Gearmotor selection/tech questions - DIY 3D printer

Gears, the universal symbol of productivity, have been a major cog in industry for hundreds of years. Before electromagnetic rotating machines were even a glimmer in Michael Faraday's eyes, there were gears.

Early gears had been produced from wood with cylindrical pegs for cogs. They had been frequently lubricated with animal fat, vegetable oils, as well as water. Gears had been utilized then for exactly the same factors they're now - simply because of their force multiplying properties. You’d discover them on ships (hoisting anchors), in catapults (tensioning fly arms), and on a number of machinery powered by wind and water wheels.

The choice of motor will depend largely on what software interface you plan to use. If you want to use pre-made software, then you might want to stick to the type of actuator they use/ suggest: it might be a stepper motor, servo or DC gear motor + encoder.

If you plan to make your own software interface, then using the same type of actuator throughout the machine has its advantages - and we'd suggest you again use a stepper motor.

If you really wanted to use a DC gear motor with encoder, you'd need a DC motor controller (serial or PWM) and connect the encoder output to the microcontroller. You would then need to program the microcontroller separately from the software you use to slice the part. It's quite involved. The Arduino would provide the 5V power for the encoder and read the states of the onboard IR sensors.

Gear types

There are many types of gears available today, each with specific advantages and limitations. Topping the list — at least for big jobs — are worm, spur, and helical gears.

Spur gears are compact as well as efficient, but they tend to be noisy and don’t always handle shock as well as worm gears. They can achieve about 10:1 ratio per stage.

Worm gears are relatively inexpensive, achieve high ratios in a single gear set (up to 100:1), and are available in right-angle configurations. They also run quietly and tolerate high shock loads. However, they are less efficient than other forms of gearing.

Spur gears by contrast are much more most likely to create noise, much less tolerant of shock in comparison to worm gears, and slightly much more costly. Around the plus side, they're compact, effective, and accessible in parallel-shaft arrangements. They're also simple to discover simply because numerous producers create them. Spur gear ratios are usually ten:1 per stage.

Helical gears are similar to spur gears, but they have angled teeth. Because helical gears have more tooth contact area than spur gears, pound for pound they can carry heavier loads, though not quite as efficiently. They are somewhat more expensive as well and, depending on the configuration, may produce thrust loading on the bearings. Versatility is a plus, however, as helicals can be used on non-parallel, even perpendicular, shafts, achieving a 10:1 ratio per stage.