Hi,

I am hinging my F-86 ducted fan Sabre. I am using Robart hinges. To get the hinge line as small as possible, I have planned to notch out the control surfaces. I have seen somewhere a method of using a hardwood block square, cutting the notch in the hardwood, cutting out the same block size in the control surface, and glueing the block in then drilling the hole in the notched block of hardwood.

First - do I have the process correct?

Secondly, what type of hardwood is good to use (one I assume that is easy to shape to the shape of the control surface)?

Also, is a wood glue prefable to use to glue the hardwood in as opposed to Hysol 9462 (BVM Aeropoxy)?

Anything else I need to know?

Thanks in advance.

Tim

My first question is... Is this an ARF or did you build it yourself?

If it is an ARF, do they call for Robart hinges? If not, you may be doing yourself more harm than good.

Hi MinnFlyer,

No it is a kit. The instructions called for Robart hinge points (see picture below) for the ailerons and the sig hinges for the flaps. As I hadn't had any experience with sig hinges, I was going to use hinge points.

What is a better method?

Tim

when i notch for robarts , i either use a really fine file, or an xacto blade...............what kit is it

i highly reccommend you use Elmer's Ulitmate, or Gorilla Glue, they are both got polyurethane glues that expand... from my experience i find the Elmer's Ultimate easier to wipe clean when it foams up

Hi MetallicaJunkie

The kit is the Trim Air F-86 Sabre. Do you use the hardwood inserts?
Tim

The only problem with using Robart hinges where they are not called for is that there may not be enough wood for them to grab on to.

In the illustration below, you can see how a standard hinge has plenty of hold while the Robart doesn't

Yup. I had wanted to use some Hinge Points this weekend, but there just wasn't enough structure to make them secure.

I could have taken the covering off of the ARF and added some balsa blocks, but that's not worth the effort to me.

Another critical thing about "hinge points" is that the hinge pin must be mounted parallel with the hinge line.

Also the mount area must be recessed to some extend to make room for the actual hinge pin in order to minimize the hinge gap

The Trim Sabre has plenty of structure on the TE, but is balsa. So given that, should I use CA hinges, or continue using Robart. This is a very large kit, and the TE has a large block of balsa for the hinges to go into. Also, if I go the Robart hinge point route, do I need to use the hardwood block method to notch the control surfaces (these do not have plenty of structure, just foam with balsa skins and fibreglass covering).

Tim

If it has a foam wing you can use the robarts and no hardwood block is needed

Thanks MinnFlyer, w8ye, Miket, and MetallicaJunkie for all your help. Very much appreciated.

Tim

As I'm building I just add some balsa blocks at the TE where the hinge points are going , not hard wood. I went back to using Pacer Hinge Glue unless my holes are over sized from test fitting and start to wobble, then I use Gorilla glue so it will expand and give a tight fit.

Thanks Gray Beard. That is an idea I will have a think about. I will see how well the hinges line up and fit before I make the decision.

Tim

I have a wing on the bench right now that gets full sheeting, I couldn't make up my mind where I was going to install them so I just added the extra wood into each wing bay and did the sheeting. Now I will be hearing about all those extra grams I just added.

A tiny drop of salad oil (soybean, wesson etc) at the pin in the hinge helps prevent gluing the hinge solid..I think everyone has done that at least once this type of hinge requires a little extra care to be sure the hinge is aligned properly to prevent binding.

You can assure alignment by rotating the hinge close to 90 degrees at insertion into the first side to check that the hinge line is parallel with the surface