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The first edition of the RepRap Magazine.
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REPRAP MAGAZINEWWW.REPRAPMAGAZINE.COM
Practical exploration of 3D printing
Issue1Interviews - Pro tips - Reviews Diy projects - Tutorials - GalleriesFe
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ry 2
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Issue1Interviews - Pro tips - Reviews Diy projects - Tutorials - GalleriesFe
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ry 2
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Slicer review & comparisonInterview with Adrian BowyerRepetier part 1: CommunicationTaxonomy of Z axis artifacts
Issue nº 1
REPRAP MAGAZINEWWW.REPRAPMAGAZINE.COM
WelcometothefirsteditionofRepRapMagazine!Thisprojectisbroughttoyoubyasmallteamofenthusias-ticandmotivatedusers,expertsanddevelopersofRepRap3Dprintersproject.Weaimtodevelopthisprojectinanopenway,workingonacloserelationshipwithourreaders. Forthisfirstissue,asourcovermentions,wefocusthemainarticleonslicers,butalsotakeacloselookatthepro-tipoftheissue,aswellasthesoftwaresectionwherewestartase-riesofarticlesdedicatedtoRepetier. WhileitishardtochoosethehighlightofthisissuewewouldhavetopointtoourinterviewwithAdrianBowyer,thepersonwhostartedtheRepRapprojectandwhowaskindenoughtogiveusaninterviewforourfirstedition. Withallthatsaid,wehopethatyouenjoythiseditionandstaytunedonthisproject.
Paulo GonçalvesEditor
Web:
www.reprapmagazine.com
Magazineteam
Developers
PauloGonçalvesGaryHodgsonRichardHorneViktorDirksCameronMacLachlan
Contacts
To the readers
Wewanttobehaveaclosere-lationshipwithourreaders.Forthatweencourageyoutoparticipateinthisproject.Sendusphotosofyourbestprintsandyoursetupforpos-siblepublicationtoourdedicatedemailatgeneral@reprapmagazine.com.Alsotakepartatthediscussionatthehttp://forums.reprap.org/list.php?305.
To the contributors
Thisisanopenmagazine,andforthatweencourageyoutosubmityourarticlesforpossi-blepublicationstoouremailatgeneral@reprapmagazine.com.IfyouarealsoadeveloperofatoolthatRepRapusersuseyoucanalsosendanemailtobeinourdatabaseforfuturecon-tacts.
Independent
Weare100%independent.Themanufactersoftheproductsfeatureddonotdetermineourcontentnorouropinions.
Our mission
ReprapMagazine
RepRapMagazine
Thisissuescovercredits:
DesignPaulo Gonçalves3DslicermodelNebule3DUpsetladymodelOnur AYTEKIN
RepRapForums
Contents
This issues team
Follow us, and get in touch, atwww.reprapmagazine.com
4 Intheworks Ifyouliketoliveonthecuttingedge thentheseprojectsmightbeforyou.
8 Interview WithAdrianBowyer.
14 Feature Slicersreview.
29 Pro-tips TaxonomyofZaxisartifacts.
33 Software Repetierpart1-Communication.
38 Beginnerspace WhatisaRepRap3Dprinter?
RolandLittwin RichardHorneGaryHodgson RichCameron PauloGonçalves
ManyintheMakercommunityarealwayslook-ingfornewandinterestingprojectstofollowandperhapstakepartin,andsothissectiongivesabrieflookatup-and-comingprojectsfrominandaroundtheRepRapcommunity.
It should be noted that unless otherwise stated these projects are most definitely works in progress and not ready for general consumption.
Ifyouliketoliveonthecuttingedgethentheseprojectsmightbeforyou.
by Gary Hodgson In t
he w
orks
In the works
5REPRAPMAGAZINE
Creating3Dmodelsviaascriptinglan-guagebringsseveraladvantages:precisedi-mensions,modularisation,andbeingabletotakeadvantageofprogrammingconstructstoeffortlesslygeneratecomplexshapes.ChiefamongstthecurrentofferingsisOpenSCAD[1],afree,opensource,multi-platformapplica-tionwithit’sownsyntaxforcreatingmodels.Inspiredbythis,andotherseffortstobringCSGmodellingtothebrowser,namelyOpen-JsCad[2],MarkMoissettehasdevelopedCof-feeSCADwhichallowstheuseofCoffeeScriptasthescriptinglanguage.CoffeeScript[3]isthecurrentdarlingofthewebdevelopmentcommunity-alanguagewhichcompilestoJavascriptandbringsaclearersyntax,plussomesugar,tothetable.ThisalsomeansthatplainoldJavascriptisvalidaswell.
SowhataretheadvantagesofCof-feeSCADoverOpenSCAD?Thefirstiszeroinstall.CoffeeSCADrunsinthebrowserandisonlyahyperlinkaway.Wanttoquicklyde-signapartwhilstawayfromyourPC?CSGdesigningisavailablewhereverthereisaninternetconnectionandabrowserthatsup-portsWebGL.However,thisbringswithitaninterestingchallenge,namelywheredothefilesgetsavedto.CurrentlytheyarestoredinthebrowserusingtheHTML5storagefeature,andMarkisworkingonalternativesolutionstosavefilesinanonlinerepository,orlocally,viaasmall,optionalbackend,forthosenotwishingtohaveeverythinginthecloud. ThenextadvantageisthepowerofCof-fee/Javascript.OpenSCAD’ssyntaxallowstheusertodoalot,butislimitedinseveralrespects:runtimevariablesandobjectsare
missingforexample.Havingamaturescript-inglanguageavailableopensupawholerangeofoptions,suchasdynamicarraysandobject-orientedprogramming.
CoffeeSCADhasseveraladditionalfea-tures,includingreal-timevisualisationup-dates,projectorganisation,andBOMgenera-tion. Thereisalsoafurther,geeky,andper-hapsslightlylessobvious,advantage.Open-SCADiswritteninC++whichhasaconsider-ablelearningcurveandareputationforbeingaformidablelanguagetomaster.ProducingasimilarapplicationinCoffeeScriptmayat-tractotherstojoinindevelopmentbyloweringthebarrierstoentry.Developingforsuchaweb-basedapplicationisdecidedlyeasierthannativeC++applications,ifonlybecausethebuildrequirementsaresomuchlower. Theprojectisstillunderheavydevelop-mentbutademosystem[4]isalreadyavail-abletoplaywithandthesourcecodeisavail-ableundergithub[5]forbrowsingorhackingon.Progresscanbefollowedviathededicat-edGoogle+page[6].
[1]http://www.openscad.org/[2]http://joostn.github.com/OpenJsCad/[3]http://coffeescript.org/[4]http://kaosat-dev.github.com/CoffeeSCad/[5]https://github.com/kaosat-dev/CoffeeSCad[6]https://plus.google.com/u/0/117965920069380418940
Mark Moissette
https://plus.google.com/CoffeeSCad
https://github.com/kao-sat-dev/CoffeeSCad
CoffeeSCAD
In the works
6REPRAPMAGAZINE
WhatstartedasaforkofCura[1],foraddingawebinterface,hasgrownandde-velopedintoit’sownfully-fledgedweb-basedcontrollerfor3Dprinters.GinaHäu-ßgestartedworkonwhatwasorigi-nallycalledPrinterWebUIattheendof2012,severaliterationslaterithasanewname,anewhomeandevenafunkynewlogo. Forthoseuserswhohaveadedi-catedlaptoporPCattachedtotheirprinter,awebinterfaceallowsthemtocheckonandcontroltheprintfromaremotemachine.Someofthedesktopapplicationshavestartedintroducingwebinterfaces,forexampleKliment’sPrintrun,butOctoPrintditchesthelo-calinterfacecompletelyinpreferenceforawebapplication. SuchaninterfaceisalsoideallysuitedforasetupusingtheRaspberryPiboardasprintercontroller,andtheinstructionsontheOctoPrintGithubpage[2]explainhowtosetthisup. Theinterfacehasmanyofthefea-turesexpectedbytoday’scontrollers:pausingandcancellingofprints;joggingoftheaxes;statusofthecurrentprint;sendingcommandstotheprinter,etc. Anotherfeaturethatissuretobeusefulforcontrollingaprinterremotelyistheabil-itytostreamfromawebcam,showingtheprogressofyourprint.Nomatterhowreli-ableyourprinterappearstobe,accidentsandfailscanhappenatanytime,andbeingabletomonitortheprogressoftheprintcertainlyaddsthatpieceofmind. Thewebcamcanalsobeusedtotaketimelapsemoviesoftheprintemerging.This
isnotonlyusefulforshowingoffyourprinterinaction,butalsoforpotentiallyanalysingthecauseofprintfailures.JasonGullickson’sre-viewofOctoPrinthasagreatexampleofhowaseeminglygoodprintturnsbadjustastheendwasinsight[3]. ThepaceofdevelopmentisbriskandsoGinarecommendstothosewishingtotestoutthenewstufftotakeabuildfromthe“devel”branchonGithub.Oncethefeatureiscom-pleteitismergedintothemorestablemasterbranch,readyforgeneralconsumption.AtthisstagetheprojectissuitablefortestingandGinaisactivelylookingforfeedback,par-ticularlyfromawiderangeofprintertypes.
ProgressoftheprojectcanbefollowedoverOctoPrint’sdedicatedGoogle+page[4].
[1]https://github.com/daid/Cura[2]https://github.com/foosel/OctoPrint[3]http://www.gullicksonlaboratories.comhttps://plus.google.com/u/0/110130855001142142895/posts
Gina Häußge
https://plus.google.com/OctoPrint
https://github.com/foosel/OctoPrint
OctoPrint
In the works
7REPRAPMAGAZINE
Resin-based3Dprintersopenupawholenewlevelofhigh-resolutionprints.Howeverthereareseveralkeyfactorsholdingbackwidespreadadoption:thecostofresin,andthelackofaffordable,opensourcedesigns.JustinHawkinsisattemptingtotacklethelatterbydevelopingalow-costSLA(Stereo-lithography)printerwhichwillbemadeopenfortheRepRapand3Dprintingcommunity. Stereolithographyhasbeenaroundsincethe1980’sbutpatentsandhighoperatingcostshavemeantthatithasonlyrecentlygarneredtheattentionoftheDIYcrowd.In2011,RobHopelesspostedanInstructable[1]detailinghowtobuildahome-madeSLAprinter,capturingtheimaginationofenthusi-astseverywhere.Sincethentherehavebeenseveralprojectsemerge,eitherusinglaserse.g.therecentKickstarterbasedcampaignfromFormLabs,orusingDLPprojectors,suchasthesuccessfullyfundedB9Creator[3]. WiththeexceptionoftheB9Creator,whosesourcedesignsaresupposedtobecomeavailableoncealltheKickstarterunitshaveshipped,thereislittleintermsofopensourceoptionsfortheMakermovement.Thelemon-curryprojectaimstoprovideinformationforthosewishingtobuildaDLPprinter,butcon-tainsnodetailedplans,andtheRepRappro-jecthasfocussedalmostexclusivelyonFDMprinting.
Justin’shopesareforasub-$1000,opensourceSLAprinterthatcouldbeapartoftheRepRapstable.Itconsistsprimarilyofofftheshelfpartssoastomakesourcingthemaseasyaspossible,andthecustomparts-suchasthelaser-cutcase,customelectronicsand
printedparts-willhavethedesignfilesmadeavailableforpeopletosourcethemselves.Heisalsoexpectingtoselltherequiredcompo-nentsviaaweb-shop,andisconsideringdoingafundingcampaigntobringtheprintertoawideraudienceatthebestpricepossible. ThecurrentversionconsistsofeletronicsbasedonaArduinoshield,alaRAMPS,whitchcontrolthelasergalvanometers.Thisisbeingredesignedintoamoreeffcient, and cheaperstandaloneboardwiththehelpofRepRapregular,Kliment.AcustomversionofMarlinprovidesthefirmware.
Theprojectiscurrentlyinintensivede-velopmentandwhilstprogressisquickthereisstillmuchtobedonebeforetheprinterseesthelightofday.Chiefamongstthethingslefttodoissourceandtesttheperfectresin,ofwhichabulkordershouldbringdownthecostsfortheend-users.
Justinadds:“OnceIreleasethedesign,Ilookforwardtoseeingwhereeveryonecantakethedesign,andjusthowfarwecantakeOpenSourceHighResolutionprinting.”Wecanonlyagree,andlookforwardtoseeingtheresults,andenjoyingthebenefits,ofhishardwork.
[1]http://www.robhopeless.com[2]http://formlabs.com[3]http://b9creator.com[4]http://code.google.com/p/lemoncurry
Justin Hawkins
https://plus.google.com/JustinHawkins
sLAMPS
Adrian Bowyer (English pronunciation: /ˈboʊjər/) is a British engineer andmathematician,formerlyanacademicattheUniversityofBath.
In1977hejoinedtheMathematicsDepartmentattheUniversityofBath.ShortlyafterthathereceivedadoctoratefromImperialCollegeLondonforresearchinfriction-inducedvibration.WhilstworkingintheMathematicsDepartmentheinvented(atthesametimeasDavidWatson)thealgorithmforcomputingVoro-noidiagramsthatbearstheirnames(theBowyer–Watsonalgorithm).
Hethenspenttwenty-twoyearsasa lecturerthensenior lecturer intheMe-chanicalEngineeringDepartment at theUniversity ofBath.He retired fromacademiclifein2012,thoughheisstilladirectorofthecompanyRepRapPro-fessionalLtd.HeinventedtheRepRapProject-anopen-sourceself-replicating3Dprinter.TheGuardiansaidofthis,"[RepRap]hasbeencalledtheinventionthatwillbringdownglobalcapitalism,startasecondindustrialrevolutionandsavetheenvironment..."[
AdrianBowyerFromWikipedia,thefreeencyclopedia
Inte
rvie
w
InterviewAdrian Bowyer
Interview with
Adrian Bowyer
The RepRap project started at Bath University, how exactly did it come about? Did the idea originate from yourself or did it come out of discussions with the University?
Despitethedictatesofmodesty,Ihavetosaythattheideawasentirelymine.Likemostideas,itwasaconvergenceofseveralpreviousideascomingtogether;here’salist,tidiedandfictionalisedbytheunconsciousprocessesofrecollection:
1. Ihavebeen interested in the ideaofartificialreplicatorssincechildhood. Ican’trememberwherethatcamefrom.
2.Aroundtheturnofthecentury,BathUniversitygotanequipmentgrant,andIsug-gestedthattheyspenditontwo3Dprinters.Thiswas nothing to dowith Item1. - I justwantedaccesstothemtomakethings.
3.AssoonasthemachinesarrivedIre-alisedthathere,atlast,wasamanufacturingtechnologythatwaspowerfulenoughtorepli-cateasignificantfractionofitself.
4. I also realised that a self-replicatingmachinehadtobeasolidDarwiniansuccess,independently of superficial and ephemeralfrothlikemereeconomics.
5.Idecidedthatthewaytodothiswastocopyanevolutionarilystablestrategyfromna-ture.TheoneIchosewasthemutualistsym-biosisbetweentheflowersandtheinsects,asIhavedescribedelsewhere.
6.AlmostassoonasIhadtheideaIre-alisedthatitwasverypowerful,andthattheonlyway to prevent that power from fallingintothewronghandswastogiveittoevery-one.
7.Literallyminutesafter I thought thatIrealisedthatyouhavetogiveanyself-rep-licating device away anyway, otherwise youputyourselfinaneternalbattletryingtostoppeopledoingwithyour idea theone thing itwasintendedtodo.
Items4.through7.wherewhatmademestartRepRapasopen-sourcefromitsverybe-ginning.
9REPRAPMAGAZINE
InterviewAdrian Bowyer
In the interest of others who may wish to at-tempt something similar, how did you convince the University to support the project? Was the indirect educational effect suffcientt
ItoldthemwhatIwasgoingtodo.Aca-demicfreedommeans(interalia)thattheindi-vidualacademichasabsolutediscretionoverhowtheydisseminatetheresultsoftheirre-search.Itisusuallyacademiccupidity(ratherthan Universities’ bureaucracy) that causesacademicsto,forexample,pursuepatentsbe-forepublication. Butanyway,myUniversitywashappywithmydecision,whichmore-or-lesscametothemasafaitaccompli.
What does your recent retirement from the Uni-versity entail for the project there? Will it continue under the direction of other staff and the students or will it be closed down?
There are other staff still pursuing as-pectsoftheproject. Mostofthiswork isofthe form “Application of RepRap to ProblemX”.
The project started with several key tenets which marked it as unique amongst perhaps similar endeavours (the DIY CNC scene for example), namely: the goal of self-replication; the GPL; and the “Wealth Without Money” essay. These, together with the pro-ject’s academic roots, defined the project as part of a much wider, more ambitious and perhaps philosophi-cal, scheme. Considering the recent commercialisa-tion, and associated hype, surrounding 3D printing, do you feel that this is a natural phase for the project to be going through, and one that ultimately supports the original goals? Or do you feel this is a distraction which must be endured before the project regains its original focus?
Moretheformerthanthelatter.Ialwaysthought that, if RepRap went anywhere, itwouldbecomeparasiticoncommerce. An old friend ofmine is highly amusedwheneverhevisitsandIsay,“IjusthavetogoandsettheRepRapsprinting.Won’tbelong.”
“Yourpredictionhascometrue,”hesays.“You always said that RepRapwould entrappeoplebymakingthemwanttoassistittorep-licate.Andithasenslaveditsveryinventortothatend,printingitself-asheseesit-forthebenefitofhiscompany.Whereasinrealitythecompanyisforthebenefitofthemachine.”
AsSamuelButlersaid,“Ahenisonlyanegg’swayofmakinganotheregg.”
Are the original goals of the project (self-repli-cation, disruption of traditional means of production) still relevant, or necessary, now that the project has reached the stage it has?
Self-replication was, and remains, theprimarygoal,formeatleast.Itisthegoaltowhicheveryotherpossiblesub-goalisneces-sarilysubservient.Thepotentialdisruptionsarenot really evengoals;moreby-products.Thespreadofthemachineisprettymuchdo-ingwhatIthoughtitwould.
RepRap is a major part of the current “maker revolution”, either directly (spin-offs such as Maker-bot), or indirectly (inspiring and enabling Open Hard-ware projects). What aspect or challenge needs to now be accomplished for RepRap to maintain this po-sition within the DIY 3D printer and maker commu-nity?
Twomaindevelopments:
1.Adesignthatisveryveryquickandeasytoassemble.
2.Multiplematerials.
Idon’treallythinkthatmaintainingthepositionisaproblem.Afterall,ifeverynon-replicating3DprintermakesjustoneRepRapatsomepointinitslife,youcanseewhatthatdoestothepopulationdynamics.
10REPRAPMAGAZINE
InterviewAdrian Bowyer
Did you imagine back in 2004 that the RepRap project would gain such global success? Has the sub-sequent growth lived up to your expectations?
At the start I thought it was 50/50: itwould either sinkwithout trace, or go spec-tacularlyglobal.Itseemedtomethatitsin-herentlyexponentialnaturewouldnotadmitofanypointbetweenthosetwo;abifurcationwasinevitable.
Thecointosscamedownheads.
The evolutionary process is sometimes used to describe the project. Considering that the RepRap project is a machine that aims for self replication, and has an evolution comparable to living species (sur-vival of the fittest, evolutionary dead ends, etc.), in your opinion what is the place that RepRap holds in the food-chain of the 21st Century manufacturing en-vironment? Who is its main predator and its favourite prey? I’maimingforthebottom:I’dmuchrath-eritwasabacteriumthanaleopard-leopards(asaspecies)arenotaroundforlong.
Idon’tthinkithasapredator -nothing
consumesit,asfarasIamaware.And-whileitisnotautotrophicwhenlookedatinabsoluteterms-initsenvironment(whichishumanso-ciety)itisprettymuchso.Thereforeithasnopreyeither.Itjusthasitshumansymbionts.
The project The organisational aspects of the project, or lack of, has always been controversial, with many wanting more control and direction, and many preferring the slightly chaotic nature. It was recently described as an Adhocracy, which I feel is a wonderfully accurate description. Do you feel that the decentralised na-ture of the project has contributed to its success?
Ihavenoidea.ButIcertainlydon’tthinkthatwewouldseethewonderfulrobustspe-ciationthathasoccurred,withmanydifferentRepRapdesignsoutthere, if theprojecthadbeenmorecontrolled.Ratherthereverse.
Considering this decentralised nature of the project, do you feel that having such terms as “Core Developers” goes against it? Would the project be better off now disbanding this teamt or replacing it with another form of representation?
11REPRAPMAGAZINE
InterviewAdrian Bowyer
I really have no strong opinions aboutthis. Indeed,oncareful introspection,IfindthatIhavenoopinionsatall.
Do you feel that the future of the project is now safely in the hands of the wider maker community and that RepRap will live on through it? Or do you feel there is a need for some form of foundation to un-derpin the core principles of the project, as originally envisioned?
Again,Ihavenoidea.
Thepsychologiststellusthat,ifyouwouldknowthefutureofsomething,itisworthlesstoconsultanexpertonthatthing.Financiersknownothingaboutwhereeconomieswillgo;agriculturalists know nothing about whereglobalfoodproductionwillgo,andsoon.Inevery study on this ever conducted, expertsinafieldarenobetterpredictorsofthatfieldthanchance.Thereisoneexception:expertswhosejobitistopredict,andwhogetregu-larandimmediatefeedbackontheaccuracyof every prediction that theymake - peoplelikeweatherforecasters.Theydobetterthanchance.
Iam,IthinkIcansay,somethingofanexpertonRepRapinparticularand3Dprint-ingingeneral.SoIhavenoideawhatthebestwaytoensurethesuccessoftheprojectinthefutureis.Myperceptionisthatthewayitisorganised,andbywhom,isvanishinglyunim-portant compared to somebody’s coming upwithareallygoodnewdesignandreleasingit,but-asIsay-IknowthatIdon’tknow.
For someone new to the project, and starting to build a RepRap from scratch, what aspect do you think is the most challenging? Have you any tips or advice on how to overcome it?
Itentirelydependsontheirbackground.I amhorriblyold, andpeopleofmyagearegenerallyquitecomfortablewithmechanical
technicalities-theyknowhowtogettwopartssquare,whentouseshims,whatsequencetotighten screws in and so on,without havingto thinkabout it. But they tend toflounderslightlywhenitcomestomodernelectronicswithlotsofstatic-sensitiveMOSFETSin,andtobequitebackwardwhenitcomestocompil-ingsoftware.Asyougodowntheagerangetheskillsreverse,withyoungpeoplehavingnotroublewiththecomputingaspectsofthings,butbeingquiteunsureaboutthemosttrivialofmechanicaltechniques,likehowtotightenanutthatisfacingawayfromthem.
Mybest tip forbuildingaRepRap is toformasmallteamoffriendswithcomplimen-taryskillstocoverallthosebases,ratherthandoingitonone’sown.
The future Even ignoring the current hype surrounding 3D printing, there are many exciting possibilities being explored around the world: biological tissue replica-tion, printable architecture, new materials and tech-niques, amongst many others. Many of these use RepRap as their underlying technology. Is there any particular area which really interests you personally, or you feel has the potential to become exceptionally interesting in the near future?
Yes-Ithinkthatthemostexcitingapplicationof RepRap will be in manufacturing equip-mentforpersonalbiotechnology.
For example, I suspect (see the caveatabout expert predictions above) thatwearereasonablyclosetobeingabletomakehumanspermandeggsinvitrofromstemcells.Imag-inethedisruptivepotentialofanopen-sourceRepRap-made machine into which a couplecould put two cheek swabs, one from eachof them. Themachinewoulddoa completegenetic analysis and offer them a consciouschoiceoverwhichallelefromonetocombine
12REPRAPMAGAZINE
InterviewAdrian Bowyer
withwhich fromtheotherall thewaydownthe23 chromosomepairs,withprobabilitiesandpredictionsonthealternativephenotypi-calresults. After they’ve designed their baby, thecouplewould thenbepresentedwithan im-plantablefertilisedzygote. Vitally, the open-source RepRap-madeaspect of such a machinewouldputthechoicesentire-lyinthehandsofthecoupleconcerned and - more im-portantly-preventeveryoneelse (relatives, religions, orgovernments) from interfer-ing. Just like all the othersevenbillionofus,Ihavenoideaifthiswouldbeagoodor a bad idea, though likeallsevenbillionIdohaveaworthlessopiniononit.Butit would certainly be inter-esting.
As versatile and fun as they are, 3D printers are only one tool amidst many. Is there a place for other tools in the RepRap fam-ily? Are there other devices you would like to see with a RepRap name badge on it?
A self replicating laser cutterwould bepossibleanduseful-severalpeoplearework-ingonthat.AndMIThaveareplicatingCNCmill.ThedefinitionofthewordRepRapcer-tainly takes in such developments, thoughpeoplemustnamethemastheywill.
Throughout the project you have explored and experimented with many techniques and tools (Piezo print-head, granule extruder, mould castings). With your day job now being at RepRapPro will you con-tinue such experimenting, or is your time consumed with sales, marketing and support?
Abouthalfandhalf. I’mpleasedtosaythatRepRapProLtdmakesenoughmoneyformeandmycolleaguesnottohavetospendallour time counting springs into plastic bags.I’malsopleasedtosaythatwedon’tmakesomuchmoney that some of us never need tocountspringsintoplasticbags.
After all the time you have in-vested into RepRap, does it still excite you today?
Yes.Ithasbeen-andcon-tinuestobe-morefunthatI couldpossiblyhave imag-inedatthestart. Ignoring your self depre-cating “I know asmuch asthe next man” position foramoment,whattechnologi-calleapforwarddoyousee,orhopetosee,happeninginthe near future which willpropel RepRap to the nextlevel?
See above about ease ofassembly and multiple ma-terials.
And looking further into the future, which truly advanced, almost science fiction, technologies can you imagine RepRap consisting of? Are nano-facto-ries feasible?
Clearlytheyare -wehaveanexistenceproof:prokaryoticandeukaryoticcells.
I foresee a scale convergence,with thebiologistsworkingupfromthebottomandtheengineersworkingdownfromthetop.IhopethatIlivelongenoughforittobecomeimpos-sibletodistinguishbetweenthecreationsofthetwo.
13REPRAPMAGAZINE
Feature separator
RepRap Gcode generators have evolved and matured to a point where we have a nice choice of features, complexity with simplicity and process-ing speeds, but what’s the ideal one for you?
Feat
ure
FeatureSlicers
15REPRAPMAGAZINE
Itsmainjobistocutupamodelintogeometricallyanddimensionallycorrectfinelayersandplanpathsfortheextrudedmaterialusedoneachlayertoallowa3Dprinter’sfirmwaretoprocessthisdataandcontrolthemovementinawaytoprintoutthefinishedpart. It’salsoimportanttoapplysomein-telligencetoslicingamodel,sothingslikeoverhangsofmaterialandsectionsofbridginghavemoreoutlinesorinsomecas-essolidlayersgoinginaspecificdirection‘tobridge’materialinawaysotheprintisbothstrongandappealinginfinalappear-ance. Itusuallymeansthatformostmodelsaslicingprogramwilldoagoodjobofana-lysingyourmodelandaddingextrainfill,outlinesandlayerswhereneeded.Thisin-telligencecancausesomeproblemswhenyouwanttoforceamodeltobeprintedinaspecificway.Forexampleahollowvase,forthisyoumaywanttoproduceasingleormultiplewalledoutlineswithoutanyinfill.Someslicingprogramsallowyoutoturnofftheinfill‘intelligence’soyougetahollowobject,usuallywithasolidbase.Otherslic-ersstillattempttoaddinfillmaterialsfor‘support’ormissoutsolidlayersevenwhenyoutellthemnottoo,frustratingbutnotimpossibletogetaround.
Anotherissuerelatingtoqualityandspeedisthewayyourextrudersarehan-dledbytheslicingprogram.Gcodecaneasilybegeneratedthathasinappropriateextrudersettingswithconstantretractionsforeverytinymove;thiscanreducepartqualityanddrasticallyincreaseprinttimefornogoodreason.Onecriticalexperimenteveryonewitha3Dprintershouldworkoutisnotonlyhowmuchextrusionretractionisrequiredbutwhentonotretractorhowmuchyoucan‘skip’withoutretractionbe-foreyougetproblemswithblobs,stringsorotherdefects.
Firstly,let’sjustgooverwhataslicerisactuallydo-ing,whyweneedtouseoneandwhythesettingsaresoimportantforgoodmodelreproduction.
FeatureSlicers
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Withextrudersettingsit’susuallynotoneruleforallmodels,butthespeedthatmost3Dprinterscannowtravelandspeedofextruderretractionallowsyoutomakeshortmoveswithoutretractingtheextrud-erfilamentatall,givingaprintspeedim-provementandnoqualityreduction. Anothervaluableslicersettingfor3Dprintersis‘lift’or‘hop’,thisraisestheprintheadupandthenbackdownduringanonprintingtravelmove.Ifyourmachinecanmoveupanddownfastit’softenaverygoodsettingtohaveenabledforalmosteverytypeofprint.Withoutliftorhopena-bledit’spossibleforthenozzletocatchofpartsoftheobjectbeingprintedeitherknockingsmallpartsofforworse. Gcodevisualisationisanessentialpartofprocessingobjects;sadlysomeslicersdonotshowa3DversionoftheGcodeyouhavejustcreated,soitcanbeamysteryifyourmodelhasanydefectsorextramate-rialyouwerenotexpectinguntilthemodelprintsornotasthecasecanbe. AnexcellentGcodeviewerisbuiltintoRepetierhost,thisallowsyoutoseeyourobjectfromtheactualGcodeyouareabouttoprintwith,it’salmostes-sentialtoviewgcodebeforeprintingjusttomakesureit’swhatyouexpectandithasbeenprocessedcorrect-ly. Another2DoptionisbuiltintoPronterface,thisallowsyoutoseeeachlayerfromthetop-down,greatifyouwanttocheckmate-rialisbeingplacedhowyouexpectandthetravelmoveslookok. Usingpronterfaceforlayeranalysisisidealforthingslikehollowobjects,soyoucanmakesurenoextrainternalmaterialisbeingaddedorspuriousmovesaregoingtomessupyourprint,ifyoujustlookatahol-lowobjectinRepetieryoucanseethe3D
modelbutit’snotaseasytoseetheinsideasitiswithpronterface. Anidealadditionforanyslicingpro-gramwouldbetoallowGcodeanalysis,evenrealtimehighlightingandeditingandmovingofthepaths,butwearealittlewayfromthatatthemoment.Ifanyonewantstoaddthisfeaturetoanyofthecurrentslicersitwouldbeverywelcome. Slicersallhavetheirpro’sandcon’sfordoingdifferentthingssohereisanoverviewofthekeyfeaturestohelpyoude-cideifit’sworthevaluatingadifferentslic-ingengine. WearegoingtolookatthreeGcodegeneratorsinthisoverview,Cura,Slic3randKisslicer,manyothersexistorareindevelopment. Togiveconsistencywithanalysiswearego-ingtouseRepetierHosttoviewtheGcodemodelandtravelmoves. Inanattempttocomparegeneralcapabili-ties,wearegoingtokeepthesamebasesettingsforallslicingofthebasicmodeltests:
Othersettingsfortheextruder,retraction,travelspeedandminimumlayertimewillallbesettothesamenominalspeedsinalltheslicingprograms,beingrunonthesamePCunderWin-dowsXP32bit.
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Curatest:Frog Firstlayeroffrog,bluelinesaresolidinfillandCyanlinesaremachinemoves-notehowcurakeepsasmanyofit’smachinemovesinsidetheobjectlayer,thishelpstostopdeftectsfromthehotnozzlecrossingperimetersasitprints. Againnoticetheperimetermovesarelimitedtoimprovesur-facequality.Thisfrogisquitesmallsoyoucanseethe0.25mmlayerperimeterscausealoosefinishonthefinaltoplayers.
Slic3rtest:Frog ComparetheSlic3rfirstlayer,youcanseetravelmovesbreakoutoftheperimetersanddonotfollowatotallylogicalpath. Thesetravelmovescontinueforallotherlayers.Onamachinewithoutperfectextruderretraction,correctmaterialtemperatureandfasttravelmoves,thiscanproducemoreartifactsontheoutsideoftheprint.Butwithawellcalibratedmachine,thisshouldbeabletobeminimised. Anothergoodwaytohelpmin-imisethisproblemistouse‘hop’or‘lift’thismovestheextruderup(Z+)beforeatravelmoveandbackdownatthenewlocationbeforethenextextrusion.
Firstlayerpreview
Firstlayerpreview
Finalpreview
Finalpreview
Frog model by Owen Collinshttp://www.thingiverse.com/owenscenic
Test 1 - Object with infill test
Lenght -With -
Height -
37.29mm30.83mm15.28mm
Dimensions:
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KISSlicertest:Frog KISSlicer,hasmainlyinternaltravelmoves,anditbacktracksonthelastmovebeforeatravelmoveto‘wipe’thenozzlebefore‘jump-ing’tothenextlocation.Thiswillusuallyhaveapositiveeffectontheprintandresultinlessdefects. ThisreallyhighlightshowlittleperimeterbreaksKISSlicerhas,almostallofthemareinter-naltothemodel,resultinginahighqualityoutputwithawelltunedmachine.
Firstlayerpreview Finalpreview
Test
1 r
esul
ts
Note:SomeSlicersmeasurefilamentbylength,othersbyweight.
Fromlefttoright:
Cura,Slic3r,KISSlicer
Cura
57 seconds12 minutes3.41 grams343 kb
Slice timeEstimate print timeUsed materialGcode size
Slic3r
41 seconds-373.1 mm325 kb
KISSlicer
12 seconds11.8 minutes373.1 mm508 kb
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CuraTest
Samesettingsasothermodels,butwiththe‘joris’settingenabled–thiscon-stantlyraisestheZheightduringasinglewalledprintsoyougetnoseamwherelayerchangeusuallyhappens,areallygreatset-tingforvasesandobjectslikethestretchletbracelet. Curaproducessomeveryniceprintswiththejorisfunctionenabled.
KISSlicer
InthePreferences–Advanced,underthestyletab,youcanwinddowntheinfilltotheright(0)anditwillselect‘Vase’–thisistheidealsettingforthesetypesofsinglewalledobjects. KISSlicer-didn’tmanageagoodjobofthismodelandtheGcodeproducedtakesalongtimetoloadintoRepieterHost,itjusthangstheprogramforafewminutes.Eventu-allythemodelappearsandshowssomema-jorissues,alongwithmakingRepieterrunat1/10ththenormalspeed.Therearealotofrandomtravelmovesandmissingextrusionsections,thisoutputGcodeisnotgood.
Curafinalpreview KISSlicerfinalpreview
The Stretchy bracelet by Emmet Lalish http://www.thingiverse.com/thing:13505
Lenght -With -
Height -
Test 1 - Model test with no in-fill, just a single outline
71.77mm71.78mm15mm
Dimensions:
Slic3r SlicerVersion0.9.7doesnotlikethismodel,ithangswhileprocessingthetriangulatedmesh.ItwillslicejustfinewithVersions0.8.3,youneedtochangetozeroinfillandnofilledlay-ers,andyoushouldthengetasinglewalledoutlinetoprint.YoushouldnotneedtouseBrim.
FeatureSlicers
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Test
2 r
esul
ts
Note:SomeSlicersmeasurefilamentbylength,othersbyweight.
KISSlicer
ViewingthegcodepathinKISSlicershowssomemoremissingsec-tions,notsomethingyouwouldwanttotryandprint.
Cura
3min 32 seconds12 minutes6.57 grams695kb
Slice timeEstimate print timeUsed materialGcode size
Slic3r
------------
KISSlicer
2min 15 seconds14min 16 seconds5.960 cm3693kb
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It going to be sliced with the same settings but with 10% infill.This model is a complex organic shape with thick walls and minor overhangs.
Cura Test –7mins15secondstoexportthefiletoGcode–2.91MBfile-veryfastindeed!!EDIT!-CuradidnotproduceavalidGcodefile,itdidhaveastartandend,butnotvalidGcodefortheLavaVase-itjustcrashedRep Slic3r test –Slic3rcrashedafter15+minutesduring‘Generatingperimeters’Secondtryafterreducingthenumberofthreadsfrom3to2=Crashedagainatasimilarpoint,it’sprobablyrunningoutofmemoryonthiscomputer. IhadtogiveupwiththisunderWindowsXp,butitdidslicefinewiththe64bitversionofSlic3runderWindows7. KISSlicer test –After23min44seconddur-ingtheGcodeexportKISSlicercrashedwith“Assertionfailed!Ext_count>0“2.989MBofGcodewaswrittenout Second try –After38minsalltheGcodewaswrittenout156MB–unfortunatelyIhadmovedthelowersliderforsupporttobe-0thinkingthiswoulddisablesupportforthemodel,butitdidtheexactoppositeandaddedsupportevery-where! Third try – Ichangedthesupportslidertobe90degrees,andthistimetheoutputGcodewas102MBandgeneratedin26mins34seconds,nosupportstructureused.OutputGcodelooksgood. Noteonsupport–Nexttime,justusethetopslider,thisallowsyoutoswitchoffsupportcom-pletely. IprintedtheLavavasefromtheSlic3rGcodeonaRostockprinter-justover5hourstoprint.
The Lava Vase by Dizingof scaled by 150% to 270mm tall
www.thingiverse.com
Lenght -With -
Height -
Test 1 - Really big and complex model
71.77mm71.78mm15mm
Dimensions:
FeatureSlicers
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CloseupofLavavaseprintedinNaturalPLA.PrintedonRostock,with0.25mmlayerheight.
FeatureSlicers
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Slic3rhashadaswiftdevelop-mentoverthelastfewyears,withmanyandfrequentreleases.It’scurrentlyatRelease0.9.7soisof-ficiallystillinbeta,itsopensourceandverycommunitydrivenfromfeedback,featurerequestsandim-provementsandisoneofthefastestGcodegeneratorsavailable.
Slic3riseasytouseandhasbuiltinadviceformostofthefieldsyouneedtoen-terdataaboutyourmachineandmaterial.IthandlesmostmodelswellandwillattempttorepairandproduceGcodeandgiveyouawarningifanyproblemsweredetected.Usu-allyrunninganybadmodelsthroughNetfabbcloudfixestheissueandyoucansliceagain.
Slic3rhassupportformultipleextrudersandalsotheadditivemanufacturingformat(AMF),thisistheproposedfutureformatfor3Dprintingtoreplacethestandard.STLfor-
matwemainlyusetoday.AMFhassupportformulti-partobjectswithmixedmaterialproper-ties,alongwithotheradvancedfeaturesitwillallowfullcolourmodelstoprintaslongasyouhavefirmwareandamachinetohandleit.
Slic3risfastatprocessingobjects;itcanhaveafewmemoryissuesandoccasionalcrashingwithhighlycomplexmodels.MostoftheseissuescanusuallyberesolvedbyusingMeshlaborsimilartoreducethenumberoffacesdown. Manymodels,evencomplexobjectsusu-allyhavesomewhereunder50,000faces,butit’squitepossibleforhighqualitymodelscansorverylargeorganicobjectstohave100,000toover500,000faces,that’susuallyastruggleformostslicerstohandleandevenwithare-ductioninfacesyouwillnotusuallynoticeanyqualityreductionintheactualprintedmodelsodocheckthemodelresolutionandreduce(decimate)ifnecessary.
Slic3r - Final review
FeatureSlicers
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OneofthemainfeaturesforSlic3risthatitisveryeasytouse,fastatprocessingsoyoucanmakechangestosettings,viewtheout-putcodeandseeexactlywhatthatdoestothemodelveryquickly.It’sanidealstartingpointforlearninghowyourmachineworksandwhatitcanandcan’tdo. Areas for improvement
Support structure.
Thisisatrickyareaastheslicerneedstofirstworkoutifapartofthemodelneedssup-porttobeprinted,itthenneedstoprintafinestructureundertheareaoftheobjecttoallowagentlesupportoftheactualmodelbutallowremovalofthesupportmaterialfromthemod-elwithoutleavingitstucktothepartneedingmoreaggressiveremoval.Muchmoreworkneedstobedoneonsupportmaterialusage,temperaturesettingstoallowweakerbondsandeasierremoval,andalsohopefullyatsomepointsoondissolublesupportmaterialsthatcouldbeextruderandpossiblyreusedagain. Slic3rhaslimitedsettingsforsupportanditcanputssupportmaterialinboththewrongplaceandormixedinwiththepartbe-ingprintedsoit’sveryhardtoremove,experi-mentwithcare. Different versions give very different output Gcode.
Thiscanactuallybeagoodthing,forexampleusingthesamesettingsVersion0.9.1seemstogeneratesmallerGcodeandwillusu-allydoabetterjobofproducinghollowobjects(vasesorcylinders)orfineobjectswithonlyoutlines(likesnowflakes)
WhileVersion0.9.7generallydoesnotseemtodohollowprintingaswell,usuallyaddinginfillorunwantedextrusions.ItdoesproducesafilewithmoreGcode,buttendstohavefinerlinesandsousuallymoreinfill,thatcanmakepartslookbetterandbestrongerbutitwilltakealittlelongertoprint. Version0.7.2bisverypopularwithma-chineslikeTantiliusandVersion0.8.3wasalsoagoodallroundreleasebutdoesnothavesomeofthenewerfunctions,settingsandmul-tipleextrudersupportof0.9.Xversions. Slic3risbeingwellsupportedbyindi-vidualcommunitymembersand3DprintingcompanieslikeLulzBot,whohavesponsoredrecentreleasesaswellasfundingafulltimesecondprogrammertofurtherdevelopthesoftwarealongsideAlessandro. Slic3risafantasticprogramtosetupyourmachineandexperimentwiththecapabilities,itslicessofastyoucantryoutthingsquicklyandseehowsettingschangetheoutputcodeandprintedparts.YoumaystillneedtousedifferentversionsforspecificthingsanditssupportmaterialistrickytousebutyougetmultipleextrudersupportandbothpreandpostGcodeprocessingsoit’saveryflexiblebaseforanyexperimentsandmostgeneral3Dprinting.
http://slic3r.org/
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Curaisacommunitydevelopedpackagethatwasoriginallybasedonthegreatbuthighlycomplex‘Skeinforge’andafasterimplemen-tationofPython‘PyPy’ CurahasbeenrefinedforusebyUltimakerbutitalsofullysupportsotherRepRapmachines. Skeinforgehasalotofoptions,didIsayalot,Imeanhundreds,it’samazingbutverytrickytouseandexperimentwith,andit’squiteslowcomparedtomorerecentslicers, CurahoweverisfastandproducessomeofthebestandcleanestGcodepos-sible,it’shyperruggedandusuallyman-agestosliceanymodeyouthrowatit,evenmodelswitherrors.
Curahassomeverynicefeatures,andasimpletool-chainthatanyonecanuse.ItcanprintfromColladafiles–thesecanbedirectlyexportedbyGoogleSketchup,soyounolongerneedtodoatranslationto.STLformatwhichcanbeveryhandy.
AfterloadingyourmodelintoCurayoucanusethemodelinspectionviewtoseeifyourmodelhasanyissuesbeforeslic-ing.Ithasaniftytransparentviewsoyoucancheckinternalareaslikenut-trapsinpartsorspotifanyunwantedbitshaveac-cidentallybeenleftinsideyourmodelafterdesigning.TheX-rayviewshowsproblemareasinthemodel,soyoucanfixtheminthedesignoratleastbeawareitmaycausetheslicerafewissuesatthosepoints.
Cura- Final review
FeatureSlicers
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The3DviewandGcodevisualisationisreallygood;it’sveryeasytoseediffer-entlayersandperimeters,infillandtravelpaths. Normalmodeallowsyoutogetgoingstraightaway,mostofthesettingsareeasytounderstand,andyouonlyhavethreelim-itedtabstosetup,afterthatyoucanpro-duceGcodeandprint. Expertconfigandexperimentalset-tingsallowmuchmorecontrolovertheprintandgeneratedgcode,soafterawhileyouwillwanttoplaywiththesesettingsforcertaintypesofobjects.ForexampleCurahasacheckboxcalled‘Joris’thiswonder-fuloptionisperfectlydesignedforvases,cylindersandmanyartisticandsculpturalpiecesyoumaywanttoprint,itprintsthepartasnormalbuttheouteredge‘shell’isprintedbyaconstantraisingoftheZaxisaroundthepart,thismeansthereisnovis-ibleseamwhereyouwouldnormallygetalayerchangeandZaxismoveuptothenextpoint.Thismakesthedifferenceinaniceprintedvasewithatinyseamtoaperfectprintwithoutanysignsofaseamorlayerchangeatall. Curahasabatchrunmodewhereyoucanaskittoslicemany3Dmodelsfromalist.Anothergreatfeatureisprojectplan-nerwhereyoucanplacemultipleobjectsonthebedtobeprinted.Youcanarrange,copyandsequencethepartstobeprinted.YouneedtotellCurathedimensionsofyourprintingheadasitusesthistoplaceeachmodelsotheycanbeprintedinse-quencewithoutknockingoffanalreadyprintedpart. ThesupportstructuregenerationisgoodinCura,manyoftheoptionsfromSkeinforgearetidiedupsoallyoucanselectnowistheamountofmaterialbe-ingusedforsupport,thelessmaterialthe
easieritistoremovebutit’smorefragiletoprintassupportforyourobject. Areas for improvement
AswithSkeinforge,pluginsareavail-abletodointerestingthings–JeremieFrancoisproducedarecentpluginforCurausinganewwoodfibrefilamentthatcansimulateawoodgrainbyrandomtempera-turefluctuationseveryfewlayers,it’squiteeffective.
Curahasnoobvioussupportformultipleextrudersyetsoatthemomentit’sadequateformostma-chines,butitwillneedtoaddsup-portfor2,3ormoreextrudersinthenearfuture.
http://daid.github.com/Cura/
Moreinfoonhttp://betterprinter.blogs-pot.fr
FeatureSlicers
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KISSlicerisquiteeasytosetupandoncetheprinterdetailsandanumberofprintingmodesareconfiguredithasoneoftheeasiestuserinterfaces,especiallywhenyoujustwanttoselectaquality,loadfileandprint,it’sextremelyfastasslicingmodelsandalthoughitusu-allyproducesbiggerGcodeoutputthanotherslicers,thatcodeisnotjustextrawastedmoves,theyaredesignedtogiveastrongpartwithhexagoninfillandcanincludeareversetravelmovecalledwipethatbacksupalongthelastpathbeforemovingtoadifferentregiongiv-ingaverynicefinishtothepartbeingprinted.
Theuserinterfaceisclearandafterchangingthecolourschemetosomethinglessintenseit’snicetolookattoo,similar
toCuraithasa3Dviewofboththemodelandtheprocessedgcodelayersandthegcodein3D. KISSlicerseemstohaveafewissuessavingset-tingsunderWindows,thefilesneedtohavebothacarriagereturnandlinefeedaftereachfield.IfounditsimpletoeditthesettingfileswithatexteditorratherthantheKISSlicersettingsmenu. SamplesettingfilesforvariousmachinesareappearingupontheRe-pRapforums.
Areas for improvement TheFreeversionofKISSlicercanonlyloadonemodelatatime,soifyouwishtoprintmultipleparts,youwillneedtocom-binethemontoaplateandexportanew.STLfilesoKISSlicercanloaditasonefile.–AsanoteSlic3rcaneasilycombinemulti-ple.STLfilesandexportaplateofthepartsasasingle.STLmeaningyoucanthenloadthatintoKISSlicer. AnotherlimitationofKISSliceristhatthefreeversioncanonlyhandleoneex-truder,wherethePROlicensecandomul-tipleextrudersandloadmultiplepartsto-gether. KISSlicer’slicenseallowsyoutouseitforbothhobbyandcommercialuseaslongasyoudon’treverseengineeritasitsnotopensourcesoftware.
KISSlicer - Final review
http://kisslicer.com/index.html
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Manyother3Dprintingslicersarealsoavaila-ble,someopensourceandsomecommercial,manyhavefallenoutofdevelopmentorarenowrefiningtheirwaytobethenextbigthing.KeepaneyeoutontheRepRapforumandWikiformorenewsandupdatesonSlicersandGcodegenerators. NexttimewewillbelookingatdifferentRe-pRapFirmwaresandtheelectronicstorunthemon.
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Taxonomy of Z axis artifacts
Recently,printerdesignshavebeenmul-tiplyinglikeStanfordBunnies.Withthe“Kick-startergeneration”of3dprinters,I’venoticedalotofoldmistakesbeingmadebypeoplewhoarenewtothecommunityandhaven’tdoneasmuchresearchasonemighthope.Someofthesemistakeshavemostlybeendocument-edincommentsandmailinglistreplies,soIthoughtitwastimetheyweremoreformallydocumented.Inthispost,Iwanttotalkaboutissuesthatcausedistortiononverticalsurfac-esofprints.
Regular Z artifacts:
Themostrecognizablecauseofthisprob-lemisZ-wobble.Itiscausedbythemisalign-mentoflayersinarepeatingpatternwithaperiodequaltotheZthreadpitch(technicallythelead,butthisisthesameasthepitchun-lessyouareusingamulti-startthread),andwasafamousproblemoftheoriginalMakebot,theCupcakeCNC.TheCupcakeCNC’sZaxiswasconstrainedbyfourM8-threadedrodsthatturnedtomovetheaxisupanddown.Theproblemisthatwhilesomeoftheserodsarestraighterthanothers,noneareeverperfectlystraight.Thetopandbottomoftherodswereheldinplacewithbearings,butwhentherodsaren’tstraight,theZaxiswillbeoffset.Rodsclampedinbearingswillalsobeoff-centerduetotheholebeinglargerthanthethread’smax-imumdiameterandsomequirksofnutmanu-facturing(Cupcakeuserslongagorealizedthatitwasbettertorestalockedpairofnutsonthebearingratherthanclampingthebear-
ingwithonenutoneachside).Whentherodsturn,theZplatformmovesupordownalongtheZaxis,butitalsomovesinsmallcirclesaroundit,causingthelayerstobemisalignedandresultinginsinusoidalridgesalongtheverticalsurfaces,withinvertedridgesontheoppositeside.
Photocredit:JohnAbella
Z-wobblewasneveraproblemforMen-del-likedesignsuntilrecently.TheoriginalMendeldidnothavethisproblembecauseitsZaxiswasconstrainedbysmoothrods,withthreadedrodsheldbybearingsononeendthatonlymoveitupanddown.ThePrusaMendelcreatedasimilarsystembycouplingthethreadedrodsdirectlytomotorshaftsatthetop(whichinturnwereheldinplacebythetwinsteppermotors’integralbearings),andthePrusai3(which,thankfully,movesthosemotorstothebottom)stillhasthose
RichhasbeenapartoftheRepRapprojectforthreeyears,andisthedesigneroftheRepRapWallace.HeiscurrentlyworkingatDeezmaker(http://deezmaker.com/).
Taxonomy of Z axis artifacts in extrusion-based 3d printing
Pro-tipsTaxonomy of Z axis artifacts
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threadedrodsconstrainedatonlyoneend.Imentionthesemodelsspecificallybecausetherehavebeenseveralderivativesandso-called“upgrades”forthesedesignsthatplaceanotherbearingattheoppositeendsofthethreadedrods.
Inthesedesigns,whentherodisonlyconstrainedatoneend,iftherodisnotper-fectlystraight(whichnoneare),thefreeendwillmoveinsmallcirclesthewaytheCup-cakeCNC’splatformdid,buttheZaxiswillnotbeaffectedbecausethesmoothrodsconstrainittoalinearpath,andtheshaftcouplersal-lowabitofflexwhentheZnutspushtherodinonedirectionoranother.Somelessexperi-enceduserswereconfusedorconcernedbythewobbleexhibitedbythefreeendsoftheserodsanddecidedtoputbearingsonthemtopreventthiswobble.Infairness,onthePrusaMendelswiththemotorsatthetop,theyalsoservedtotaketheweightoftheXaxisandextruderoffoftheshaftcoupler,whichwaspronetobeingpulledapartinearlyversions,butthedownsidewasthesame.WithbothendsofthethreadedrodnowconstrainedasontheCupcakeCNC,thecurvatureoftherodagainstartedpushingtheZplatforminsmallcirclesaroundit.Thesmoothrodsresistedthisforce,andtriedtobendthethreadedrodsstraighttocounteractit,butthethreadedrodswerejustasthick,sotheresultwasthatbothrodsdeflectedabit,andZwobblewasallowedtooccur.
Aspeoplehavebeenpushingforhigher-quality,errorduetoZaxisquantizationandprecisionlimitshavestartedtoappear,creat-ingbandinginaninterferencepatternthatI’llcallZribbing.I’veseenthisissueoverandoverrecently,anditistheprimaryreasonforthispost.Insteadofentirelayersbeingoffsetinonedirection,thiserrorappearsaslayersstickingouttoofarornotfarenoughineverydirection.LikeZwobble,thiserroroccurswitharegularperiod,butitisnotthesameastheZthreadpitch(thoughitmaybeveryclose).Itoccursduetoaroundingerrorinthenumberofstepsperlayercausingsomelayerstobeshorterortallerthanothers,andthreadsbeinglaiddownwiththesamecross-sectional
areawillcomeoutwideriftheyarecom-pressedtoashorterheight,andthinnerforerrorintheotherdirection.ThiserrorisoftenmistakenforZwobble,andiseasilyobscuredbyactualZwobbleaswellasseveralotheris-sues.
Photocredit:JasonGullickson
ZribbingiscausedbychoosingthewronglayerheightforyourZscrews.Itismoreapparentwiththinnerlayersbecausethepercent-errorinthelayerheightisgreater,andbecausetheverticalsurfacesofprintswiththinnerlayersshouldotherwisebesmoother.Theerrorismuchhardertoavoidifyouuseaninchmeasurementthreadpitch(moreonthisinlater)orifyouhavesomemi-crosteppinginaccuracy.Becausemicrostep-pinginaccuracycanbehardtogetridofen-tirely,youshouldassumethatyouhavesome,andshouldalwayschooselayerheightsthatareamultipleofyourfull-steplength.Ifyouareinhalf-stepmode,yourhalf-stepswillallbeaccurate,butthe3/16steppositionwillnotreliablybehalfastepawayfromthe11/16stepposition,soyoushouldonlyrelyonaccu-ratehalf-stepintervalsifyouareactuallyinhalf-stepmode.
ToavoidZribbing,youshouldalwayschoosealayerheightthatisamultipleofyourfull-steplength.Tocalculatethefull-steplengthforthescrewsyou’reusing,takethepitchofyourscrews(IrecommendM6,withapitchof1mm)anddividebythenumberof
Pro-tipsTaxonomy of Z axis artifacts
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full-stepsperrotationonyourmotors(usu-ally200).Microstepsarenotreliablyaccurateenough,soignorethemforthiscalculation(thoughusingmicrosteppingwillstillmakethemsmootherandquieter).Formyrecom-mendedM6screws,thiscomesoutto5mi-crons.It’s4micronsfortheM5screwsusedbythei3,and6.25micronsfortheM8screwsusedbymostotherrepraps.Alayerheightof200microns(.2mm),forexample,willworkwithanyofthesebecause200=6.25*32=5*40=4*50.
Thisalsoillustrateswhyyoushouldneverusescrewswithaninchmeasurementthreadpitch.Theyarefineforthestructuralconstruction,butshouldnotbeusedfortheZscrews.The5/16-18threadedrodscommonlyusedasasubstituteforM8,forexample,haveapitchof1.41111111mm(therepeatingdeci-maltellsyouyou’rescrewed,sotospeak)forasingle-steplengthof7.0555555microns.Herearetheonlylayerheightsyoucanusewith-outaroundingerrorcausingartifacts(inmi-crons):63.5,127,190.5,254,317.5,381,444.5.Anymultiplesofthefull-steplengthbetweenthesewillhaveroundingerrorsevery9layersduetotherepeatingdecimals.LayerheightsthatarenotmultipleswillexhibitZribbingwithadifferentfrequencydependingonhowoftentheysyncupwiththefull-steplength.Theerrorswillbesmallerifyouhaveaccuratemicrostepping,buttherewillstillbeerror.
Similarbandinghasbeenseenwithaperiodequaltothethreadpitch.ThisbandingiscausedbyamechanicalissuecausingtheZscrewstomoveupanddownslightlyand/orvaryindegreesperstepoverthecourseoftheirrotation,butthesearerarenowthatmostprintershavetheirZscrewscoupleddi-rectlytomotorsratherthanthroughabeltsystemthatcanintroducethistypeoferror.ThisbandingismorecloselyrelatedtoZwob-ble,butitresultsinlayersbeingoffsetverti-callyratherthanhorizontally.
Irregular Z artifacts:
Thereareseveralissuesthatcancauseirregularbanding.ThesecauselayerstospreaddifferentlylikeZribbing,buttheyaremorestochasticratherthanoccurringatregu-larintervals.Thesecanbelumpedintotwocategories:thosethat,likeZribbing,causevariationsinlayerheight,andthosecausedbydifferencesinthevolumeoffilamentextrudedintolayersofequalheight.
Irregularvariationinlayerheightiscausedbytheplatformortheextrudernotmaintainingtheproperheightwhileprinting.OnacantileveredZaxis,thiscanbecausedbybindingorbywirespulling.Inthesecases,thisresistancewillcausetheaxistonotmoveenoughinsomelayers,makingthosetooshortandwide,andthencatchupinothersthatwillbetootallandnarrow.
Asimilarandprobablymorecommoner-rorisresistancefromthespoolpullingagainsttheextruder,whichwilltendtoliftit.ThisismostprevalentonmachinesthatmovetheextruderontheZaxis,especiallyifitisonacantileveredplatformlikeontheThing-o-mat-ic.Inthesecases,thefilamentwillpulluntilthereisenoughtensiontopullitloose,andtheextruderwillfallbacktoitsnormalposi-tion.HowlongthistakeswilldependonhowmuchplasticisfedthroughtheextruderratherthanhowfartheZaxismoves,sotheartifactwilllookdifferentonprintswithalotofareaperlayervs.oneswithverylittle.Youcanpreventthisproblembyrunningthefilamentthroughalow-frictiontubefromtheextrudertothespool(ortosomestructuralfixedpointbetweentheextruderandthespool.Themate-rialdoesn’thavetobequiteaslow-frictionasabowdentube,butitshouldbelooseraroundthefilamentbecauseatighttubeincreasesfrictionandpreventingbacklashinsideitisnotaconcern.Dirt-cheapandwidelyavailable(HomeDepotstocksit).17”IDHDPEtubewilldothejobnicely.
Pro-tipsTaxonomy of Z axis artifacts
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Low-frequencytemperatureswingscanalsocausesomelayerstospreadoutmorethanothersbecausetheyareextrudedtoosoft,andI’vealsoseentemperatureswingsonaheatedplatformcausethisunevenheights.Someplatformswillexpandorbowastheyheatenoughtoaffectthelayerheightandcre-ateinconsistentlayers.Thisshouldbepar-ticularlytrueofplatformswithalowenoughresistancetoheatquicklywiththesuppliedvoltagebecausethefastheatingwillcausemoredifferentialexpansionandbowingastheheaterturnsonandoff.InthecaseIsawthis,theboardwasaprototypeandthenextversiondidn’thavetheissue.Shortofreplac-ingtheheater,I’mnotentirelysurewhattodoaboutthis,butyoucanidentifythisissueifPLAonbluetapeprintsfine,butyougetincon-sistentlayerheightswhenyouheatittoprintABS.TuneyourPIDsandmakesureyourtem-peraturesareassteadyaspossible.Thepopu-larMarlinfirmwarecanautomaticallytuneitsPIDwiththeM303code.
TheotherclassofirregularZartifactiscausedbylayersthatarethesameheight,butdonothavethesameamountofplastic.Theseartifactsarecausedentirelybytheextruderandfilament.Forlayerswithalowvolume(thinlayersthatalsodon’thavemucharea),thiscanbecausedbyaneccentricextrudergear,butmostgearswillmakeseveralfullro-tationsandspreadtheerroroutwithinalayerratherthancausinganinconsistencybetweenlayers.Amorelikelycauseisinconsistencyinthefilament.
Filamentmustbeuniformlyround(flat-tenedfilamentwillhavedifferentminorandmajordiameters,whichwillaffecthowitpressesintothedrivegearandthushowfastitfeeds)andmusthaveaslittlevariationindi-ameteraspossible.Somelow-qualityfilamentalsohasbubblesdownthecenterthatchangethecross-sectionalarea.Thesearenotissuesforplasticwelding,whichiswhatalotoflow-qualityfilamentisactuallymanufacturedfor,andreal3dprintingfilamentismanufacturedtomoreexactingspecifications,soyouwon’t
getthebestqualityprintsfromElCheapofila-ment.Thisisnottosayyouneedtobreakthebank,justchecktoleranceratingsandlookforreviewsortestsampleswhenlookingforasupplier.Therearesomegoodvaluesuppli-erspoppingupthesedays.Thisisalsoama-jorreasonthatnoneofthedesktopfilamentextruderprojectshaveyetbeensuccessful.Therehasbeentalkofdevelopingsensorstodetectchangesinfilamentdimensions,butthisiscomplicatedbythedelayinreactionbe-tweenplasticfeedingthroughthedrivemech-anismandcomingoutofthenozzle.
Photocredit:BenVanDenBroeck
Software
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How it works?
Asyousee,thehostusestheserialdriveroftheoperatingsystem.Thefirstthingyoushouldnoteisthatthisisnotarealserialconnection.Inthepast,comput-ershadaserialconnection,theseweretheD-Subconnectionswith9pins,ifyoure-memberthem.Whenyousentabytethere,itappearedimmediatelyattheport. Nowadays,moderncomputershavelostthisusefulport.Asasolutiontocon-tinueusingthesimpleserialconnectionformicrocontroller,theboardsnowhaveaUSB-serialconverter.Thebadnewsis,that
itisnotthesameasanativeserialcon-nection,however,theprogramusesitthesameway.USBisapacketdevice.Itsendsadatapacket,wheneverthedriverthinksitshould.Tomakeitclear,thinkofthehostwantingtosendanewcommand,e.g.M105torequestcurrenttemperatures.Thestringissenttotheserialdriver,andthedatais5bytes,whichislessthanaUSBdatapacketcanhold.Thedriverwaitsawhilebeforeitsendsthelinetotheprinterhopingtogetsomemorebytes.Thisisalatencydelayingthecommunication.Theexacttimedependsonthedriverused.Forexample,thewidelyusedFTDIdriverhasa
Dipl.-Ing. Roland Littwin
Aut
hor Alias:
RepetierCountry: GermanyWebsite: www.repetier.com
What is the problem? With some luck you have no problems at all. Youconnectyourprinter,settherightbaudrateandthereyougo.Ifitisthatsimplethenwhywriteacompletear-ticleonit?Well,workingisnotthesameasworkingasbestaspossible.IncombinationwithRepetier-Hostyoucanchangethecommunicationbehaviorandchangethespeedconsiderably.Butatthebeginningtakealookatfig.1,whichshowswherecommunicationoccurs,untilthesteppersaremoved.
Repetier part 1: Communication
The softwareRepetier
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defaultvalueof16ms.Youcanchangethisinthewindowshardwaresettings.Soafterthesetlatency,theUSB-serialconvertergetsadatapacketwithourcommandandconvertsitintosignalsforaserialport. ThesearethensentwiththeselectedbaudratetotheAtmelmicrocontrollerontheboard.Themicrocontrollerreadsacompletebyteandthenissuesaninterrupt,sothefirmwarecanstorethebyte.Thishastobedonefastenoughtobefinishedbeforetheconvertersendsthenextbyte. Toallowfastresponsetimes,thestep-perinterruptsaremadeinterruptibleinnoncriticalsections.Asaconsequence,thecommunicationcanshiftthesteppertimingafewmicroseconds.Notenoughtocausetrouble,sodon’tworry. Whentheendofthelineisdetectedandacommandbufferisfree,thecom-mandisparsedandthechecksum,ifsent,ischecked.Ifthesumiscorrectan‘ok’issentbacktoindicatethatthehostcansendthenextcommand.Ifthelinenumberofthechecksumiswrong,thefirmwarere-queststhelineinquestionagainfromthehost.Inthiswaynocommandsarelost.Onthewaybackwehavethesamelatencyproblem.Theconvertermayalsowaitawhilebeforesendingthepacket.Addingupalltimeswehave:
Consideringthespeedofusb,wecanignorethepacketsendtimesandconcen-trateonlatencyandserialcommunicationtime.
Improving throughput.
Let’smakesometestsandseehowwecanimprovetheresults. Iwillstartwith250000baud.InthehostIsetASCIIprotocolandenableping-pong.ThatwaywegetexactlywhatIdescribedandhowcommunicationwasplannedforthefirstcontroller.IfyouareusingRepetier-FirmwareyoucansendM111S20totestthecommunicationonly.Allcommandsgetacknowledged,butwillneverbeexecuted.Sending41496linestookme332seconds,whichgives125lines/second.Sothetimeperlineis8msforanArduinoMegaR3.TheR3hasnoFTDIchip,soIcan’tseethelatencyusedhere.LaterIwilluseadifferentboardwithknownlatencyforcomparison. Are125lines/secondfastenoughforyou?IfyouareuploadingtoanSDcard,youwillnevergetenoughspeed.Oh,youonlywanttoprintandyoudon’tthinkyourprintercanprintthatfast!Ok,let’stestthistheory.Ifweareprintingwith125mm/syoucansendsegmentswithalengthof1mm.Ifyoursegmentsgetsmalleryourprintbufferwillrunempty,whichcancauseblobsandstuttering.AndIcanas-sureyou,therearealwayspartswhereyouhavesmallersegments.Finecircles,infillbetweennarrowwallsortheperimeterof
scannedobjectstendtohavepartswithmanyshortsegments.
Convinced? You want more lines/second?
Ok,herecomestrick#1,whichworkswithallfirmware.Thefirm-warehasaninputbuffer,whereitstoresthecharacterscomingfromtheconverter.Itislargeenoughforacompletecommandand,infact,itcanevenstore2ormorecommands,dependingoncommandsize.Allfirmwarehasatleast63bytesofinputbuffer.DependingontheArduinoIDEver-
Time for a line :
time to driver +computer latency + usb send time + serial in time +
serial out time + converter latency + usb receive time
The softwareRepetier
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sionandfirmwareversionitmayevenbe127bytes.Fromversion0.80onwardsRepetier-Firmwarehas127bytes,olderver-sion127ifcom-piledwithArduino023orolderand63bytesforArdui-no1.0andnewer. ForthenexttestIwilldisabletheping-pongmode.Nowthehostwillcounthowmanybytesithassentandwhichcom-mandshavebeenacknowledgedtobepro-cessed.ThatwaythehostcansendmorecommandsinoneUSBdatapacketandin-creasethethroughput.Sendingthesamedatanowtookonly116seconds,whichequals358linespersecond.Thatis2.8timesfasterthanthelastrun!
Do you want more? Ok, you asked for it.
Wehaveseenthatpackingmorecom-mandsinadatapacketincreasesthrough-put.Solet’sputsomemoredataintoit.Uhuh,bufferisalreadyfulltoitslimitfromtrick#1!Itlookslikeweneedsomecompressionthen.IfyouuseRepetier-Firmwareyoucanusetrick#2-sendcom-mandsasbinarydatainformoftheRepe-tier-Protocol.ThisprotocoldoesnotsendASCIIdata,insteaditsendsallvaluesasbinarydata.Thatwaythelengthofanav-eragecommandisreducedby50-60%.Asafurtherbenefit,thefirmwarehasmuchlessworkparsingthecommands,reduc-ingprocessingtime.Runningthesamejobagainnowgetsfinishedin61seconds,whichgives680linespersecond.Thatis5.4timesfasterthantheoriginalcommu-
nicationmethod.Thisisanaveragecombi-nationspeedof12875bytespersecondor115875baud. Weareonlyat250000baud,I‘msuretheboardcanhandlemore! Yes,youareright.Itestedthesamewith500000baud.Unfortunatelythetimeremainedaround60seconds.Sothereisnobenefitinahigherbaudratewiththebi-naryprotocol.FortheASCIIprotocolIgot89secondsforthetest,whichcorrespondsto466linespersecondinsteadof358for250000baud.Forfirmwarewithoutbinaryprotocolasmallincreasecanbeachieved.
ForthelasttestsequenceIusedaboardwithanFTDIchip.Hereyoucanse-lectthelatencyinthewindowshardwaremanager.Parametersare250000baud,binaryprotocol,127bytebuffer.Firstrunwith16mslatencytakes117secondsor355linespersecond.ForthesecondrunIre-ducedlatencyto4ms.Thisruntookonly62secondsor669linespersecond.ThatisnearlythevaluewegotfortheArduinoMegaR3. Fromthiswecanfollow,thattheMegaR3serialdriverhasquiteashortlatencycomparedtotheFTDIdriversdefaultvalue.ReducingtheFTDIlatencyto4msgives
Baud Rate
250000 Mega R3 ASCII Ping-Pong 125
250000 Mega R3 ASCII 127 358
250000 Mega R3 Binary 127 680
500000 Mega R3 Binary 127 680
500000 Mega R3 ASCII 127 466
250000 FTDI 16ms Binary 127 355
250000 FTDI 4ms Binary 127 669
Drive Protocol Buffer size Lines/Second
Table 1: Max. Communication speeds for different settings
The softwareRepetier
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comparableresultsandamoreconsistentcommandstream.
Communication problems:
Whileitshouldbeverysimpletocre-ateaworkingcommunicationwithyourprinter,Ioftengetquestionsaboutcom-municationnotworking.TohelpallthoseinfindingthereasonquicklyImadealistoftypicalcauses:
•Firmwareandhostneedthesamecommunicationsettings.Allfirmwaretest-edhavenoparityand1stopbit.Theonlyparameteryoucansetisthebaudrate.
•IfyouhaveactivatedtheEEPROMsettingsforyourfirmware,thebaudrateistakenfromtheEEPROM.Ifyouchangeitinyourconfigurationanduploadthefirmwareagain,thenewbaudrategetsignored.
•Ifyouarenotusingtheping-pongmode,youneedtherightreceivecachesize.Ifyousetittoolarge,youwillgetmanycommunicationerrors.Typicalvaluesare63and127byte.
•WithLinux,useonlyANSIbaudrateslike115200or57600.Often250000andothernonANSIratesdonotwork.
•Ifyousometimeshaveasuddendis-connectwithouterrormessages,tryashieldedUSBcable.YoumayevenwanttoputaferritearoundtheUSBcableattheprinterside.
Firmware internal communication:
Thenextstepofcommunicationisinternaltothefirmware.Thispartisnotthemostimportantfortheuser,althoughunderstandingitcouldhelpunderstandingwhysomethingshappen.ForthisreasonIwanttogiveashortoverviewoftheinter-naldataflow.
Step 1: In the internal input buffer.
Datasentfromthehostisstoredhereuntilthefirmwareisreadytoprocesstheinput.Thebufferhasasizeof127bytes,exceptifcompiledwithArduino1.0forRepetier-Firmware<0.80.Thisisthebuff-ermeantinthehostcommunicationset-ting. Thefirmwarerunsinanendlessloopcheckingfornewcommands,parsingnewcommands,executingparsedcommands,watchingtemperaturesandupdatingtheuserinterface,ifoneisconnected.Besidethisloop,3timerfunctionshandletheex-truder,PWMoutputandreadstempera-tures.
Step 2: The next step for the send data is to get parsed.
Thefirmwarehasacommandbuffer,where2commandsgetstoredinapre-parsedformat.Ifthefirmwaredetectsnewinputandthecommandbufferisnotfull,itscansanewcommandfromtheinput,putsthescannedvaluesintothebufferandfreestheinputbuffertomakeplaceforthenextdatasent.Afterclearingthein-putbufferitsendsan‘ok’inresponse,tell-ingthehostthereisnowroomforthenextcommand.Iftheparsingrevealsacheck-sumerrororamissinglinenumber,itwillinsteadaskthehosttoresendthelastline. Ifthecommandbufferisnotemptythenthenextcommandissenttothecom-mandparser.Theparserexecutesthecom-
The softwareRepetier
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mand.Thesecommandscanbelonginoneofthreegroups,dependingonthetimeofexecution:
Group 1- Move commands:
Thesecommandsarenotexecutedim-mediately.Instead,thefirmwaredoessomepre-computationsandaddstheresultintothemovebuffer.Oneofthetimerfunctionswillcheckthisbufferandturnthestepperaccordingtothisdata.Thatwaythereisnodelaybetweenconnectedmoves,atleastaslongasthebufferdoesn’trunempty.Suchamovebufferalsoallowsformakingnicemovementoptimizations.Knowingthesub-sequentmoves,thefirmwaredoesnotneedtodeceleratetotheminimumspeedattheendofamove. Thispathplanningisthebestwaytoimproveyourprintquality.Themoremovesarestoredinthebuffer,thebettertheplan-ningcanbe. Thereareonlytwoproblemsyoushouldconsider.First,eachentryrequiresmemoryandmemoryissomethingrare.16entriesfora4kbRAMsystemisnoprob-lem.8kbRAMsystemscangohigher,ifnootherlargememoryusersareenabled(e.g.deltaprinterneedmuchmemoryforsubsegments).Second,longerbufferscanleadtolongeroptimizationtimes.Soyouhavetofindagoodbalancebetweensizeandspeed. Thissetupiscritical,iftheprintergetsmanysmallmovesinarow,likeonhighlydetailedcurves.Theneventhemaxi-mumspeedmaygetreduced,ifitisnotpossibletoaccelerateanddeceleratetofullspeedinthemovelengthstored.Inthisoc-casionitbecomescriticaltorefillthebufferasfastaspossibleasalreadydescribedearlier.
Group 2 - Immediately executable commands:
Mostcommandsbelongintothisgroup.Theydependonnothingandgetex-ecutedassoonastheyreachthecommandparser.Mostareexecutedfastenough,thatthemovebufferdoesn’trunemptyiftheprintisinterruptedbysomeothercom-mandsliketemperaturerequests.
Group 3 - Move dependent com-mands:
Somecommandsrequireanemptymovebuffer.GoodexamplesareextruderswitchesorG4dwell.OneparameterwhereyoumightwantitisM104.IfyoudefineEXACT_TEMPERATURE_TIMINGinyourconfiguration,thefirmwarewillemptythebufferbeforeitchangesthetemperature. Thedrawbackisthatthebufferisthenemptyandtheextruderwillpauseashorttime,allowingblobstooccur.Forthatrea-sonthedefaultisnottowait.Evenifyouturntheextruderoff,thelatencyshouldbelongenoughtofinishtheprint.
Now you know everything about the communication, you should know. With these infor-mations, you should now be able to understand why things happen as they happen.
Check your communication flow and find the bottleneck causing your problem.
http://www.repetier.com/
Beginner spaceWhat is a RepRap 3D printer?
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RepRap 3D printers have been around for a couple of years but if you have been miss-ing the party then this section of the magazine is here to as-sist you getting into this world in an easy way. Forthisfirsteditionwearegoingtocov-erthebasicanatomyofa3Dprinter,thework-flowofprinting,andsomeadviceonchoosingtherightmodeltofityourneeds.Butfirstletscoverthebasics. Thereareseveralpopularmodelsofprinterscurrentlyavailable,andthefactthatthereisnotonlyonepopularmodel,butsev-eral,showsyouthediversityoftheproject.Now,oneoftheaspectsthathelpsthisdiver-sityisthatforeachcomponentoftheprinteryouhavemorethanonetypetochoosefrom.Justtogiveoneexample,letsfocusontheextruder:youcanchoosefromaBowden,ageared,oradirectdriveextruder. Let’sassumewechoosethegearedex-truderwethencanchoosefromWade’sorGreg’sextruderforexample.ThiscanlookalittlebitoverwhelmingandconfusingforsomeonenewtoRepRapwhowantstosourcethepartsandbuildtheprinter,insteadofjustbuyingakit,butitcaneasilybedonewithoutmuchtrouble. Let’sstartbyunderstandingyourprinteranatomy.
Prusa I3http://reprap.org/wiki/Prusa_i3
Mendel90http://reprap.org/wiki/Mendel90
Huxleyhttp://reprap.org/wiki/Huxley
Beginner spaceWhat is a RepRap 3D printer?
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Thefilamentispushedbythesteppermotortoahot-end,whichmeltstheplastic.Itisthensqueezedthroughthenozzleandde-positedontotheprintbed.
Theprintbedcanbeoftwotypes,heatedornotheated.Aheatedbedmini-misescurlingandpartsfallingoffthebedduringprinting.
Theelectronicsarethebrainsofyourprinter.Theycontroleverything,fromthemotorstothetemperatures.
Fora3Dprintertobeabletolaydownfilamentinor-dertobuilda3Dobjectitneedsformovementin3axis(X,YandZ).ThenatureofRepRap3DPrintersbeingopen-sourcesetsthegroundforanexponentialdevelopmentofdesigns. Currentlythemostpopularmodelsarebuiltontwotypesonmotionoftheaxis,Cartesianandpolar.
OnethingthatmakesRepRapinter-estinganddifferentfromsomecommercialprintersisthelevelofcustomisationandtheeasinessofhackingyourprinter. Youwillfindthatforeverypartofyourprinterthereismorethanonechoiceavail-able.
3Dmodelcredit:MattHodder
Thisarejustsomeoftheprintermodelsavailable.ForacompletefamilytreeoftheRepRapprojectvisitthispage:http://reprap.org/wiki/RepRap_Family_Tree
Beginner spaceWhat is a RepRap 3D printer?
40REPRAPMAGAZINE
Asyoucanseeinthisgraphicthecontrolboardaswhatwecanconsiderthemaincon-nectionsandsomeoptionalones,buttheyalsoneedtotakecareofthesteppermotorsthatmovetheaxisoftheprinter.Todothattheyhavestepperdrives,Pololubeingoneofthemostpopular,anddependingoftheprintermodelwemightneedaboardwithfourorfivestepperdrivers. Addingtothisminimumnumberofstep-perdriversrequired,anddependingonthebudgetonehasavailable,onemightconsideraboardthatalowsmoremotorsthenthenum-berrequiredsothatdualextrusionmightbeapossibleroutetoexplore. OntheoptionalaspectSdcardreadersallowfortheuseoftheprinterwithoutithav-ingtobeconnectedtothecomputerduringaprint.TheLcdandencoderareagoodchoiceastheyallowyoutostillmonitortheprinter. Severalfanscanbeaddedtoaprinter,butthemostcommonusesareforcoolingthefilamentnearthehotend(especiallyonabowdensetup),forcoolingthecontrollerboardandtocoolthefilamentduringaprint(morecommonwithPLAfilament).
TheRepRap3Dprintercanbeequippedwithavarietyofextruders,andsomehavere-allyinterestinguses.Thereareextrudersthathavemorethanonesteppermotorandtheyusemorethanonefilamentcolourduringoneprintprovidinguswithamulticolouredobjectasyoucanseeabove. Thereisalsothedualextrusion,whereyoucancombinemorethanonematerialatoneprint.Forexampleitcanbeusedtogettwocolours,ortwotypesofplasticatthesameprint.
Anotheravailabletypeisthepasteex-truder.Thistypeofextrudersdonotuseplas-ticfilament,butasthenamepointsouttheyprintpastes. Thispastescanbeceramicforexample,butitcanalsobefood,aschocolate.Yes,wecanputapasteextruderonaRepRapandprintchocolatecookies!
ColourBlending Pasteextruder CeramicprintPhotoscredit:RichRap
Beginner spaceWhat is a RepRap 3D printer?
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Beginner spaceWhat is a RepRap 3D printer?
42REPRAPMAGAZINE
TheprocessofgettingaRepRapcanbeassimpleasbuyingafullkitorsourcingyourselfthepartsandbuild-ingityourselffromscratch.Thereareadvantageswithbothoptions,butoneofthemainadvantagesofsourcingyourselfthepartsisthatitwillprobablygettospendlessmoney.
But,firstthingsfirst.Beforeyouchoosebetweenthesetwooptionsit’sprobablyagoodideatochoosewhichmod-elisthebestforyou.
Forthiswecreatedthislittlechecklist,tryingtomakeyourlifethatlittlebiteasier,andgiveyouthechanceforsomemoreconsciouschoices.
PrinterdimensionsPrintingenvelopeCostofbuildingLevelofcustomizationEasinessofsourcingtheparts
As a conclusion we can say that Re-pRap is a very versatile project, that you can explore more and more as your knowl-edge grows. Probably you will run into some problems on your path, but you will also run into a community of users willing to help you solving them.
Printing envelope
200x200x400mm245x315x225mm100x100x100mm140x140x110mm200x200x250mm200x200x200mm
Printer model
RostockMendel Max 2.0TantillusHuxleyPrusa I3Mendel 90
Printvolume%Printervolume%
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Follow us, and get in touch, atwww.reprapmagazine.com
ThenatureofthisprojectistohaveacloserelationwithourreadersandwithRepRapusersanddevelopers.Withinthisspirityouarefreeandinvitedtogetintouchwithusbyemailorpostingontheforums.
