{"id":6850,"date":"2021-04-28T07:34:56","date_gmt":"2021-04-28T14:34:56","guid":{"rendered":"https:\/\/www.corbinstreehouse.com\/blog\/?p=6850"},"modified":"2021-04-28T07:34:56","modified_gmt":"2021-04-28T14:34:56","slug":"the-duality-unicycle-handle-part-2-strength","status":"publish","type":"post","link":"https:\/\/www.corbinstreehouse.com\/blog\/2021\/04\/the-duality-unicycle-handle-part-2-strength\/","title":{"rendered":"The Duality Unicycle Handle – Part 2 Strength"},"content":{"rendered":"

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This is a continuation of the last post<\/a> introducing the project.<\/p>\n\n\n\n

This project isn’t done (it isn’t strong enough), but feel free to play with things and download the files. I uploaded the latest STL, a strength area for more infill, the latest print settings (PrusaSlicer), and the Fusion 360 CAD file: Duality Unicycle Handle<\/a><\/p>\n\n\n\n

My 16 hour print finished with a new prototype! I was excited about this one because it was printed in PETG, which should be a lot stronger than PLA. I also printed with more infill: 50% overall with a gyroid pattern along with a special “strength area” defined in PrusaSlicer set to 80% gyroid fill. I also addressed a few small things with the last design: the grips tilt down ever so slightly (5 degrees) and I smoothed out some more corners. The disadvantage of this is that the whole bottom requires supports.<\/p>\n\n\n\n

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I did some quick cleanup and tossed on the unicycle and immediately tried to break it. Sure enough, it easily snapped — not as easily as the 10% infill PLA, but still way too easy. <\/p>\n\n\n\n

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The break point isn’t too surprising. I pushed down on it, and the parallel layers first separated on the thin lip due to poor adhesion and then allowed the perpendicular layers to snap. In the above photo on the right I flipped over the base piece to show where the layers separated. <\/p>\n\n\n\n

This is going to be a hard problem to fix. It might require annealing; re-melting the plastic in an oven to blend together the layers. To do that properly I might have to print at 100% infill, which will use a lot more plastic, take a lot longer, and weigh more. <\/p>\n\n\n\n

With regards to weight I compared the standard handle to my duality handle; 103 grams vs 111 grams. This isn’t too bad, but it will require more weight to make it stronger.<\/p>\n\n\n\n

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So, what to do? I printed the PETG at 250C. I might be able to try it at 260C to see if I get better adhesion, but possibly at the risk of distortion. I can modify the model a bit to increase strength in this specific area, but I don’t think I can get it strong enough based on how easily it failed. I’m considering printing with less infill to leave more holes and backfilling with something such as epoxy. However, most epoxy is rather brittle so this may not work.<\/p>\n\n\n\n

I’m open to ideas and suggestions! Feel free to comment below.<\/p>\n","protected":false},"excerpt":{"rendered":"

This is a continuation of the last post introducing the project. This project isn’t done (it isn’t strong enough), but feel free to play with things and download the files. I uploaded the latest STL,… [read more]<\/a><\/p>\n","protected":false},"author":1,"featured_media":6852,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[3],"tags":[257,252,60,260,258,18],"class_list":["post-6850","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-unicycling","tag-3dprinting","tag-fusion-360","tag-handlebar","tag-i3mk3s","tag-prusa","tag-unicycle"],"jetpack_featured_media_url":"https:\/\/www.corbinstreehouse.com\/blog\/wp-content\/uploads\/2021\/04\/IMG_6905-scaled.jpg","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/www.corbinstreehouse.com\/blog\/wp-json\/wp\/v2\/posts\/6850","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.corbinstreehouse.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.corbinstreehouse.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.corbinstreehouse.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.corbinstreehouse.com\/blog\/wp-json\/wp\/v2\/comments?post=6850"}],"version-history":[{"count":3,"href":"https:\/\/www.corbinstreehouse.com\/blog\/wp-json\/wp\/v2\/posts\/6850\/revisions"}],"predecessor-version":[{"id":6860,"href":"https:\/\/www.corbinstreehouse.com\/blog\/wp-json\/wp\/v2\/posts\/6850\/revisions\/6860"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.corbinstreehouse.com\/blog\/wp-json\/wp\/v2\/media\/6852"}],"wp:attachment":[{"href":"https:\/\/www.corbinstreehouse.com\/blog\/wp-json\/wp\/v2\/media?parent=6850"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.corbinstreehouse.com\/blog\/wp-json\/wp\/v2\/categories?post=6850"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.corbinstreehouse.com\/blog\/wp-json\/wp\/v2\/tags?post=6850"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}