Filler around plastic tail cones and plastic fins ???

[Flash]

Could someone give me a good recommendation on what type of fillers to use around a plastic tail cone with plastic fins after they have been glued to make them look better and hold up?


Thanks!
JAR

 

[Lee Reep]

Squadron putty -- available at your hobby store. Available in green and in white. I've used this for all kinds of repairs, fillets - -wood or plastic. I recommend you buy a box of disposable latex or nitrile gloves. I like to use my finger to smooth the putty, but if you do not use gloves, you'll be using plenty of solvent to clean up. Best not to expose your skin to this kind of abuse -- never know how much gets absorbed!

It sets up fast, and sands really easily.

 

[Zippy]

Bondo Spot Putty in the tube (not the two part Bondo Body Filler) works well on thicker blow molded plastics and it's cheap and available in most hardware stores. Don't use it on vacume form stuff though except in miniscule amounts or it will melt it.

 

[DynaSoar]

Originally posted by Flash
Could someone give me a good recommendation on what type of fillers to use around a plastic tail cone with plastic fins after they have been glued to make them look better and hold up?


Thanks!
JAR

I just picked up some Testor's contour putty, made specifically for plastic joints. I haven't tried it yet.

I've been experimenting with plastic fins, particularly folded styrene with an internal balsa insert at the root, or single ply styrene with external L rails for the root. I've actually been having very good luck with plain Testor's plastic cement, the thick kind in the tube. After initial gluing, I run a very thin fillet, but spread it well out on the fin and body. Then I go back and pour in more to make the fillet rounded. That initial coat protects the plastic from the larger amount of cement (with its thinner). Too much cement on unprotected styrene can make it pucker and wrinkle. The result is very nice, like a poured epoxy fillet used on larger birds. When you put it on thin, it can get bubbles and bumps. This thicker treatment almost always comes out very smooth.

By the way, all this has been on paper bodies so far. The plastic cement takes to paper just as well as plastic. The fillets have been better than I usually get with white or yellow glue and balsa fins.

If you need added strength, try the trick they use on the bigger birds: poke a line of small holes along the line on the body where the fin will go. The glue gets squeezed down into the holes and grips to the inside like a rivet if you put enough glue, or at least provides for more surface area for the glue to grip to. I've been using a push pin (thumbtack with a plastic head, for bulletin boards) for this, using a drilling motion. I put a hole every 1/4 to 1/2 inch. I do it on everything that has an internal engine mount, and on minimum diamater birds as long as it's not in the area the engine will fit. The danger on smaller diameter tubes (with thinner walls) is in pushing too hard and collapsing the tube; that's why the drilling action.

 

[sandman]

I used Testor's Contour putty on my Maxi V-2 waaaaay back in 1978 (I think) the trick I learned was to soften it even more with the Testor's liquid styrene cement. Then it really bonds to the plastic!

After all those years and at leat 30 or 40 flights...not a crack in the plastic fin/body joint!

Honest!

sandman