CA hinges installation - and CA talk

Thu Feb 27 08:49:12 AKST 2003

One little trick that some of us have been using for a long time is to
put the hinges in 90 degrees from what we view as normal.
The long axis of the hinge material should run parallel to the hinge
line. In most cases you are inserting a 1/2 X 3/4 hinge into 2 pieces of
1/4 inch balsa. If you put the hinge in the "conventional way" you will
have 1/8 inch hanging out in the foam, if you turn it the other way, all
of the hinge will be in contact with the balsa, and you will have a 3/4
inch hinge instead of a 1/2 inch.

Terry T.

On Thu, 27 Feb 2003 08:17:12 -0500 Ron Lockhart <ronlock at comcast.net>
writes:
> Ive been using various brand CA hinges, and
> various brands of CA, and had no problems
> with any of them.   Agree, the CA doesn't seem
> to migrate past the wood edges into the foam.
> I don't use crayon or anything else in the hinge
> joint.  I don't use a hinge machine to cut
> slots - even the thin blades make a wider slot
> than I like.  I hand slot with an exacto, and 
> force the CA hinges in.  It's a bit pesky.  
> I use about 4 to 5 hinges on each elevator, and 
> about 5 to 7 hinges on each aileron.  That may
> be a few extra, but CA hinges are light, and
> easy to install.
> 
> As someone pointed out a few days ago, it is
> important to NOT apply a second layer of CA to
> a hinge joint.
> 
> Later, Ron Lockhart
> 
> 
> 
> ----- Original Message -----
> From: Keith Black <tkeithb at attbi.com>
> Date: Thursday, February 27, 2003 3:44 am
> Subject: Re: CA hinges installation - and CA talk
> 
> > Re: CA hinges installationI have some questions regarding the foam 
> 
> > friendly CA. 
> > 
> > Is it as thin and as strong as the regular stuff? 
> > If so why isn't all CA made to be foam friendly? It would seem to 
> 
> > me that if the chemistry of the CA is changed such that it didn't 
> 
> > damage foam then it is reasonable to assume that other properties 
> 
> > may differ as well. In other words, what does one "give up" by 
> > using the foam friendly stuff?
> > 
> > Without knowing this I'd be very concerned about using it rather 
> > than the regular stuff. 
> > 
> > Personally I'd think with just a few drops on the hinge there 
> > wouldn't be enough foam damage to make a difference anyways. Think 
> 
> > about it, people honeycomb their wings. What's the big deal if a 
> > wee bit of foam is eaten away? One argument may be that the 
> > trailing edge and control surfaces aren't honeycombed and foam 
> > lost in these areas is more critical. Well I have a hard time 
> > buying that. 
> > 
> > BTW, after writing the above paragraph I experimented with this 
> > several times using a Radio City 1/4" scale hinge going through 
> > 1/4" balsa into foam attached to the back side of the balsa. The 
> > CA never did any damage to the foam and seemed to be absorbed 
> > completely by the balsa. Of course, I didn't use the "Slot 
> > Machine" to make the slots, I used a #11 blade. With wider slots 
> > the CA may make it's way to the foam more easily.  
> > 
> > One thing I've noticed that all thin CA's are not created equal. 
> > Therefore I would think the quality of the hinge may be effected 
> > by type of CA one uses. For example, it's been my observation that 
> 
> > the Bob Smith Industries stuff (that every hobby shop puts their 
> > own name on) doesn't soak in nearly as well as Zap CA. (If Bob 
> > Smith is on this forum my sincere apologies for singling you out 
> :-
> > ) ).
> > 
> > And while I'm on a roll here. I've heard the crayon idea many 
> > times before, and quite frankly it never made sense to me. My 
> > first thought was that hinges are absorbent enough to wick the CA 
> 
> > down into the hinge slot, so why would crayon on the "outside" of 
> 
> > the hinge prevent the CA from wicking right through the middle of 
> 
> > the hinge? Well, I did some tests with the Radio City hinges and 
> > found that the hinge itself really isn't absorbent, not without 
> > contacting balsa anyways. You can drip CA right on these hinges 
> > and it will just puddle in droplets and not soak in. But touch a 
> > piece of balsa to it and SLURP, the CA spreads through the wood 
> > and across the surface of the hinge and bonds instantly. It 
> > appears that the balsa actually absorbs the CA and the surface of 
> 
> > the hinge provides a superb bonding surface. Probably due to its 
> > texture (the chemist among us could probably explain, Gray, you 
> > there?).
> > So, in trying to prove that CA would soak under the crayon I found 
> 
> > that what really happens (on these hinges anyway) is that it 
> > doesn't soak in at all, at least not deep into the hinge fabric. 
> > As to the crayon I marked a hinge with a heavy crayon line on both 
> 
> > sides and applied drops of CA and as stated it pooled not only on 
> 
> > the crayoned portion, but on the non-crayoned portion. Therefore, 
> 
> > my theory was incorrect, but I still am unsure that the crayon 
> > would do any good. If you ended up with excess CA caked on the 
> > hinge gap and you had a crayon line there then you'd just have CA 
> 
> > caked over the crayon line (I tested this and it does bond to the 
> 
> > crayon line).  
> > 
> > I'd be interested in hearing other's experiences with different 
> > types of CA and opinions/suggestions about CA hinges.
> > 
> > Keith Black
> > 
> >  ----- Original Message ----- 
> >  From: Bill Carpenter 
> >  To: discussion at nsrca.org 
> >  Sent: Monday, February 10, 2003 11:13 PM
> >  Subject: Re: CA hinges installation
> > 
> > 
> >  Another suggestion FWIW, if you have a foam wing core under the 
> > balsa sheeting and glued to the trailing edge, use foam friendly 
> > CA.  It will not eat the foam if it gets in that deep.  Also, some 
> 
> > people either drill a hole in the center of the slot to allow CA 
> > to go deeper into the slot at the center, or some CA hinges come 
> > with a slot in the middle of them to allow CA to go in the slot 
> > deeper.  
> > 
> >  Bill 3544
> > 
> >  ----------
> >  From: "Chris Larson" <csmulti at volcano.net>
> >  To: <discussion at nsrca.org>
> >  Subject: Re: CA hinges installation
> >  Date: Mon, Feb 10, 2003, 9:59 PM
> > 
> > 
> > 
> >    Xavier-
> >    I have used a crayon from my sons toy box, sharpened, and 
> > drawn along the hinge line.  This not only serves as an alignment 
> 
> > point, but also as a release agent for the glue.  I guess I should 
> 
> > also note I haven't used that method on most of my planes ( just 
> > wicked in CA at the hinge line, let dry, and flex vigorously back 
> 
> > and forth ) with great results too.  You shouldn't worry too much 
> 
> > about making the hinge stiff - just be sure you are using THIN 
> > CA!! :-)
> >    Chris Larson
> >    NSRCA 3484
> > 
> >      ----- Original Message ----- 
> >      From: Anne & Xavier <')" >xavier.mouraux at sympatico.ca>  
> >      To: discussion at nsrca.org <')" >discussion at nsrca.org>  
> >      Sent: Monday, February 10, 2003 7:56 PM
> >      Subject: CA hinges installation
> > 
> >      Hi guys,
> >       
> >      I am about to install the CA hinges (fiberglass) on two of 
> > my winter projects and I would appreciate any recommandations on 
> > the proper procedure to do it. I have the tight slots done. I am 
> > worrying about the glue making the hinge stiff. How do I ensure 
> > the glue doesn't go in the flexing area ?
> >       
> >      Note that these are 2 sport planes that I am using to 
> > improve my building skills before moving on to pattern plane 
> > building next year. I have been flying second hand pattern 
> planes.
> >       
> >      Thanks
> >       
> >      Xavier
> > 
> > 
> > 
> 
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