Scaling up production and working with resin

As part of our STFC funding we made 20 kits of galaxy models.  Early on we realized that 3D printing all the galaxies would take over 20 weeks of non-stop printing, so we started looking into ways of mass producing our galaxies.

To help with this process we partnered with Ted Turnbull who is part of the University of Portsmouth’s Faculty of Creative and Cultural Industries (CCI) and works with the Eldon Production Centre (EPC).  After some testing we settled upon making silicone moulds and use those to cast our final models in clear resin.

Making the masters

This process starts with making high quality “master” models for each of our galaxies.  This was done using a CNC milling machine and high density foam.

four galaxy models milled out of high density foam
CNC milled masters made out of high density foam

Making the moulds

Next 3D printed name plates were attached to each of the masters and a silicone mould was made for each galaxy.

M51 u-band galaxy master with the 3D printed name plate attached.
M51 u-band galaxy master with the 3D printed name plate attached.
17 silicone moulds used to cast our galaxy models
Silicone moulds used to cast our galaxy models.

Before poring the resin each of the moulds needed to be clamped closed.

The silicone moulds after they have been clamped closed
The silicone moulds after they have been clamped closed

Poring the resin

Clear resin was pored into each of the moulds using a paper funnel.

Silicone mould with a paper funnel sticking out of the top
A paper funnel is used to pour the resin into each mould.

After the resin has set (about 10 hours) the models can be taken out of the moulds and the pour spouts are cut off with a band saw.

Clear resin cast of NGC4305 in the i-band
Resin cast of NGC4305 in the i-band
The resin cast of M100 in front of a band saw blade
The pour spouts are cut off with a band saw

Sanding the edges

The edges were sanded down using a belt sander.  This removed any imperfections along the sides.

A clear resin model in front of a belt sander
Sanding down the edges

Filling in any air bubbles

Wood filler was used to fill in any air bubbles along the edges.  After it dried the filler was hand sanded to a smooth finish.

The top edge of M88's model after wood filler was used to fill in air bubbles
Wood filler applied to the top edge

Attaching the images to the back and painting the edges

After the filler was sanded the black and white galaxy images were attached to the back.  This was done with two-sided adhesive sheets that were placed between the image and the model.  Finally black acrylic paint applied to all the edges. This paint acts to both cover up the filler and to seal the edges of the attached image in so they do not peal off.

The back side of NGC5257's model after the original images has been attached to the back
After attaching the image and painting the edges

Improving the image embedding process

After casting the first few kits we started embedding the galaxy images directly inside the resin models.  This was done by placing the galaxy images inside the moulds before pouring the resin. To ensure the image stays in the correct place a 3D printed plastic frame holds the image directly in the middle of the model.

The silicone mould for M61 being held open. Inside the mould is the black and white galaxy image and a plastic frame holding the image in place.
Embedding the images directly in the models

As with the clear models the edges are filled, sanded, and panted.

A model of NGC5257 with the galaxy image embedded inside the resin. The edges of the model have been panted black.
Panting the edges

The final model

When finished our galaxy models are ready to be packed into a kit.

The finished resin model for M109
The finished model
A full set of 20 galaxy models inside a wooden box
A full set of galaxies
A stack of 20 wooden boxes containing all the resin cast tactile galaxies
All the 400 galaxies packed inside their boxes

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