Gluing Bulkheads into Plastic Nosecones

[dpoceta]

Hi Everyone

What kind of glue would one use for gluing in a plywood bulkhead into a 3" plastic nosecone?

I just had one rip out (while being tested, thankfully) that was glued in with 15 minute epoxy and milled fiberglass, but maybe I just didn't rough up the plastic enough.

Thanks

 

[Pantherjon]

Hi Everyone

What kind of glue would one use for gluing in a plywood bulkhead into a 3" plastic nosecone?

I just had one rip out (while being tested, thankfully) that was glued in with 15 minute epoxy and milled fiberglass, but maybe I just didn't rough up the plastic enough.

Thanks

Good possibility(roughing up the plastic)..I have also read of a technique of drilling a hole thru the sides of the NC and putting a dowel just below the bulkhead..And of course, trimming and sanding the dowel ends to conform to the contour of the NC

 

[SpartaChris]

Hi Everyone

What kind of glue would one use for gluing in a plywood bulkhead into a 3" plastic nosecone?

I just had one rip out (while being tested, thankfully) that was glued in with 15 minute epoxy and milled fiberglass, but maybe I just didn't rough up the plastic enough.

Thanks

I've never had this happen to any of my rockets, so I'd suggest roughing up the nose cone better. My 4" Pterodactyl has 2 lbs. of nose weight in the tip and I used 5 min. epoxy to secure the bulkhead. To date (knock on wood) I have not had a problem.

 

[powderburner]

I am a little surprised that epoxy came loose. Or maybe you have an extra 'soft' plastic and it flexed at one edge of the blkhd enough for it to break loose?

My experience is limited to heavy cardboard (laser-cut CR-type 0.050 black board, and matte-board type cardboards of similar thickness) and very light plywood (1/8 ply), into OTS estes-type plastic NCs, but gorilla glue has held them in just fine.

 

[Micromeister]

I'll just ditto most of the earlier posts.
I've never had an epoxied bulkhead fail. the Key is roughening up the inside and/or drilling a couple epoxy rivet holes in the shoulder. Once sanded smooth these rivets are very strong.

 

[quickburst]

Option 1:
Rough up the inside of the plastic nosecone well (use 80 grit sand paper), as others have stated. I have found that Gorilla Glue works best on plastic to wood. Be sure to dampen the surfaces to be bonded with a little water first, gorilla glue needs the water to react and form a good bond (read the label). Set up time is longer than most epoxies.

Tip: Buy a small can of the gorilla glue, it has limited shelf life due to it absorbing moisture from the air. I'm on the Gulf Coast where humidity runs 85% norm. so this is a big issue.

Option 2:
Pinning the nose cone.
Drill 1/2" deep holes through the side of the nosecone and into the edge (center) of the bulkhead and insert short dowels (1" long; use Elmer's yellow glue for wood to wood). I use three dowels at 120 degree spacing. Let adhesive set then cut dowels off flush then sand. Works like a charm, and your bulkhead will never come off.

 

[TWRackers]

Do fiberglass nose cones (like in HP rockets) share this problem with plastic nose cones? Or is the rough unfinished (kinda like me) inner surface of fiberglass noses less prone to this type of separation? Or is there a difference due to the materials themselves? Aren't fiberglass noses a matrix of fiberglass in an epoxy resin? Does epoxy bond to epoxy better than it does to plastic?

(Wow, that's a lot of question marks in one post, isn't it? )

I think I like option 2 in the previous post. May do that with my L3 rocket just to be sure it stays together.

 

[kandsrockets]

Here is how I put my bulkheads in my L3 rocket, LOC plastic nose cone. I use screws and epoxy

 

[dpoceta]

Thanks for all the replies so far.

Yeah, its weird that the bulkhead ripped out. After checking it out, every bit of epoxy came loose along with it, so its clear that the epoxy did not at all penetrate the plastic.

I am now going to really rough up the plastic with 60 grit and install some dowels or screws like Quickburst and KRS suggested.

 

[ben]

Do fiberglass nose cones (like in HP rockets) share this problem with plastic nose cones? Or is the rough unfinished (kinda like me) inner surface of fiberglass noses less prone to this type of separation? Or is there a difference due to the materials themselves? Aren't fiberglass noses a matrix of fiberglass in an epoxy resin? Does epoxy bond to epoxy better than it does to plastic?

(Wow, that's a lot of question marks in one post, isn't it? )

I think I like option 2 in the previous post. May do that with my L3 rocket just to be sure it stays together.

I have noticed that the epoxy hold better to epoxy and since the cloth has all thos 1/2 filled holes on the inside there's alot to grab onto. I have also built up a small line of 30min epoxy and waited till it got tacky then pushed the bulkhead onto the (so the bead is on the inside of the cone) then I layed a thick bead of chopped FG and west on the top. Still holds strong today! (This is also what my friend did on his 10" SatV and the cone weighs 30lbs)

Ben