Don't scale the entire part unless caliper show you the entire part is scaled too small. (this is very unlikely) Better to simply adjust the one hole you need to be larger. Or if it is less than about 0.1mm put the part on a lather and bore it out to size. I did this to all my timing belt rings to make them fit perfectly to the 24mm hubs. If you go slow so as not to melt the PLA the carbide boring bar works and just took off "fuzz"
The hole seems small but usually, it is because the plastic was not laid down perfectly and there are bumps and ridges and lines inside the hole. Make the hole perfect rather then making another larger not-perfect hole. Also it is MUCH quicker to bore the hole then re-print the part. The other trick I do is to make "temporary" bearings with either aluminum or even PLA while waiting for the real bearing to arrive. You could make them on a manual lathe in a few minutes and then you could verify the parts work and there is not OTHER problem before doing another 16 hour print I'd be surprised if you did not need to clean up the fine pitch gears with a nail file. Most 3D prints require some post-processing with a tiny file and maybe #600 wet and dry paper. A boring bar makes the inside of holes smooth as glass. A read a translation of the designer's blog page and it seems he wants to make a 6 axis arm with these. He will probably need to make some of the parts near the base of the arm in metal On Tue, Jul 28, 2020 at 4:08 AM Gene Heskett <[email protected]> wrote: > On Tuesday 28 July 2020 02:59:01 Chris Albertson wrote: > > > .STEP started out as the native format for Solidworks but is now an > > ISO standard. You can read and write the file with many different > > programs. FreeCAD is one. > > > > But the file is just a plain old ASCII text file. If there is some > > data inside try "grep" or just a text editor and search for a word. > > > > NIST has a web app that puts a .step file into a spreadsheet > > https://www.nist.gov/services-resources/software/step-file-analyzer-an > >d-viewer > > > > <https://www.nist.gov/services-resources/software/step-file-analyzer-a > >nd-viewer> What are you making? I read a post about 50 ball bearings. > > THat is a complex machine. A four legged walking robot? Got a link > > to the .step file? > > > No, 3 of a harmonic drive I found on thingiverse, each of which uses 7 > ball bearings. One larger one for output shaft, and 6 smaller ones for > the wave driver. Drives with a std nema-17 motor. The link has been > posted to this list twice. > > <https://www.thingiverse.com/thing:4505585> > > But if making it, a warning, the bearing carrier is a couple hairs small, > so when rendering it. I'll have to wait on the bearings and build one to > see what sort of a ratio to set the printers x,y scales to in order to > build the right size for those final 6 parts. It has IMO a slightly > small flex gear, and it could be that a similar correction might be > needed for that. It looks like a good design otherwise, but these mods > will bring its precision more into line with the several hundred dollar > metal clones. Making the flex gear bigger by 1 or 2%, will reduce the > flexion needed to drive it, extending its life. Or one could scale the > outer spline down that same %. I'll fix the wave bearing carrier first > for full engagement, and if that pulls the teeth too far apart at the > inside flex where the teeth clear and are stepping across each other, > and tips are pointed at each other, what they clear by could be reduced > to zip by scaling up the flex gear as it prints, probably by reprinting > them once that ratio is determined. That should reduce the flex and make > a longer lasting drive. > > 2 of these 3 will become telescope drive parts, I've had a Meade DS-10 > for ages that needs driven from a linux proggy called stellarium and one > might wind up redrilled for a nema-23 mount and maybe adapted to drive > that BS-1 indexing head's worm. That will stress it a lot harder as I > intend to be able to move it under cutting load. Might have to remake > the moving parts from PET for that. We'll see... > > > On Mon, Jul 27, 2020 at 11:10 PM Gene Heskett <[email protected]> > wrote: > > > Greetings all; > > > > > > Freecad newbie, and I'd like to get a printout of the parts list in > > > this .step file. The list it shows in the upper left panel. > > > > > > This is version 16, is it possible, and if so how? > > > > > > Thanks. > > > > > > 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 > -- Chris Albertson Redondo Beach, California _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
