This week in ENGI210, we are exploring the vast world of 3d printing. 3d printing has been around for a number of years, but due to the more recent Re-Rap project and cheaper technology, has made vast improvements on the commercial and consumer levels.

To test out this constantly improving technology, we were tasked in printing an impossible object from thingiverse. In terms of the definition of impossible, that just means that we had to print an object that would otherwise be very difficult to manufacture using another manufacturing method. This means, either the part has too many small intricate parts, or it it is all made as one object, or it is so small that it requires a laser to print the detail. This object would be put into a gumball machine for sale.

For my print, I decided to print a CrocFullOfSass from the thingiverse website. This object is less than an inch tall and has many small features that I wanted to try to test the printability of. I decided to use the FormLabs 2 printer as the consumer 3d printer (which is a resin based printer, meaning it uses a liquid as printing material) and the Objet as the industrial 3d printer (which is also a resin based printer) for this project. Both machines use different types of light curing technology, so this would be a test to see which would produce a better object with the ability to show all the details in the small figurine.

The first step is to download the .stl file from thingiverse. The STL file is the file that is read by the 3d printing slicing software that is then converted into gcode for the printer to use. Gcode is the script that is read and processed by the 3d printers that tell them where to move and how much to print. For the Formlabs 2 printer, they have their own slicing software that makes it really easy to set up a print.

1. Load in the STL file.
2. Generate supports
3. select material (in this case I used the black resin)
4. Send print to printer and print.

The print time for the object depends on the size and the amount of layers there are. For the Croc, the print time was 1hr 15min. After an hour, you have to take the print and rinse it in the alcohol bath to get rid of the excess resin.

The final step is to cut off all of the support material that was generated to be able to print it correctly. This involves taking a pair of needle nose pliers and snipping off all the support structures. This process can be time consuming, but supports are necessary to have a successful print.

The Objet printer, much like the FormLabs 2, has its own slicing software. This software has many more options that that for the FormLabs, which allows you to customize the material used, or if multiple materials can be used. Much like the FormLabs 2, the steps are similar for processing the part.

1. Import STL file.
2. position on the bed using the Placement function
3. Validate object
4. Build Object

The Objet also has the ability to determine the cost of the object depending on the material used. This can be done in the software using the fine estimation function to determine amount used, and then plugging those values into the cost calculator that the OEDK uses. The print on this machine took 1hr 48min. This means that the printer was slower than the the FormLabs 2, but there is much more support that needed to be printed using this printer. This printer prints from the bed up, unlike the FormLabs that prints from the the top down (which require less support).

To post process the part, you need to spray them with high pressure water to get rid of the support. On the Objet, the post processing is much faster that with the FormLabs.

In terms of each machines print quality, the FormLabs did a very good job printing the fine detail on the object, but there were clear layers on the model if you looked closely. I could have gone to a finer detail, but decided to see how visible they would be on the fastest print setting. The supports that were cut off of the model did leave some visual impact on the part where they had to be cut off. For the Objet, the part had no visible layers and was also printed on the fastest settings possible. The part was smooth and well printed. One thing that I did notice is that there was a distinct layer where the support was no longer used for the model. It appears that the support material creates a different effect of the outer coating of the part. This could also be due to the fact that the areas that did not need support were exposed to the light more so they were cured a bit more. While the areas that were supported were soft and dull, the areas that did not need support were shiny. There was also a slight loss of detail in the eyes of the Croc, but this also had to due with the material.

Overall both machines were able to print the small object quite well. I would say that the FormLabs printed the part a bit better in terms of detail, but the objet wins when it comes to production size.

In terms of cost, the FormLabs took 20 min to set up and about 20 min to cut off all the support. I we do count the print time as part of the cost (at minimum wage since the printer is a robot), then the cost of the part comes out to ~15$. For the Objet, the part had material costs already calculated at 9.88$ and with the machine earning minimum wage the const comes out to ~23.88$

 

Disclosure: I also printed a round object pictured above to determine which one I wanted to use for the gumball machine.