In the never ending quest for more time imaging and less time setting up, I designed and built the AstroCube imaging computer for use on my 11″ RASA. The AstroCube was a game changer for my imaging time, easily saving me over an hour of setup time each session. However, after 6 months of using it, I begin to think about how to improve the design. One of the main design features for the AstroCube was only having one cable (12v power) coming off the scope. While this made cable management a breeze, it meant that all my components had to ride on the scope which imposed severe wight/size limits. Additionally, one of the features I wanted was a built in screen to monitor the system…which turned out to be even more useful than I had imagined. So much so, that I often used the system without a laptop RDP connection. There were two issues with the AstroCube touch screen. First, it was just too small to use easily. Secondly…and I can’t believe I didn’t think of this ahead of time…with the scope slewed to certain angles, the screen wasn’t visible without a step ladder!
So, about 18 months ago, I started to design a new control computer. For this unit, I decided that I was willing to manage multiple cables coming off the scope which would allow me to build a larger console. I still wanted the unit to be built into the scope/mount assembly so that I could still roll the telescopes out and connect a single 12v power cable to be ready for imaging. Design and construction of the first unit took about 2 months. After using it for 3-4 months, I loved it so much that I built a second one for the 14″ EdgeHD.
I’ve dubbed it the AstroWedge 
The process began by deciding on a location and basic form factor. Based on where I typically sit when preparing an imaging run, it seemed that a unit built into the rear of the tripod would be ideal. So I took some black foam board and mocked up some ideas to see what type of space I had under the tripod and what angle for the face plate was the most comfortable.
Now it was time to begin designing and printing. I do most of my design work in SketchUp and I print using a CR-10s (about a 12″ cube build volume) and a CR-10 s5 (about 20″ cube build volume). The s5 printer has a huge build plate that would define the maximum width for the design. No dimension could exceed 19.8″.
Step one was designing a rough mockup of the lower portion of the shell to validate the fit.
With the basic footprint confirmed, I designed and printed a few jigs to help determine the complex angles involved with the tripod legs. I needed to fit the console perfect into the space and factor in the angle the two legs made with each other and the tilt inward to the head of the tripod.
The next step in the process was to design a basic shell with the correct angles, shape, and interior supports for the USB hub and Compute Stick. I printed this in PLA (easy and cheap) at low resolution (fast) to use as a model to mockup all other components and interior spacing.
Using this PLA shell, I began to layout most of the interior components:
- Intel M5 ComputeStick
- External High Power WiFi (compute stick doesn’t have great reception)
- 100 Watt Fully Isolated DC-DC Converter (without this the ComputeStick sometimes shuts down when the dew heaters cycle or the mount slews)
- Powered USB 3.0 Hub w/charging ports
- Temperature relay (fan control)
- Power Distribution
This mockup helped to refine the final design including power distribution placement, turning the ComputeStick 180o, and the need for 90o adaptors to better rout the WiFi antenna cables.
I next used black foam board and the PLA mockup shell to layout the face and top panels which needed to include:
- Discreet power switches for the Mount, USB Hub, Dew Controller, Camera, Fans, PC, and Aux.
- 4 channel dew control
- PC power regulator
- Power monitor
- 10″ HD touch screen
- 12v power output (Mount, Camera, Unswitched, 3 Aux)
- 4 dew strip outputs
- Dimmer
- USB hub
This also provided an additional chance to confirm the fit on the CGX-L Tripod/Mount.
A few more test prints in PLA to mockup the final interior layout and face panels.
After many tests, mockups, and trial fits, I finalized the design in SketchUp. The final design included internal mounting points for all hardware, LED light boxes to fit under each face plate, and captive screw points for assembly.
Satisfied with the final design, I switched the printers over from PLA to Matter Hackers CarbonX Carbon Fiber reinforced nylon filament. I found I could get amazing results with a filament dryer and a heated enclosed build volume…and printing slowly! The final shell took 84 continous hours to print and used 1.8kg of filament!
With all the parts printed it was time to polish them. You can’t get the same finish with 3D printing that you can with injection molding but I wanted a as close to a glass smooth, hard, shiny surface as I could get. The secret is sanding, and patience, and more sanding! I worked up from 120 grit all the way to 3000 grit wet sanding.
Assembly time!
The first step was to simply install all the external switches, power jacks, and voltage/current monitors.
Next, it was time to install the LED backlighting that would illuminate all the control labels. Using a pack of pre-wired red LEDs, I inserted the LEDs into the printed light boxes and sealed them in using a 3D Pen. Each control label was printed with a rear inset that allowed me to place a piece of white defuse plastic inside before inserting the Lightbox and attaching it to the face plate with the 3D pen. All wires were routed through printed cable management pathways using shrink wrap tubing and the 3D pen.
Next I began to install components into the main shell. The small power regulator/USB hub for the ComputeStick (read more about this important part in my AstroCube computer write up), WiFi adaptor, fans, dew controller, isolated DC-DC supply, ComputeStick, and 12v ground distribution.
The next step was to install the captive nuts that would be used to attach the face plates. The shell has 8 locations designed to hold small nuts. Once the nuts were inserted, I held them into the correct position with the same screws that would be used on the face plates. Then I filled the holes with the 3D pen to seal and hold the nuts in the correct alignment. I then removed the screws.
Finally, it was time to wire up all the components. I used a Dymo Rhino 4200 label printer that can print on heat-shrink tubing to label all the wires. All the wiring used BNTECHGO Silicon insulated wire which is insanely flexible. The inside of the Wedge is tight and traditional rubber insulated wire is to stiff to route. Even the heaviest gauge wire used in this project is as flexible as cotton string. Small transistors were also added to each switch backlight to allow the same dimmer circuit to control the brightness of those LEDs as well without any back-feed from the switch’s main circuit.
The top face plate was then attached using the captive screws
The final step before closing the face plates was to install the 10″ touch screen into the front face plate and secure with a 3D printed bracket and connect it to power (shared with the ComputeStick), USB (for touch), and the HDMI output from the ComputeStick.
The final AstroWedge assembly
Installing the AstroWedge onto the telescope is very easy. Simply place the unit between the spreader plate and head of the tripod and lock it onto the spreader center rod with two T-shaped locking brackets. Then hook up the USB and 12v connections.
Here’s a short video of the dimmer function.
The final product made quick driveway imaging so easy. In fact, it was so successful that I built a second AstroWedge so both imaging rigs would have one!
The only feature not pictured was the attachment of two thin neodymium magnets inside the front face plate just about the monitor. These internal magnets allow me to use small external magnets to hold a red film in place over the monitor when I use them at a light controlled dark site.
