Brainpad AR-1 processing

Once your Microbit controller has been 3D printed (see CAM page for more information) it is time to start post-processing the model. There are several steps of manufacture to follow. See below for details:

Step 1 - Snip away the supports (goggles must be worn)

Goggles must be worn when snipping.

Always snip to cut and never lever, twist or pull parts off as this will create pressure on other sections and will crack the plastic.

Snip section by section.

Supports will need to be removed carefully.

Some supports removed. More careful snipping needs to be carried out.

Most supports removed inside

All suports removed from both halves of the casing - ready for the next step.

step 2 - Use wet and dry paper

To make your model outer surface smooth you will need to use wet and dry paper. The goal is to achieve a high quality of finish so that when you start step 4, your primer spray paint will have a good surface without imperfections or marks on it.

There are different grades of wet and dry paper

Start with a low number and work your way through the grades

The lower the number, the rougher the paper

Carry out quality control checks to ensure you achieve a high quality finish.

step 3 - prepare the model for spray painting

After sanding and filing the surface of your model, you will need to rinse or wash it to remove any dust. Paint will not stick well to the surface if it is covered in dust and will flake off easily.

Prepare a clean and dry, dust free surface.

Dry carefully with a tissue.

Wooden dip stick holders may help you steady the model when spraying or hydrodipping. Ask you teacher if this is suitable for your model. Thinner models should avoid this step.

step 4 - primer spray paint

Prime your model with a thin dusting of primer paint. This creates a layer that adheres to the plastic surface and allows paint or hydrodrip film to adhere to it.

Hydrodipping or spray painting directly onto the plastic will not give the best results beacause the film or paint will not adhere to the plastic well.

Spraying to close or for too long will create drips, dribbles and lumpy paint. You must spray softly and light from a distance. Give short bursts of spray or a dusty as you move the can across the model.

Primer paint can come in different colours and does not make a different to outcome. Common colours are, white, grey, black or burnt red.

step 5 - base colour spray paint

Hydrodip film comes in a variety of patterns and apperances. Some have colour however, fundamentally, hydrodip film is clear. Therefore the appearance of the film relies on choosing a suitable base colour to make the hydrodip film finish look good. An example would be choosing a black base colour for a carbon fibre hydrodip or a brown base colour for a wood pattern hydrodip.

Building up very thin layers of paint by dusting over the model will offer the most success.

Make sure you use the fume cupboard with the extraction turned on to draw out the paint fumes.

step 6 - hydrodip

Hydrodipping involves floating a pattern film (Hydrodip film) on top of water. The film is then sprayed with a chemical substance called activation spray which reacts with the film. Once the reaction has taken place we can push the model through the film to add the pattern onto the surface. The part should be rinsed under running water immediately and then left to dry.

Watch the video to see the process.