Adjustable Foot with Silicone Rubber Grip (mold in-place)

thingiverse

This is an extension foot with adjustable height (screwable) and a silicone bottom for better grip. I use it to lift two of the feet on a laptop stand. Lift height is approximately 33-40 mm, adjusted with variables: #inserted_height and #unscrewed_height. Note that the max height is less than #unscrewed_height. Onshape file (CC-BY-SA): https://cad.onshape.com/documents/32bca8acba1a1fd1f3c8f8f4/w/e9e86668686cdf7434ae2e03/e/9d4dafa1c0570036404808f3 To improve this design: * Create a better mold cap that makes it easier to remove and excess silicone. * Design a wider base for better stability, especially if the silicone is very soft. Possibly lower silicone height. Silicone Details: The silicone is molded in-place, fastened mechanically to the foot. You'll want a silicone that's slightly soft or rubbery. I use CHT MM730FG, which has a "hardness" of 30 (Shore A). Ideally, I would have used something softer. Initially, I filled the silicone without a cap, just a ring above the plastic to get it started. However, this resulted in a very smooth surface and "walls" due to capillary action pulling the silicone against my mold ring. Now, I use a full cap. Pour the silicone into the four holes. Air bubbles may get trapped, but they don't matter on the underside of the foot. A design issue is that the silicone in the sprues (pouring holes) angles outward and holds the mold cap against the foot when cured. To fix this, I pull the excess silicone with pliers and cut it off with a scalpel. Alternatively, you can try pulling the cap a short distance and using a scalpel to reach between the foot and the cap. The volume of silicone for one foot is approximately 4495 mm^3 (4.5 ml). To convert this to weight, use the density or Specify Gravity value of your silicone. I recommend weighing it on a scale that shows weights in tens of grams, such as 0.01-200 g. Printing Instructions: Print as provided in the files; no supports are needed. Print the top part with the screw down for a smooth finish. The bottom part has a membrane that needs to be removed using a screwdriver and pliers. The surface doesn't need to be smooth, as the silicone will form around it. If the screw is tough to move initially, try moving it back and forth a few times until it becomes easy to turn (spacing: 0.1 + 0.1 = 0.2 mm).