Hi all,
I am installing my control surfaces and have solid circular CA hinges. I read a few posts on CA installs and am confused about the slot drilling. Should I drill a 3/32 hole in the trailing edge of the wing, in the middle of the slot where the hinge will go or somewhere else? Any help would be appreciated, Thanks.

Every install of CA hinges I have done ( my tiger 2 kit, a GP cherokee and now the Big Stik 60 arf) say to drill that hole right in the middle of the hinge slot. I assumed it was to help the CA get into the entire hinge. I would really like to hear why this is done. I always dutifully drilled the hole as directed.

This is exactly what the hole is for. I've always done it in all my installs?? Is it necessary?? Maybe, maybe not. But that's the way that I learned to do it, and I've never had a CA hinge fail on me. So that's what I do when I install CA hinges.

Ken

to answer you exactly, yes drill the hole directly in the center of the hinge slots I used this http://www3.towerhobbies.com/cgi-bin...&I=LXL466&P=ML instead of a power drill. balsa makes me nervous LOL

Another question that goes along with this, should I cut a small portion of the covering away from the area where the hinges are to be installed?

I wouldn't, inside the slot is the actual glue surface.

Thank You so much for your help.

use good thin Ca, 3 drops each side(top and bottom),NO acellerator,flex and lit sit overnight.
Really I'd toos the round ones and get some name brand ones that are rectangle,you need the surface area for holding power.

[link=http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXE229&P=0]hinge slotter[/link] if you don't have one these they are worth their weight in gold

Minnflyer has a very good how-to on installing CA hinges. Take a bit and read through it.

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

Ken

Also, make sure the hinges are installed before applying the glue.
I new a fellow who was putting the glue on the hinge and then trying to put it into the slot.\
It didn't work.

I like to put a straight pin right in the middle of the hinge.
This makes sure you have equal amounts of hinge on both sides of the gap.
Additionally, the width of the pin is going to make sure the surfaces don't bind
and it isn't so wide that it will cause flutter.

Good Luck,
KW_Counter

Eventually, you may want to get these neat tools:


I use these all the time, as you may have noticed already that many pre-slotted parts are too tight, too short, in the wrong place or add some extra slots. I refuse to dig and gouge at the slot with a slitting knife so here’s the ultimate tool:
http://www.greatplanes.com/accys/gpmr4010.html
Get some spare blades for it, practice on a piece of scrap balsa.
Don’t force it or get the blades hot, let it cool.

This guide works OK too:
http://www.greathobbies.com/producti...od_id=GPMR4013



This is optional, but I like to use this saw with a Dremel tool and router attachment to get the slot started perfectly instead of the above guide. This is mandatory if you need to replace a blown CA hinge in the same spot as before. Keep the speed as low as you can.
http://www.hobbylinc.com/htm/gyr/gyr8211015.htm

http://www.hobbylinc.com/htm/dre/dre565.htm

Ok, here's the deal:

Do you NEED to drill the hole? Maybe, maybe not.

Do you NEED to remove a small amount of covering around the slot? Maybe, maybe not.

The only way to tell for sure if you need to do these things is when you have enough experience with CA Hinges to know whether to do them or not.

Doing either of them will certainly not hurt anything, so when in doubt - Do it!

Read the article that RCKen posted above. It will show you exactly how they should be installed.

None of my instructions included remove the covering, I did not know that it was recommended until Ken posted the link. Follow Minnflyer's advice he has likely forgotten more about RC airplane building then I will ever know.. I will remove the covering in the future myself.

QUESTION...NONE of my CA installs have the covering removed around the slot. I can not budge any of my control surfaces without breaking something, BUT is it something I should worry about ???

You need not worry about it. If your hinges won't budge, they are good to go.

The whole idea here is to get the CA to "Wick" into the slot. The deeper it goes, the better the bond.

Technically, the Thin CA SHOULD easily wick into the fiberous surface of the hinge, which will carry it into the slot (Even if the covering is not cut away). But if the CA is old and has thickened even slightly, it may need a little help getting in there. So by drilling a hole and removing the covering, it creates a channel for the CA to ride in and spread out sideways.

Probably the most important things about installing CA hinges are:

1) Flex the surface BEFORE adding the glue (And then do not close the gap again)

2) Use only fresh, THIN CA for good penetration

3/32” (.093) is a bigger hole than I would make. The CA hinge is only .012 to .015” thick so a hole 1/16”(.062) is all you realy need.


Mike, That's a very good link. Most of the time the push pins serves as a good gap spacer too.
I like to put my reading glasses on and watch the wicking action as I add CA. Depending on how porous the wood is, usually at 4 drops it slows and this is the time to stop because a bead or fillet of CA at the joint can make the hinge brittle. I keep a corner of paper towel handy to QUIKLY dab out the excess. This is rarely needed.

I've been removing a small strip of MonoKote on either side of my hinges on my last few planes. It's kind of pain, but with a sharp #11 you kind of get a rhythm going and it doesn't have to be perfect. One thing I notice is that by removing that small amount of MonoKote, when I add the CA, it doesn't create a lip right at the hinge line and therefore makes for better flexibility.

I must say thanks to everyone who has responded. This is the best resource for people new to the hobby.