Hinge Line Options

Guys, looking for best policy with regards to installing Robart pin hinges. In the image you will see that the hinge is fully inserted but the pin head is still proud of the bevel edge due to the swivels size larger than the hole. With the control surface located on the fin the gap is still about 5mm. In my mind I would open up the top of the hole on both to allow the pin to be level with the edges. This is the same issue with all the control surfaces, aileron, elevator on this kit. But how to, without tearing up the covering?

When I've used these I've had to use a drill bit ( used by hand) big enough to allow the hinge point to recess such that the hinge point center is in line with center line of the control surface.
I've heard that some people use a counter sink bit to achieve the same result. Make sure you dip the hingey bit of the hinge point in vaseline if your'e fixing with epoxy. There is a robart Youtube covering the detail,I'll hunt it out if you need it

How hard is the wood making the surfaces and the trailing edges? If it's soft enough, just push hard and the gain will expand to accommodate the wider part of the hinge. Make sure the hole is the right depth (at least as long as the hinge) because you'll be pushing in vain otherwise.

If the wood is hard use a tapered grinding tool in your dremel.

And like Alan says, put a little vaseline on the pivot AND put vaseline on the leading edge on the surface and trailing edge of the wing/tail/fin. Use 5-minute epoxy (for the brave) and 10-15 minutes for the wimps. Glue all the hinges into the control surface first and DO NOT try to clean off any splooged epoxy. When it goes rubbery, you can simply peel it off and it leaves a clean pivot. If you try to remove the epoxy when it's still runny, you will tend to push it into the pivot. When all the hinges are in the control surface it's time to glue it to the wing. Again, DO NOT try to remove any epoxy until it goes rubbery. Final tip...use a blunt tool to pick out the rubbery epoxy, not a sharp knife. Something like the tip of a bradawl to poke into the rubbery exopy and pull it out in one go.

Mike

Interesting Mike, There seems to be two methods here:

Glue both surfaces in one go ( my favourite)
or
Glue one surface, leave till set and then glue to the opposing surface ( the robart way)

Whats the consensus chaps and why?

As Alan said, you need to open up the hole at the top. More than one way to do this, I usually just use a sharp blade. However you do it though, as the model is already covered make sure that you cut away the film first so it doesn't snag when you open the hole up.

Also you must make sure you lubricate the knuckle as Alan said. It is also best to install them all to one side first, make sure they are lined up correctly then let the glue set before bringing the 2 parts together, this ensures that the hinge line is straight or you will end up with a stiff hinge.

edit. Was typing that while Mike was posting, clearly I am on the side of one surface at a time, trying to do it all in one go is a big risk and is likely to end in tears!!

I'm a one side at a time man too. I first use a narrow scalpel blade to make the round hole square which helps the hinge push right in without the wood swelling in the area of the hinge which is very unsightly. Inserting the hinge with the free end turned down to check that it is at right angles to the control surface makes it easier to ensure that the hinge pins all line up and avoids any stiffness in the finished article which will be outcome if they are out of line.

When you have finished preparing the holes, if they pass through the edges of the covering film, you could run around the periphery with a soldering iron (before full heat) to seal the film and prevent tears /separation. If you adopt Mikes method it will prevent surplus epoxy seeping under any overlap on the film

I glueone side at a time too - but I always install the moving surface (unglued) and work the hinge before the glue sets. This allows for fine alignment of the hinge centres, otherwise even a tiny misalignment ends up in a warping or sticky control surface.

Trust me to be different :silly: , I have always used 30 minute epoxy and done both sides at the same time, line the hinges up by eye to ensure they are square and the flex the surface to ensure you have full deflection. Have plenty of paper towels ready for cleaning up and a little bit of white spirit on a cloth cleans off any excess epoxy

Thanks to you all for your input. I'll use a combination of most of your suggestions and also follow Kevin's idea of a soldering iron tip to re-glue the film into the hole a little.