Well, if they are paper or phenolic tubes, sometimes a bead of CA around the edges (still will need some sanding) helps keep the edges from fraying/tearing. Then tape can be used as a shoulder builder, if necessary, and painting the inner surfaces with a thin epoxy layer (yes, will mean more sanding) also helps.

I would second the suggestion on CA soak for paper/phenolic tubes.

Also, if you go with a coat of epoxy, you could add graphite to the mix (I believe West Systems has an additive, but any graphite powder should work), to make the resultant hard slippery surface.

-Ken

If you need graphite I've got it by the pounds at my house. Let me know and I can get you some. Byproducts of turning lots of graphite parts.

Edward

I actually used a brush and painted on a coat of CA glue on one coupler and on another one I used some 20 minute epoxy painted on it. Both worked well, but I think the CA absorbed a bit better. Made for easier sanding too.

I use rattle can spray paint to paint most of my
rockets. I have found (after having some overspray)
inside the tube) that after drying and a little sanding
it makes for a nice firm fit.

I also bevel the coupler slightly

Meant to post a few days ago. I finally got finished redoing all the tube/coupler ends per your suggestions and it worked great! I tapered all the incoming and outgoing edges then hardened them with CA. I spread about an inch of CA on the inside and outside of each joint also which seems to give me enough slide. Thanks guys.

All that's left is to get the wiring back in order and a L2 attempt will be within reach for the December launch.

Kevin