openscad class

8/12/2019 OpenSCAD Class

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Introduction to OpenSCAD

Steve Graves


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Teaching Goals Concepts Not Nuts and Bolts Ask questions. Classes are for active learning. There are

pro a l! "an! levels of e#perience in class. Don$t e sh!%ever!one &as a nu ie once.

If a question refers to so"ething co"ing up% it is a goodquestion. But I "ight defer it.

I plan on la!ing the foundation first% ut have several usefulconcepts that go a little further than the asics. Going to tr! totouch all of the".

I e#pect that after this class !ou &ill feel confident to create asi"ple o 'ect.


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(se the )anual I a" not going to regurgitate the "anual. Concepts are "ore i"portant than details. In the real &orld% open ooks are allo&ed. (se help "enu to open "anual. Don$t clutter "ind &ith para"eter details. It &ill

happen auto"aticall!.


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Concepts *hat is OpenSCAD+ *hat is the ,D printing process and ho& does OpenSCAD fit in

it+

*hat are asic concepts for all progra"s that create ,D o 'ects+ *hat is OpenSCAD$s s!nta# and ho& is it unique+ *hat are so"e OpenSCAD user interface tips+ *hat are so"e design patterns+ (se Divide and Conquer. Don$t reinvent the &heel.


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*hat is OpenSCAD+ -rogra" to design ,D o 'ects. It has eco"e the defacto

standard on thingiverse for para"etric designs. Open source and free.

Other free progra"s are Blender% Sketch(p% reeCad and/eeksCad

OpenSCAD generates o 'ects fro" progra"s0scripts+1 andis "ostl! non2interactive.

A progra" "eans para"etric designs that are"athe"aticall! precise.


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OpenSCAD (ser Interface 3eft hand side is te#t edit &indo& for &riting code. Other

te#t editors can e used. 4e"acs is a good e#a"ple. 5ight hand side is &indo& for inspecting rendered ,D

o 'ect. O 'ect in right hand &indo& can e "anipulated using

standard OpenG3 "ouse "oves. 3eft "ouse allo&s one to rotate o 'ect. 5ight "ouse pans. )iddle "ouse or &heel 6oo"s.


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*hat is the ,D -rinting -rocess+ ,D o 'ect is designed 0OpenSCAD1 An ST3 file is e#ported. A slicer progra" reaks ST3 file into la!ers and

generates G code. G code is sent to printer.


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General ,D O 'ect Creation Concepts 7e! concept is 8Transfor"ed Shapes are Co" ined9 into

ne& "ore co"ple# shapes. Co"ple# o 'ects are created fro" si"ple 8Shapes9 called

pri"itives. Si"ple and co"ple# shapes are "odified &ith

8Transfor"ations9 like translate% si6e% color. -ri"itive shapes are 8Co" ined9 in various &a!s using

oolean logic and other "ore co"plicated functions. Au#iliar! functions are used to do "ath% etc.


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,D 0and :D1 -ri"itives Cu e Sphere C!linder -ol!hedron Square 0:D1

Circle 0:D1 -ol!gon 0:D1


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)aking ,D fro" :D :D pri"itives are turned into ,D ! e#trusion T&o asic t!pes of e#trusion linear;e#trude rotate;e#trude


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Co" ining Shapes (nion 0All shapes added together1 Difference 0Shapes after < st shape are su tracted1 Intersection 0Intersection of all shapes1 )inko&ski 0 unction &ith interesting properties to

add t&o shapes1 /ull 0=nclose "ultiple shapes in "ini"u" shape1


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Transfor"ing Shapes Scale 5esi6e 5otate Translate )irror

)ult"atri# Color


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OpenSCAD ,D O 'ect Creation

,D o 'ects are created using the general pattern

Co" ine01>

optTransfor"01 optTransfor"01 ... Shape01?

optTransfor"01 optTransfor"01 ... Shape01?

...

@*ork fro" end of line to&ard front of line.

*ork fro" inner"ost to outer"ost


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S!nta# unctions 0"odules1 are overloaded. aria les have unusual scope. aria les do not store shapes. Shapes are i"plicit entities.

Arra!s are used a lot to represent points or vectors. er! often as para"eters to functions. Be&are 5e"e" er to use as &ell as 01. In"ost cases there is no s!nta# error if !ou don$t.

3ines are ter"inated &ith se"icolon.

A 8line9 of code has a shape 'ust efore the se"icolon. That shapecan e 8transfor"ed9 ! functions efore it. These functions have nose"icolons. The transfor"ations are applied in reverse order 0closestfirst and &orking ack1.


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)ore on s!nta# *e can learn "ore a out the &orking s!nta# !

looking at the s!nta# for a "odule. )odules i"plicitl! return shapes. So a "odule "ust create a shape internall! or get

one 8passed9 to it. Shapes are 8passed9 as children% not para"eters.

5e"e" er shapes are not stored in varia les.


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Calling a "odule as a Co" ine

Na"e0-ara

Child0F1?

Child0 % call to another "odule% etc.


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Calling a "odule as transfor"

Na"e0opt-ara


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Calling "odule as shape

Na"e0opt-ara


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(ser Interface Tips (se 8Thro&n Together9 vie& and 8Co"pile9 for a quick

and dirt! look at design Break large s!ste"s into files to est use a ove technique.

(se .stl files to speed up rendering in co"ple# designs. (se 8Co"pile and 5ender9 for "ore refined look 0and

longer &ait for processing1 There is a co""entEunco""ent function Set fs high during develop"ent


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(seful Design -atterns Identif! all the para"eters for o 'ect0s1 eing

created Assign a varia le to each para"eter efore creating

design


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)ore Design -atterns

difference01>

union01>

union child0F1?

union child0


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)ore Design -atterns

"odule oneShape01>

...?

@

"odule shapeT&o01>

...?

@

union01>

transfor"ations01 shapeOne01?

transfor"ations01 shapeT&o01?

@


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Divide and Conquer Shapes are o vious )oves and rotates can also e divided. Create parts

in local coordinate s!ste"s% then "ove the" into

position in glo al coordinate s!ste".


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Don$t 5einvent the *heel So"e od! has alread! &ritten a 8*heel9 "odule. (se uiltin )CAD li rar! Search thingiverse Search the Internet


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Tip (se fn for "ore shapes The fn para"eter can e used &ith c!linder to

create shapes &ith sides.


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)inko&ski 0Operation 1 er! useful ut hard to understand. One shape is added to another shape at ever! point in the

shape. Order doesn$t "atter.

Si"ilar to "atri# addition. The additions at the surface are the onl! ones that have an

effect. I"agine one shape eing s"eared onto the other shape. *arning )inko&ski is incredi l! slo& &ith spheres.


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)inko&ski =#a"ple


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(se "odule for shape 8varia les9

/* * This creates a shell of given thickness * around an arbitrary shape */module shell(thickness){ difference(){ minkowski(){ child(0); sphere(r thickness! center true); " child(0); ""shell(#0){ cylinder(r $%);"


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Creating "anifold designs )anifold effectivel! "eans &ater2tight. 3eaks happen at shared oundaries. Shared

oundaries also slo& do&n processing. =#tend o 'ects that su tract e!ond surface. =ither use 8glue9 o 'ects or e#tend surfaces into

other o 'ects for unions. Spheres can so"eti"es fail to e "anifold. (se

circle and rotate;e#trude instead.


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)ore on "anifold designs (se thro&n together and co"pile to see

questiona le oundaries.

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