Intro to fabrication – Mounting Motors

This weeks assignment was to create a project involving a motor. This could be either a servo motor, stepper motor or DC Motor.

My idea for this weeks assignment was to make a “Useless device”. The initial idea was to create a button you would press. This button would turn on a motor which would press another button and a light would come on. The actual challenge would be to mount the motor onto something and attachment to the shaft of the motor.

This is a cardboard version of what my initial plan looked like. Spinning a circle attached to the shaft of my motor would extend the reachpoint of an arm. This arm would hit a button and turn on a switch.

The pieces would be cut out of acrylic and I would attach the parts using mechanical screws. After talking to a few people I realized that the many pieces in the plan would cause a lot of friction – making it difficult for my motor to create enough torque. For that reason I decided to create a more simplified version of the idea – taking out a few parts. This is what my new plan looked like. Basically, it would be the same concept as my first idea, but it would have fewer parts.

First I needed something to mount my motor onto. I found two pieces of leftover wood in the shop and cut them on the Miter saw. I then layered them, so that if I drilled a hole thorugh them they would cover up my motor – and keep it in place. Since the motor had an awkward shape i chose to drill two holes next to each other and file them into one shape where the motor would fit. This took a few practice attempts.

First practice attempt to make a motor-shaped hole in the wood:

Cutting the actual holes in the two layered piece of wood:

Filing and fitting of the motor. Practice attempts on the right – fitting adjustment being made on the left.

With the DC motor was now mounted to the wood, I would have to attach something to the shaft. I measured the dimension of it and cut a circular shape out of acrylics on the laser cutter. This circular shape would have a hole in the middle that would fit onto the shaft of my DC motor. Additionally, I cut a rectangular shape which was intended to go onto the spinning wheel and function as an arm turning on and off the light switch.

Everything was going well and this is what my “useless device” now looked like:

I connected 6V to my Motor and found that it was spinning really fast (a lot faster than I expected). So instead of 6V I tested 3V and found that the motor moved at a slower pace. The speed was now well suited for what I had intended for this project. The problems started to occur when I mounted the acrylic pieces to the motor. The motor now wouldn’t move. I assumed it was because of the low voltage supply to the motor and changed it back to 6 volts – also this time I added a potentiometer to the circuit to control the amount of voltage going into the motor. I could now control the wheel attached to the motor shaft without problems.

Testing different voltage-supplies and potentiometers for the circuit:

I then tried to reattach the acrylic pointer to the wheel. Also I found two pieces of wood that would go onto the device to limit/control the movement of the pointer/arm intended to touch the switch-button.

My “useless device” had now turned out to be exactly what I had in mind to start out with:

The motor would spin the wheel and the pointer would hit a toggle switch located exactly at the end of reachpoint of the “pointer”. The only problem was that it didn’t work. Every time the pointer was attached to the wheel it would either stop spinning or go very fast depending on the amount of voltage applied to the motor. Additonally, some parts of the circuit would start to get overheated.

Frustrated, I figured that the pieces controlling the movement of the “pointer” was maybe too narrow. For that reason I broke them off and tried one more time with two new on pieces that would allow for more movement of the pointer and (maybe) less friction.

However, this provided the same issues as before. The motor would either spin very fast (with a high voltage supply) or not spin at all. Mostly, it would spin a few rounds and then stop. I tried many different constellations – changing the voltage supply, changing the position of the pieces controlling the movement taking parts on and off. But nothing seemed to work.

The best explanation I can think of as to why this doesn’t work is the DC motor. I should have probably used a more powerfull motor. What really surprised my though was how well it worked with just the spinning wheel as opposed to mounting the “pointer” to the device – where it didn’t work at all. I was really happy with the mounting of the motor into the wood and the mounting of the wheel to the shaft, but the movement of the pointer didn’t end up the way I wanted it to.

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