On Sunday 23 October 2016 01:45:58 Danny Miller wrote: > You CANNOT expect any high-strength bond on HDPE that rivals the > strength of the material, not with any glue. Typically it is bolted. > I am reaching that conclusion, Danny. I still have enough of those mini-wood screws to do that. 8 of them will nicely hold what I have in mind ATM.
> E6000 (same an Amazing Goop except uses PERC solvent instead of > toluene) is the highest strength. > > Locktite makes a system for cyanoacrylate where you use a primer to > activate it and then use this superglue stuff. I tried that last week on some freshly machined alu, had to make an outboard holder for the index ATS667, clamped for about 1/2 hour. A 2 oz bump as I was taking it out of the vice and it slid right off that faintly colored layer of dried primer. Never penetrated the primer. Total waste of 10 bucks for the can of primer/prep spray. Scraped it clean, drilled & tapped for a 3mm socket head capscrew now with a drop of cyanoacrilate in the joint as I was tightening the screw. Cleaned with acetone before the s-glue went on. That has survived a trip into the milling vice for a part trench to be milled into it. Needs one more 1/16" cut for wire exit. Or the edges dulled and the kynar wire formed and gooped in place. But that stuff is fragile at the solder joint, so I am tempted to cut off 3" of ribbon cable & slit it to 3 conductor pieces. Its crowded under the cover when its in place on the spindle, more room below than above. I'll have to machine a pcb by hand to serve as an anchoring point for the encoders output cable and it will be mounted on this index extension. Not happened yet tho. And while there is room under all the gears to run it to an existing 1/4" hole in the back face of the bottom half of the spindle housing, its also going to be swimming in oil, and I have no clue how oil resistant that grey plastic jacket is. I have several lengths of SS tubing commonly used on race cars that this cable could be pulled thru, which is another picky to do it way to get this cable out of the spindle houseing. > HDPE can be thermally/ultrasonically welded to more HDPE. UHMW, that > doesn't really work because it has a melt index of 0. If you put it > in an oven, UHMW becomes a semi-transparent floppy sheet- but it DOES > NOT melt before it starts decomposing. Its chains are so long and > entangled it can't become a liquid and remain UHMW. > > Now I do know this. Society of Creative Anachronism uses UHMW blocks > on fiberglass arrow shafts for live-combat arrows. To do this, they > bore a tight, deep hole that requires compression to seat the shaft > and use E6000. The joint never goes out of compression and has a lot > of surface area in shear alone. That holds for life, no matter what. > But you really won't have that scenario. No, but that is an interesting use scenario. :) > Danny > > On 10/22/2016 5:22 PM, Bruce Layne wrote: > > In general, no matter what your glue question is, my glue answer is > > epoxy. Epoxy or JBWeld hasn't proven to be the answer in plastic scenarios for me. > > HDPE is almost as difficult to glue as UHMW or Teflon. Very low > > surface energy. I'd recommend cleaning with isopropyl alcohol to > > remove every trace of oil from the surfaces (HPDE and panel), allow > > it to air dry, and then use a liberal amount of RTV silicone. You > > seemed to be heading in that direction with your Goop musings. Don't > > be stingy. Slop it up the sides of the HDPE if possible so it has > > more surface to grip and it's protected from shear loads, which are > > the enemy of adhesives. I considered dropping the face to be joined on my big bench belt sander for about long enough to make the surface good and "hairy", but haven't actually tried that. About a second maybe as the melting point is reached very quickly and I'd want it badly scuffed without melting. 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) Genes Web page <http://geneslinuxbox.net:6309/gene> ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, SlashDot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
