{"id":703,"date":"2011-11-07T16:47:42","date_gmt":"2011-11-07T23:47:42","guid":{"rendered":"http:\/\/www.built-to-spec.com\/blog\/?p=703"},"modified":"2011-11-07T16:51:49","modified_gmt":"2011-11-07T23:51:49","slug":"modifying-the-tgy-s4505b-servo-for-continuous-rotation","status":"publish","type":"post","link":"http:\/\/www.built-to-spec.com\/blog\/2011\/11\/07\/modifying-the-tgy-s4505b-servo-for-continuous-rotation\/","title":{"rendered":"Modifying the TGY-S4505B Servo for Continuous Rotation"},"content":{"rendered":"<p>If you don't already know, continuous rotation servos are servos who's output shafts rotate freely and continuously rather than through a fixed range like a normal RC servo.\u00a0 They're great for all sorts of robotics projects and are pretty easy to make from your typical cheap RC servo with a few modifications.\u00a0 I picked up a few TGY-S4505B servos from Hobby King (which seem to be good servos for the price) for a project I'm working on and modified a few for continuous rotation so I thought I'd share some pics and an overview of the two ways to go about tricking the servo controller into thinking the servo is always centered.<\/p>\n<p>Here's a couple pictures of the\u00a0TGY-S4505B servo disassembled:<\/p>\n<p><a href=\"http:\/\/www.built-to-spec.com\/blog\/wp-content\/uploads\/2011\/11\/apart.jpg\"><img loading=\"lazy\" class=\"aligncenter size-medium wp-image-705\" title=\"apart\" src=\"http:\/\/www.built-to-spec.com\/blog\/wp-content\/uploads\/2011\/11\/apart-300x258.jpg\" alt=\"TGY-S4505B servo disassembled\" width=\"300\" height=\"258\" srcset=\"http:\/\/www.built-to-spec.com\/blog\/wp-content\/uploads\/2011\/11\/apart-300x258.jpg 300w, http:\/\/www.built-to-spec.com\/blog\/wp-content\/uploads\/2011\/11\/apart.jpg 1024w\" sizes=\"(max-width: 300px) 100vw, 300px\" \/><\/a><a href=\"http:\/\/www.built-to-spec.com\/blog\/wp-content\/uploads\/2011\/11\/back_off.jpg\"><img loading=\"lazy\" class=\"aligncenter size-medium wp-image-706\" title=\"back_off\" src=\"http:\/\/www.built-to-spec.com\/blog\/wp-content\/uploads\/2011\/11\/back_off-300x269.jpg\" alt=\"TGY-S4505B disassembled\" width=\"300\" height=\"269\" srcset=\"http:\/\/www.built-to-spec.com\/blog\/wp-content\/uploads\/2011\/11\/back_off-300x269.jpg 300w, http:\/\/www.built-to-spec.com\/blog\/wp-content\/uploads\/2011\/11\/back_off.jpg 1024w\" sizes=\"(max-width: 300px) 100vw, 300px\" \/><\/a><\/p>\n<p>First off, you'll need to eliminate anything that mechanically limits the output shaft from turning all the way around.\u00a0 This means removing the tab that limits the motion of the servo on the output gear, which I filed off (compare with the first photo above where the tab was still intact):<\/p>\n<p><a href=\"http:\/\/www.built-to-spec.com\/blog\/wp-content\/uploads\/2011\/11\/tab_gone.jpg\"><img loading=\"lazy\" class=\"aligncenter size-medium wp-image-709\" title=\"tab_gone\" src=\"http:\/\/www.built-to-spec.com\/blog\/wp-content\/uploads\/2011\/11\/tab_gone-300x270.jpg\" alt=\"\" width=\"300\" height=\"270\" srcset=\"http:\/\/www.built-to-spec.com\/blog\/wp-content\/uploads\/2011\/11\/tab_gone-300x270.jpg 300w, http:\/\/www.built-to-spec.com\/blog\/wp-content\/uploads\/2011\/11\/tab_gone.jpg 1024w\" sizes=\"(max-width: 300px) 100vw, 300px\" \/><\/a>Next we'll need to remove the potentiometer or decouple it from the output gear.\u00a0 The potentiometer looks glued in pretty well, so I cut off the top and filed it down as well:<\/p>\n<p><a href=\"http:\/\/www.built-to-spec.com\/blog\/wp-content\/uploads\/2011\/11\/pot_filed.jpg\"><img loading=\"lazy\" class=\"aligncenter size-medium wp-image-707\" title=\"pot_filed\" src=\"http:\/\/www.built-to-spec.com\/blog\/wp-content\/uploads\/2011\/11\/pot_filed-300x253.jpg\" alt=\"\" width=\"300\" height=\"253\" srcset=\"http:\/\/www.built-to-spec.com\/blog\/wp-content\/uploads\/2011\/11\/pot_filed-300x253.jpg 300w, http:\/\/www.built-to-spec.com\/blog\/wp-content\/uploads\/2011\/11\/pot_filed.jpg 1024w\" sizes=\"(max-width: 300px) 100vw, 300px\" \/><\/a><\/p>\n<p>Next you'll need to fool the controller into thinking the servo is centered all the time.\u00a0 You can do this one of two ways, by centering the feedback potentiometer and locking it in place somehow (glue most likely) or by replacing the potentiometer with 2 resistors of equal value.\u00a0 The second method requires a little more work on your part, but you can always fall back to substituting resistors if locking the potentiometer didn't work.<\/p>\n<p>The stock potentiometer is a 5k ohm but you should be able to substitute in any reasonably sized (2k-10k or greater), equal value resistors for the potentiometer as shown here:<\/p>\n<p><a href=\"http:\/\/www.built-to-spec.com\/blog\/wp-content\/uploads\/2011\/11\/resistor_replacement.jpg\"><img loading=\"lazy\" class=\"aligncenter size-medium wp-image-708\" title=\"resistor_replacement\" src=\"http:\/\/www.built-to-spec.com\/blog\/wp-content\/uploads\/2011\/11\/resistor_replacement-300x189.jpg\" alt=\"\" width=\"300\" height=\"189\" srcset=\"http:\/\/www.built-to-spec.com\/blog\/wp-content\/uploads\/2011\/11\/resistor_replacement-300x189.jpg 300w, http:\/\/www.built-to-spec.com\/blog\/wp-content\/uploads\/2011\/11\/resistor_replacement.jpg 1024w\" sizes=\"(max-width: 300px) 100vw, 300px\" \/><\/a>All that's left to do now is to reassemble and verify that everything rotates freely and the output shaft doesn't move if you attempt to center the servo with whatever controller you happen to be using.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>If you don't already know, continuous rotation servos are servos who's output shafts rotate freely and continuously rather than through a fixed range like a normal RC servo.\u00a0 They're great for all sorts of robotics projects and are pretty easy to make from your typical cheap RC servo with a few modifications.\u00a0 I picked up [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[35],"tags":[],"_links":{"self":[{"href":"http:\/\/www.built-to-spec.com\/blog\/wp-json\/wp\/v2\/posts\/703"}],"collection":[{"href":"http:\/\/www.built-to-spec.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.built-to-spec.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.built-to-spec.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/www.built-to-spec.com\/blog\/wp-json\/wp\/v2\/comments?post=703"}],"version-history":[{"count":6,"href":"http:\/\/www.built-to-spec.com\/blog\/wp-json\/wp\/v2\/posts\/703\/revisions"}],"predecessor-version":[{"id":713,"href":"http:\/\/www.built-to-spec.com\/blog\/wp-json\/wp\/v2\/posts\/703\/revisions\/713"}],"wp:attachment":[{"href":"http:\/\/www.built-to-spec.com\/blog\/wp-json\/wp\/v2\/media?parent=703"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.built-to-spec.com\/blog\/wp-json\/wp\/v2\/categories?post=703"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.built-to-spec.com\/blog\/wp-json\/wp\/v2\/tags?post=703"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}