Kleine Lüfter / small ship mounted air vents

Dear fellow modellers,

I have posted this thread to share my experience with building small ship mounted vents.
These are the type of vents that include two parts: a tube and an intake.

The construction method I present is a mix of tips I took from the forum and the experience and skills I developed while building the large number of vents for the Kaiser Wilhelm der Grosse model.

I have chosen to write in English to make this thread widely available. Apart from that I think the pictures are largely self explanatory.

Cut the parts on the inside of the line such that the edges of the parts are free from black color.
This is particularly important for the two edges of the tube that later join to form the tube and for the rear curve of the intake part. On all other edges it is a matter of taste I guess.

For cutting the two joining edges of the tube slightly tilt the blade inwards to obtain a wedge shaped cut. This will result in a join without a gap when the tube is curved into shape.

The jagged top edge of the tube part is not a problem as this will be cut to shape later.

Seal the edges of the parts with diluted white glue to prevent delamination of the card material.

Moisten the part on the rear. Do not soak as this will lead to surface damage when the part is formed into shape.

Start curving the part by pressing and rolling it with a rod (I used the rear end of a paint brush) in the palm of your hand. After the part has received this initial curve complete the job by applying the same technique on a smaller scale with a needle and your fingertip.
Continue until the join is evenly closed and there is no tension left in the material.

Leave the tube to dry and firm up.

Apply a drop of diluted while glue to the inside of the tube and spread it through the gap.
The glue should be diluted far enough (without losing its adhesive capability) to allow the gap to act as a capillary and soak in the glue.

Gently press to close the gap. The diluted glue weakens the edges of the tube. To prevent these edges from bulging outwards hold them in place with a flat object (I used the rear end of a pair of pincers).
Hold until the glue has set .

Less is more here. A minimal amount of glue will have least impact on edge firmness and minimise glue setting time and with that minimise the time force needs to applied to the tube.

Curve the intake with a needle on your fingertip. I do not moisten this part as it delaminates very easily when moist. It also does not need moistening as, being long and narrow, it curves very easily.

The edges need not join evenly after shaping. I have tried this but the prolonged pressure I had to apply lead to surface damage.

The edges are made to join with two pairs of pincers.
There will be some tension left in the material when the edges are joined so the white glue applied here will have to be a little bit heavier.

The tube and intake do not match.

I want to build it as close to the assembly instruction as possible (although I suspect this assembly drawing allows for two parts to occupy the same space at the same time).

Some additional part shaping is required.

With a used razor blade two cuts are applied to the top of the tube.

Judging the position and the angle of these cuts requires some practice and even then it remains difficult to get it right all the time with parts this size......

A third cut is applied to shave off (no pun intended :D) some material from the top of the tube in order to obtain a smooth edge to the arc shaped top of the tube.

Generously apply white glue to the top of the tube and push the intake part in place.

The glue softens up the card material and makes it easier to push it into shape. The (excess) white glue dries transparently

Shape the intake part such that the rear opening is covered by the arc shaped top of the tube (now is the time to find out whether the tube was shaped correctly...).

Please bear in mind that these are macro pictures.....

Close observation shows that the arc shaped top of the tube might have been a little bit larger and that the white glue has left a bit of a rim where tube and intake join. This can be prevented by applying white glue that is a bit more fluid.

At the bottom the intake is not quite circle shaped yet. Nothing a gentle squeeze with a pair of pincers wont solve....

Applying paint is a good idea for the inside of the intake (acrylic).
For the join on the outside it is a matter of taste I guess. A perfect join is possible, it would not require any additional paint.

Paint will cover up any imperfections but also leaves a bit of a rim at the join. I use gouache here as this type of paint provides the best cover. It is very susceptible to damage though so I always protect it with a cover of diluted white glue.

Thats it. I trust it will be useful.

Kind regards,

Bruno