On Wednesday 11 November 2020 11:43:37 Chris Albertson wrote: > Remember the workflow. You start with a 3D model where the resolution > is literally "perfect" as the curves are defined by mathematical > functions. Then you convert the 3D model to an STL and an STL can > contain only straight lines. No circles, no curves. When you make > the STL you get to specify a maximum error but small errors mean big > files. > > So when you look for a gear or sprocket ALWAYS look to see if you can > get the 3D CAD file and not just the STL. The best places are the big > resellers like Boston Gear, McMaster Carr, SPD,.. they all have > "perfect" 3D CAD models, usually.STEP file type. > > If you do download an STL then you are accepting some other random > person's idea of what is a good error tolerance without even knowing > what he specified. > > *So make the STL file yourself. * I usually go overboard with > resolution in the STL and specify something like 0.001 mm or less > allowed error. > > The next step is manufacturing where you get to specify how it is > sliced and printed or how the file is cut on a mill. > > On Tue, Nov 10, 2020 at 9:15 PM Gene Heskett <[email protected]> wrote: > > Greetings 3d printer X-spurts; > > > > I just downloaded the .stl kit for a nema 17 powered, gt2 belt > > driven reduction gear. I thought I see how it rendered since I had > > such poor luck with that previous harmonic drive. so I update cura > > to 4.8.0, loaded up the teeny little gt2 belt sprocket that fits the > > motor shaft.
I have now rendered all the pulley's in PLA, and am starting on the smaller box bits in PETG. I'm still impressed. This stuff has sharp corners etc, and just screams precision like I have never seen this printer do before. I haven't adjusted any of the printers scales as they were last set for a good fit of the bearings that the harmonic drives used. I may be able to salvage the bigger ones from those but I think they are bigger. I found on his latest video, a BOM of sorts, he didn't count or spec the lengths or numbers of the 3 and 4mm bolts and nuts. I generally buy that stuff by the bag anyway, but I'll have to render the whole box before I'll have a good idea how long the bolts are. The big box is about a 28 hour render. By then I may have to switch colors of PETG as I've used over half a spool of candy red, and have 2 spools of kelly green left. I'm even dreaming of it having the cajones to drive the bs-1 as I think my nema-17's are longer than what he used in the video.. The rear of the motor is going to stick out around 2" above the top of the bs-1 when its facing horizontal as its the only way to make it clear when tipped up to vertical. Sticking out to the side means it will hang out a good 4" but that's in the air where its not going to hit anything, not even the choker straps I pick it up with. Since the encoders index will be a home switch on the bs-1, I wouldn't need the index hall effect this one can have. I enjoy playing what if? :) A good winter project. But you likely had that figured out already. ;-) Where this could best be used is on the A axis of the 6040. With more geardown than it has ATM. With a teeny little nema-23, & my drivers from the micromill, it can do about 50 rpms. Take care & stay well, Chris. > > I noted that cura was lifting the head and moving it off about 2cm > > to about half a cm above, I assume to give that small a part a > > chance to cool between layers. But it still finished in about the 15 > > minutes it said it will take when cura sliced it. And the print is > > easily 5x sharper, a quite usable gt2 rendering where before, an xl > > pulley was just barely usable with a belt tight enough to satisfy > > Jack Benny! > > > > So I've come to the conclusion that quite a bit of what you can > > download as .stl's, are intended to be very low resolution so as not > > to compete with the same you-toobers commercial offerings. And my > > printer isn't the piece of crap I turned off in disgust 6 weeks > > back. I am impressed. > > > > 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 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
