On Monday 13 September 2021 06:00:25 Gregg Eshelman via Emc-users wrote: > You almost sound disappointed that you couldn't break it. ;)
I noticed that too. I haven't broken my version but once, tried to make it from PLA, but I had a different idea because I wanted a smaller version, and I have the attitude that I can print another for 10 bucks worth of plastic and 3 bucks worth of bb's. But since I switched to PETG, and that caused a few thou $ in printers to find one that could handle a steady diet of PETG, most can't. But PETG can make a very servicable loose belt as its lots more flexible than PLA. But in the interests of cheap, I didn't use an armature with off the shelf bearings. My armature is printed, including the hub which because the motor I chose has an 8mm shaft that I put on the 0704's table and ground the d-flat much wider, needs no alu or steel insert hub, the PETG as a press fit on the 8mm shaft has not failed. That armature is printed, and eccentric by 1.1mm. Its wrapped by two printed ball bearings, which in turn distort the loose belt in the same manner that Sam's much more expensive off the shelf bearings do. Probably with less flex stress on the loose belt because the push is fully distributed. The drive I made is aimed at the A drive supplied with cheap gantry mills as the kit supplied has virtually zero holding power and 100x the rpms needed for such duties. Designed for a 30/1 ratio, and another nominally 4/1 between it and the A axle, by way of a small pitch timing belt. Its a hair loose and needs a tensioner idler designed and built that I haven't found the round tuit to do yet. I've had it running on the kitchen counter at about 3 rpm at the chuck for something over a month now. All except the bearing balls which are crosmann bb's, is 3d printed. Currently driven by a 1NM 3 phase stepper/servo, I think it will do the job on my 6040 mill. And if I break it, a $20 bill prints another. Its also got about an hours worth of running at just short of that small motors stall speed, 2000+ rpms for about a minute at a time so the armature bearings don't get too hot. At that speed, the bb's are probably spinning in the 100,000 rpms category. The output end houseing and shaft only have 1 bearing,, another row of bb's, 75mm in diameter. There is more flex in the 3mm thick disk holding the output sprocket than anyplace else. It is less than 4" in diameter, and under 20mm thick not including the output sprocket, it is plenty strong enough to do _that_ job. > > On Sunday, September 12, 2021, 06:52:23 PM MDT, Sam Sokolik > <samco...@gmail.com> wrote: > > Small update > > https://youtu.be/eW1GGI55Epc > _______________________________________________ > 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
