ULF-1 Discussion Archive
Anonymous static archive of the former Mailman list
Anonymous static archive of the former Mailman list
[ULF-1] Best Glues
In case I might have missed something in the last fifteen years, all of the resourscinal glues mentioned in the Forest Products Labs "Member 60 INFO BOOK" that are the only glues that qualify as "exterior structural" (which is the highest rating) were completely removed from and are still no longer available to private users in the USA because of environmental hazards. Is that still correct? -------------------------------------------- On Wed, 6/13/18, Member 116 <[email]> wrote: Subject: Re: [ULF-1] Ulf-1 Digest, Vol 70, Issue 14 To: [email] Date: Wednesday, June 13, 2018, 7:57 PM Member 67, you are absolutely right! Flocked cotton (flox) is structural, micro is not. Also micro is porous. If you fix a fuel leak with micro the fuel will wick right through. I've built two LongEZ's, ask me how I know - LOL. On Wed, Jun 13, 2018 at 2:03 PM, <[email]> wrote: Send Ulf-1 mailing list submissions to [email] To subscribe or unsubscribe via the World Wide Web, visit http://lists.ulf-1.com/ listinfo.cgi/ulf-1-ulf-1.com or, via email, send a message with subject or body 'help' to [email] You can reach the person managing the list at [email] When replying, please edit your Subject line so it is more specific than "Re: Contents of Ulf-1 digest..." Today's Topics: 1. Re: Epoxy bonding (Member 121) ------------------------------ ------------------------------ ---------- Message: 1 Date: Wed, 13 Jun 2018 09:12:17 -0700 From: Member 121 <[email]> To: [email] Subject: Re: [ULF-1] Epoxy bonding Message-ID: <CALUQ4rd1+YpvK9Ck0+ QsJ1dZ6tMm=4QX6ZpFFAarKzZjKi=b [email]> Content-Type: text/plain; charset="utf-8" Cool . Did you ever hear of fiberglass drywall tape? Wrapping struts near the cocpit to prevent splintering impaling effects ? But some fiberglass is unravel -ish when cut into strips . Cotton linen was used in ww1 on propeller tips . On Wed, Jun 13, 2018, 9:06 AM Member 72 <[email]> wrote: > Hi Doug, > > All very good advice. One thing we did on our ULF-1 build was to mix flox > (floculated cotton) into our T-88 glue batch when we needed to thicken it > up a bit to help fill some voids in the joint, rather than micro balloons. > We found flox to be structural in nature and added strength to the joint, > while microballoons was more cosmetic, not adding much strength to the > joint. > > Thanks, > Member 72 > > > > Sent from my iPad > > > On Jun 13, 2018, at 1:43 AM, Member 1 <[email]> wrote: > > > > I'm with Bob on this. To me, there is a lot of superstition involved in > peoples' beliefs about gluing Member 60. The shiny surfaces created by blades > have always intuitively struck me as a deterrent to a good glue bond. I am > now working as a violin-family luthier, and I am up against the same > superstitions there as well. > > > > Having said that, though, I'm not sure it makes a big difference. While > building an aircraft, you end up with leftover epoxy from many small > batches. Grab some sticks out of your trash or scrap pile, and do some > semi-scientific testing with your leftover glue. It only takes a minute or > two. For example, I would cut two sticks about 10 times as long as their > width/thickness, overlap them 2 or 3 times their width/thickness, and glue > them together with light or moderate pressure, and then break them after > curing for a couple days. The Member 60 should always fail before the glue joint > does. If it does, then who cares how the joint was prepared? > > > > Do this often, throughout your project, during different environmental > conditions, and as your epoxy gets old. As soon as you find yourself > airborne, your life hanging from all those glue joints you've made, you may > think about those glue joints (as I did) and find comfort in the fact that > they are stronger than the Member 60 itself and you've done the best you could. > Then it all comes down to proper design which doesn't allow any joints to > get stressed to the point that the Member 60 itself fails. > > > > To me, it is more important to not apply too much clamping pressure to a > glue joint than it is to worry about cutting vs sanding. I always let my > wet joints sit open either until the epoxy is thickening a bit, or it is > obvious that the Member 60 is saturated and won't be absorbing any more glue. > Then I'd assemble and clamp with moderate pressure. Epoxy has several times > more tensile strength than hardwood, so even if you're sloppy and end up > with a thick seam of glue, there should be no strength penalty. A small > weight penalty perhaps, but that would be over-nit-picking. If you join the > parts before the glue has stopped soaking in, and/or apply excessive > clamping pressure, you are asking for a weak, glue-starved joint. (I use > T-88 which is relatively thick... if you use a glue that has a thinner > consistency, this attention to soak-in is even more important.) > > > > Epoxy is really good at filling imperfections and allowing stresses to > be spread out over larger areas, so a perfect fit is not as important as it > was with previous glues. For large voids that can't be easily avoided in > structural joints, I recommend wetting the bonded surfaces with epoxy and > then making a light slurry with epoxy and micro-balloons to fill the voids > with. > > > > Test your glue and your methods. Then you'll know, and nothing anyone > writes will bother you. There are some photos of the glue-starved joint > risk here (and other gluing tips throughout my old AirBike building web > site): > > > > http://questiongravity.com/ airbike/feb03-1.htm > > > > $0.02, > > > > Doug > > > > PS: We have 307 members! So glad to see you all here, and thanks to all > who have been contributing. And thanks to Dieter for continuing to fund the > domain fees to keep this service available. > > > > > >> On [phone]:56 AM, Member 116 wrote: > >> I disagree about not sanding before gluing. A power planer of a hand > planer bends the fibers over and leaves a shiny surface, not good for glue > penetration. I have a cabinet shop and glue stuff together daily. For a > couple years I glued up 12 ply (birch and maple) propeller blanks for a > prop manufacturer. All those ply's after planeing were smooth and shiny > because of the bent over fibers. Before gluing (with Resorcinol glue) I'd > run over them with a belt sander/80 grit across the grain, one pass to give > the Member 60 some (tooth). Then use a shop vac to clean and make those > (damaged) fibers stand up straight and accept more glue penetration. > > > > ______________________________ _________________ > > ULF-1 discussion list -- [email] > > > > Subscribe, Unsubscribe, Preferences, List information: > > http://lists.ulf-1.com/ listinfo.cgi/ulf-1-ulf-1.com > > ______________________________ _________________ > ULF-1 discussion list -- [email] > > Subscribe, Unsubscribe, Preferences, List information: > http://lists.ulf-1.com/ listinfo.cgi/ulf-1-ulf-1.com > -------------- next part -------------- An HTML attachment was scrubbed... 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