{"id":2291,"date":"2012-09-29T00:07:00","date_gmt":"2012-09-29T04:07:00","guid":{"rendered":"http:\/\/www.etotheipiplusone.net\/?p=2291"},"modified":"2012-09-29T00:49:29","modified_gmt":"2012-09-29T04:49:29","slug":"the-pre-maker-faire-madness-of-chibikart","status":"publish","type":"post","link":"https:\/\/www.etotheipiplusone.net\/?p=2291","title":{"rendered":"The Pre-Maker Faire Madness of Chibikart"},"content":{"rendered":"<p>Along with most of the rest of <a href=\"http:\/\/miters.mit.edu\/\" target=\"_blank\">MITERS<\/a>, I&#8217;ll be party vanning down to the <a href=\"http:\/\/makerfaire.com\/newyork\/2012\/index.html\" target=\"_blank\">New York Maker Faire<\/a> on&#8230;. well, <em>now<\/em>. It&#8217;s this weekend.<\/p>\n<p>Like last year, I&#8217;m hauling an immense pile of MITERS cargo in addition to a few hapless freshmen and sophmores (who I think count as cargo anyway?). Last time, I brought <a href=\"https:\/\/www.etotheipiplusone.net\/?p=1570\" target=\"_blank\">Landbearshark<\/a>. This time, I&#8217;ll be bringing something about equal in mass but a little more fun: <a href=\"https:\/\/www.etotheipiplusone.net\/?page_id=1987\" target=\"_blank\">Double<\/a> <a href=\"https:\/\/www.etotheipiplusone.net\/?page_id=2036\" target=\"_blank\">Chibis<\/a>! Tagging along also because they fill space efficiently will be <a href=\"https:\/\/www.etotheipiplusone.net\/?page_id=2128\" target=\"_blank\">RazEr REV2<\/a> and <a href=\"https:\/\/www.etotheipiplusone.net\/?p=2069\" target=\"_blank\">Kitmotter Display Stand<\/a>.<\/p>\n<p>There go any chance of flying down the hillsides at the NY Hall of Science though.<\/p>\n<p>The Chibikarts, unlike most of everything I build, have been working rather reliably. Chibikart 1 suffered 2 broken motors when MITERS used it for Orientation activities &#8211; I&#8217;m not really sure went on, but the front two motors were just totally unresponsibe &#8211; but the controllers were fine. However, Chibikart 1 still worked with the 2 rear motors, so that&#8217;s been its demo state for most of this month.<\/p>\n<p>Last week I decided to crack them open in anticipation of repairs for the NYMF.<\/p>\n<p style=\"text-align: center;\"><a href=\"\/pics\/ck\/chibi60-mid.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter\" src=\"\/pics\/ck\/chibi60-mid.jpg\" alt=\"\" width=\"512\" height=\"384\" \/><\/a><\/p>\n<p>Well damn. It looks like my somewhat hastily-soldered phase star-point connections exploded. The solder joints became little balls of solder &#8211; indicative of a serious current overload or something. Either way, the damage to both of the motors was similar, so I just re-terminated them. I coated the windings in a thick layer of polyurethane varnish that the high-voltage crew at MITERS like to seal their Tesla Coil secondaries with.<\/p>\n<p>A few days ago, Chibikart1 was involved in a&#8230;. &#8220;filming accident&#8221;.<\/p>\n<p><iframe loading=\"lazy\" src=\"http:\/\/www.youtube.com\/embed\/fBeHQr4Q1lY?list=UU8nPyF_ceT0sirYhZWXc_9g&amp;hl=en_US\" frameborder=\"0\" width=\"640\" height=\"360\"><\/iframe><\/p>\n<p>While I was in the middle of the Poorly Coordinated Death Spiral, the right front motor lost power and started smelling <em>real funny<\/em>. Upon opening the motor again, I discovered that the windings were actually not burnt &#8211; but just shorted. As I unwound the stator,huge chunks of the magnet wire insulation were flaking off and coming apart. I was literally pulling lengths of bare wire from the stator.<\/p>\n<p>My suspicion is that the urethane varnish damaged the insulation of the wire either by being too tenacious (typical cheap magnet wire with sub-300 celsius insulation rating are coated with polyurethane-based enamels) which caused the insulation to prefer the urethane coat instead of the wire, or the solvent was too strong and dissolved or damaged the insulation chemically.<\/p>\n<p>Bottom line is, <em>don&#8217;t seal your motor with urethane if it has wires made of urethane<\/em>. On a similar note, titanium screws in titanium threads will degenerate into the slightly less useful case of a solid blob of titanium.<\/p>\n<p style=\"text-align: center;\"><a href=\"\/pics\/ck\/chibi62-mid.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter\" src=\"\/pics\/ck\/chibi62-mid.jpg\" alt=\"\" width=\"512\" height=\"384\" \/><\/a><\/p>\n<p>What was worse, actually, was that the urethane sealed the whole stator into a solid mass of wires. I could not hope to ever unwind this without baking or chemically destroying the urethane in some way. The magnet wire strands just broke off as I tried to pull on them.<\/p>\n<p>I had to rewind both of the front motors, which didn&#8217;t take that long since I was used to it:<\/p>\n<p style=\"text-align: center;\"><a href=\"\/pics\/ck\/chibi61-mid.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter\" src=\"\/pics\/ck\/chibi61-mid.jpg\" alt=\"\" width=\"512\" height=\"384\" \/><\/a><\/p>\n<p>To give the wires one more layer of protection, this time I insulated the crossing strands with some Kapton layers.<\/p>\n<p style=\"text-align: center;\"><a href=\"\/pics\/ck\/chibi63-mid.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter\" src=\"\/pics\/ck\/chibi63-mid.jpg\" alt=\"\" width=\"512\" height=\"384\" \/><\/a><\/p>\n<p>Completed rewind. I decided to group the star point connections into one termination this time instead of attempting to solder a ring of wire around the outside of the windings. The whole mess was coated in epoxy (like I should have done to start with&#8230;), and Chibikart 1 is now kicking again.<\/p>\n<p>Chibikart2\/DPRC has received no mechanical mods or upgrades, but I did jump the shunt on the 350W Jasontrollers a bit to give it some more punch. Because of the ~25A constant current limit of the Jasontrollers, DPRC is actually a little anemic despite having higher potential power. To really use those motors, I&#8217;d need some sensor boards (hmm, I wonder where I could get some) and use higher-current <a href=\"http:\/\/kellycontroller.com\/mini-brushless-controller-kbs12v-72v-c-60.html\" target=\"_blank\">Kelly controllers<\/a>.<\/p>\n<p>Come see Chibikart and DPRC (and RazEr &amp; co.) at the MITERS display area in the Hackerspaces area (Zone B) at NYMF!<\/p>\n<p>Oh yes, a preview of things to come:<\/p>\n<p style=\"text-align: center;\"><a href=\"\/pics\/moter\/rage28.jpg\"><img decoding=\"async\" class=\"aligncenter\" src=\"\/pics\/moter\/rage28-mid.jpg\" alt=\"\" width=\"512\" \/><\/a><\/p>\n<p>&nbsp;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Along with most of the rest of MITERS, I&#8217;ll be party vanning down to the New York Maker Faire on&#8230;. well, now. It&#8217;s this weekend. Like last year, I&#8217;m hauling an immense pile of MITERS cargo in addition to a few hapless freshmen and sophmores (who I think count as cargo anyway?). Last time, I [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[90,92,5],"tags":[],"class_list":["post-2291","post","type-post","status-publish","format-standard","hentry","category-chibikart","category-d-p-r-chibikart","category-project-build-reports"],"_links":{"self":[{"href":"https:\/\/www.etotheipiplusone.net\/index.php?rest_route=\/wp\/v2\/posts\/2291","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.etotheipiplusone.net\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.etotheipiplusone.net\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.etotheipiplusone.net\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.etotheipiplusone.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=2291"}],"version-history":[{"count":5,"href":"https:\/\/www.etotheipiplusone.net\/index.php?rest_route=\/wp\/v2\/posts\/2291\/revisions"}],"predecessor-version":[{"id":2295,"href":"https:\/\/www.etotheipiplusone.net\/index.php?rest_route=\/wp\/v2\/posts\/2291\/revisions\/2295"}],"wp:attachment":[{"href":"https:\/\/www.etotheipiplusone.net\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=2291"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.etotheipiplusone.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=2291"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.etotheipiplusone.net\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=2291"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}