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IMPORTANT THINGS WHEN MODELING FOR 3D PRINTING

Published In: Instructions Created Date: 2015-03-26 Hits: 538 Comment: 0
THERE ARE SOME THINGS TO KEEP IN MIND WHEN CREATING 3D MODELS FOR PRINTING.
IT IS BEST TO FOLLOW THESE GUIDELINES TO MAKE SURE YOUR MODEL PRINTS NICELY.
MODELING FOR 3D PRINTING
 
THERE ARE SOME THINGS TO KEEP IN MIND WHEN CREATING 3D MODELS FOR PRINTING.
IT IS BEST TO FOLLOW THESE GUIDELINES TO MAKE SURE YOUR MODEL PRINTS NICELY.
 
UNITS
MAKE SURE YOUR SOFTWARE IS USING MILLIMETERS, NOT METERS OR INCHES. TO DOUBLE CHECK (OR IF YOU WANT US TO SET THE SIZE FOR YOU) ALWAYS LET US KNOW WHAT SIZE THE MODEL SHOULD BE.
 
DISABLE SMOOTHING
ALL 3D MODELS ARE MADE FROM LITTLE TRIANGLES FORMING A MESH, AS YOU PROBABLY KNOW.
MOST 3D SOFTWARE USES "SMOOTHING" TO MAKE THINGS LOOK NICE...
BUT THIS SMOOTHING IS USELESS FOR 3D PRINTING UNLESS YOU APPLY THE SMOOTHING TO THE MESH.

WE OFTEN RECEIVE MODELS CONTAINING (FOR INSTANCE) SPHERES THAT ARE CONSTRUCTED
OUT OF 32 OR LESS PLANES. THE MODEL LOOKED NICE IN THE DESIGN PROGRAM,
BUT THE ACTUAL MESH IS NOT DETAILED ENOUGH TO MAKE A NICE SMOOTH SPHERE.
SO SWITCH OFF ALL SMOOTHING OPTIONS TO AVOID THIS MISTAKE, AND MAKE SURE YOU USE
PLENTY OF POLYGONS TO CREATE SMOOTHLY CURVED SURFACES. BUT DON'T EXAGGERATE,
AS USING TOO MANY POLYGONS WILL SLOW YOUR SYSTEM DOWN.

 
WATERPROOF MESH
YOUR MODEL SHOULD CONSIST OF A SINGLE CLOSED MESH WITHOUT ANY HOLES (MISSING POLYGONS).
THIS DOES NOT MEAN THERE CAN BE NO HOLES IN YOUR MODEL, BUT IF THERE ARE, THESE HOLES
MUST ALL BE PART OF THE ONE SINGLE MESH (SO THERE ARE INSIDE WALLS TO THE HOLES).
SO THE MESH CAN BE ANY SHAPE AS LONG AS IT COULD BE "FILLED WITH WATER WITHOUT LEAKING".
 
INSIDE INSIDE & OUTSIDE OUTSIDE
ALL THE TRIANGLES IN YOUR MODEL HAVE AN INSIDE AND AND OUTSIDE SURFACE. MAKE SURE ALL
INSIDES ARE ON THE INSIDE, AND ALL OUTSIDES ON THE OUTSIDE OF THE MESH.
IN TECHNICAL TERMS: NO FLIPPED NORMALS PLEASE.
 
NO LOOSE OR NON-MANIFOLD VERTICES
THIS MIGHT SOUND QUITE TECHNICAL.  DON'T WORRY, WE'LL KEEP IT SIMPLE.
ALL THIS MEANS IS THAT
A: THE MODEL MUST CONSIST OF A SINGLE MESH ONLY.
SO NO LOOSE PLANES OR "ISOLATED VERTICES" FLYING AROUND OR INSIDE THE MODEL,
AND
B: (MORE IMPORTANTLY): ALL THE EDGES CONNECTING THE VERTICES MUST ALL BE PART OF
THE SINGLE MESH. ANY CONNECTING EDGES THAT ARE NOT PART OF THIS "SKIN"
MAY CAUSE UNWANTED EFFECTS IN THE PRINTER SOFTWARE.
 
THE 45 DEGREES RULE
THIS RULE STATES THAT THE MODEL'S SKIN SHOULD NOT LEAN OUTWARDS MORE THAN 45 DEGREES -
(SAME GOES FOR INWARDS IN CASE OF HOLLOW OBJECTS).
HERE'S WHY:
OUR PRINTERS WILL PRINT THE BOTTOM LAYER OF YOUR MODEL FIRST.
SUBSEQUENT LAYERS HAVE TO BE (PARTLY) PRINTED ON TOP OF THE PREVIOUS LAYERS.

FOR INSTANCE: IF YOUR MODEL IS A SAUCER, THE SKIN IS LEANING OUTWARDS TOO MUCH.
EACH PRINTED LAYER WILL EXTEND OUTWARDS SO MUCH FURTHER THAN THE
PREVIOUS ONE THAT THERE WILL BE NOTHING THERE FOR THIS LAYER TO PRINT ONTO.

ANOTHER EXAMPLE: IF YOUR MODEL IS A STANDING FIGURE WITH ITS ARMS HANGING DOWN,
THE PRINTER WILL START WITH THE FEET, THEN BUILD UP THE LEGS, KNEES, ETCETERA. NO PROBLEM.
HOWEVER, AT SOME POINT IT WILL START PRINTING THE TIPS OF THE FINGERS  -  IN MID-AIR...

THIS DOES NOT MEAN THAT WE CAN NOT PRINT A SAUCER OR A FIGURINE, BUT IT DOES MEAN THAT
IN THESE CASES WE WILL HAVE TO ADD A SO-CALLED "SUPPORT STRUCTURE".
THIS WILL PROVIDE A BASIS FOR THE PARTS OF THE MODEL THAT BREAK THE 45 DEGREES RULE.

SUPPORT STRUCTURES ARE REMOVED AFTER PRINTING. MODELS THAT NEED A LOT OF SUPPORT
WILL TAKE MORE TIME TO PRINT AND ALSO TAKE MORE TIME TO "CLEAN" AFTER PRINTING.

PLEASE NOTE HOWEVER THAT ON OUR WELL-TUNED PRINTERS WE CAN PRINT OUTWARDS AT
AS MUCH AT 65 DEGREES WITHOUT NEEDING SUPPORT !   WE LIKE STRETCHING THE RULES...

 
TINY, THIN AND FLIMSY BITS
OUR PRINTERS CAN PRINT MINUTE DETAILS, BUT THERE ARE SOME LIMITATIONS WHEN IT COMES TO
TINY, THIN AND FLIMSY BITS LIKE TREE BRANCHES, POINTY EARS, THIN WALLS AND SUCH.
THIS HAS TO DO WITH THE SPECIFICATIONS OF OUR PRINTERS - LET'S HAVE A LOOK AT THEM.

THE MOVEMENT PRECISION IS 0.01 MM (!) SO NO PROBLEM THERE.

VERTICAL RESOLUTION IS DETERMINED BY THE LAYER HEIGHT. WE OFFER 3 DIFFERENT OPTIONS:

 
 - MEDIUM RESOLUTION (STANDARD): 0.2 MM PER LAYER (= 5 LAYERS PER MILLIMETER)
- HIGH RESOLUTION: 0.1 MM PER LAYER (= 10 LAYERS PER MILLIMETER)
- ULTRA-HIGH RESOLUTION: 0.05 MM PER LAYER (= 20 LAYERS PER MILLIMETER)

  HORIZONTAL RESOLUTION (FOR THE X-Y PLANE) IS A BIT MORE COMPLEX. HERE'S WHY:                    

 
ALTHOUGH THE MOVEMENT OF THE PRINT HEAD IS CONTROLLED WITH AN ACCURACY OF
0.01 MM, THE MODEL IS BUILT OUT OF "LINES" THAT ARE 0.4 MM WIDE.


SO IN A MODEL OF A BUILDING, THE HORIZONTAL RESOLUTION OF THE BRICKWORK IS VERY HIGH.
HOWEVER, IN AN OBJECT WITH THIN VERTICAL PARTS, OR A THIN-WALLED OBJECT LIKE A CUP
OR A VASE, THESE THIN BITS MUST HAVE A THICKNESS OF AT LEAST 0.4 MM.

ALSO, SUCH THIN BITS ARE PRINTED AT BEST QUALITY
WHEN THEIR THICKNESS IS EXACTLY 1, 2 OR 3 "LINES".


SO A THIN WALL WILL BE PRINTED NICER WHEN IT IS 0.4 OR 0.8 OR 1.2 MM THICK THAN
WHEN IT IS 0.5 OR 1.0 OR 1.384 MM THICK.   ONE IMPORTANT ISSUE HERE IS THAT ANY
VERTICAL WALLS OR THIN BITS THAT ARE LESS THAN 0.4 MM THICK CAN NOT BE
PRINTED PROPERLY AND SHOULD THEREFORE BE AVOIDED.

ALL THIS MEANS THAT FOR MANY OBJECTS THERE IS AN OPTIMAL ORIENTATION FOR PRINTING.
WE ALWAYS MAKE SURE YOUR MODEL IS PRINTED IN THE BEST WAY POSSIBLE, WHICH MAY
TURN OUT TO BE UPSIDE DOWN, SIDEWAYS OR EVEN LEANING UNDER A CERTAIN ANGLE.
OF COURSE WE WILL ALWAYS LET YOU KNOW IF WE THINK IT IS NECESSARY TO
CHANGE THE ORIENTATION OF YOUR MODEL BEFORE WE PRINT IT.

 

 
HOLLOW OBJECTS
MOST "SOLID" OBJECTS ARE PRINTED WITH A WALL FOLLOWING THE SHAPE OF THE MESH, AND A
"FILL" OF 20 - 25 %, WHICH MEANS THAT THE INSIDE IS FILLED WITH INTERNAL WALLS INSTEAD OF
A SOLID (100 %) FILL. THIS SAVES A LOT OF PRINTING TIME (=COST) AND IMPROVES PRINT QUALITY.

IT IS ALSO POSSIBLE TO PRINT HOLLOW OBJECTS (0 % FILL). IT IS EVEN POSSIBLE TO PRINT A TOP
ONTO A HOLLOW OBJECT, EITHER BY CURVING TOWARDS THE CENTRE OR BY "SPIDERING".

TO CREATE A MODEL FOR A HOLLOW OBJECT, YOU CAN MODEL IT AS IF IT WAS A SOLID OBJECT.
THIS WAY YOU DON'T HAVE TO WORRY ABOUT CREATING THE RIGHT WALL THICKNESS IN YOUR
MODEL - JUST TELL US WHAT SIZE AND WALL THICKNESS YOU WANT AND WE'LL TAKE CARE OF IT.

(THIS ALSO WORKS FOR CUPS AND VASES - JUST TELL US TO PRINT THE MODEL WITH NO TOP)

OR YOU CAN CREATE A HOLLOW MODEL WITH YOUR OWN PREFERRED WALL THICKNESS(ES)
TO YOUR OWN EXACT SPECIFICATIONS, BUT THIS IS A BIT MORE TRICKY. IT'S UP TO YOU.

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