Tehnologija 3D printanja

8/10/2019 Tehnologija 3D printanja

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3D Printers - How Do They Work?

The topic of 3D printing has peaked your interest? Have you tried to find information on this vast

subject, but got lost either in a multitude of 3D printing news only sites, or short and/or superficial

articles? re you still trying to get your head around the ins and outs of 3D printing technology?

!f you answered yes to any of the above "uestions, you are not alone# 3D printing can be comple$ to take

in initially, as the learning curve may be "uite steep% &e know the feeling since we have been there

ourselves% 'ut, do not despair, we have written this article to e$plain 3D printing technology with the

beginner in mind% To make all of this easy to understand, we have added "uite a few pictures and

illustrations% Hope you enjoy the read#

(tarting assumptions)

This article only looks at *used *ilament *abrication printers +***, also known as *used Deposition-odelling +*D- printers or -olten .olymer Deposition +-.D printers% &e will not discuss any of the

other 3D printing technologies, like Digital ight .rojection +D., (tereolitography +( and

(elective aser (intering +((, etc% The reason is simply that *** printers are by far the most common

3D printer type used for home 3D printing, i%e% desktop 3D printers% !f you are considering to buy your

own 3D printer, a *** is most likely the 3D printing technology that you will end up using% 0ote that

*** is a synonym of *used Deposition -odelling +*D- 1 both terms describe e$actly the same

techni"ue% However, *used Deposition -odelling and its abbreviation *D- are trademarked by

(tratasys !nc, one of the major 3D printing companies%

&e use our 2ltimaker 3D printer +note) it is an 2ltimaker riginal, not the newer version called the2ltimaker 4 as a reference throughout this article% lthough the 2ltimaker5s working principles do not

differ fundamentally, it should be noted that other printers models may look somewhat different%

However, the functioning principles of all *** printers are largely the same%

What is Fused Filament Fabrication (FFF)?

*used *ilament *abrication is nothing but a fancy word to describe a process by which a machine

deposits a filament +picture something like a small string of a certain material +normally

thermoplastics, wa$ or similar products on top or ne$t to the same material, in order to create a joint

by heat and/or adhesion% Thermoplastics are plastics which become semi1li"uid above a specific

temperature and return to a solid state when cooling down%

*** printer prints a 31dimensional object by e$truding a stream of heated or melted thermoplastic

material, which is carefully positioned into layer upon layer, working from the bottom up% 6ust imagine

a heated print head that is oo7ing out a permanent flow of molten plastic onto a surface in order to

form, through multiple layers, the virtual object you chose to print% 'y adding layer upon layer, which

will almost immediately harden upon leaving the hot print head, you will see the object that you chose

to create materiali7e right in front of you%

http)//3dprintingforbeginners%com/3d1printing1technology/ 1
http://3dprintingforbeginners.com/3d-printing-technology/http://3dprintingforbeginners.com/3d-printing-technology/


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6ust have a look at Illustration !which gives you a clear understanding of ***%

!llustration 8 1 9 :eprap%org



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Workin" in 3 Dimensions - Workin" Princi#les o$ %inear &obots

!n order to be able to print a physical object, i%e% an object in 3 dimensions, a 3D printer needs to be able

to move on 3 coordinate a$es +i%e% most commonly referred to as length, width and height%

!llustration 4 1 9 3Dprintingforbeginners%com

'ut how do you tell the machine where to put its no77le at a specific moment? -athematicians generally

refer to the term of ;


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!llustration 3

a$is

and may therefore help you understand the process% nce you had finished typing your document, the

computer translated the document into coordinates for your printer% moving head printed the letters

on paper, usually on one fi$ed a$is +going from left to right and back 1 i%e% the hori7ontal a$is while little

motors drove wheels which advanced the paper page on the other a$is +up and down 1 i%e% the vertical

a$is% The principles are the same for a 3D printer, e$cept that it is able to move in one more direction

+depth and thus is able to physically print objects%

0early every 3D printer is built around the principle that its 3 principal a$es are linear% This means that

their a$es are at right angles to each other and that they move in straight lines +that is) they do not

rotate% -achines which use this principle are known as linear robots or cartesian coordinate robots, as

opposed to Delta1 or .olar1type robots% Typical e$amples of linear robots are 3D printers, but also

computer numerical control +


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"uite some noise and cheap stepper motors can be especially noisy% However, more recent models have

been addressing this particular issue and are far "uieter then the older models%

!llustration @

2ltimaker (tepper -otors 1 'efore and after installation9 3Dprintingforbeginners%com

truder


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!llustration B

!ntegrated e$truder on a .rintrbot (imple 9johnbiehler%com

ther printers, like our 2ltimaker riginal, have a ;material feeder; or a ;filament driver; +i%e% the

e$truder separated from the ;e$trusion head; +i%e% the hot1end% 6ust have a look at Illustration +for

a better understanding of this particular setup%

!llustration C

Detailed views of the e$truder and the separate hot1end and their respective positioning +circles on the 2ltimaker



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9 3Dprintingforbeginners%com

The confusion around the wording used to describe 3D printer parts stems from the fact their e$act

terminology is not yet fi$ed% Aspecially if you consider that the action of pushing the heated plastic

through a print no77le is called e$truding 1 pretty frustrating, isn5t it?

nyway, both systems, the integrated type e$truders or the remote one5s both have their pros and cons%!ntegrated type e$truders don5t need a complicated filament delivery system 1 just look at Illustration

*, where you can see the filament arrive directly into the e$truder of the .rintrbot (imple% These

e$truders therefore rarely e$hibit feeding problems +like friction problems caused in 'owden1cable type

systems 1 see below, but they are heavier than remote e$truders% Due to added weight and bulkiness,

the integrated type e$truders generally are far slower than the remote e$truders and this lack of speed

results in longer print times% n advantage however is the ease with which one can change the filament 1

no hassle and no time loss%

The remote type e$truder systems generally push the filament through a hollow cable +Teflon or asimilar material in order to obtain a permanent feed of thermoplastic material to the moving hot1end%

This sort of setup is called a ;'owden cable;, which are fle$ible cables used to transmit mechanical force

by the movement of an inner cable +filament relative to a hollow outer cable housing% The 'owden

cable therefore does not only ensure the permanent feed of filament to the connected hot1end but also

enables retraction of the filament if needed% :etraction is an important techni"ue in 3D printing in

order to obtain clean prints +read more on retraction below% !n order to control filament feeding or

retraction, a ;filament driver; is connected to a stepper motor% The filament driver +normally a

toothed/grooved bolt and a push wheel at its opposite side s"uee7e the filament and via this tor"ue and

pinch system, they overcome friction and manage to push the filament through the 'owden1cable +cf%

!llustrations , and for detailed views of ;pinched; filament%

!llustration 1 Erooved drive marks




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!llustration F 1 Erooved drive marks


The problem is that the 'owden1cable setup does create a lot of friction and the e$truder systems,

especially the feeding systems on early printers were often having feeding problems% lso, certain

materials like for instance fle$ible . do create "uite a lot of friction, as their rubbery surface chafes

while being pushed through the 'owden cable% Therefore, 3D printing enthusiasts are permanently

looking for better solutions and, in true -aker spirit, created a lot of 3D printable alternatives for

e$truder systems% 6ust have a look at Illustration ., picturing the incredible :ollerstruder, a complete

replacement of the 2ltimaker e$truder developed by 6eremie *ranGois 1 available at)

http)//www%thingiverse%com/thing)3F4%

The big advantage of the remote type e$truder system however is that the hot1end is very lightweight,

which results in "uicker travel speeds as well as "uicker prints% ur 2ltimaker original does use a

remote e$truder and this e$plains why this printer is among the "uickest 3D printers in its class%

nother slight disadvantage for such a 'owden1cable style setup is that changing the filament can

sometimes be a bit of a hassle, as you need to work out what procedure works best with your specific

printer% &e always heat up the print head first, before trying to remove any kind of filament% This is

necessary, as the filament cools down after printing +the printer by default is set to cool down after

finishing a print% 'y cooling down, the filament gets stuck to the melted but not yet e$truded plastic left

http://www.thingiverse.com/thing:73082http://3dprintingforbeginners.com/3d-printing-technology/http://3dprintingforbeginners.com/3d-printing-technology/http://www.thingiverse.com/thing:73082


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in the heating chamber% >ou should never try to yank it free with force% (imply heat it up and gently pull

back on the filament reel, after opening your material feeder mechanism% r make and install 6eremie5s

system, which also allows for a "uick filament change%

!llustration I 1 9 6eremie *rancois

&etraction

:etraction is a special techni"ue used in 3D printing, whereby molten plastic is ;sucked back; into the

heated hot end, while printing% n an 2ltimaker, you will notice that, while retracting, the ;material

feeder; drives the filament in the opposite direction than usual% !t does basically pull a small part of

filament back through the 'owden tube% The effect of this can be compared to s"uee7ing the edges of

your toothpaste tube to suck back in some of the e$cess toothpaste you accidentally s"uirted out%

&hile printing a part, molten plastic is normally e$truded continuously, e$cept when the no77le needs

to create a gap or jump across a gap to the opposing part of the wall or another part% s the e$truded

thermoplastics are not completely li"uid, they tend to create cobweb1like thin strand of plastic which



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tend to follow the no77le across that gap% !n order to obtain a proper print, you would need to clean

those strands, which is messy and time1consuming% The solution is to retract the filament back up into

the no77le just before jumping across the gap or the new part% Then, upon arrival at the other side, the

filament is pushed back to where it was before retraction% This effectively eliminates the ;cobweb

creation;, which also known as ;stringing;%

!llustration 8 1 9 3Dprintingforbeginners%com

Dual Extruder

(ome *** printers feature a dual e$truder% This means that the printer has two filament drivers as well

as two hot1ends%


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!llustration 88 1 9 -akergeeks%com

!llustration 84 1 9 0otcot%com



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!llustration 83 1 9 Tested%com

The advantage of this particular feature is that you can feed two different filaments for one print,

enabling you thereby to either print in dual colour +look at the great two1coloured cat in Illustration

3 or even with two different materials% &hy two materials you ask? &ell, as you know, 3D printers

print from the ground up% 'ut some prints are impossible to realise, as the printer cannot print on airJ

that5s why you need ;support structures; or support, in short% The parts of your print which would be

floating on air are called ;overhang;%


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Illustration * shows you the printed product, with its support structure and Illustration + shows

you the finished cat, after cleaning the support structure away%

!llustration 8B 1 9 6ohn 'aichtal, -ake7ine%com

!llustration 8C 1 9 6ohn 'aichtal, -ake7ine%com

!f your are printing with . or '(, you need to know that the plastic will get pretty stiff after cooling

down 1 so cleaning the support structure can take "uite some time% lso, you need to pay attention not



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to damage your print, especially if you use a knife or a power tool like a Dremel%

n easier way to get around this is printing with .K on the second e$truder% .K, short for polyvinyl

alcohol, is a special water1soluble thermoplastic% . is used to print your object and .K is used to

print only the support structure% nce your print is finished, just put it into water for some time and the

.K support structure will dissolve itself +check out our materials post to get more information on

.K% Koila, you have a perfect print without the hassle or time loss for cleaning up your object%

Illustrations , to . demonstrate how this techni"ue works% The same also works with printing '(

in conjunction with H!.( +High !mpact .olystyrene% H!.( can be dissolved in imonene, a chemical

dissolvent widely available% The big advantage over .K is that H!.( is far less hygroscopic, i%e% it does

not attract water from the air as easily as .K% .K needs to be stored in an airtight bo$, ideally

together with some desiccant +like silica gel, so that all the moisture in the air does not get absorbed by

the .K filament% H!.( is clearly the easier solution giving you less headache when it comes to storage%

!llustration 8 9Tony 'user

http://3dprintingforbeginners.com/filamentprimer/http://3dprintingforbeginners.com/3d-printing-technology/http://3dprintingforbeginners.com/filamentprimer/http://3dprintingforbeginners.com/3d-printing-technology/


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!llustration 8F 9Tony 'user

!llustration 8I 9Tony 'user



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Hot nd

The hot end is usually made up of a bloc of aluminium +s"uared or barrel1shaped, which is heated up to

temperatures up to 4BL


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Printbed

The printbed is the surface upon which the printed part sits on while being built% The most common

printbeds are made out of .le$iglass +acrylic, aluminium or glass% &e have even created one out of

carbon fiberJ we will publish a detailed article on this build soon% &hen buying a 3D printer, you should

always check out what the e$act printbed si7e is, as it plays a determining factor in the ma$imum si7e of

your future printed objects% lso, you need to differentiate between simple +non1heated printbeds and

heated printbeds%

0on1heated printbeds normally need to be covered in blue tape +painters tape or even Napton tape +i%e%

polyimide tape 1 very heat resistant in order to make the print stick to the printbed% The tape helps with

initial adhesion of the thermoplastic and keeps everything in place during the print% The object needs to

be firmly fi$ed to the printbed, as the slightest movement of the printed object itself will most probably

result in a botched1up print% s the adhesion factor of the blue tape wears out "uickly, it needs to be

replaced regularly% !nstead of blue tape, some people recommend using glue, hair spray, sanding down

the Napton tape, etc% The biggest disadvantage of using a non1heated printbed is that you may

e$perience warping +Illustrations //-/' or cracking +Illustrations /* and /+ of your prints% This

is a direct conse"uence of the plastic cooling down too fast and the effects are especially prominent

when using '( plastics%

!llustration 44 9 :eprap%org



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!llustration 43 9 microfabricator%com

!llustration 4@ 9 3dprintedsculpture%com



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!llustration 4B 9 3dprintedsculpture%com

!llustration 4C 9 flashgamer%com



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(o if you don5t want to build a heat chamber around your printer +check out Illustrations /, and /,

you should consider buying a model with a heated printbed, or, in true maker spirit, build one on your

own%

!llustration 4

(imple D!> Heat Heat


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The heated printbed prevents warping of the prints while cooling down, but also provides for a much

smoother surface of the first layers of the print% 0ormally, printbed temperatures vary between CL to

88L<


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Filament

*ilament is the consumable for your 3D printer% 6ust as the inkjet printers we referred to earlier needed

ink cartridges to work, a 3D printer needs filament in order to be able to print% *ilament is usually

bundled in spools +Illustrations /. and 30), but some is also sold by the meter +ideal for test prints%'efore making any purchase of filament, you need to know what filament diameter your printer works

with% !t will be either 8,Bmm or 3mm, which are the two standard si7es%

!llustration 4I 1 9 3Dprintingforbeginners%com

!llustration 3 9 iEo3D%com



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There also e$ist many different filaments materials, but the two most common are . and '(% Aach

material has its own physical and chemical properties, which means that each filament type needs its

own specific setup within your printing software% &hile some materials can be e$truded at temperatures

around 8FL

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Tehnologija 3D printanja