Sunday, February 9, 2014

Fastening and Attaching (2/4/14)

During class on Tuesday, we learned about the different fastening and attaching techniques in preparation for the upcoming windless assignment.

Piano Wires
Our group first learned about using piano wires to attach two pieces of delrin together. Using a wire cutter, we cut piano wires of different diameters and learned to measure the diameters using a caliper. It was my first time using a digital caliper, so I thought it was very convenient compared to the non-digital ones. We also measured the diameter of the drill bits in order to determine what size we would use for a particular piano wire. Depending on how tight we want our wires to fit, we would adjust the size of the drill bits. Then, we were given the opportunity to try drilling a hole into a piece of delrin using the drill press and fitting a piano wire through the hole also using the drill press.
The piano wire technique is great for making hinges and joining corners. One precaution that we need to take when using this technique is to make sure that the holes are lined up perfectly and that the wire is mostly straight. Also, we need to be careful when using the drill press and slowly drill little by little. 


Press Fit
The second technique we learned was press fitting. Press fitting is another technique that is used when joining delrin pieces together. We first need to measure the width of the delrin we are using with a caliper. For a tight fit, there notches need to accurately cut using the laser cutter and the height of the notches need to be about 0.005 inches taller than the width of the delrin. The fitting can be removed using pliers, but not easily with just bare hands.
My partner and I tried cutting small test pieces using the laser cutter, but our notches were too small. It takes very accurate measurements for the press fit to work perfectly, but it is one of the methods that require the least amount of technical work.


Heat Staking and Bushings
Lastly, we were introduced to heat staking and bushings.
Heat staking is simply melting the delrin onto another piece of delrin and attaching the two pieces together. Using a laser cutter, a square hole is cut onto a piece of delrin and another piece is cut so that there is a part that could fit through the square hole. Then, using a heat stake that is set to about 400 degrees F, we melt down the delrin until it is completely melted onto the other piece of delrin. Then we turn off the heat stake and use the air valve to cool down the delrin for about 50 seconds. 
This is a great technique for joining pieces of delrin, but it would be difficult to join edges in an angle due to the nature of the machine. 

In order to make our windless using rods, making bushings is an absolutely useful technique. Similar to the press fit, we need to measure the diameter of the rod and make the bushings using the measurements. We could have bushings that are loose fitting and tight fitting. For tight fitting bushings, we need to make the diameter larger than that of the rod by ~0.002in. 


The class was very hands-on and interesting, and we learned a lot of useful techniques that I am excited to utilize for the next assignment! 
 

1 comment:

  1. I thought the piano wiring was interesting as I am sure I have seen that technique before, but I too believe that learning how to do the bushings was the most helpful technique to learn for our assignment. Best of luck!

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