There are an incredible number of ways to mount a motor in your custom project. At the top-right of this page, search Robot Room for 'motor mount' or 'motor bracket' to see some of my previous DIY designs.
Most motor attachment methods require you to buy a ready-made motor mount or to machine your own. With the advent of 3D printing, prototype motor brackets are much easier for a hobbyist to make, although the slow speed of printing limits the quantity that can be produced.
Surprisingly, even though many creators regularly utilize the precision and strength of printed circuit boards, few people use PCBs to connect to motors. For small and low-power motors, PCB motor connectors are quite easy and practical. For example, here is a 24 mm diameter Maxon motor with gearhead mounted beneath standard perfboard.
PCB motor mount with 24 mm Maxon motor
The image above shows that the motor mount is soldered to the circuit board using common double-row headers. This is purely for mechanical purposes, and does not carry electrical signals. So, don’t panic if it looks like a lot of wiring.
The top of the mounting board includes multiple methods of attaching the mounting bracket to the project circuitry or case.
Printed circuit board (PCB) motor mount can be attached by screws, solder, right angle headers, or double row headers
In fact, the motor mount PCB can be attached in four ways:
Soldering both sides of the motor mount to copper clad
With solder only, there is a risk of the copper delaminating from the fiberglass substrate of the PCB. Because headers pass through the board, they are physically stronger. Also, they are easier to solder.
Single row right angle connector for motor mount
Mounting with dual row headers
For this project, I intentionally chose motors with a slightly complicated motor hole arrangement. This gave me the opportunity to show how to quickly lay out screw holes at angles or in a circle without the human being needing to know trigonometry.
Maxon motor with gearhead dimensions
A digital caliper can be used to measure the critical dimensions of the motor. Fortunately, in this case, the gearhead data sheet is available from Maxon.
Maxon gearhead drawing
I rounded the bottom of the motor mount PCB to prevent the sharp corners from snagging carpet. However, for many electronic projects, a rectangular board is easier. Also, some PCB manufacturers do not support non-rectangular boards or they charge extra.
PCB mount board layout in Copper Connection
A PCB motor mounting bracket can be designed in your favorite printed circuit board layout program. The great thing about using this type of computer aided drafting tool is that it is precise, proven, and ubiquitous. You don’t need machining skills because you can have the board manufactured wherever you please.
To see the example presented in the article, click on the file and save it.
Download Copper Connection, the PCB layout software.
Free to display, edit, and etch at home.
The following video shows the motor mount and how the board was designed in the PCB design tool.
As stated earlier, some manufacturers do not support non-rectangular boards, or they charge extra. However, a bigger trap is that some manufacturers have a maximum drill size smaller than the motor-shaft bearing hole. For example, on the following manufacturer’s website, does everything look good?
Always read the manufacturers rules
Yes? Did you spot it? “Maximum is 360 mils”. That’s 0.360 inches, which is 9.144 mm. This design includes a 10.1 mm drill hole.
If the hole size is too large and the manufacturer doesn’t support internal cut outs, you’ll end up with a board that is solid where a large whole should be. Oops. Yeah, I didn’t read or clearly understand what the manufacturer was trying to tell me.
Maxon motor mount missing the center hole (left) and with a center hole (right)
I tried drilling out the center hole on my milling machine. Of course, this defeats the purpose of not needing a machine shop.
Mill out motor mount hole
Unfortunately, the side of the board where the hole punched through was deformed. The mount is still usable, but less optimal than desired. So, be sure your PCB manufacturer can make big enough holes.
Exit hole damage
On a side note, because I used a milling bit to make the hole, the copper layer with gold flash came off intact. It’s kind of cool to see the normally-hidden glued side of the copper layer.
Gold flash copper clad popped off board
If you have the inclination, try making a board with a non-rectangular outer edge. And, don’t shy away from selecting a motor with mounting holes angled with the respect to the motor shaft.
What price did I pay? $5.50 for three, including shipping, from OSH Park.