Hinges

[David Davis]

Last week I was visited by a club colleague who is building his first balsa aircraft from a kit; the kit is a classic French trainer, the Baron.

http://www.envergure-modelisme.fr/avions/456-baron-1914.html

He had brought the fin and rudder. I was to show him how to slot the fin and rudder to take the hinges, when it occurred to me that I have nearly always covered the flying surfaces before cutting the slots for the hinges. This means that there are bits of balsa swanning around inside the wing or tailplane of the model. Not perhaps best practice but my models seem to fly!

What do you do?

[Robert Welford]

Cut the slots first.

[Richard Wood]

For solid sheet surfaces & veneered foam wings - after covering. Before covering
for built up surfaces - for the reason you mention!

[Peter Miller]

After covering. I add blocks of scrap balsa behind the members of the surfece (usually the wing and the blade does not go right through. No bits of balsa come off.

[Former Member]

[This posting has been removed]

[Andy Green]

I hinge first, and trial fit any control surface - that way any sanding can be done to make sure the fit is good.

I agree with Tom you have to remember where the slots are, I do this by keeping the hinges in the moving part whilst I cover the other, I then have a reference, and move the hinge to the newly covered part as a reference for the surface.

Just re read that and it sounds complicated, but its not really.

Andy.

PS have you seen my hinging article from a few years back?

[Martin Harris - Moderator]

For a tight fitting hinge line, conventional hinges need their pin housings to be recessed so finding the slots should be easy after covering, which I prefer to do along with when I'm using pin hinges, whose holes are easy to locate. I tend to slot for mylar type (I only use "furry" ones) after covering.

Edited By Martin Harris on 31/10/2016 14:08:49

[Broken Prop]

I'm with Andy. The slots for mylar hinges can normally be found without too much of a problem.

[ChrisB]

Cut the slots then cover and use split pin hinges and epoxy and use dress makers/florist/craft pins for pinning.

[Hamish]

In the past I have had great difficultly digging out a mylar hinge. Is there any need to pin them?

[trebor]

The last hinges I used were Kavan flat type, I found you can fit them before covering and pop the hinge pins out to separate items when covering. Once covered slot together and pop the pins back in, has anyone else done this ? It worked ok for me.

[Martin Harris - Moderator]

Posted by Hamish on 01/11/2016 09:04:58:
In the past I have had great difficultly digging out a mylar hinge. Is there any need to pin them?

I'd say it depends on the model. Small lightweight ones should be fine without pinning but on anything with some weight/speed I would (if using mylar) pin them. Don't underestimate the power of aerodynamic flutter, especially on larger/faster models.

Whatever you do, you must check that the hinges are glued correctly - and check before pinning if you do so. Our club operates a policy of checking of all new models and as one of those nominated to do the checks, I've seen many mylar hinged control surfaces come away with a gentle pull - even on models built by experienced modellers!

[Martin Harris - Moderator]

Posted by trebor on 01/11/2016 11:02:45:

The last hinges I used were Kavan flat type, I found you can fit them before covering and pop the hinge pins out to separate items when covering. Once covered slot together and pop the pins back in, has anyone else done this ? It worked ok for me.

Some hinges of this type are supplied with separate pins so if they are the same type with L shaped pins designed to lock into the wood then there's not likely to be a problem removing/reassembling them. The only consideration is how you intend locking the pins in place?

[will -0]

It's very important to hinge before covering

 

Otherwise you can't pre-assemble the thing before covering and desk fly it.

 

 

On a more serious note  - any issues with the hinging arrangement are best found before covering rather than after.

Edited By will -0 on 01/11/2016 11:50:31

[Martin Harris - Moderator]

...and even more to the point (although where would a build be without those desk-flying sessions!?) check for any unexpected complications.

[John F]

Posted by Martin Harris on 01/11/2016 11:17:13:

Posted by Hamish on 01/11/2016 09:04:58:
In the past I have had great difficultly digging out a mylar hinge. Is there any need to pin them?

I'd say it depends on the model. Small lightweight ones should be fine without pinning but on anything with some weight/speed I would (if using mylar) pin them. Don't underestimate the power of aerodynamic flutter, especially on larger/faster models.

Whatever you do, you must check that the hinges are glued correctly - and check before pinning if you do so. Our club operates a policy of checking of all new models and as one of those nominated to do the checks, I've seen many mylar hinged control surfaces come away with a gentle pull - even on models built by experienced modellers!

If you use the fluffy mylar hinges and cyano that risk is gone. Ever since I saw this vid I've used this and have never had a hinge fail, nor managed to prise one apart for re-covering either! 

Edited By John F on 05/11/2016 06:23:04

Edited By John F on 05/11/2016 06:23:59

[Hamish]

Thanks John, it's the fluffy hinges I have used and in the odd occasion I had to replace found them hard to dig which prompted my question about pinning.