On Wednesday 03 June 2020 23:05:12 Chris Albertson wrote: > 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-Embedm >ent/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=U >5P0Q&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
Preview has a camera view angle that takes the image off the bottom of the screen, long before the magnification has reached a usefull level. Changing its view style does not allow the image to remain on screen in either mode. Its aimed at a point about 160mm above the bed. It needs to scroll vertically and doesn't. xray view is blank. But I finally got that, but still can't blow it up enough to see. So I increased the wall thickness, and reduced the nut height half a mill and fired off another make. Sped it up to 100mm too. > > 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 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
