On Sunday 31 May 2020 18:07:15 Chris Albertson wrote: > I was about to post the same thing. OpenSCAD s not a general purpose > CAD system that you can use for machine design. > > How to check for clearance: On a normal CAD system you can have > commands like "move this enough so it contacts this other object." I > do that, then move it back by the required clearance distance. > When working to 0.001" using eyeballs and scales don't work. > > If boring a bearing I'd say to make the hole "shaft diameter + twice > the clearance" With gears yu now the pitch diameter so you place the > gear shafts at "pitch diameter A + pitch diameter B + required > clearance" Almost all CAD system allow dimension to be expressed as > formulas > > A good CAD system is very much like working on a mill, you would touch > the part then move from that reference. The only hard references I > would use come from external requirements. Others are calculated. > Never trust your eyes or hands. > > On Sun, May 31, 2020 at 1:06 PM Thaddeus Waldner <thadw...@gmail.com> wrote: > > OpenSCAD doesn’t have a measure feature. All that you get is a model > > preview overlaid on a 3D scale > > > > You can, of course, look at the code that created each feature and > > read the dimensions there. > > > > I can’t imagine drawing up a complex machine with OpenSCAD, but > > apparently some people do it. > > > > > > https://medium.com/@urish/designing-3d-printable-mechanisms-in-opens > >cad-5838dcb65b39 > > > > Can’t argue with the price. > > > > > On May 31, 2020, at 12:50 PM, Chris Albertson > > > <albertson.ch...@gmail.com> > > > > wrote: > > > Any CAD system should allow an exact measure, click on a circle, > > > and see the diameter out to the full resolution you have set, > > > typically 0.001mm. You should be reading out the numbers not > > > visually comparing to an on-screen scale. An on-screen scale > > > would be limited to the pixel resolution of the monitor > > > > > >> 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? > > In this case, I'd be far more confident once I get the motor in position, so I can measure center to center distances. And since the motor mount will block the back holddown cutaway in the base of the BS-1, it appears I'll need to clear access to that nut via socket from the top. So the xl belt is going to be quite long, as the pulley it will be driving has to clear the worm shaft severely limiting its size, and therefore the attainable gear ratio. But I need an anchor point at the center of the tilt axis. So there are 2 measurements I can't make very precisely until both of those operations are completed. See previous msgs. And in order to get a straight bore in the side, I'll have to make a pair of parallels to space the other side of this thing above the table and level. But at least the mill itself is passably square for Z now. > > _______________________________________________ > > 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
