Kensington Expert Mouse Trackball - Scroll Ring Mechanism (SUPERCEDED)

thingiverse

This has been superceded by [thing 4207516](https://www.thingiverse.com/thing:4207516). This is a replacement scroll ring mechanism for the Kensington Expert Wireless Trackball Mouse. I created this because the scroll ring on this trackball is problematic. As Wirecutter put it, "[T]he scroll ring felt gritty when we turned it.... Many owners report the same problem ... 'the scroll ring feels so jerky and janky.'” In addition to turning poorly, the Kensington scroll ring also has problems giving feedback to let the user know that scrolling is about to occur. The scroll wheel on most mice creates a tiny but noticeable amount of resistance immediately before scrolling happens, as if the scroll wheel mechanism has a series of notches built into it. The Expert Wireless Trackball Mouse tries to do this through use of a magnet. However, the magnet works so poorly that many sites recommend removing it entirely. My replacement scroll ring spins on 4mm-diameter chrome steel ball bearings and--optionally, for those of you who are interested--creates scrolling feedback by having a 623ZZ miniature bearing press against a portion of the side of the ring that is shaped like a wave. Caveats: - I don't have much time to support this, so if you run into issues don't be surprised to be left on your own. - The tolerances for this thing are extremely small. Expect to do some sandpapering and even that may not be enough for some of you. - Assembling this requires that you first disassemble the existing scroll ring, which unfortunately cannot be easily re-assembled if you decide this replacement scroll ring isn't for you after all. You literally have to break the (weak) connection between two pieces that are held together by four tiny, molten plastic pegs. - This thing is for the wireless version of this trackball. I have no idea if it will work with the wired version. Parts needed aside from printed objects: - 4mm diameter chrome steel ball bearings (available in a package of 100 from VXB.com; you'll need no more than half that) - 623ZZ miniature bearing (3x10x4) (also available from VXB.com) - M3-0.5 x 5mm screw and nut (pan or flathead recommended; socket cap screws are too big) - Superglue (the parts snap together, but some glue reinforcement isn't a bad idea); I personally like Loctite Ultragel Control Super Glue See videos for instructions. I've changed or noticed a few things since creating some of the videos: - The version in the assembly video only has 16 "windows" for scrolling purposes. The current version has 48 [edit 2020-02-10: now 40], which is shown in one of the other videos. The increase in windows means that you get more scrolling for less turning of the ring. (The Kensington ring has 39 windows.) - The three Component7 pieces that hold Component3 & Component6 together are very difficult to get into place. Expect to do quite a bit of sanding here, or just use superglue. - I had to sand down the bottoms of the top mouse buttons in addition to the nubs on the top plate. None of this is visible when the device is reassembled. - The top of the ring (Component6) mimicked the design of the Kensington version but I found it to be a trap for debris. I tried coating it with black Sugru but that made it slick. I eventually redesigned it completely and am happy with how it turned out. https://youtu.be/cPR0LcLYwPs https://youtu.be/3OxpM4YOF1k https://youtu.be/gQpbLYEUtiM https://youtu.be/QqUpg-sxk5I https://youtu.be/6w2GZ3K86D4 Edits: - 2020-02-02: Original version. - 2020-02-08: I've reworked the wave on Component5 and Component9 also received a couple corrections. - 2020-02-09: I've continued to tweak Component9 so that (1) the scroll ring windows are properly centered with the scroll sensor and (2) Component9 presses against the scroll ring with the right amount of force. - 2020-02-10: Component5 now has 40 windows instead of 48. Component9 now presses against the wave on Component5 more tightly. (If it's too tight for your liking, you can bend it back a bit.) The changes better ensure a predictable amount of scrolling occurs when one turns the scroll ring. - 2020-02-13: I redesigned Component6 to make it "grippier." I also reduced the size of Component7, including the slots it fits into on Component6 and Component3.