Covering
It is important to test film covering on testing part before you start. Covering of 3D printed parts is a
bit special because of thermal expansion of plastics. When heating up the plastics it expands a bit.
Covering is then actually done on slightly enlarged wing and when the wing is cooling down it
shrinks back. But the covering foil does not and that causes wrinkles.
That is why some covering materials work better than other. Some are very stretchy and have the
capacity to shrink down even more together with the printed wing as it is cooling down and
shrinking and some do not.
I tested couple of brands and in my opinion Solarfilm Lite is the best option for 3D printed planes
from Kraga. Unfortunately the company Solarfilm stopped production, so this material is very hard
to get. Other good options (which I did not test myself) should be AeroLITE rolls and Coverite 21st
Century Microlite.
If you cannot get one of the above mentioned covering materials, then in general lightweight
options of covering materials work the best. For example Oralight from Oracover or UltraCote lite.
I strongly advice everybody to use trimming iron instead of standard sized one, because with
trimming iron you don't heat up the wing that much.
Another very useful tool is covering film adhesive for example Cover grip from Deluxe materials.
When using covering adhesive the foil sticks better and one doesn't have to heat it up that much,
what again prevents expansion of the wing.
Finally the technique is also important, but that comes with practice. Covering video guide can be
found in how to section on KRAGA web page:
https://3dprintedrcplanes.com/how_to/
My recommendation is to cover wings after they are fully assembled (center wing, tip wing and
aileron are glued together). It is a little bit more demanding but it is definitely worth it. Otherwise
you are risking, that when gluing aileron to hinges and hinges to wing tip, glue might leak and
spread all over hinge pin which will block the hinge and aileron would get stuck.
The same is valid for tail covering. Cover it after you glued on the moving part with hinges.