Heaviest(?) Fidget spinner - 10oz (283g)

prusaprinters

<p>This fidget spinner is engineered to give the greatest moment of inertia possible. Read the "How I Designed This" section for more information.</p> <p>My own build uses steel weights to weigh in at 10oz (283g) but if you have the money for tungsten it would be around 19oz (539g) and &gt;$90 in weights. Even with the steel weights I have not been able to find another spinner with greater mass.</p> <p>After hand spinning, I timed a spin at 4m 10s with a hybrid bearing.</p> <p>Hardware &amp; weight:<br/> 35x 1/4oz (3/8"dia x 1/2"h) steel cylinder pinewood derby car weights OR 1/2oz tungsten weights<br/> 1x 608 bearing of choice<br/> 8x M3x16mm bolt<br/> 8x M3 nut</p> <h3> Print Settings</h3> <p><strong>Printer:</strong></p> <p>Geeetech Prusa i3 Pro C</p> <p><p class="detail-setting rafts"><strong>Rafts: </strong> <div><p>No</p></div><strong>Supports:</strong></p> <p>No</p> <p><p class="detail-setting resolution"><strong>Resolution: </strong> <div><p>0.2mm</p></div><strong>Infill:</strong></p> <p>100%</p> <h3> <br/> <p class="detail-setting notes"><strong>Notes: </strong> </p><div><p>Printed in MeltInk Red PLA</p></div> Post-Printing</h3> <p>The first few inner walls for the bolt/nut holes will not be supported. But it is so close to the bed, that it builds its own support quickly. I was always able to cut those first loops out, leaving a somewhat level surface. It is the edges of the holes that are important. They will be sandwiched against the weights.</p> <h3> How I Designed This</h3> <p>I set out to build a fidget spinner with the greatest moment of inertia possible. For a thin cylindrical shell I = mr^2. Increasing the radius of weight would be the most effective, but it wouldn't be a fidget spinner if you can't hold it in your hands. So r is limited to the typical 3" radius. The next best thing is to locate as much mass (weight) as close to the outer edge as possible.</p> <p>Going down the list of densest metals, platinum and plutonium were out of the question. Searching for tungsten weights, I found a 'standard' sized weight, 3/8" diameter x 1/2" height, normally used for pinewood derby cars. They are available in both tungsten ($$) and steel.</p> <p>As i started to design around this weight size I concluded that I could fit 21 weights along the standard 3" radius for fidget spinners. Another 15 could fit one diameter inside that. The cheapest tungsten I could find was ~$2.50 per 1/2oz weight. I'm not ready to buy $90+ in weight so I chose 36 steel weights (~$16). Tungsten weights would have totalled 18oz (510g), and steel is half that at 9oz (255g). My final design dropped 1 weight so that it was a repeatable pattern as 7 groups of 5 weights.</p> </p></p> Category: Mechanical Toys