On Wed, Jun 3, 2020 at 7:33 PM Gene Heskett <ghesk...@shentel.net> wrote:
> On Wednesday 03 June 2020 19:17:14 Chris Albertson wrote: > > > You are going to have to post a photo. First off, I hope you are > > printing these pulleys flat, With rotational axis vertical. I hate > > to ask but with no photos we don't even know this. > > > > Assuming you are, the teeth are called "walls" and only if bubbles are > > in the plastic would you get voids. Print slower or maybe cooler. > > The outer wall layers should run at maybe 30 mm / second. > > > > Here is a cell-phone shot of a 30T GT2 profile pulley that has been > > sitting around on my desk for a couple weeks. It is dirty and the > > flanges need to be cleaned up with a small nail file. The walls > > are made in the direction of motion and are smooth enough. It is a > > 3mm tooth pitch by 9mm wide. I think this one was printed on "draft > > mode" with 0.2mm layer height. This is from an Anet A6 printer with > > default settings in Cura. A steel hub goes in the 20mm hole. THe gear > > was downloaded from SPD/SI website than modified in Fusion 360 > > > > [image: IMG_0542.jpg] > Thats a heck of a lot nicer looking, and 10x smoother than what I have in > my hand from this afternoons run. That said, an XL belt fits it nicely. > So this one is usable for a test fit mock up except the slot for the nut > is about a 20% infill. One might be able to epoxy it to the motor shaft > with JBWeld. But despite 2mm walls around the hub, I can feel the > elasticity and that bothers me. And while I can sort of see the solid > walls around the nut pocket, I have serious doubts of ever getting a > decent grip because it will open up from the outward pressure the nut > would exert. > Yes, That is why I make pulleys with a 20 or 24 mm hole. They get epoxied to a steel hub. Steel hubs are easy to make on a lathe by hand. I use two set scres at 90 degrees. I could epoxy to the motor shaft but then I might want to use the motor later with a different pulley. One thing that does work for a while, If the motor has a "D" shaft or a keyway you can print a D or keyway in the pulley. D-holes don't spin but the loose concentric over time. There is one more technique I want to try. Brass thread inserts. You heat these on a solder iron tht press them into a hole. When the plastic cools they stick amazon.com/Uxcell-a16041800ux0824-Knurled-Thread <https://www.amazon.com/Uxcell-a16041800ux0824-Knurled-Threaded-Embedment/dp/B01IYWTCWW/ref=pd_sbs_60_2/140-9661733-2175833?_encoding=UTF8&pd_rd_i=B01IYWTCWW&pd_rd_r=adfaa131-87de-4bc3-9678-232764f895cb&pd_rd_w=U5P0Q&pd_rd_wg=rKlV4&pf_rd_p=d9804894-61b7-40b3-ba58-197116cffd9d&pf_rd_r=X28MD5MCYFYFCWH10C9X&psc=1&refRID=X28MD5MCYFYFCWH10C9X> If you have access to the backside you can press-fit normal hex nuts and embed them into the plastic but these knured nuts press in from the front side and might work for gears. That would be quicker them making a steel hub. Kind of a compromise. 6 cents each. Finally if you print threads, the wall and skin thrickness setting applies to the plastic around all holes, threaded of not Use "preview" in Cura to see exactly how each layer will stack up > So I'll probably use this as the motor pulley while I am mocking up the > real drive, the next stage being a hubless, larger model, which will be > epoxied to a smallish possibly herringboned gear, driving a much higher > tooth count matching gear on the worm shaft. The herringbone may get > lost in the translation to metal for the final parts though. > > I set up a "raft" for this one, and made it 15mm bigger than the hub, and > it was 30 minutes just laying the raft. 4 layers. Bed cold, I wiggled > the putty knife under it, popped it off, then the raft separated nicely > just like cura said it would. I upped the speed to 60mm/sec but I don't > think it ever moved that fast. But I think a 5mm skirt would be ok and > 20 minutes faster. > > Now I need to make some parallels so I can lay it down on the mill table > without taking out all the lock levers etc, and drill and tap for the > axle the intermediate stuff will turn on. Then make the shaft out of > some .500" A2, figuring on some 8mm ID bearings if torrington makes > their needle cartridges that small, I haven't checked yet. Need the > smallest to make room for the relay gear to the bigger gear on the worm > shaft. > > I got the motor adapter yesterday, a 34 to a 23, and I'll need to get > another alu pulley with an 8mm bore to drive the Sheldons Z with the > other motor. Same tooth count, should move the Sheldon ok and 60 db > quieter that the 1600 oz/in doing it now. If I ever get a knee mill, it > would make a good knee motor. Better yet, somebody should make me an > offer for it. 14mm shaft. > > Thanks Chris. > > > On Wed, Jun 3, 2020 at 1:37 PM Gene Heskett <ghesk...@shentel.net> > wrote: > > > On Wednesday 03 June 2020 14:54:31 Chris Albertson wrote: > > > > > > > > > The pulley teeth are very low density, mostly air with a filament > > > bridge at a 45 degree angle. How do solidify the teeth? What I'm > > > getting would cut up an XL belt in an hours work, its that sharp. > > 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 > -- Chris Albertson Redondo Beach, California _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
