Glue / Adhesive

[AKPilot]

Am I off base here, if gluing plastic to plastic do you use epoxy? What about plastic to wood - Aileens?

Your ideas are appreciated. Just am tired of feeling guilty when a kit says to use "model glue".

 

[m85476585]

Model glue probably means plastic cement. If this is an Estes kit and it is plastic to plastic, use CA glue (some kinds work better than others). If it is plastic to wood, you can try CA, but plastic cement might be better. If you really want to make it strong and don't mind the weight, you can use some epoxy for wood to plastic.

 

[adrian]

I'd have thought it's the other way round - use plastic cement to glue plastic to other plastic, use CA or epoxy to glue plastic to wood.

Plastic to plastic is what plastic cement is designed for - it's not very good for anything else. Tube type plastic cement will just about glue plastic to other things, although I wouldn't trust it in a rocket. Bottle type plastic cement relies on melting the two plastics, then the joint solidifies into a single piece; it will have little effect on anything other than plastic. Tube type plastic cement also melts the plastic, so watch out you don't apply too much or it will damage the plastic part.

For building non-flying plastic kits, I use plastic cement. For building flying rockets, I use CA, epoxy and wood glue.

 

[jflis]

For plastic to plastic, you can't get a much stronger bond than plastic cement as you are actually welding the plastics together. One problem that many have is when they do such gluing and the joint stays soft and flexible. That is usually because too much cement was used and it hasn't vented all of the solvents. This can take a while if too much is used (days or more some times)

Plastic cement is useless for plastic to (anything else) as no welding can take place. CA is *ok*, but I only use it for tacking in place as it is too brittle for me (but the rubberized type sounds interesting). I would then follow with epoxy filets

fwiw
jim

 

[AKPilot]

Thanks guys, this was along my same lines of thinking. I just feel guilty, for some reason, when I use model glue/cement on plastic to plastic.

Oh well, I guess I'll see how some of my X-prize's hold up . . . .

 

[m85476585]

Actually, what I use is "all purpose adhesive". It doesn't really work on Estes plastic, but it is a kind of tube-type plastic cement. CA is the strongest thing I have tried for plastic-to-plastic, but since it doesn't fill gaps, it doesn't wok as well on porous surfaces sometimes (like wood). Maybe I should get some thick CA.

The all purpose adhesive in my Spaceshipone failed (I think it melted - It also failed in my Thunderstar the same day, plastic-to-plastic.). It was a plastic-to-cardboard joint. I repaired it with Epoxy and it is fine now. (except that it weighs just over the max recommended liftoff weight for a C6, but it is still stable.)

 

[adrian]

For my SpaceShip One, I used epoxy to glue the motor mount into the tail cone, after roughing up the inside surface of the cone with coarse sandpaper. The tail cone is glued to the body tube with PVA. It survived my attempts to pull it apart, and then it survived both of its flights so far. I haven't weighed it, but with the recommended double nose weight and a heavy paint job, it's one of my heaviest C powered models. That didn't stop it from going straight up on a C6-3. Given the paint job and the nose weight, I don't think the epoxy has made significant difference to its weight.

 

[Micromeister]

Originally posted by akpilot
Am I off base here, if gluing plastic to plastic do you use epoxy? What about plastic to wood - Aileens?

Your ideas are appreciated. Just am tired of feeling guilty when a kit says to use "model glue".

AK:
It totally depends on the type of plastic being cemented. Glues generally refer to organic matter. cements and adhesives are more inorganic chemically formed materials typically matched to the substrate they are intended to join.
Polystyrene, especially polystyrene that has been drawn very thin by vacuum forming (like the SSO boattail are very succeptable to any agressive adhesive. for most molded pieces where it's not a structural joint 5 mnimte epoxy is probly the best choice as it's generated curing heat usually doesn't bother the thin styrene.
Tube type "plastic cement" can be very destructive to these thin drawn plastics as the solvent chemically softens the styrene (to the point of destroying the part. Liquid (Testors) plastic cement and MC (Methylene Chloride) and MEK are the main ingredents in both liquid and tube type cements. MC flashes off much quicker but is still very agressive and must be used carefully.
It's important to determine what kind of plastic your working with before attempting to join it to what ever.
Usually Estes kits that have hard plastic parts are another form of styrene, forumlated for use with tube type cements which (Solvent Weld) these materials to themselves, like your everyday Plastic model kit. but these same type cements which are ment to soften these plastics and remain soft for days can ruin your kit with thin molded parts. Nearly All Plastic kit craftsmen use MC for must joints with a small amount of CA for tack ups and some gap or detail filling repairing. CA as about the same sanding characteristics as rigid styrene plastic
Hope this helps.

 

[maxpower]

I have the blue kind. The stuff that smells like citrus. It doesn't hold the plastic pieces together at all. The first time I used it was on a little Freaky Flyer. It never cured. I ended up using epoxy. I tried it again on my Thunderstar and let it sit overnight. This morning, the pieces pull apart easily. Do I have bad tube of glue? Is the non-toxic citrus kind not good?

Thanks

 

[Stymye]

I've had fair results with testor's liquid cement
the tube stuff hasn't worked well for me mainly
Testors "rocket cement"

Micro made a comment that many get confused including myself

Products made from natural materials are generally considered "glues"( hyde glue, some wood glues)
products made from chemicals(cya,epoxy,plastic cement) are generally considered "adhesives"

not important to the thread but clears up the terminology

 

[sandman]

I have "EXCELLENT" results using the Testor's liquid solvent cement on Estes plastic parts.

Here is my technique;

Test fit all the parts ahead of time to verify a perfect fit!

First, carefully apply the cement to both parts seperately only where the two parts will meet...then let them sit apart for a few minutes (3 or 4 minutes). This lets the solvent "melt" the plastic on the surface a bit.

Then apply another dose of the liquid to the same area and carefully, press the parts together and hold for one full minute!

For clamshell halves I use masking tape but be carefull! Make sure the solvent doesn't travel under the masking tape!!

The bond that I get is unbelievably strong!. The plastic is WELDED together.

I have built two Super Nova Payloader and the first one even suvived an F21-8 CATO.

Unfortunately when the second F21-8 motor worked like it was supposed to...Well, let's just say the rocket..."went away"! Never to be seen again!