kregan

I finally got started on my Sig Somthin Extra!!

The last Kit I built was about 10 years ago and I used to use
Robart Pin hinges... http://www.robart.com/Hinge.aspx
#307 or #309. I have never used a CA hinge and I am
a little leery of them. Am I way off base?

Thanks for the help

touch and go

My Feedback: (11)

If you do a search here on RCU you will find many posters who will not use them and many who swear by them. I've used them many times without any problem; proper installation is very important. I think when you get into the larger planes as a general rule its best to go with a hinging system other than CA hinges, such as Robart hinge points. For good instructions on how to install CA hinges, look at any Great Planes assembly manual for any plane which uses CA hinges. You can find them online at GP's website. Good luck.

ekrcflyer

Advent:

So far I had no issues with CA hinges. I guess the trick is to do it right, meaning - the slot(s) are tight enough, you have a hole drilled in the middle of the slot (this helps CA to wick the hinge evenly) and (MOST IMPORTANT) USE THIN CA ONLY!!!

There are number of other suggestions you can find here on RCU, but to be brief I'd say "use them with no fear").

CafeenMan

I don't use them so I can't speak from personal experience. What I can say is that 99% of the time that you hear about hinge failures, it's a CA hinge. No other type of hinge ever made has the failure rate of CA hinges which is why I don't plan to ever find out about them firsthand. It is possible to learn from others.

Scar

My Feedback: (3)

The only hinges I've ever had fail were Robarts. I had two shatter like glass on a Meister Corsair rudder. Drilled out the remains and installed two new ones with epoxy, which are still working now after many flights.

Never ever had a CA hinge fail. I have seen evidence of improper installation in failed CA hinge documentation. Usually they neglect to get CA wicked into each of the 4 contact surfaces. Some actually break the Tyvek cloth, by setting up the joint with zero gap between the control surface and the stationary surface - and then apply lots of travel, which stresses the cloth each time the control surface goes to extreme travel.

Looks to me like the common failure mode for CA hinges is breakage due to improper installation, while the common problem mode for any other hinge is binding - which doesn't necessarily break the hinge. People who try CA hinges can install them without much technique, no binding, and only have to make sure they drip CA into 4 locations per hinge, with the control surface deflected to its extreme position (away from the side being CA'd.)

If you're comfortable with Robarts, by all means use them.

Best wishes,
Dave Olson

flipstart

I have used CA hinges without any failures on 40-46 size planes-but I did have some GP CA hinges delaminate when I was checking them prior to assembly. I since only use Radio South Giant Scale hinges and they seem to be thicker and really suck up the CA-just use the suggestions mentioned above and they should work fine. On larger planes- I only use the Robart style hinge. With their drill guide the Robarts are easy to install.

I was recently flying a combat plane with RS CA hinges, got "shot down" and about all that was left was the engine, part of fuselage, and stab with elevator still intact. Rest was left hanging in a pine tree, did not get to inspect those parts. Flipstart

MinnFlyer

My Feedback: (4)

I have two planes that are each over than 10 years old with CA hinges. No prob.

But installing them correctly IS important.

Read this "How To" for a simple explaination of how it's done:

http://www.rcuniverse.com/magazine/a...?article_id=55

cknaack

My Feedback: (1)

Advent,

As you can see, opinions vary. As for me, I limit the use of CA hinges to smaller (<=.40 size) aircraft, and have not had any failures (Knock on wood)
If you read the article that was linked by MinnFlyer, you will notice that there is a reference to using a crayon in the area that will do the flexing. It does in fact protect the hinge material form the CA. The reason this is done is that CA is essentially liquid Acrylic. Although Acrylic is tough, it is also brittle. During the initial flex/CA application process, the unprotected hinge material fibers (which are typically a woven material or a laminate of woven material and Nylon film) becomes filled with CA. No harm, no foul............so far. When the surface is flexed back the other way, the familiar snap occurs. This is the CA and some of the hinge fibers breaking, somewhat weakening the hinge. [:@]This is where the crayon comes in. The wax does not allow the CA to penetrate the hinge material.

IMO, if you are looking for a bit of extra throw on the Somthin Extra, or are looking for a hinged surface with little or no resistance, you may want to consider hinge points or pinned type flat hinges that are offered by companies like DuBro.

P-40LUVR

Yep,used many CA hinges without a failure,I use the crayon method also!

kregan

Thanks for the help everyone,
I willthink about it and decide in a few days.

FlyerBry

My Feedback: (8)

If it helps your decision any my experience may apply to the plane you are building. I have had two CA hinge failures. Both were on the hinge at the end of the wing (both ends failed at different times) on a Hangar 9 Twist. This plane is flown with extreme throws and the roll rate is very high. The hinges lasted quite a while but with the pounding I put the Twist through they both eventually failed and were repaired. The Somethin Extra you are building is a similar style plane so you may keep this in mind when making your decision. If you don't push the plane too hard the CA hinges will probably be fine but be sure to keep an eye on them just in case!

kregan

I decided to use Robart hinges....

They have never failed me, my stick is 10 years old, and I
have the drill guide to install them.

I also decided to build the rudder stock on the Somthin Extra,
however I will be adding the Robart hinge sockets to the rudder
so I can remove it and replace it with a larger one if I need to.

And a pull pull system on the rudder.


Thanks again for all the help,