Prototypes and rejects from the 3d printer. All part of the design process for my robot:
I spent all day at hacman Tuesday and Wednesday printing and tweaking robot parts. I put it all together when I got home. This is the front, the lifter arm has holes to allow me to screw in different attachments, I’ve still not designed that part of the robot yet:
Here is the back view, you can see the lifter arm gear housing (the curved structure) and the motor that drives it, also the battery (underneath the ball hopper)
The lifter arm gear system looking through where the hopper would be:
I need to design an attachment for the end of the lifter arm. Here I’ve created a simple one using meccano. It’s too heavy, the bolts catch on the floor and it dumps the ping-pong balls short of the hopper. Other than that it’s perfect. You can see the camera with capped lens that I’ve just wedged into the structure temporarily:
Next-up: better lifter attachment design, a couple of re-prints with tweaks and some software.
Today I printed out and glued together the first iteration of the ping-pong ball hopper that takes up most of the space of the robot.
The assembled hopper:
Full of ping-pong balls, I can get 12-14 in without packing them manually. That seems like enough for now, but a larger hopper would be good.
Mounted on the robot. You can see the completed camera mount and Raspberry Pi mounted on the side in the foreground:
The reverse angle:
I needed to re-design the motor mounts on the robot base, they didn’t hold the motors securely enough and tended to shift around.
The new mounts are better fitting and include a small wedge that fits between one of the gearbox plates where there are no cogs.
One of the great things about 3d printing is being able to pull out part of a design and iterate over in isolation, then when you’re done incorporate it back into your main design.
I’ve re-designed a prototype robot mount in OpenSCAD as Sketchup wasn’t up to the job. It took a while, you have to program the model in a text editor so there’s lots of trial and error. Will have to wait to print it to see if this design will work.
I’ve made some improvements over the original design, most notably thicker side walls and motor mounts, more accurate measurements and added the cross-pieces with a Raspberry Pi mount.
Here’s the original Sketchup design for comparison:
Sketchup was great, really easy to use, the only problem was that it seemed to create invalid model files.