I was surprised to find a lack of mounting brackets in the OpenBuilds catalog for mounting stepper motors to the side of a frame (see image below for example: source). This seems like it would be a relatively common thing for people to need to do. Is there a reason this is not present in the store? I'm new to building 3D printers, so maybe there's a reason these should not be used that I'm not aware of?
There’s generally not much call for having the shaft centered that far off the extrusion. If you look through the standard ACTUATOR | OpenBuilds designs the motor axis is generally held fairly close to the extrusion. Not that there aren’t exceptions, just not enough to make stocking the additional parts financially viable.
And being a modular system, we tend to rather have two parts that can be put together to make one part, so you can use both on their own too: So, for example, Motor Mount Plate - NEMA 17 Stepper Motor or Threaded Rod Plate - NEMA 23 Stepper Motor and Black Angle Corner Connector effectively achieves the same, as does just threading the ends of an extrusion and using the same plate, without the corner brackets. Another option is to side-mount it using Tee nuts into the V-Slot. Very flexible - and then we can also use both parts in many many different other configurations too. Makes it worthwhile. Designing around our modular parts we can design pretty much anything - without needing specific parts. Once you move from a modular system to kits that can only be used in one specific configuration - then custom parts with bends in specific places that affects the spacing of the leadscrew/belt in a way that means you also need a custom carriage etc - becomes more viable. The mount in your example is unusable with our other stock parts - as the offset would not match the spacing of our leadnuts / carriages / belt paths running on the rails