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6. 3D Scanning and printing

Group assignment

  • Test the design rules for your printer(s)

Individual assignment

  • Design and 3D print an object (small, few cm3, limited by printer time) that could not be made subtractively
  • 3D scan an object (and optionally print it)

Group assignment

Our group is Perttu, Gleb, Lukasz and I.

To evaluate 3D printers we selected three different printers to be used: Stratasys Fortus 350mc, Leapfrog Creatr HS and Raise3d Pro2.

Stratasys Fortus 350mc

Technology: Fused Deposition Modeling (FDM), additive manufacturing process printing from bottom to top, layer-by-layer (each layer with each corresponding model material and support material).

Most common defect in FDM is warping: it happens when the extruded material cools during solidification, its dimensions decrease. Design considerations for preventing warping.

Solution: Avoiding large flat areas, thin protruding features and sharp corners.

Specifications:

Max build size: 355x305x305 mm  
Typical layer height in FDM: varies between 50 and 400 microns  
Material: ABS  
Software: Insight (provided by Stratasys Fortus)

Leapfrog Creatr HS

Technology: Fused Filament Fabrication (FFF), additive manufacturing process printing from bottom to top, layer-by-layer (each layer with each corresponding model material and support material).

Most common defect in FFF is warping: it happens when the extruded material cools during solidification, its dimensions decrease. Design considerations for preventing warping.

Solution: Avoiding large flat areas, thin protruding features and sharp corners.

Specifications:

Max build size: 280x270x180 mm  
Typical layer height in FDM: varies between 20 and 350 microns  
Material: PLA     
Software: slic3r

Raise3d Pro2

Technology: Fused Deposition Modeling (FDM), additive manufacturing process printing from bottom to top, layer-by-layer (each layer with each corresponding model material and support material) or Fused Filament Fabrication (FFF), printing process that uses a continuous filament of a thermoplastic material. Filament is fed from a large coil through a moving, heated printer extruder head, and is deposited on the growing work. The print head is moved under computer control to define the printed shape.

Most common defect in FDM is warping: it happens when the extruded material cools during solidification, its dimensions decrease. Design considerations for preventing warping.

Solution: Avoiding large flat areas, thin protruding features and sharp corners.

Most common defect in FFF is weakness of filaments: it happens when designed object has too thin walls/lines or nozzle is small Design considerations for preventing warping.

Solution: Avoiding thin outlines, walls and lines, use reasonable nozzle size and printing speed.

Specifications:

Max build size: 305x305x300 mm  
Typical layer height in FDM: varies between 10 and 250 microns  
Material: ABS 
Software: Built-in

Testing

We used this Thingiverse test piece with all printers.

The test piece includes following tests:
01 Nut, Size M4 Nut should fit perfectly
02 Wave, rounded print
03 Star, Sharp Edges
04 Name, Complex Shapes
05 Holes, Size 3, 4, 5 mm
06 minimal Distance: 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7 mm
07 Z height: 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1 mm
08 Wall Thickness: 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7 mm
09 Bridge Print: 2, 4, 8, 16 mm
10 Sphere, Rounded Print 4.8mm height
11 Sphere Mix, 7 mm height
12 Pyramide, 7 mm height
13 Overhang: 25, 30, 35, 40, 45, 50, 55, 60, 65, 70°
14 Warp, does it bend?
15 3D Print Font, optimized for 3D printing
16 Surface, Flatness
17 Size, 100 x 100mm x 23.83 (10mm width)
18 Spike, minimum Layer Time, 21 mm height from Bottom (include Baseplate)
19 Hole in Wall, 4 mm diameter, check for proper print
20 Raft Test, raft should be just under the model
21 Retract Travel, check retract settings for longer travel

Here are the test pieces:

Here are pictures of the test details:

Test piece, Stratasys Fortus 350mc:

Test piece, Leapfrog Creatr HS:

Test piece, Raise3d Pro2:

Minimal Distance, Stratasys Fortus 350mc:

The thin spaces are blended together. Only the biggest ones are open.

Minimal Distance, Leapfrog Creatr HS:

Thin spacing has over extrusion. Only the biggest are open, rest are fused.

Minimal Distance, Raise3d Pro2:

Only the last two are fused together, rest of the spaces are open.

Overhang, Stratasys Fortus 350mc:

Overhangs are ok, some stringness.

Overhang, Leapfrog Creatr HS:

No failures in overhangs, some stringness.

Overhang, Raise3d Pro2:

Overhangs are ok.

Minimal wall thickness, Stratasys Fortus 350mc:

The thickest thin walls are ok and under sized walls are omitted.

Minimal wall thickness, Leapfrog Creatr HS:

All of the walls are printed, stringing between the thin walls.

Minimal wall thickness, Raise3d Pro2:

Everything is printed as in design.

Text, Stratasys Fortus 350mc:

Text is very unclear.

Text, Leapfrog Creatr HS:

This text is better, but there are some failures in printing.

Text, Raise3d Pro2:

The best quality of the samples.

Reflections of the group work:

Stratasys Fortus had the weakest quality in all tests, even if it the most expensive and the biggest 3D printer.

Minimal distance: Raise3d had the best quality, but none was good.

Overhang: All lines were printed somewhat ok.

Minimum wall thickness: Stratasys did not print the thinnest walls at all, Rais3d printed everything.

Text: Stratasys letters were unreadable. Remaining two are ok.

In general: You need to think which filament (and which printer) is the most appropriate for the use. The filament properties differ a lot and the used filament also affects to the printing quality. See e.g. MatterHackers for the filament properties.

Individual assignment

Design and 3D print and object

What is additive technique and subtractive technique?

ADDITIVE - It is a process of build any object in layer by depositing any material.
SUBTRACTIVE - a process by which 3D objects are constructed by successively cutting material away from a solid block of material.

Why 3D printing is unique?
Additive refers to a process of starting from nothing and adding material until the desired object is produced. In additive techniques, 3D printing is different in its manufacturing process as it successively add material to the object instead of forming everything at once. Therefore every area of the object is accessible during the manufacturing process.
The main advantage of a 3D printer, is customization, which means that you are able to print any design no matter how complex it might be. So you are able to create objects that are encased in other objects and movable or even flexible parts. Basically, 3D printing has the unique ability to produce almost every imaginable 3-dimensional object, which is due to the successive additive technique.

I used Fusion 360 for the design. I wanted to create a ball that has inside another ball and the inner ball is freely moving inside the outer ball. The inner ball is smaller than the holes of the outer ball and it does not come out. Milling bit can not bend to reach all the parts of the inner ball. You can see the inner ball through the holes in the bigger ball. This structure is very difficult to create with any other technique.

First I created a sphere with Fusion 360 and I set the surface thickness to 3 mm, inside.

After that I created another, smaller sphere inside the original sphere by creating a sphere of smaller size and positioning it near origo.

Then I made holes to the original sphere using “Hole”-tool, having 3 mm depth. I used “Pattern/Circular Pattern” -tool, having quantity of 8 to have holes around the sphere.

Now my design file is ready and I took it with USB stick to the FabLab printer. I used Stratasys Fortus 380 mc 3D printer.

First in the PC I opened Sphere stl-file with Insight. I chose the Parameter style “Sparse” and pressed green flag for the slicing.

I pressed Build-button and the Control Center-window opens. I chose the placement for my sphere and pressed the “Build Job” to send the job to the printer.

In Stratasys you first open the door with gloves (it is hot!) and attach the build sheet to the bottom. It needs to be sucked in its place by air.

In the Stratasys screen the correct job was chosen from the job list and the placement checked. After that you just press “>”. Printing time (3h 30 min) and required amount of material (39,81 cm3 model material and 28,06 cm3 support material) can be seen on the screen.

After printing the build sheet is removed with gloves and the object is removed from the sheet by spatula. Support material is removed by hand. Rest of the support material is soaked in lye. Check that the temperature of the lye (sodium hydroxide, NaOH) tank is around 55C and that the pump is on. Then object is added to be soaked in the lye tank. Remember to wash the gloves.

I left the object to the tank for the weekend and on Monday morning I took it away, using gloves, of course.

After that I washed the object and the gloves and here is my sphere.

Here is also a video clip of the sphere

3D scan an object

I did the scanning with two different apps which I installed in my phone. Here is a normal photo of the scanned object, it is a Cloudberry shaped candle.

Scann3D:

Scann3D gives good advice how to do the scanning:

  • Encircle your target: To make a good model you need to move around the object. Follow a circular path and stop when taking pictures.
  • Glue regions: Make sure each segment of the object is present on at least two pictures. Glue regions tie your model together.
  • Distance matters: Aim for distance where you need 15-20 images to cover your target with glue.
  • Lightning matters: Spotlights, hard shadows and uneven lightning generally results in incomplete models. Diffuse, even lightning and soft shadows result in good models.
  • Be mobile: It is insufficient to move the target object. You need to move the device itself; you need to be mobile.
  • Moving targets: Moving targets cannot be made into models.
  • Suboptimal targets: Reflective, transparent and untextured homogenous objects do not make good models.
  • Excellent targets: Textured, vivid and rough items make excellent models.

I set the object on a paper on the table (just old A4 size paper with some text), to get the object to separate from the table. After that I took 20 photos according the instructions the app gave me. To make a good model, you need to move around the object in a circular path and stop when taking pictures. Even light is the best. The app showed indicators around the object (little dots) that are green when the camera is in a good position. Dots are red or yellow if the position is not good. After taking about 20 pictures the scanning is done and app is processing the work. In my first trial the result was failed. App just said “Failed”. I had to do the scanning again. This time I focused to have better picture quality (pictures with green dots mainly).

Sometimes the position of the target is lost and you need to capture the last position with help of the overlay picture in the screen. You should take the pictures only when the indicators are green, sometimes it is difficult to find a good position for the picture.

Here is a screenshot of the scan. To export the files you need to buy Scann3D Pro.

I also tried Qlone-app. The web-page provided a Qlone mat that needs to be placed below the scanned object. Using the mat, the app creates a dome and shows you which part you need to scan more. You don’t take separate photos but you just scan as long as needed. The mat can be turned around so that you don’t need to move yourself.

Qlone-app did not give any tips, you just move the phone so long that the dome get transparent. Sometimes when moving the dome disappears and that indicates that you are too near or too far away. Scanning continues when you move so that the dome appears again.

Here is the screenshot of the scan. With this the situation was the same as with Scann3D, I was not able to export the file.

I uploaded the Scann3D pictures to Autodesk ReCap to create 3D file. The processing took over night, because I used education license and the priority for that is low. Anyhow the result was ok, but the file size was huge, 32 MB. I imported the obj-file to Fusion 360 and opened Mesh-tool. I selected the body and used Modify/reduce -tool and changed the Density from 0.25 to 0.14 to reduce the file size. Then I exported the file as .f3d format. The final size of the file is now 220 kB.

Here is a picture of the Mesh

Reflections of 3D scanning

The tools I tried seem easy to use at the first look. But it is not so easy to produce a good quality results. This clearly needs practicing. Apps have helping features; Scann3D has the colored dots and Qlone has the dome.
Now I have seen several tools that can be used and I am sure that from now on I will use also 3D scanning, if I e.g. need to capture an object for a basis of a design.

Files

Fusion 360 Sphere stl file
Fusion 360 Sphere f3d file
Scann3D stl file
Cloudberry 3D mesh f3d file
Cloudberry stl file