Fuel proofing and hinges
 

Couple of questions.

1. I just fuel proofed my firewall and fuel compartment. I just used a brush to brush on 30 min epoxy. Is that a good way to do it?

2. I am getting ready to glue my hinges. Do I need to drill the holes in the middle? and How do you get just 6 drops of ca on them with out getting more than you need or getting it all over?


Any input would be very helpful. Thanks.




john

RE: Fuel proofing and hinges
 

I am still a newbee, The epoxy fuel proof is the way I have fuel proofed my repairs, seems to work, No clue on the hinges as I have never done that yet! Good to see a fellow northerner on here! Looks like monday is going to be a great day to fly!!!( at least in NW south dakota) These guys will fix you up with all the right answers for sure!

RE: Fuel proofing and hinges
 

next time you fuel proof cut the epoxy 50/50 with alcohol...goes on easier with less weight.....
as far as the CA hinges...I've never used them...they're ok.... I've always used the flat nylons or the round Robarts

RE: Fuel proofing and hinges
 

When installing CA hinges, I use an old Xacto blade, touch the point to the hinge, and put the drops on the flat part of the blade. They run down into the hinge just fine. I feel I have better control of the glue that way.

The alcohol you want for thinning is not isopropyl, it has too much water in it - read the label and you will see. Use the paint thinner alcohol, up to 50% t o thin with. I use balsarite to seal with. There are 2 types, one for fabric, and one for film. I use the one for film, since that is what my planes are covered with.

RE: Fuel proofing and hinges
 

Probably too late now, but if you use straight epoxy to fuel proof, you can hit it with a heat gun (AFTER it has been applied) and it will get very thin and smooth itself out. It will also cause it to set up quickly, which is why you want to heat it afterward.

For CA hinges, drilling the hole is not essential, but until you really know CA hinges, it's a good precaution to make sure it wicks in far enough. If your hinges are the type with a slot cut out of the center, the hole is not necessary.

Please read this, it has a lot of important info on CA hinges:

[link=http://www.rcuniverse.com/magazine/article_display.cfm?article_id=55]Installing CA Hinges[/link]

RE: Fuel proofing and hinges
 

tips on using ca hinges are to draw a center line on the ca hinge in crayon on both side, this will keep the ca from setting on the hinge line itself so that it does not become to hard. this step is not really necessary but it does reduce the amount that the hinge will get brittle. the second tip is to stick a pin in the hinge on the center line so that when you push the hinges into the pieces to be hinged you don't over press them into one side

RE: Fuel proofing and hinges
 

Actually, drawing a line with a crayon is a really bad idea. It serves no purpose whatsoever and can actually be detrimental to the hinge.

RE: Fuel proofing and hinges
 

Minn I just checked my CA and was wondering how you tell if it is still good or not. On the link you gave it said to make sure it hasnt gotten thick with age. It still seems to look like it did so should i be safe with it?



john

RE: Fuel proofing and hinges
 

Shake the bottle. If it wiggles around like water, you should be ok. But if it clings to the bottle at all, like a light oil, you can still use it for building, but I wouldn't trust it for hinges.

Think about this:

The CA MUST wick into the hinge fibers and into the balsa fibers. Picture dripping 4 or 5 drops of water on a napkin. The water will wick its way out from where you dripped it. But if you dripped pancake syrup instead of water, it may wick a little, but nearly as much.

It's worth the price of a bottle of new Thin CA to be safe.

RE: Fuel proofing and hinges
 

AND read this post.

http://www.rcuniverse.com/forum/m_84...tm.htm#8423993

The whole thing. Some good information there about CA hinges.

CGr

RE: Fuel proofing and hinges
 

Thanks again guys. I will probably just wait till i get another bottle of CA, to be safe, since I wont be getting my raidio for another month Im in no hurry. Ill just have to start my next plane I guess.:D



john

RE: Fuel proofing and hinges
 

Isopropyl comes up to 91% pure from a drug store and $1 will get you enough for 50 models. That's what I use. 100% alcohol is a lab grade product and almost impossible to keep that way as all alcohol is hydroscopic and will pull water from the air.

Stove and solvent alcohol are also about 92% to 94%, the other 6% being water. It's bound up and dissipates as the alcohol evaporates out of the epoxy and isn't really a problem. The balsa itself has a moisture content of about 6 to 7%. :)

RE: Fuel proofing and hinges
 

Charlie,

Some pharmacies do carry 99% alcohol. You just have to search for them and get lucky! It's about twice the cost of 70% at a local independant pharmacy near me.

Jack

RE: Fuel proofing and hinges
 

I guess you would have to look around, I usually only see the 71% stuff, and they do put down water as the other ingredient.

RE: Fuel proofing and hinges
 

The bottom line is...

If you're only using it for fuel-proofing, it really doesn't matter if there is water in it.

I have used 70% Isopropyl many times to thin epoxy for fuel-proofing and there is absolutely no problem doing it.

It DOES make the epoxy a little weaker, but you don't need strength for fuel-proofing.

RE: Fuel proofing and hinges
 

If you plan to build another model........ or more models............

Go get some Epoxy Finishing Resin. It's good for a number of special tasks. Tasks that you'll need to do in the future. And that the stuff does better.

It's already thin. So it works great for firewalls. And it doesn't setup within a minute or two after you quit with the heatgun when you try to thin to brushing consistency. So it both brushes and penetrates naturally and without any extra time or effort on your part.

It's also very good at repairing cowls. Clean on the inside. Paint it on and place some glasscloth into it. Or just about any cloth. You can even make sections of cowl with it and some fiberous paper (like target paper). Replace missing cowl, etc.

It's kewl to be as cheap as you can be when doing anything. That is, if you actually benefit from the cheap without losing quality . But it's not really required for modeling, especially if you want your work to be worth the time you took to do it.

RE: Fuel proofing and hinges
 

Is this correct! I install these little ca hinges in the wing and the aleron after
I made the slits and drilled a 1/16 " hole in the center of each slit.
now I tilt the aleron and drip ca thin into the holes in the elevator and wing,
then do I need to turn the wing over and do this again? how do I stop
the aleron from being glued to then wing what happens if I use to much ca.
Is it easer just to go to my local hobbie shop and buy better hinges.

RE: Fuel proofing and hinges
 

wzak, I hope you covered the wing before you hinged it. If not, it will be a challenge to cover.

Please read this:

[link=http://www.rcuniverse.com/magazine/article_display.cfm?article_id=55]Installing CA Hinges[/link]

RE: Fuel proofing and hinges
 

I have not coverd anything or hinged anything, I will cover the plane before I install the hing.
Just starting on the wing today still very concerned abou those hinges this is my first kit and
I am putting a lot of work and time in it don't want some cheap hing to mess it up.

RE: Fuel proofing and hinges
 

Those hinges will work just great as long as you install them properly.

The Thin CA will "wick" into them - Think of the wick in an oil lamp. You dip the wick into the oil and the oil defies gravity and climbs up the wick. CA Hinges work on the same principle.

When you apply a few drops of CA to the hinge, it will wick into the hinge and the hinge slot. You want to work quickly, but carefully - there's no need to rush. Just apply 5 drops to each hinge, then flip it over and apply 5 drops to the other side of each hinge.

Now, occasionally, you may get some glue that will travel along the gap between the aileron and the wing (Or the elevator and stab, etc ) This is no cause for alarm. You can just blow it out. If it spills onto the other side, it will wipe off with Acetone (or nail polish remover which usually contains acetone) and it won't hurt the covering.

RE: Fuel proofing and hinges
 

5 drops to each side of the hing then turn it over and apaly 5 drops to each side again for a total of 20 drops to each hing.

RE: Fuel proofing and hinges
 

No...

5 drops to each hinge on the bottom, then 5 drops to each hinge on the top.

So if you have 4 hinges, you put 5 drops on each one (5 drops per hinge x 4 hinges)

Then flip it over and repeat.

So EACH HINGE will get a total of 10 drops. Five on each side.

RE: Fuel proofing and hinges
 

Well i finally decided to go ahead and do my hinges and now i wonder what i was worried about it really wasnt that difficult. Specially with all the great info out there for doing them.



john

RE: Fuel proofing and hinges
 

Good for you John. About the alcohol. I really like the 1 gallon cans of Denatured Alcohol from the paint store, Home Depot, of Lowes for this hobby. I use it all the time and keep a small bottle close at hand on my build table. Use paper towels and precut them into approximately 2" squares and keep the stack of squares and small alcohol bottle handy to clean up your fingers when glue gets on them, your covering when using epoxy on your planes, etc. Its a great degreaser and I wipe down the surface of any covering with it prior to applying decals or trim or wipe out the hinge gap before ironing a strip of monokote in to seal it. I picked up the tip on cutting the paper towels up on the web somewhere; possibly here. Its been one of the best I've received. A small bottle of clear nailpolish is handy to keep things stuck down or seal up nicks and scratches.

If you'll find a sharpening steel or croc sticks you can really extend the useful life of those exacto blades. Some of the best glue clamps you'll ever use are the same #64 rubberbands some use to hold the wings to the fuselage. So keep an eye out for everyday household items that can be used towards your new pasttime.

Regards,

Clay

RE: Fuel proofing and hinges
 

After gluing the ca hinges should I pin the edges together so there is no gap?