On Sunday 09 August 2020 11:40:12 Bruce Layne wrote: > On 8/9/20 10:19 AM, Gene Heskett wrote: > > The different support base came off the glass, not easily but a bit > > easier than the previous run. > > PLA is generally considered to be easier to print but If you printed > in ABS, the higher thermal expansion rate (that can cause warping or > delamination problems when printing) ensures that the parts will self > release from the glass bed when it cools. Around 15 minutes after the > print has completed, you'll hear what sounds like glass cracking but > it's the ABS popping loose from the glass bed. The cracking sounds > continue for another 15 minutes. After approximately 30 minutes the > ABS part is completely separate from the glass bed. There is no > scraping or prying needed. These violent acts can knock a bed out of > level and cause print problems on subsequent prints, and could even > damage the delicate motion control components on a 3D printer. > > I'm currently running a 100 part 3D print job. Each ABS part takes > three hours to print. After 3.5 hours, I pick the part off the bed, > squirt a couple of milliliters of glue juice (water with a small > amount of dissolved glue stick) onto the glass bed, evenly distribute > it with a nylon bristle brush, and select Print Another Copy. Easy > peasy. > > PLA doesn't self release as well as ABS, but you should be able to > squirt some water around the periphery of the part and it should > dissolve the glue that bonds it to the glass build plate. Give it 30 > minutes for capillary action to float the part off the glass bed. > Even with ABS, I'd recommend 30 minutes for the glass plate to cool. > PLA has less contraction when cooling than ABS but the contraction > will still greatly help reduce the bond strength between the part and > the glass bed. > > Very little glue is needed. I have best results when I can see only a > slightly hazy glue layer on top of the glass. I think it helps to use > a nylon bristle brush to scrub the old glue and new glue water into an > evenly distributed emulsion. That's a few seconds well spent to > ensure a strong first layer bond.
I'm now dealing with lox clean glass, no glue remains, and its still sticking way too well. And I just broke the 2nd of the flexgears, the 2nd one in the lathe trying to make the 35mm that plugs into the bearing fit the bearing after the printer has been scaled up nominally 1.1% in order to get the proper flexgear size to fit the internal spline. So I have one last choice, go back to a unity scale on the printers xy, which is about 79.35 OOTB, make a flexgear that fits the main bearing after I nail file the knobs off, and free enough I can get it apart again, then make 2 more at that printer scale, then make 3 smaller internal splines that actually fit the flexgear, which will take about a 1.5% shrink and then make 3 more sets of bearing carriers that push it out of round to make it work At whatever scale works. That will be a similar shrink or less cuz I'll have to load the 1st ne with bearings and test it for size. Thats 14 days work since this thing uses about a day a part. And another 2kg or more of plastic. Discouraging is what it is. Basically thats keeping the housings which were made at the original scale but it takes 3.5 days for one houseing and one motor cap, then custom size everything inside it. The output shaft is solid enough I can fix it in the lathe, made to a guess, they're currently 35.17mm and won't enter a 35mm bearing either, but I'm hoping the screws will cut threads going in w/o stressing the PLA too much. Centering it to make that cut is a long backache per part fixed tho. But still quicker than making 3 more. So I guess this is the plan: 1. make 3 flexgears that fit a 35mm bearing at whatever scale that takes.. 2. Make 3 internal splines that properly fit the flexgear, at whatever printer scale gives that fit. 3. Make 3 more sets of bearing carriers at whatever scale gives the flexgear the proper exersize of full engagement and just enough side clearance to work, with a couple thou of overpush flexing the internal spine and houseing will be a wear reservoir. 4. Make the current output shafts fit. 5. Power the nema-17's to lock and make a 2nd flat on the shaft's 180 degrees from the first one. 6. Assemble the bearings to the carrier, wax coat and and install the nuts and grub screws putting some jbweld on the mating faces, letting it squeeze out and bond the nut carrier to the lid. Let cure for 24 hours. Back out the grub screws, and ream shaft hole with a 5mm reamer. 7. assemble the spline ring to the body. 8. Assemble motor to cap. 9. install bearing carrier on shaft. 10. Install cap, inserting bearing carrier into mouth of flexgear. 11. hook up stepper driver and power it up with a function generator. 12. run it for about an hour. 13. take cap back off, blow all wear crud away, and grease the teeth 14. reassemble and test run again, with silly grin on face if it works, extra points exchangeable for 2nd near beer if its quiet. :) I dream a lot, but thats the new order of things. 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
