So, I have been the proud owner of a galileoscope for about a month now. While I am quite happy with the optical quality (and the price!), the focusing mechanism leaves a bit to be desired. In order to cut costs, the ‘scope focuses (changes the distance between the objective and eyepiece lenses) simply by having a pair of concentric tubes that you manually pull out or push in to focus. While this may be fine for the 25x eyepiece, the additional wobble from having to push or pull the eyepiece tube as well as the imprecise nature of the motion makes using the 50x barlow VERY difficult. So, I spent Sunday night at protospace hacking together a brand new focusing mechanism! Behold my new galileoscope, in all it’s ugly-yet-functional glory:
So, you might be asking: how can I get my hands on this marvel of modern engineering? Well, you can do what I did: scrounge for junk parts and throw it together on a lazy Sunday!
- Polycaprolactate Thermoplastic (AKA Polymorph)
- Yup, that’s all. Lego and Thermoplastic
I’m not going to give an exact step-by-step guide on construction, as I mostly worked with what I had, and so my setup is far from perfect. Essentially, you need these two Lego parts (among others for simply building the structure
Together with a wheel for turning the gear, a rod to attach to the linear gear, and a mounting harness to attach one part to the main body, and another to the eyepiece tube, that pretty much sums up the Lego components you need.
The other component you will require is thermoplastic. This will both bond your two harnesses to the telescopes (PCL bonds well to ABS, which is what Lego and the galileoscope are made of) and keep you Lego from flying apart from the force of pushing the tubes against each other.
So that is pretty much all there is to it it. The gear mechanism pushes the Lego bar, which in turn pushes the eyepiece tube. Easy radial-to-linear force conversion. A few things to be wary of when constructing your focusing mechanism.
- Make sure you mount the harnesses with enough range of motion. You need to be able to push the eyepiece tube fully out, and pull it fully in. This means mounting the eyepiece and body harnesses at the right distances for the length of your bar. It also means you want your eyepiece harness to be as thin and mounted as far back as possible, as it will jam against the body, limiting your focusing range.
- Mount your focuser on the SIDE, not the TOP. I made this mistake, and now I have no use of the galileoscope’s built-in iron sights. Luckily I have a hole in the focuser that I can viewfind with, but your design may not include this.
- The body tube is curved. Make sure you mount the mechanism so that the Lego rod is parallel to the eyepiece tube, NOT the body tube. If the angle between the Lego rod and the eyepiece tube is not 0, then you will be applying perpendicular force to the eyepiece tube, and it may make it impossible to extend the focuser all the way, or possibly even damage your scope.