HOW TO MAKE SPRINGS.docx

HOW TO MAKE SPRINGS.docx

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HOWTOMAKESPRINGS

HOWTOMAKESPRINGS

Therearethreethingsyou'llneedtoreadbeforeyougetstarted.First,theDISCLAIMER:

Thisdocumentisdesignedtoprovideinformationinregardtothesubjectmatterbeingcovered.Everyefforthasbeenmadetoensuretheaccuracyofitscontents.Howevertheremaybemistakes,bothtypographicalandincontent.Additionally,workinthemetaltradesimpliesanacceptanceoftheriskofinjury,loss,ordamage,thecauseofwhichisclearlybeyondthecontrolofthewriterofaworkonthesubject.Therefore,theauthorofthisdocumentacceptsnoresponsibilityorliabilitywhatsoeverforanyinjury,lossordamagesustainedbyareaderwho,havingreadthismaterial,thenseekstoapplywhatheorshehaslearnedtherein.

PleasereadtheTermsofUse.

Second,beforeyoustarttoworkwithspringwire,readthesectiononsafety.Whenyouhavereadthatsection,readitagain.Nokidding.

Andthird,aboutthisdocument:

I'vetriedtowriteforthebenefitofsomeonewhohas（orcangainaccessto）basichandandpowertools.Thesectionsofthedocumentarearrangedinlogicalorderpresumingaminimalknowledgeofthemetalworkingtradesingeneralorofspringmakinginparticular,andcross-linkedtoprovideaforwardpaththatleadsfromthispointthroughtheentiremanufacturingprocess.There'saglossaryofspringterminologyandanaddendum,whichshouldhelpyoutodefinetermsandfindadditionalresources.Wherepossible,I'veindicatedwheretofindadditionalinformationinthemainbodyofthetext.Mostofthecurrentmaterialrelatingtothesubjectiswrittenformechanicalengineers,buttherearesomeotherwriteupsI'veheardof,too--seetheaddendumforlinkstothese.

Initsfirstincarnation,thissitewasmadeinframes.Inthesecond,Ididawaywiththeframesforthesakeofdesignsimplicity.Myapologiestoanyonewholinkedto"frameset".Theothernewadditionisthesitemap,whichwillgiveyouabird's-eyeviewofthewholeshebang.Thisisnowthethirdincarnationandexceptforfresheningthelinksfromtimetotime,Iconsideritdone.Ifyouwanttohaveitasahandyreference,feelfreetodownloadthezippedversion.Lastly,thetextitselfisofverylimitedusewithoutthegraphics,andthereisno"text-only"versionofthissite.Soifyou'vegotyourgraphicsturnedoff,turn'emon,OK?

Anycommentsorsuggestionsforimprovementshouldbemadetoyourstruly.

INTRODUCTION

Thissectionwillgiveyousomebasicinformationaboutsprings,whattheylooklike,whattheirpartsare,andhowtheywork.

Ifyoualreadyknowaboutspringsandwanttogetrighttoit,bemyguest.

Therearethreebasictypesofsprings:

Compressionspringscanbefoundinballpointpens,pogosticks,andthevalveassembliesofgasolineengines.Whenyouputaloadonthespring,makingitshorter,itpushesbackagainsttheloadandtriestogetbacktoitsoriginallength.

Extensionspringsarefoundingaragedoorassemblies,vise-grippliers,andcarburetors.Theyareattachedatbothends,andwhenthethingstheyareattachedtomoveapart,thespringtriestobringthemtogetheragain.

Torsionspringscanbefoundonclipboards,underneathswing-downtailgates,and,again,incarengines.Theendsoftorsionspringsareattachedtootherthings,andwhenthosethingsrotatearoundthecenterofthespring,thespringtriestopushthembacktotheiroriginalposition.

SeetheGlossaryfordetaileddiagramsofthesetypesofsprings.

ForwardtoSpringDesign

SPRINGDESIGN

Ifyou'retryingtomakeaspringtoreplaceabrokenone,youdon'tneedtoknowawholelotaboutdesign.Ontheotherhand,ifyou'remakingaprototypeofamachine,forinstance,andyoudon'tknowexactlywhatyouwant,thenthispageisforyou.Hereyou'lllearnsomebasicdataaboutspringdesign,whichiswhatyou'llneedtoknowtomakeexactlythespringyouwant.

∙Generalprinciples

∙Mathematics

∙Designlimitations

∙Buyingdesign

GeneralPrinciples

Therearethreebasicprinciplesinspringdesign:

∙Theheavierthewire,thestrongerthespring.

∙Thesmallerthecoil,thestrongerthespring.

∙Themoreactivecoils,thelessloadyouwillhavetoapplyinordertogetittomoveacertaindistance.

Basedonthesegeneralprinciples,younowknowwhattodotochangethepropertiesofaspringyoualreadyhave.Forinstance,ifyouwanttomakeautomotivevalvespringsalittlestrongerthanstock,youcana）gotoaslightlyheavierwireandkeepthedimensionsandcoilcountthesame,b）decreasethediameterofthespring,keepingthewiresizeandcoilcountthesame,orc）decreasethenumberofactivecoils,keepingthewiresizeandspringdiameterthesame.Naturally,youcanalsogotoastrongermaterialtoachievethesameresult.

Now,whatifyou'remakingaspringfromscratch,withnothingtogooninthewayofasample?

Youcanengineeryourowndesign（seethenextsectionofthispageforthemath）,coilaspring,andthentestit.Ifit'swhatyouwant,fine.Ifit's,let'ssay,askoshtoostrong,thenyoucana）gotoalighterwire,b）openupthecoildiameter,orc）increasethenumberofactivecoilstogetaslightlyweakerspring.

Or,ifyouwanttomakethingsreallysimple,gototheAddendum,whereyou'llfindafewwebsitesthatofferonlinedesign!

Mathematics

Naturally,springdesignsoftwareisavailable--youcanfindoutwheretogetitintheAddendum.Forthepurists（orthosewhodon'twanttopayforaprogram）,here'saveryshortsummaryofthemathematicsofspringdesign.Theseequations,bytheway,aretakenfromTheNewAmericanMachinist'sHandbook,publishedbyMcGraw-HillBookCompany,Inc.in1955.Idon'tpretendtounderstandthem.

There'salotmoreinthewayofengineeringthatgoesintospringdesign:

theseareonlythebasicequations.Ifyou'reinterested,youcancontactsomeonewhomakesspringdesignsoftwareor（gasp!

）finditinthelibraryunderDeweyclassificationnumber621.824.

YoucanalsocontacttheSpringManufacturers'Institute:

theymakeahandy-dandyspringcalculator,suitableforsimpledesignwork,thatanyonecanlearntouse.Theyalsohavespringdesignsoftware,trainingclasses,andabunchmorestuff.Davesez,"Checkitout."

DesignLimitations

Dependingonwhatkindofspringyouwanttodesign,anddependingonwhereitwillbeused,yourdesignwillbelimited:

Forallsprings:

∙Aspringunderloadisstressed.Ifyouputtoomuchstressonaspring,itsshapewilldeformanditwillnotreturntoitsoriginaldimensions.

∙Thematerialfromwhichthespringismadewillhaveaneffectonthestrengthofthespring:

itwillalsohaveaneffectonhowmuchstressthespringwillwithstand.Thesectiononspringmaterialswilltellyoumoreaboutthis.

∙Whenyouheatspringwire（whichyoualwaysdo）,itmaychangeitsdimensions.Again,thesectiononmaterialswilltellyoumoreaboutthis.

Forcompressionsprings:

∙Ifthespringwillsetsolid（compressalltheway,sothatallthecoilstoucheachother）atthelimitofitstravel,thediameterofthewiretimesthenumberofcoilscannotbegreaterthanthespaceallowed,unlessyouwantthespringitselftoactasamechanicalstoptothemotion.

∙Springsthatoperateinahigh-temperatureenvironment（likeforinstanceinsideanengine）willneedtobemadeslightlylongertocompensateforthefactthattheheatmayhaveaneffectonthelengthofthespring.Thesectiononfinishingwilltellyoumoreaboutthis.

∙Asacompressionspringassumesaloadandshortens,thediameteroftheactivecoilswillincrease.Thisisonlyaproblemwhenthespringhastoworkinaconfinedspace.

Forextensionsprings:

∙Thereshouldbesomemechanicallimitonhowfarthespringwillextend,orthespringwillloseitsshapeandnotreturntoitsinitialconditionwithallcoilsclosed.

∙Extensionspringsoperatinginahigh-temperatureenvironmentmayhavetobecoiledextra-tight,astheheatwilltendtoweakenthespring.Thesectiononextensionspringswilltellyoumoreaboutthis.

Fortorsionsprings:

∙Whenatorsionspringsassumesaload,thediameterofthecoilbodywilldecrease.Ifthespringhassomethinginsidethecoil,itwillactasamechanicalstoptotheactionofthespring.

BuyingDesign

Ifyouwanttohaveamechanicalengineerdesignyourspring,yourbestbetistocallaspringshop.Youcanfindspringshopsinthephonebook.Ifyourphonebookdoesn'tlistany,gotothelibrary:

theyshouldhavephonebooksformajorcitieswherespringfactoriesare--tryDetroitorLosAngelesiftherearenoneinyourarea.

Aspringshopwillgenerallydothedesignworkforyouforasmallcharge.Theywillalsotrytogetyoutoletthemmakethespringforyou,whichyoumayormaynotwant.

Thesectiononspringshopswilltellyoumoreabouthowtheirbusinessoperates.Theaddendumwillgiveyoulinkstospringshops,suppliers,peoplewhomakespringdesignsoftware,andawholeslewofotherstuff.

SPRINGMATERIALS

Thissectionwilltellyouaboutthedifferentkindsofmaterialthatspringsaremadeoutof.Itwillalsotellyouwheretogetyourwire--makesureyoureadtheSafetysectionsoyouknowhowtohandleitsafelyonceyou'vegotit.

∙Typesofwire

∙Buyingwire

TypesofWire

Springsareusuallymadefromalloysofsteel.Themostcommonspringsteelsaremusicwire,oiltemperedwire,chromesilicon,chromevanadium,and302and17-7stainless.Othermaterialscanalsobeformedintosprings,dependingonthecharacteristicsneeded.Someofthemorecommonoftheseexoticmetalsincludeberylliumcopper,phosphorbronze,Inconel,Monel,and