Nerdy Gurdy improved shaft nut

thingiverse

The major changes are:1) Enlarged the flange diameter as much as possible without it contacting the top of the Nerdy Gurdy2) Removed the radius between the hex section and the flange. Any radius there could prevent the flange from mounting completely flush in the wheel.3) Added mounting holes for #2 wood screws so it can be installed without glue for easy removal4) Removed the radius from the edge of the flange surface that contacts the wheel, as the goal is to get as much face contact with the wheel face as possible5) Revised the center hole diameter to 6.8mm (from 7.0mm) to match the drill spec size for M8-1.25 hole tapping. This ensures we have as much thread material as possible.IMPORTANT TIPS ABOUT ASSEMBLING A NERDY GURDY 6.3 OR SIMILAR WHEEL1) If you use the standard kit 3d printed flange bushing you only have a 50% chance of getting a straight wheel. That’s because the radius on the 3d printed flange bushing can interfere with the edges of the hex shaped hole and prevent it from sitting flush – but only on one side of the wheel. Due to the slope on the edges of the parts resulting from the laser cutting process (the kerf) the hex shaped hole is larger on one side of the wheel than the other, so if you randomly inserted the bushing into the wheel side with the bigger hole you got lucky.2) If you follow the directions and glue the wheel halves together before you glue in the flange bushing, your wheel will most likely wobble. That’s because by “eye” you can’t get the two halves perfectly aligned, and any amount of misalignment will cause the center hole to be at an angle. Which will put the bushing at an angle. If the two halves are misaligned by just the thickness of a piece of paper, the outer edge of the wheel will wobble by 1-2 mm.3) If you use double nuts to hold the wheel in place they will never be exactly perpendicular to the shaft. This is due to slight differences in the thread angles of the nuts and the shaft, and even differences in angle between each side of the threads on the nuts and the shaft - just manufacturing tolerances. When you tighten the wheel against the nuts they will try to force the wheel face to match the plane of the face of the nuts, making the wheel wobble.4) If you use the double nuts to hold the wheel as shown in the instructions, they will embed into the wheel or the plastic flange bushing in the wheel differently each time you install the wheel. The nuts are hard, the wood and plastic is soft. So how can we solve these problems? 1) If you still want to use the original flange bushing from your kit, then you have to install it on the “loose” side of the wheel where the hex hole is the largest in order to clear the radius on the 3d print. But a better method is to use my Improved Flange Bushing where the radius has been removed and the flange is wider.2) Don’t glue the wheel halves together first and add the bushing later (I made that mistake). Instead, glue the flange bushing into one half of the wheel first. If you use this improved bushing design then the flange can be against either side of the wheel and it will still align well assuming you make sure the flange sits flush against the wheel face. Let the glue dry.Then glue the second wheel half on to the first, with the “tight” side of the hex hole in the middle of the two halves. That will give the best centering of the second wheel half on the flange bushing.3) Don’t use double nuts to retain the wheel, instead use an aluminum 8mm split shaft coupler. This eliminates any issues caused by the threads, ensuring that the face that presses against the wheel is perfectly perpendicular to the shaft. These are available on Amazon for less than $10.4) Add a large OD fender washer between the wheel and the coupler (with the wheel oriented such that the flange bushing flange is on the side toward the tuning pegs). This will ensure the load from the coupler is spread across such a large area that no deformation of the wheel can occur. Then you can tighten the wheel against the coupler very tightly and the coupler will force the wheel to flex as needed to match its face, eliminating all wobble.