I created an enclosure for the ATtiny85-based Roomba virtual wall prototype board using FreeCAD.
A couple of design goals:
- The LED is positioned about 7cm from ground level.
- The 3 x AA battery holder is 3D-printed, completed by battery clips salvaged from old toys (or readily available online).
- The parts are designed to print with as little support as possible, and attached together using superglue and screws.
I printed the parts using 0.8mm nozzle to save time, so they look a little rough. It takes about 7 hours to print all the parts on my Creality Ender 3.
Nine M2.5 screws are required, one for the battery cover, eight for holding the body together. Superglue can be used for the latter, but I like the option to easily take the body apart for repair.
Here is the battery box with battery clips inserted:
JST male connector wire soldered at the back:
Mounting clips attached with superglue. When working with superglue, move the parts in position and hold down with pressure for 60 seconds. A small grip clamp is useful for this, otherwise just apply pressure with your fingers. The pressure is very important in order to create a strong bond.
Insert the main body and secure with four M2.5 screws.
Attach mounting clips for top cover:
Attached prototype board with hot glue. Superglue could be used, but hot glue is easier to remove if I ever needed to detach the prototype board:
Prepare the top cover by pushing in the insert:
Attach top cover to body with four M2.5 screws:
The all white body is a little bland, so I made it more noticeable by covering the joints with some 3M electrical tape:
I found the IR LED has a (half) angle of projection of about 30°:
This means having to offset the virtual wall by about 20cm from where you want the actual boundary to be.
I know the angle of projection is a function of the IR LED, and parts with narrower projection angles are available. But I was wondering if this could be improved by encasing the LED in some sort of cover, so I printed one:
In case you are wondering, it didn't help. But it broke the monotonous outline of the blockish looking unit and made it visually more pleasing (at least to my eyes), so I decided to keep it.
I also tried fitting pieces of straw over the LED, but it didn't help too. Maybe it's because the material of the straw is translucent and does not block enough of the emitted IR.
See it in operation:
I have uploaded the FreeCAD schematic to the Github repository.