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Start A Movement Design Challenge - Kit Unboxing

dougw

This is an unboxing of the kit supplied in the "Start a Movement" design challenge, but it also includes a first power up with motor motion.

My project will implement two machines although some of the parts will be common to both applications.

The more complex machine will require 2 stepper motors and lots of mechanical apparatus, but not a lot of electronics beyond what was supplied in the kit.

I figured I needed to include some electronics in the project, so the second system only needs one stepper motor but has lots of electronics, including a PCB and software beyond what was supplied in the kit.

Unboxing

This video shows the parts that came in the kit supplied by Analog Devices and element 14:

The stepper motor and controller are demonstrated in the video below.

System Description 

This section briefly describes what this project will try to do with the supplied kit. 

System 1 - The Tapster

The Tapster is a machine that will automatically tap screw threads into 3D printed plastic parts. Fastening 3D parts together and fastening them to other things often involves screws. Tapping threads into holes is a tedious and somewhat risky operation so it will be very useful to have a machine that will automatically thread holes and do it right.

The machine will use 2 stepper motors, one to drive the tap forward and one to rotate the tap. The forward motion needs to be precisely synchronized to the tap rotation so that the tap screws into the plastic without stressing and stripping the threads.

The forward motion will be implemented using a lead screw to drive a tap chuck assembly. The forward motion is constrained to move precisely in one direction by linear bearings on guide rods. The stepper motor driving the lead screw will include an optical encoder to ensure the tap depth is precisely executed.

The tap chuck chassis has a pillow block bearing that allows the chuck to rotate. The rotary motion will be supplied by a planetary gear head driven by a stepper motor. The gearbox will be extracted from an old electric screw driver. The gearbox will increase the torque of the stepper motor and decrease the speed of chuck rotation.

System 2 - The Connector Tester

The Connector Tester has 2 main functions:

  1. It can cycle test connectors to determine how many connect/disconnect cycles they last before failure 
  2. It can test cables and connectors to see if there are any unwanted shorts or open circuits

The cycle tester function is the one where a motorized mechanism comes in handy. It would be incredibly tedious to connect and disconnect a connector thousands of times by hand.

The connectors will be mated and disconnected by a linear actuator fabricated from a lead screw driven by a stepper motor.

The connection integrity tests will be performed by a custom PCB with LEDs indicating what is connected, what is shorted and what isn't connected. The PCB will be connected to an Arduino Mega which will sequence through all the pins and record and display test statistics.

Preliminary Motor Test

A quick motor test was set up to start getting a feel for how the kit of parts work.

The steps followed were:

  • Download the TMCL-IDE software (65MB) from Analog Devices (https://www.analog.com/en/resources/evaluation-hardware-and-software/motor-motion-control-software/tmcl-ide.html)
  • Install the TMCL-IDE
  • Connect the 3 TMC5272 EVAL cards together
  • Make a power cable and connect 12V to the +VM connector as shown below
  • Add some bootlace connectors to the stepper motor leads and connect them to the Motor 1 connector as shown below
  • Connect the motor controller via USB C to the PC
  • Run The TMCL-IDE
  • Select "Current Settings"
  • Set Target motor current (I used .5A just as a quick test)
  • Select "Calibrate settings automatically" and exit Current settings
  • Select "Velocity Mode" to pop up a control window and "Velocity Graph" to bring up a velocity display window
  • In the control window, set the velocity and acceleration dials
  • select the control arrows to start the motion and the stop button to stop motion

Note that the documentation does not explain which motor leads go where. You can see the colors in the image below of how I connected the motor.

  • OA1 - black
  • OA2 - green
  • OB1 - red
  • OB2 - blue

Connection Image

image

Discussion

I really have not assimilated the documentation yet and do not have the IDE set up properly, but the system is up and running.

I spent quite a while trying to find documentation of how to connect a motor without success. Eventually I just took my best guess and it seemed to work.

Some of the parts I need for the project have not arrived yet, so that is limiting how much I can show at this stage.

The kit arrived while I was at work, so my wife ended up paying FedEx $30.85 in shipping fees and taxes. That was unexpected and not budgeted, but projects don't always go as planned.

In that vein I already have an issue with my second stepper motor, hopefully I can resolve it soon.

Next Steps

  • Design the Lead screw and linear bearing assembly and assemble it
  • Design the connector brackets and print them
  • Design the chuck assembly and build it
  • Build the cable tester electronics and test them
  • Program the Arduino Mega and test it.

There is a lot more detail, but this provides some idea of what is coming.

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