Wing Rib marking Jig

[Gearup]

I just realized this particular tool and technique was hidden in my Storch build. So here is the section on marking wing ribs using wood glue.

I thought I would try a different method for emulating the rib stitching / taping.

I made a small fixture that essentially allows me to follow a straight and perpendicular line across the wing surfaces. General construction of the fixture is two 1"x 0.5"x 10" rails screwed to a board and spaced apart the width (chord) of the wing plus about .5" extra width. I double side taped a copy of the wing plan to reference the rib spacing on top of one of the rails. I placed the wing in reference to the drawing on some spacer blocks to get the top surface to just below the tops off the rails. Double sided tape is used to secure the spacers and wing together on the base. Small pieces only required. Tape off areas that do not have rib stitching ie: smooth panels.

I mixed a small quantity of water proof wood glue  (Elmers glue, PVA that was on hand). The waterproof glue seams to be a bit better at remaining as a raised line. About 2ml of glue thinned with 0.5 ml of water (few drops); enough that it drips off a toothpick. Now using a small square that spans over the wing and sits on top of the rails, line it up with a small offset from the drawing to allow for the pen width. Dip a ruling pen into the glue and touch off the excess. Now draw the pen along the edge of the square to mark the rib. A ruling pen can be adjusted to get the line width you want. I set it about 1/32" wide. Continue along making rib lines, refilling the tip as needed. Since the square is sitting above the wing surface, there is no risk of smearing the wet glue and you can go over a rib again if needed. When done, peel off the tape and continue to finish the model.....
Please see the attached pictures of a test (using a roughly finished test wing) that I did. It only took about 5 minutes to mark the ribs. Building the fixture took about an hour, but it can be used to make future models.

Tools needed:
Ruling pen
Small square
Simple fixture as described above

Materials:
Double sided tape
PVA type glue thinned with water
Regular masking tape


Update 31 October 2023

I've made some modifications to the jig s improvements.

Also for marking the ribbing on the flight controls, I improved on my marking jig by adding an adjustable hold down for the wing., Only the tips are held down to secure it to a flat bar.

The whole thing is held in position by a thin stick sprung over the wing center section.

[lastvautour]

Good tip.

Lou