will physically fit and this keeps the percent error > down. > > I any case my A6 primer is the same as your Ender except mine uses ground > steel rods for track and yours uses extrusions, But everything else is the > same all down to the Merlin firmware. My 3mm pitch by 9mm wide GT3 > profile pulleys came out pretty good. I had to make the flanges wider > as the aluminum pulley design has tapered flanges that came to a point. I > made them thicker and blunter and used a 20mm center bore. Odd that I > could print the tooth profile just fine but not the flanges. > > > > > On Tue, Jun 2, 2020 at 10:26 AM Gene Heskett <ghesk...@shentel.net> wrote: > >> On Tuesday 02 June 2020 12:50:54 Karl Jacobs wrote: >> >>> Gene, just make it executable and run the appImage. I use Cura to >>> slice for a Delta-printer and use LinuxCNC (actually, Machinekit on a >>> Beaglebone) to drive the hardware. Marlin on Arduino hardware works >>> nicely too, of course. Good luck with 3D-printing, just needs the >>> usual learning curve. >>> Karl >>> >> Which for my ancient 85 yo wet ram seems pretty steep, but I think I have >> the top of this hill in sight. That 3d cat is printing now... :-) Ought >> to be done by dinner time. >> >> I think I need to find some .2 nozzles before doing any XL timing pulleys >> though. Thats about next. Then I suppose I'll appreciate the speed its >> doing now. >> >> Thanks Karl. >> >> 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 >> > > > -- > > Chris Albertson > Redondo Beach, California > > _______________________________________________ > 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
