How do I mount motors and gearboxes to a PCB? I've seen one photo of a pcb with mounting hardware drilled directly into it, but I don't know where to find this type of hardware. This is my first 'from scratch' robot project and I know NOTHING about how to construct a frame. Ideally, I would like an aluminum or other metal frame ~4"x4"; enough to hold a microcontroller and a few sensors and sturdy enough to last through many projects. How do you experienced builders handle bases for small projects like this?
Under most circumstances, mounting larger hardware items to circuit boards is not a good practice. For small robots, it can work as long as the mechanical loads are not enough to flex or stress the board much. Most mounting devices are as simple as right angle brackets. Many can be found in hardware stores, usually intended as mounting for shelving or other devices. Use your imagination with small fasteners. Hobby shops and surplus stores are excellent places to look for mounting hardware. For small motors with small loads, you can often use conduit clamps or Adel clamps. A pair of Adel clamps along the body of a cylinder shaped motor can provide a nice, firm mount that is easy to adjust.
Well, you will find yourself having to learn a little metal forming to get what you want cheaply. I often buy flat aluminum stock and use a simple vise with some angle iron in the jaws to allow me to form and bend the aluminum into complex shapes. Using the bare vise jaws will "eat" the aluminum. Covering them with steel angle will create a smooth, non-marring jaw for holding your aluminum. A hammer and a little patience can allow you to create really nice right angle brackets, frame pieces, or circuit card mounting devices. Have a look at my page and you might get a few ideas from looking at some of the robots I have built. I have to admit that I do machine a lot of pieces on a mill, but I also create quite a few pieces using nothing more than vise, hammer, some pounding blocks, and a few of those low-temperature aluminum "welding" rods. Alumalloy is pretty easy to get and allows you to weld (actually braze) aluminum together with a propane bottle torch, so with a little practice you can create some really nice pieces from bare aluminum stock.
I'll second Chip's idea for using a vise and angle iron for metal forming. By adding a little leverage, you can form fairly thick stock for very sturdy motor mounts.
Home Depot is your friend -- shelf brackets make very good motor mounts if your motor has a flat-surfaced gearbox.
As far as a base, at the sizes you're talking about you can use a small sheet of plexiglass. You can even use wood; some of the stock (meant, I suppose, for paneling or other finishing work) makes sturdy bases for smaller robots, is really easy to work with, and at least once side will take paint quite nicely -- allowing you to hide the fact that your robot is made of such a low tech material as wood. Pretty adequate for a 4"x4" platform.
You can also get really cheap base chassis and parts from
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(no affiliation, yada yada). I think the base panels run around 7 bucks or so. They are PVC whic is extremely easy to drill.
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