On Sunday 31 May 2020 12:07:51 Martin Dobbins wrote: > Caveats: > > 1:I'm not a 3d printer user, but I may become one after reading this > thread: Thanks (I think<grin>) > > 2:I have very little experience with Openscad. > > Serve the required grains of salt with the following as required > > Gene Heskett wrote: > >1; Which is a measure of the OD of the rendered pulley, those areas > > of the preview gfx are blank, although the scale marks are there, > > they are drawn behind the sprocket image. so one could get a very > > rough idea of the total radius of the finished gear in mm. Am I > > missing a font, or is this a more serious concern that will need me > > to make the gear before I can determine how it fits? > > Melted plastic contracts as it cools, so getting something on size is > an iterative process > > Print, measure, calculate percentage shrinkage and reprint that > percentage oversize. I understand that most slicer > > software includes an easy way of doing this (at least I hope so). > Rinse and repeat to get something that meets > > tolerances. I don't know the answer to the openscad rendering > question, but don't you have the parameter values > > for everything drawn? > > >2; This motor runs uncomfortably hot, and I've not found anything to > >indicate the controller goes into a low current mode at balance, I > > left it running at about 1500 revs for half an hour and cannot lay a > > hand on it to pick it up, and an extended stop didn't seem to cool > > it any, and since that heat will telegraph up the motors 8mm shaft > > to the PLA, is this going to be a life of the sprocket limiting > > factor because the PLA will soften and eventually cold flow to a > > loose and likely out of concentricity warpage? > > That's something that you can figure out now, melt temperature and (I > just found out from the link below) > > glass transition temperature 111 to 145F. Can you squeeze a metallic > hub in? Or maybe an aluminum heat sink > > on the shaft between the motor and where the gear will sit? > I am thinking of a alu hub with some closely spaced holes drilled thru it to reduce the cross sectional area between the 8mm shaft and the plastic. That should give a temp loss of maybe 10-20F across the thin web between the holes. But would it be enough? IDK. Otherwise some sort of a forced air cooling system, or give up and use a solid alu pulley just for the motor. At the end of all this, it will need swarf protection too, and that would also get in the way of any normal convection cooling. > > https://www.creativemechanisms.com/blog/learn-about-polylactic-acid-pl >a-prototypes > > >3; I have the pi3b I took off the Sheldon, and another of those 5v5a > >supplies, and I've downloaded the octo-pi image that includes that > >slicer. So that I think solves the slic3r problem of having to > > compose a working multi-variable config for slic3r. Unless someone > > has a slic3r config to drive an Ender that they can share. > > Nope, but a google search found this-any good? > > https://www.youtube.com/watch?v=3yIebnVjADM
Yes, where he is done with the assembly, there are some setup hints for whatever slicer he is using, I didn't catch it if he did say. but he was manipulating it from the printers panel. So I guess I'll have to build mine and see what it has when turned on. That one can be restarted in the middle of a job, and generally the first print was excellent. I am hoping I can do as well. > > > I hope some of that helps? > > Martin > > > > > _______________________________________________ > 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
