Airfield Models - Installing Robart Hinge Points

Install Robart Hinge Points in a Model Airplane

May 03, 2015



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Airfield Models (http://www.airfieldmodels.com/)Install Robart Hinge Points in Sheet Control Surfaces

I use the all-metal Hinge Guide made by Robart which has worked well for me.  The Robart hinge guide is the best of all the hinge guides made.  It has threaded inserts so that it can be used with any size Hinge Point made by Robart.

Unfortunately, hinge guides are not foolproof.  The guide must be held firmly against the surface of the wood that is being drilled and not allowed to shift.  It is best if you have someone hold the guide while you drill.  Use a wheel collar on the drill bit as a depth stop.  The hole in the control surface must be deeper than the hole in the fixed surface to allow the hinge to be inset.

I do not use a power tool to drill for Hinge Points.  Instead I use a Pin Vise which gives me greater control.  A power drill or Moto Tool drills through balsa so fast that mistakes can be made in the blink of an eye.  If the wood is exceptionally hard, then I will sometimes drill the first 1/4" or so with the pin vise to get the hole started in the proper direction and then switch to a Mini Mite to finish it off.

Constantly check the progress of the drill bit by sighting from the top of the control surface to ensure the hole is perpendicular.  Also sight from the end of the surface to ensure the bit is centered in the surface.  The bit can cut through the outside surface if the hole is drilled at an angle.  This is more of a problem with tapered or thin surfaces.

The bit should be backed out frequently to clear wood chips because balsa will clog the bit.  If the bit is clogged it tends to tear balsa wood rather than cut it cleanly.

Place your fingers over the wood where you are drilling so you can feel the bit moving into the wood.  This will alert you if the drill starts moving in a direction that will cause it to break through the surface of the wood.

Tip!  One little trick I like is to sandwich a Hinge Point between the screws that attach the control horn to the control surface.  It works only when the control horn has screws on each side of the horn rather than aligned front to back.  The screws must be spaced at least the diameter of the Hinge Point apart.  I use this technique to sandwich tail wheel wires in the rudder as well.

 
 
Tools used to drill a surface for Robart Hinge Points These are the only tools you need to drill holes for Robart Hinge Points.

I use a Pin Vise to drill the holes because it gives me better control.

Note that the hinge point drill guide made by Robart has interchangeable steel guides.  I don't know if they make one for their 1/2A Hinge Points, but I don't have it.

I used CA to glue a piece of 1/8" brass tubing with a 3/32" inside diameter inside the guide.  I'll soak it in acetone to remove the CA when I'm finished.

Also note that the drill bit is set up such that the holes are the correct depth when the vise contacts the guide.

Drilling 3/32" holes in 1/8" wood is challenging, but possible. This is a 1/8" thick elevator that has 9 hinges.  That means there are 18 holes total that need to be drilled.

Centering 3/32" holes in 1/8" wood is challenging, but possible.  I managed to get all the holes drilled without breaking through.

Always drill practice holes in scrap wood before drilling the actual surfaces.  Different grain woods behave differently so it is important to use the same wood as used for the control surfaces.

Make hinge dummies from appropriate diameter dowel. Make hinge dummies from appropriate diameter dowel.  In this case, round toothpicks are the correct diameter.
The dummies will be used to hold the two parts in alignment while sanding so that the surfaces remain in alignment. The tail surfaces have not been sanded at this point.  The dummies will be used to hold the two parts in alignment while sanding so that the surfaces remain in alignment.
The dummies will be used to hold the two parts in alignment while sanding so that the surfaces remain in alignment. It is very important to mark and drill each hinge location accurately no matter what hinging system is used.
 
 

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How To Install Robart Hinge Points
Use a Drill Press to Install Hinge Points in Stick-Built Surfaces

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Copyright 2002 Paul K. Johnson