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/)Aligning and Gluing Robart Hinge Points in any Control Surface

Note that much of what is presented here applies to flat hinges as well.

I always use slow-drying epoxy for hinges.  Others have told me they have had good success with Pacer Hinge Glue although I have never used it.

  • Pour a small amount of alcohol in a small container and soak the hinges in it to remove any surface oils from the plastic.

  • Mix up some slow-drying epoxy.  Do not use 5-minute epoxy or CA.  You will not have time to make sure everything is right before the glue sets up.  It is better to have too much epoxy mixed than too little.

  • Never thin epoxy!  When the solvents evaporate the glue will shrink.  There is also the risk that the solvents will become trapped in the cured glue which will leave it rubbery and weak for a long time.  Thinned epoxy also tends to turn brittle as it hardens.

  • I mix the glue in a one-ounce disposable measuring cup and then set it in a pan of warm water to reduce the viscosity.

  • It will be easier to drop the epoxy in the hinge holes if the surface is held vertically between a couple paint cans or something similar with the hinge holes or slots facing up.  You can hold the epoxy pot in one hand and the toothpick in the other.  Use a toothpick to drop epoxy into each hinge hole.  Go from hole to hole repeatedly until you've put several drops of epoxy in each hole.

  • You do not need to push the epoxy into the hole - it will flow in on its own if you have warmed it.  Just move on to the next hole and when you've put a drop in each one, go back to the first and repeat the process as many times as necessary to get plenty of glue in the hole.

  • Do not put glue directly on the hinge.  If you do this the glue will be smeared off the hinge when it is inserted.  The glue ends up in the hinge pin area and also ends up between the control and fixed surfaces.  Just put the glue in the hole or slot and all will be well.

The hinges are not actually being glued in place in the following sequence.  I cover and finish the model before gluing hinges in.

Caution! Do not attempt to glue hinges into both a control surface and the fixed surface in the same operation doing so almost guarantees misaligned hinges.

When the hinges are in one surface and then inserted into the other surface, there is no way you can control how much the hinges shift in the first surface.

Instead, glue the hinges into the control surface and let the epoxy cure.  Now glue the hinges into the mating surface.

 
 
When gluing in hinge points, glue them in the control surface first.  Do not push them in all the way. Slowly push the hinges in.  If glue starts to ooze from the hole then back the hinge out slightly and use a paper towel to carefully remove the glue without getting any on the hinge pin.  Leave about 1/8" of the hinge to be inserted as shown here.

It is not a bad idea to coat the hinge pin area with Vaseline.  Do not let any Vaseline get on the hinge body!

Ensure the hinges hang perpendicular to the hinge line. Set the control surface on a surface so that the hinges hang over the edge.  Make sure they hang perpendicular to the leading edge.

A small triangle will confirm that the hinges hang true.

Press the leading edge of the control surface down on a flat surface to ensure the hinge pivots are aligned perfectly.

With a piece of waxed paper on a flat surface, push the control surface down until the leading edge of the surface is on the table.  Check that the hinges still hang perpendicular to the control surface.

The hinges are now aligned perfectly.  Set the component aside to cure and move on to the next one.

Caution!  Do not move the hinge to ensure there is no glue in it.  This is how glue gets worked into the hinge in the first place.  The hinge will pop loose when you flex the hinge after the epoxy has cured assuming the hinge pin area is not totally immersed in glue.

You should be able to put hinges in two or three components with one batch of epoxy.  Do not start hinging a new surface if the epoxy has started to thicken.  It will take too long for the epoxy to flow into the hole which means you will not get enough epoxy in the hole and a poor bond will result.  Normally I glue on the rudder and elevator with one batch of epoxy and the ailerons with another batch.

 
 

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Hinge Point Sandwich Technique
Make Monokote Hinges for Flying Model Aircraft

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Copyright 2002 Paul K. Johnson