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The follower includes a slider, which holds the rails. The slider is made up of four 3D printed linear bearing holders offset from the vertical base by raisers. The linear bearing holders keep the provided 8mm linear bearings in place and space the two 8mm rails at a predetermined distance to avoid binding. The rails are kept from sliding out of the bearing by 3D printed shaft collars. At the end of the rails are two 3D printed L shaped rail holders that each slot in a rail from the slider, as well as the two 8mm rails that the follower rail holder slides along. The rails are held in these slots by clamps which are built into these parts. By building the clamps into the parts, we are able to avoid teh the struggle that come comes with press fitting the rails, while maintaining a firm hold on the rails. One of the rail holders is also designed to fit the pen brush, using a slot and 3D printed pen holder piece. Additionally, due to the weight of the final system, we added a spring that we could tune by changing the height of the attached shaft collar to minimize issues of slippage when the follower climbs a steep slope on the cam.
Sliding along the two rails are four 8mm linear bearings, 2 per rail, which are held inside of the upper portion of the follower rail holder. The upper rail holder is bolted to the lower follower rail holder, with a sponge-like double-sided tape placed between the two, to decrease unwanted motion. The lower part of the follower rail holder keeps in place the 6 mm rail holding the follower, and is designed to be rigid to reduce out of plane motion that would resulting in slippage. At the base of the rail is the follower, in contact with the cam, that consists of a wheel, a 3d printed wheel holder, and a metal dowel, which keeps the wheel and holder together.
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