Glueing couplers

[Danh]

This has probably been discussed before but.. I seem to have issues gluing my couplers sometimes they just lock right up when I'm putting them in place sometimes before I get them in place and they are Crooked. is there a trick to sliding them in place without locking up?

 

[G_T]

Um, twist as you slide?

You'll likely have to provide more info. What material, what size, what glue? How are you going about it?

Gerald

 

[Zebedee]

I'm gonna guess Elmers wood glue or equivalent - had the same issues myself. I think the next card/paper kit I do will be with Gorilla glue on those kinds of parts (CR's and couplers) which can bind up on you.

 

[Danh]

Paper body tubes and couplers I've been using tite bond 2 wood glue . I put a thin layer of glue on the areas I am glueing and slide it in place .

 

[samb]

+1 on the Gorilla polyurethane glue.

 

[Cl(VII)]

Paper body tubes and couplers I've been using tite bond 2 wood glue . I put a thin layer of glue on the areas I am glueing and slide it in place .

If you must use TBII for this don;t use a thin layer. Add a bit more than you need and wipe away excess once the part is in place. I usually use a thin coat of 5 min epoxy for couplers because it does not cease.

 

[qquake2k]

Yes, I've had that problem with yellow wood glue. The dreaded "coupler grab". Now I only use two-part epoxy, usually the 5 minute version. Never had one grab with epoxy.

 

[luke strawwalker]

DO NOT use yellow wood glue (carpenters wood glue)... it locks up NOTORIOUSLY fast, ESPECIALLY when smeared into an extremely thin layer, as it is when snug to tight-fitting couplers are inserted into tubes... The wood fibers (paper) inside the tubing and the coupler both wick moisture out of the glue, causing it to "lock up" extremely quickly.

For paper/paper joints, WHITE GLUE (not school glue, actual white glue) is a better choice. White glue is just as strong if not stronger with white glue than yellow wood glue, and it doesn't lock up AS QUICKLY... meaning that it can *still* lock up, so you have to use two countermeasures... 1) lay on a thick and heavy layer of white glue inside the tube and outside the coupler so that it "self-lubricates" the joint as the tube and coupler go together, so they don't lock up as quickly, and 2) twist the parts together quickly and smoothly as possible... have everything marked clearly (how far to insert the coupler into the tube) and use a firm, strong, motion to get them together and into the final position as quickly as possible. Then clean up the excess glue...

This is also an application where EPOXY particularly shines... because epoxy hardens by the catalyzing reactions between the resin and hardener, NOT via evaporation or wicking away of moisture as white and yellow wood glues do, the time until it hardens (working time) is CHEMICALLY predetermined (well, it is affected by temperature, but by and large, this holds true). This makes it much easier to assemble tight-fitting, high wetted surface area parts that mate with sliding contact, like couplers. The epoxy actually lubricates the parts as they go together, and then will cure in position when the working time has elapsed. The only downside to epoxy is that it's slightly heavier when cured than an equivalent amount of yellow or white glue, and of course there's more waste from the mixing and spreading equipment needed. The biggest drawback is that it requires the use of NITRILE gloves (not latex, which the chemicals in epoxy pass through easily) for mixing, handling, and application. Using and applying epoxy without gloves will lead to epoxy sensitivity over time (basically an allergic reaction that occurs whenever one is exposed to epoxy or its fumes after they develop the condition). It's also harder to clean up and smooth out. BUT, for GUARANTEED "no-lock-up" coupler installation, epoxy is probably THE best choice...

Later and good luck! OL JR

 

[Danh]

I will have to try epoxy on my next build , I do a lot of wood working so the tb2 is always on hand. without getting into the glue epoxy debate From what I understand wood glue is best for paper/wood. I tried gorilla glue years ago when it first came out. I never liked how it bubbled up and expanded so I quit using it never thought about trying it on rockets.

 

[luke strawwalker]

I will have to try epoxy on my next build , I do a lot of wood working so the tb2 is always on hand. without getting into the glue epoxy debate From what I understand wood glue is best for paper/wood. I tried gorilla glue years ago when it first came out. I never liked how it bubbled up and expanded so I quit using it never thought about trying it on rockets.

Every glue has its strengths and weaknesses...

---Carpenters yellow wood glue-- ideal for wood-to-wood and wood-to-paper joints... in that order
high shrinkage can cause "coke bottle" effect.

---White glue (Aileene's, etc, NOT "school glue")-- ideal for paper-to-paper joints... better in this role
than yellow wood glue. Shrinkage in thick
applications (pinholes, voids, especially in fillets).

---Carpenter's Trim and Moulding Glue-- Thickened version of yellow/white glue. Stays put when
applied to fillets. Almost no shrink, won't pit or void unless
applied VERY heavily (use repeated applications to avoid).
Smooths and cleans up with water. Excellent for fillets.

---Cyanoacrylate (CA, "super") glue-- ideal for "hardening" balsa parts and making in-field repairs or
extremely lightweight joints (like for gliders). Eats foam unless
"foam safe" is used. Very weak in shear plane (fin to tube
joints). Brittle and gets more brittle over time.

---Epoxy-- excellent all-around adhesive, but a little heavier when dry (no evaporation). Requires
gloves for mixing/handling/applying. More waste material (due to mixing requirement)
than other glues. The longer the cure time, the greater the strength (IE 1 hr. vs. 15 min.)
Can lead to sensitivity through prolonged exposure. Excellent for coupler joints and other
joints prone to "freezing" (motor mounts), or on non-wood/paper materials

---Urethane (Gorilla) glue-- foams up on curing. Difficult to clean up. Cures by reacting with moisture
Excellent for use "locking in" weight inside nose cones (BB's, lead shot, etc.) Will dry in a
confined area with little/no air circulation (inside nose cones) by reacting with a drop or so
of water added with the glue. Some report excellent results using EXTREMELY THIN
applications to glue on plastic detail wraps on scale models (too thick and it will foam
up badly).

That's the high points anyway...

Later! OL JR

 

[samb]

I will have to try epoxy on my next build , I do a lot of wood working so the tb2 is always on hand. without getting into the glue epoxy debate From what I understand wood glue is best for paper/wood. I tried gorilla glue years ago when it first came out. I never liked how it bubbled up and expanded so I quit using it never thought about trying it on rockets.

Epoxy is certainly a good choice. I like Gorilla glue when I'm too lazy to mix up a small batch of two-part . You do have to watch where it goes and clean up any drips but I haven't found it to be a inconvenience. I've been using it for years for couplers and motor mounts on lpr's with no ill effects. I'll post a picture of a recent zipper repair when I get home later.

 

[Danh]

Every glue has its strengths and weaknesses...

---Carpenters yellow wood glue-- ideal for wood-to-wood and wood-to-paper joints... in that order
high shrinkage can cause "coke bottle" effect.

---White glue (Aileene's, etc, NOT "school glue")-- ideal for paper-to-paper joints... better in this role
than yellow wood glue. Shrinkage in thick
applications (pinholes, voids, especially in fillets).

---Carpenter's Trim and Moulding Glue-- Thickened version of yellow/white glue. Stays put when
applied to fillets. Almost no shrink, won't pit or void unless
applied VERY heavily (use repeated applications to avoid).
Smooths and cleans up with water. Excellent for fillets.

---Cyanoacrylate (CA, "super") glue-- ideal for "hardening" balsa parts and making in-field repairs or
extremely lightweight joints (like for gliders). Eats foam unless
"foam safe" is used. Very weak in shear plane (fin to tube
joints). Brittle and gets more brittle over time.

---Epoxy-- excellent all-around adhesive, but a little heavier when dry (no evaporation). Requires
gloves for mixing/handling/applying. More waste material (due to mixing requirement)
than other glues. The longer the cure time, the greater the strength (IE 1 hr. vs. 15 min.)
Can lead to sensitivity through prolonged exposure. Excellent for coupler joints and other
joints prone to "freezing" (motor mounts), or on non-wood/paper materials

---Urethane (Gorilla) glue-- foams up on curing. Difficult to clean up. Cures by reacting with moisture
Excellent for use "locking in" weight inside nose cones (BB's, lead shot, etc.) Will dry in a
confined area with little/no air circulation (inside nose cones) by reacting with a drop or so
of water added with the glue. Some report excellent results using EXTREMELY THIN
applications to glue on plastic detail wraps on scale models (too thick and it will foam
up badly).

That's the high points anyway...

Later! OL JR

Wow that's a lot of info. thanks.

 

[dave carver]

+1 on the Gorilla polyurethane glue.

View attachment 248034

This is by far the best way. Put a glopy line out on a shiny piece of paper and roll the coupler through it several times to spread it evenly and thinly over the complete surface. It's also best to sand the coupler lightly to make it smooth. Dampen a paper towel to where it's wet but not dripping and wipe the inside of the body tube until it gets the slightly dampened look of just being a bit darker. Slide the pieces together. You're going to have some scrub off but just use you damp paper towel to wipe it up. It really doesn't matter how much you scrape off, The Gorilla Glue expands to fill the entire space, it foams up and sets like epoxy. Tear apart one of your fouled up woodglue couplers and your lucky to have even 50% contact. Tear apart a Gorilla Glue joint....good luck. I'd say you get 90-95% or better. Because you have a set up timeframe what I do is strap the rocket in the "\/" of a piece of 1" angle aluminum to keep it aligned as it dries, takes 1-2 hours.

 

[JRThro]

If, like me, you're too lazy to switch to a different type of glue, then just use more than you think you need, so the glue can act as a lubricant for the coupler before it begins to seize up.
Apply the glue to the inside of the body tube, not to the coupler itself. That way the excess will stay inside the tube instead of getting all over the outside, your hands, your work table, etc. Then wipe the excess off the inside of the tube.

 

[rharshberger]

There's absolutely nothing wrong with using good ole Elmers white (now sold as Elmers Glue-all) , on a paper to paper joint like a coupler (if both pieces are cardboard). The point of failure will be the paper not the glue. I have been flying rockets that were assembled nearly 30 years ago with nothing but Elmers white glue.

Epoxy is still the best for not seizing couplers though, and its what I use when doubling tubes for rockets like my Mean Machine and BlueBird Zero with 29mm motors.

I generally stay away from Gorilla Glue because: A.) Titebond products are stronger. B.) I hate dealing with the mess, if I get any in the wrong spot.

 

[samb]

Ain't glue threads cool ? :grin: Different strokes.

 

[o1d_dude]

Epoxy for me. Works every time. Also use if for installing motor mounts so as to avoid the "coke bottle" effect of glue shrinkage.

 

[enderw88]

Ain't glue threads cool ? :grin: Different strokes.

Sure beats the Chinese ad gripe fest.

 

[luke strawwalker]

Wow that's a lot of info. thanks.

You're welcome...

That's just the basics...

Later! OL JR

 

[luke strawwalker]

Sure beats the Chinese ad gripe fest.

That's not difficult... LOL Later! OL JR

 

[TopRamen]

Yeah, when I got back into Rocketry I had that problem too, so now couplers are always an Epoxy Job. Generally 5 or 15 Minute stuff, but sometimes I use JB Weld, just to be blasphemous. I like JB Weld on Centering Rings and Chute' Shelves too.:y:

 

[Cl(VII)]

Epoxy for me. Works every time. Also use if for installing motor mounts so as to avoid the "coke bottle" effect of glue shrinkage.

Titebond Molding and Trim will also let you avoid the coke bottle effect as it has negligible shrikage on drying. Like you said, epoxy is great for this too.

The answers in this thread illustrate why my adhesives caddy has 16 different types in it. The right tool for every job...so far.

 

[luke strawwalker]

Yeah, when I got back into Rocketry I had that problem too, so now couplers are always an Epoxy Job. Generally 5 or 15 Minute stuff, but sometimes I use JB Weld, just to be blasphemous. I like JB Weld on Centering Rings and Chute' Shelves too.:y:

JBWeld is just "souped up" epoxy... metal filler added IIRC...

Good stuff... I like it... OL JR

 

[o1d_dude]

JBWeld is just "souped up" epoxy... metal filler added IIRC...

Good stuff... I like it... OL JR

I like it, too.

Slow curing, looks like glass when done.

 

[qquake2k]

Yeah, when I got back into Rocketry I had that problem too, so now couplers are always an Epoxy Job. Generally 5 or 15 Minute stuff, but sometimes I use JB Weld, just to be blasphemous. I like JB Weld on Centering Rings and Chute' Shelves too.:y:

What is a "chute shelf"?

 

[Zebedee]

bulkhead with a hole large enough for ejection pressure but small enough that the chute sits on top of it and does not fall through?

 

[qquake2k]

Like the baffle plates in my zipperless designs?

https://www.rocketryforum.com/showt...scratcher-Unguided-Mayhem&p=320138#post320138

https://www.rocketryforum.com/showt...scratcher-Unguided-Mayhem&p=325643#post325643

 

[luke strawwalker]

bulkhead with a hole large enough for ejection pressure but small enough that the chute sits on top of it and does not fall through?

I think so... basically glue another centering ring just below where you want the chute to ride...

Later! OL JR

 

[K'Tesh]

Like the baffle plates in my zipperless designs?

https://www.rocketryforum.com/showt...scratcher-Unguided-Mayhem&p=320138#post320138

https://www.rocketryforum.com/showt...scratcher-Unguided-Mayhem&p=325643#post325643

bulkhead with a hole large enough for ejection pressure but small enough that the chute sits on top of it and does not fall through?

Yup!

They have the added benefit of keeping the laundry higher in the rocket. Thus it can't fall down inside the body tube and possibly prevent the deployment because parachute couldn't pull out of the tube.

 

[Rex R]

also keeps the chute etc. from moving the cg aft and thus reducing the need for nose weight. not to mention providing an anchor point for the shock cord .
Rex