I’m an electronics fabricator but am new to robotics and so don’t quite know what my options are. Were I to mount these brackets to an aluminum plate, I would have to drill the plate by hand. I read one user’s experience with mecanum wheels who reported that alignment was critical, and so am worried that even careful hand drilling isn’t accurate enough. Maybe there is a technique a more experienced builder can share? I’m also wondering if the 3 bracket mounting holes match an off-the-shelf structural part, e.g. something from Actobotics? Or if there is another sturdy motor mount that is available within some other structural parts standard? Thanks in advance for your experience!
The holes on the machined aluminum bracket for 37D mm metal gearmotors are not designed specifically to match any particular hole pattern, and we do not know of any off-the-shelf structural parts that match. Our main recommendation is to use a center punch to mark your hole locations so that you can get the holes drilled accurately. If you have access to a drill press, that would help.
Hey, I just wanted to report back on my experience with this in case it’s helpful to someone else. A friend of mine suggested this solution, which worked out great. First, build or buy an L-shaped jig that could be clamped to a drill press table. I just used a carpenter’s square. That keeps the piece you’re drilling in alignment. Next, make 2 spacer blocks, approx 15mm wide, to insert between the piece you’re drilling and one leg of the jig, which will move it 15mm in one direction (the mounting holes on this particular bracket are 14.8mm apart). I used a piece of scrap wood to which I glued a thin piece of vinyl to bring it’s thickness up to 15mm. With the piece pressed firmly against the jig with no spacers, line up the first hole, clamp the jig to the drill press table, and drill. Add a block and drill the second hole. Add the second block next to the first block and drill the third hole. Result: 3 holes, 15mm (or so) apart, in a straight line.
Also, my initial impression is that mecanum wheel alignment isn’t super critical in the scheme of things. The wheels aren’t very accurate to begin with, and the modest accuracy they have depends on the surface they’re rolling on. On top of that, any differences in motor calibration can also throw off your results. So while it’s nice to get wheel alignment perfect, it’s just one factor among several.