3D printer and first case for Gyro’clock

The 3D printer arrived a week ago and I have been using it pretty much every day since. The Prusa I3 DIY printer kit I ordered from Amazon came from a company called Shenzhen Anet Technology. They provided instructional videos of how to assemble it, and it took me about a full day to put it all together. Assembling the printer was quite fun and it’s great to know what every nut and bolt in it does. The printer also came with two spools of PLA filament.

Here’s the completely assembled 3D printer:

Fully assembled 3D printer

Fully assembled 3D printer

So for my first test I decided to print the Gyro’clock case I designed previously. The 3D printer firmware understands G-code. To convert the 3D design made in FreeCAD to G-code it must be given to a slicer software. The 3D printer manual recommended to use Cura for slicing, so I decided to use it. The slicer program literally slices the 3D model into many layers for the 3D printer to print one by one.

After exporting the design in FreeCAD as a .stl (stereo-lithography) file I opened it up in Cura. When you first start up Cura, you have to give it information about your 3D printer such as print size, nozzle and filament type etc. After loading the .stl file, Cura also gives options to scale, rotate and mirror the object, which is handy. After converting the image to G-code I saved it in an SD card, which can be inserted into a slot in the printer.

It took about an hour and a half to print the bottom part of the case, and this is how it turned out:

Bottom piece of the Gyro'clock case with the Gyro'clock PCB

Bottom piece of the Gyro’clock case with the Gyro’clock PCB

The top piece took only 30 minutes or so since it was smaller in size, and this is how it turned out:

Top piece of the Gyro'clock board

Top piece of the Gyro’clock case

During this first run of the printer I noted a few problems with my design and a few issues with the printer:

  1. The walls were too thin. I designed the walls to be 0.8 mm wide. This made the case too flimsy and it was too flexible. My attempt to remove the pieces from the printer bed caused them to bend slightly.
  2. The holes were too small. The screw holes I made to attach the board to the case and the top piece to the bottom piece were non-existent in the print.
  3. Printer does not wait for minimum time interval before moving to the next layer. There is a setting in Cura for selecting the minimum time spent on a layer. I set this value to 5 s. But I noticed when the top piece was printing the printer does not wait the minimum interval between the layers. This caused the snap on part of the top piece to deform. Could be a firmware bug.
  4. I forgot to create a window for the switch and the charger LED. There is no excuse for such carelessness!
  5. The printer has trouble making small overhanging features at 90°. This is understandable because there is no support underneath to hold the thin strands of melted plastic. So the first few layers of an overhanging section (or a bridge) does not hold well. But if the overhang is thicker and the bridge is not that wide then later layers will build up properly.
  6. Masking tape on the heated bed lifts causing the print to bend. This printer has a heated bed. Masking tape is put on the metal bed so the print job will not stick to it. On repeated use this masking tape looses its adhesiveness and lifts from the bed causing the printed object to bend. The solution for this is to replace the masking tape for each print.
  7. Formation of snags causes the printer head to jump. It was good that I noticed this problem before it became an issue. When the printer head moves across a gap following the same route multiple times, excess plastic can cause snags to form. The next time the printer head comes around the same path the snag could block it. This could cause the printer to misalign. Fortunately I saw the printer jolt a few times on a snag and cut off the snag before it got too large. A good reason not to leave a print job unattended for too long.

After cleaning up the two pieces of the case to remove snags and excess plastic I put the two pieces together. There was no need to attach the board to the case with screws since it fitted snugly. I also cut off the deformed snap on piece of the top part.

And here’s the resulting case:

First 3D printed Gyro'clock case

First 3D printed Gyro’clock case

This was a good learning experience about 3D printing. Now I know what to do for the second version of the case. It’s coming soon!

 

Making a case for Gyro’clock

I officially finished all my school work since last week and finally had some time to think about my projects. There are two projects I started a while ago that I would like to finish off first. They are the Smart Turn project and the Gyro’clock project.

The only big thing left to do for the Gyro’clock is to make a case for it.  This means that I am finally getting around to the 3D print scene. This is exciting because I am going to be learning a new trick that has lots of potential. But first I have to learn about making 3D models.

There are many software programs out there for making 3D designs. After some search I decided to go with FreeCAD mainly because it is fairly sophisticated. After spending some time playing around with it and watching some tutorials I am able to find my way around it.

My approach for designing a case was to import the board layout that I have already created in KiCad and then build a simple case around it. Importing a 3D model of a PCB designed in KiCad to FreeCAD is quite simple. But the problem is I didn’t have 3D models for all the components in my Gyro’clock PCB. Importing 3D models from FreeCAD to KiCad is not that straight forward since KiCad only accepts a certain kind of .wrl files only.

After doing a bit of search online I found a nice tutorial that explains step by step how to create 3D models for PCB components. The steps I followed to make 3D models for components in KiCad are

  1. Design the 3D model in FreeCAD
  2. Export the 3D model as a .stl (stereolithography) file
  3. Import the .stl file to Wings3D
  4. Add colour to the model
  5. Export the model as WRML 2.0 (.wrl) file
  6. Import the .wrl file to KiCad
  7. Scale and position as necessary

Here’s the complete 3D model of the Gyro’clock board:

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3D model of Gyro’clock board

After completing the 3D model of the board I imported it to FreeCAD. The case has two pieces. The bottom piece wraps around the board and holds the rechargeable Li-poly battery. The top piece is just a cover and snaps on to the bottom piece.

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Bottom piece of the Gyro’clock case holding the PCB and the Li-poly battery

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The top piece snaps on to the bottom piece

Designing the case in FreeCAD is just a matter of knowing the proper dimensions. Since I had a life size model of a fully assembled Gyro’clock PCB it was really easy. Of course I don’t know how well it will come out of the 3D printer yet. Since this is going to be my first 3D experiment I am not going to go super fancy.

Speaking of 3D printers I have already ordered one and waiting for it to arrive. It is a Reprap Prusa I3 3D printer kit and I found it on Amazon.ca for $420 (CAD). It is a DIY kit so it comes with more fun.