No, swarf protection could help with cooling. What if the swarf protection where a form fitting plastic shell that was (say) 4mm larger than the motor and pulley and covered everything with just a 4mm air gap? Then you used forced air from a fan in the gap.
Hand held drill motors work like this. They have a form-fitting shell and put a fan on the motor shaft and push air through screened vents in the case. Or just reduce the current in the motor. The formula for heat is I-squared-R so you get 4X less heat if you cut the current in half. On Sun, May 31, 2020 at 1:35 PM Gene Heskett <[email protected]> wrote: > 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 > -- Chris Albertson Redondo Beach, California _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
