Today we learned three different methods of fastening and attaching: heat staking, fastening with piano wire, and attaching using slots and pegs. Each of these ways of fastening and attaching were taught at individual stations where we also learned how to use new tools and equipment. For this activity, I went around to the stations with my partner from the bottle opener project, Vivian.
Heat Staking:
The first station we went to was heat staking where we learned how to use the thermal press:
Heat staking is a way of permanently joining pieces of Delrin together. It is done by melting a tab of Delrin onto another piece that has a slit for the tab. It looks like this once the Delrin has been melted:
This is a great way to fasten something permanently. It is a very strong connection and it cannot be un-done. If you foresee that you will need to make changes or adjustments to your project, this is not the best way to fasten something. If you need a strong, permanent connection, this is one of the best methods.
Bushings, Pegs, Slots and Calipers:
The second station Vivian and I went to was the bushings, pegs, slots and calipers station. We first learned how to use the calipers, and then we were tasked with measuring all the dimensions of the bushings, slots and pegs.
By measuring the different pegs, slots and bushings we got an array of different measurements. For the bushings (station 1) we got measurements of 6.36mm, 6.63mm, and 6.42mm. For the peg (station 3) we measured a height of 6.89mm, a base of 4.92mm, and a width of 4.98mm. For the large slit we measured a height of 9.98mm, a base of 5.01mm, and a width of 4.94mm. For the small slit, we measured a height of 7.07mm, a base of 5.02mm, and a width of 4.98mm. For the other slits (station 2) we got a measurement of 3.23 for the thickness. For the heights, we measured a range of values of .5075 in, .5085in, and .5085in. For the bases we measured values of .14in, .1325in, and .1155in with actual values of .135in, .125in and .115in respectively. The difference in our measured values and the values in SolidWorks is likely due to the slight inaccuracies of the laser cutter. When you cut with a laster, the laser is hot enough to melt the plastic around the cut and make the cut bigger than the original design. Also, when using a laser cutter, the intensity of the laser decreases the deeper it is in to the material which causes angled cuts and a slight variation in measurements. Because of these discrepancies in measurements, its a good idea to slightly change the measurements in SolidWorks to account for the variation in cutting. Also, it is a good idea to test smaller pieces with sizes you need to make sure that the pieces will actually fit together. This way you can adjust the sizing in SolidWorks so that when you go to print the actual pieces of your project they fit perfectly.
Bushings, pegs and slots are a good way to fasten things if you do not need a permanent attachment. If you get the sizing just right however, you can create a secure, tight attachment that will work well for many things while still having the option of undoing the connection if you need to. Tight bushings are good for strong fits that restrict motion of parts. They function as if the parts were glued together without actually physically joining them. They will often work permanently, but can be undone if necessary. Loose bushings are great if you want to allow motion of parts while still connecting the pieces. For example, if you wanted to be able to slide the bushing on and off, you would use a loose one.
Drill Press, Arbor Press, Piano Wire:
At the final station Vivian and I visited, we learned how to use the drill press, the arbor press and how to fasten pieces using the piano wire and the two presses. The drill press is a machine used to drill holes in to your material. Here is my partner, Vivian, drilling a hole in some Delrin to create a hinge:
By changing the size of the drill bit you use, you can change the size of the hole to adjust for your specifications. The arbor press is used to apply a strong force to an object. For example, if I needed to put some piano wire through a hole I just drilled, and there is a very tight fit between the wire and the piece, I could use the arbor press to push the wire through the hole. Piano wire can be used for a lot of things. It can be used to just attach pieces loosely together. It can also be used to create hinges that can move freely. It is not a permanent fastening device or the strongest, but it is versatile.
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