Step 20: Stepper Driver Part 1 - Resistors

Well... here we are, finally getting started with the electronics portion of the video series. The entire structure of the CNC machine is complete with the exception of the router mount. We will get to that a little later. For now, we will start on the assembly of the HobbyCNC 3 axis chopper unipolar stepper driver. This is a great driver kit and can handle up to 3.0 amps per phase. Another great site for CNC drivers is CNC4PC. They seem to have a great variety. Amps are a measure of the current running through a circuit (not a thing that makes music louder). A phase is actually a single coil within the stepper motor. Most stepper motors have four coils or phases. A coil is just a winding of conductive material to form an electromagnetic phenomenon (a magnet that turns on and off with or without electrical flow). When coils are electrified in a specific combination or sequence, the motor will react in a turning motion (or not, depending on the sequence, or the wiring scheme).

Ok... back to the board. Other features include microstepping (each step can be subdivided by 2, 4, 8 or 16). You probably notice the word chopper and it does not describe the cutting part of the CNC machine, nor will it dice and slice. It essentially chops up the current through the stepper to keep it cool, stable and efficient (well, relatively cool). When we get to the power source for the board and stepper motors, I will explain the electricity and flow in more detail, with formulas (basic electronic stuff that is a definite need to know). Get your calculators ready!

First, take a look at some of the equipment you will need. On the left, you will see what is usually termed as "extra hands." How cute! Although, it does look a little sinister. This was a hard sell with the wife, however, but well worth the investment. Yeah, that's a super worn piece of sponge. The spong is used for cleaning the point of the soldering iron. It usually comes with a magnifying glass, but I removed that since it get in the way most of the time.

The soldering iron that I use is a Weller 40 watt. Ay, geez... a watt is voltage multiplied by amps (power x current). HobbyCNC recommends a lower wattage soldering iron, so if you're not too experienced, use the recommended iron. Let me explain, the iron is used to melt solder. The iron get extremely hot. I've burned myself many times and it doesn't fell good by any means. The recommendation for lower wattage is to reduce the likelyhood of burning components (stressing them beyond their temperature threshold). Follow instructions that are provided with the kit very closely. Oh, and by the way, the instructions are impecable. Read the warning lables on the solder. Moreover, do your soldering in a well ventilated area and keep your kid(s) away from the iron (this includes your pets, cat hair smells horrible when ironed). If touched by one of the kids, they will have a very clear definition of punishment (this would not be good). Read the safety instruction that came with the soldering iron. In addition, get some solder wick (it sucks up solder). For other more in depth tutorial on how to solder, go to sparkfun electronics tutorials page.

Another important item that you will need is a multimeter. They are pretty cheap so there is no reason not to have one. You will receive the benefit of this gadget the first few times you use it. You will need it for this assembly at many stages. Testing components that they function properly prior to soldering them. Testing power, power levels, resistance, currents are all uses of this device. Test everything, you now have the power!

I like to individually package all like components, so when they are called upon, I can find them easily. It's also good to use this method and verify that you have the proper count of each sets of components.

Todays video, I will demonstrate the installation of the resistors, the first component that is recommended to be installed. Resistors are installed first due to their size. It would be very difficult to insert these small components after the larger ones have been installed.