We live in a world of plastic consumer goods held together with screws.\u00a0 These are thread-forming screws with sharp threads that cut threads into unthreaded holes in the molded plastic parts with the intention of never being removed.\u00a0 Unfortunately sometimes removal is necessary for repair or, increasingly, simply to replace batteries in inexpensive goods.\u00a0 The problem is that simply screwing the fasteners back in cuts new threads each time, destroying the integrity of the plastic threads and the strength of the joint.\u00a0 All is not lost, however:<\/p>\n
There is a technique to reinstall thread-forming screws without damage.\u00a0 Place the screw at the start of the hole on the end of your screwdriver.\u00a0 Using the tips of your fingers loosely on the shaft of the screwdriver, turn it backwards, i.e. counterclockwise, with only the weight of the screwdriver pushing on the screw.\u00a0 Since the screw is turning backwards the sharp threads will not cut into the plastic.\u00a0 Turn until you feel or hear a light click – immediately stop.\u00a0 This means that the screw thread has dropped into the start of the original plastic thread channel.\u00a0 Now turn the shaft gently forwards, clockwise, to make sure the screw threads slide in smoothly.\u00a0 If so,\u00a0 run the screw in.\u00a0 Do not over torque it.\u00a0 When you feel it bottom out, stop turning.\u00a0 That will be firm enough for most plastic assemblies.\u00a0 If it does not turn easily or feel smooth,\u00a0 back off and turn backwards feeling for the click and try again.\u00a0 Some screws are called double lead or hi-lo and have two thread heights.\u00a0 In that case you will get two clicks, one lighter and one harder.\u00a0 The harder click is the proper thread channel.\u00a0 In general it is a good idea to turn backwards at least a full to turn to find the most definite click.\u00a0 This can also make the best of an already compromised hole.<\/p>\n
This technique works as well for reinstalling wood screws without damaging the threads in the wood.\u00a0 It also works well to avoid cross threading things like wide-mouth cosmetic jars and threaded photographic filters, especially ones made from aluminum.<\/p>\n
While I’ve done this for decades, I was reminded that it is not a universally known technique while working on my Dyson vacuum.\u00a0 These are pricey vacuums with the subassemblies held together internally with screws that you really want to be careful with.\u00a0 The subassemblies themselves snap to each other.\u00a0 Dyson only sells subassemblies on their web site that can be replaced without removing and replacing screws.\u00a0\u00a0 As all I needed were beater bars and not the entire floor head I kept looking.\u00a0 I found the smaller parts I needed at evacuum.com for much less than the assembly cost.\u00a0 After carefully removing the old parts and installing the new screwed on parts without damage I realized why Dyson only sold snap-on parts to consumers but sold smaller parts to dealers.\u00a0 They did not want consumers to inadvertently\u00a0 damage their units trying to repair them, but assumed repair shops would know how to do this safely.<\/p>\n
Hence this post.\u00a0 I hope it helps you with future plastic and wood repairs.<\/p>\n
Please leave comments using the post in my comments category.<\/p>\n","protected":false},"excerpt":{"rendered":"
We live in a world of plastic consumer goods held together with screws.\u00a0 These are thread-forming screws with sharp threads that cut threads into unthreaded holes in the molded plastic parts with the intention of never being removed.\u00a0 Unfortunately sometimes removal is necessary for repair or, increasingly, simply to replace batteries in inexpensive goods.\u00a0 The … Continue reading “Reinstalling screws into plastic”<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[5],"tags":[80,79],"class_list":["post-580","post","type-post","status-publish","format-standard","hentry","category-engineering","tag-plastic","tag-repair"],"_links":{"self":[{"href":"https:\/\/www.irrelevant-tech.com\/index.php\/wp-json\/wp\/v2\/posts\/580","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.irrelevant-tech.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.irrelevant-tech.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.irrelevant-tech.com\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.irrelevant-tech.com\/index.php\/wp-json\/wp\/v2\/comments?post=580"}],"version-history":[{"count":10,"href":"https:\/\/www.irrelevant-tech.com\/index.php\/wp-json\/wp\/v2\/posts\/580\/revisions"}],"predecessor-version":[{"id":792,"href":"https:\/\/www.irrelevant-tech.com\/index.php\/wp-json\/wp\/v2\/posts\/580\/revisions\/792"}],"wp:attachment":[{"href":"https:\/\/www.irrelevant-tech.com\/index.php\/wp-json\/wp\/v2\/media?parent=580"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.irrelevant-tech.com\/index.php\/wp-json\/wp\/v2\/categories?post=580"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.irrelevant-tech.com\/index.php\/wp-json\/wp\/v2\/tags?post=580"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}