THE CASE OF THE STAR ADVENTURER

By Federico Arribas and José Luis Martín

Ever since we bought the Sky-Watcher Star Adventurer star tracker we have been thinking of getting a case to carry it. For that purpose we embarked in a search for the best suitable case: should it be soft or hard surface?, plastic or metal?, wheels or no wheels?, how big or small?

After careful considerations, which included the possibility of taking it abroad frequently, we decided we should find the smallest possible hard case to fit all the necessary parts in. We visited several online sources and encountered a diversity of options, most of which were too big, too expensive, too flimsy or too risky a buy without "feeling" it.

Our SA didn't come in that box with the reusable silhouette pre-cut foam packaging we see in unboxing videos like the first one below, but instead came in this other packaging with individual cardboard boxes for each component. So, if we were to use foam filling, we'd have to buy a case with pre-cut foam, like this one, buy the pre-cut foam apart, like this one, or make it ourselves.

Foam packaging

Cardboard boxes packaging

Another thing we thought of was that the case should be tall enough to provide cushion on the top and at the bottom, not only on the sides and between parts.

After looking in local stores, we found this case wich seemed too good to be true.

Brand: LAKOT

BRICOR sale for €14.95

The external measurements of the case were 335 x 260 x 160 mm, small and tall enough for our requirements. But we wanted to be sure, so we cut paper silhouettes of each component and tested if they fitted on a mockup suitcase (a paper rectangle with the inner measurements). They did. Then we repeated the process on the real thing in the store. Everything checked, so we bought it.

Inner case paper mock up

CASE STUDY

The case came with its own pre-cut foam in cubes of roughly 15 x 15 mm, and you had to remove the cubes all the way through because it was only one piece of foam 75 mm thick. 

To create each piece's silhouette you have to "round up" the shape to squares the closest possible. Since we are talking about rather small pieces, it meas sometimes you exceed the measurements needed, allowing some lateral movement. But you can disregard this in most cases. But although the diced cubes system can provide fair lateral stability, it can not prevent tilting. 

Tilted

Straight

In other words, the section of each component varies with height, lenght and width, so the silhouette (or horizontal projection) aproximation is not good enough to provide stability all around. For that you would need vertical dicing also to create the necesary levels or steps to provide support throughout the consecutive sections. To achive that implied buying several thinner diced sheets to stack, and it would become an expensive project.

But the main problem with the provided diced foam was not shaping, it was density. When we made our first attempt and diced out the main shapes, we tried carrying the case with the components in place, and the results were disastrous. They moved and got scrambled inside because the foam was not firm enough to keep them in place, and it got smashed by the weight of the motor, counterweight, dovetail and wedge. We needed a denser foam. 

We killed two birds with one stone by buying three 20 mm and one 30 mm plancks of 24 kg/m3 polyurethane (light blue) to fill the 90 mm hight of the bottom half of the suitcase, and one 20 mm planck for the lid, cut to the exact size. This way we could cutout each layer to meet the section of each piece at a given height while providing a firm material to withstand the weight of the components.

DIY