6. 3D Scanning and printing¶

This week we had a group assignment to:

• Test the design rules for the 3D printers.

• Document your work and explain what are the limits of your printer(s) (in a group or individually)

• Document our work to the group work page and reflect on your individual page what you learned.

This week we had an individual assignment to:

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

• 3D scan an object, try to prepare it for printing (and optionally print it)

Group assignment¶

The documentation of the group assignment can be found here.

I learnt basics of the 3D printing and scanning. I learnt about the three working 3D printers we have in the lab. There were two very different methods for producing models which had their limitations and advantages.

I also learnt about the 3D scanning options we have available in the lab and about the limitatios of the 3d scanners and different tehcnologies they use.

Individual assignment¶

3D print an object¶

Here I am going to describe how I design and 3d-print an object which can’t be manufactured by using substractive methods. Probably a ball divide to two halves which connect together such a way that there is no room to remove the halves enough by using the substractive methods.

This is a very interesting task, because I haven’t printed anything with 3d printers before Fab Academy.

I created a 20 mm sphere and extruded it with a 17 mm sphere. Then I split the sphere by xy-plane and created a 17 mm high cylinder inside it. Then I added another cylinder with larger diameter and extruded it by the first one in order to make the cylinders fit inside each others.

3D scan an object.¶

I used the MakerBot digitizer to scan an object. After multiple unsuccessful attempts I ended up scanning a vase.

The vase vas placed on the rotating scanning table.

The digitizer cable was not installed into the USB port and the power was not turned on. I installed the USB cable (the white cable). Note that the same computer is used for controlling multiple devices and there was no port left for USB stick. Time to purchase an external USB hub?

The power was then turned on in the scanner device. A green led turned on.

Makerware for digitizer application was started.

The application guides the user throught the scanning process. The first step is to place the object on the scanning board. The object was already there.

The second step was to describe if the object was light or dark. The Medium darkness was selected.

The next step was to check, if the filter was over the camera lens.

The filter appeared to be there.

Then I stepped out of the camera view and began the scan.

The red laser point on the right side of the scanner turned on. The scanning time for the scan was about 9 minutes.

The table rotated and the camera observed the shape of the laser on the surface of the object.

After half the scanning time had passed, the laser turned on changed to the left side and the rotation continued.

After the image was scanned, the software began calculating.

The scanning process is finished.

For testing purposes, I ran thru the process twice. At the first time I tried continuing the scan with Multiscan. Multiscan does the scanning again with the object in a different angle. I repeated a process again without multiscan.

The stl file for a vase of one of my scans with Makerbot digitizer is included here.

What did I learn about 3D scanning?¶

Doing 3d scanning properly probably needs a dedicated environment i.e. place with ambient light and solid colored background. Some materials appear to be more difficult to scan than the others. The instructions in Makerbot scanner warn that there should be no people in the field of the camera. This is hard to arrange in a FabLab full of people.

3D printing.¶

The individual task for 3D printing was to design and 3D print an object (small, few cm3, limited by printer time) that could not be easily made subtractively.

In a design point of view, the object must have some property that for example, makes it impossible to mill it. I decided to make an object that has too big a feature inside other object to reach it with the commin substractive methods.

The idea¶

I decided to use Autodesk Fusion 360 as the program. I chose ball as the basic form for the object. This was not the simplest selection, because the ball has very small foot area. I cut the ball half and inserted a shaft like structire to the middle of the ball. The shaft continued via a hole to the cavity inside the other half. In the end of the shaft there is an extension that makes it impossible to remove the halves from each other. The fitting between the hole and the shaft is so tight, that it is practically impossible to use substractive methods for printing the object.

This time I decided to start the construction with bodies instead of extensing the sketch first.

The basic for was a sphere, divide to two by xy-plane. The lower part was made hollow by cutting it by a smaller sphere.

I created a ball by using sphere, Create -> Sphere.

I splitted the ball by using Modify -> Split body.

I created another cocentric ball wit smaller radius by using Create -> Sphere and substracted it from the previous ball.

I moved the upper half of the sphere (Move, M key) and added a shaft by using Create -> Cylinder.

I considered the size of the shaft again, created a smaller one and added another cylinder to the top of the new shaft by using Create -> Cylinder.

I used the Create -> Cylinder twice to create a bottom for the upper half of the sphere. I also tried to make a hole, but I didn’t connect it properly. These didn’t work as I wanted them to work.

I replaced the lower part of the shaft by deleting it and using Create -> Cylinder for making the new one.

The shaft was positioned into the lower part of the sphere.

*Modify -> Filet was used for the edges of the shaft top cylinder and to the ninner edge of the lower sphere.

I made a smaller sphere (Create -> Sphere) and substracted the top part of the main sphere with it.

I created two cylinders, one as a floor for the top sphere (again) and one as a hole for the shaft (Create -> Cylinder). This time the positioning was done more successfully.

Chamfer (Modify -> Chamfer) was used for chamfering the hole.

In the lower part, the edge around the equator is rounded as described earlier. This is done in order to make the separation of the parts easier. Also the extension at the top of the shaft is rounded. This is also done in order to make the separation of the supports easier inside the object by twisting the object

I exported the file as an stl file and opened it in 3DVOX for Sindoh 3D printer software.

The software sliced the ball. There was a slider for browsing thru the design.

I helped to check the result.

The software created supports.

There was a display for positioning.

The display showed the duration of the printing.

The results of the first round showed that there was a problem in the supports. The ball has really small surface against the floor, so the default supports were not enough.

I started the printing process again.

I added raft support in order to avoid the previous results.

The slicer produced a ball with better support.

The printing time was increased by a few minutes because of the supports.

The result on the table.

I removed the table and used a plaster tool to remove the printed part from the table.

I removed the supports with the help of the plaster too land by hand. The removing of the supports was hard at first, but when I learned the correct force to use, the supports were quite easy to remove after all. The supports inside the object were cracked open by turning the object. There was no way to make sure that all the supports inside the object are removed.

The result:

The printing took 1.09 meter (3.3 grams) of wire that happened to be in the Cartridge 1. It was most likely the same 0.4 mm black PLA material used in the group work. The printing took about 24 minutes.

Files¶

The .stl file can be downloaded here. The Autodesk Design file can be dowloaded here (93k).

What did I learn from 3D printing?¶

I learnt how to construct a 3D model. I learnt how to move it to the 3D printer, how to do the slicing and the meaning of the supports. I also learnt what kind of items cannot be easily manufactured by substractive methods.