PROCESS:

For Homework 6, we were tasked with 3D printing an impossible object using 2 different 3D printing techniques. I decided to use FDM and SLA, using the UltiMaker and Form 2 respectively. I went on Thingiverse and looked for the impossible object that I’d use. I chose “Interlocking Square Earrings” by ‘genuinecrafts’: https://www.thingiverse.com/thing:425209

Although these are intended to be earrings, I also think it could serve as a cool key chain!

As for how many of the 5 trinkets I’d make through SLA and FDM, I decided on making 4 of them on the Ultimaker and 1 on the Form 2, as the Ultimaker took around 3x less time (37 min. vs. 2 hours and 30 min.).

The progression of my work went like this:

1. Find object on Thingiverse
2. Upload to 3DprinterOS and resize appropriately for gumball capsule
3. Print 4 objects on Ultimaker
4. Remove supports using pliers/ultrasonic cutter
5. Post-process reachable inner pieces
6. Upload STL file to desktop of Form 2 computer
7. Resize appropriately and follow recommended set up procedures
8. Print 1 object on Form 2
9. Soak in alcohol for 10 minutes
10. Shine UV on finished part
11. Remove supports using pliers/ultrasonic cutter
12. Insert into gumball capsules

STEP 2:

When I uploaded to 3DprinterOS, I took measurement of the gumball capsule in order to influence my decision for scaling the object from Thingiverse. The dimensions for my object were (in mm.):

However, when I was all set up to print, and sliced and previewed my file, it looked like this:

Obviously, I was initially freaked out by the amount of supports that were being displayed here. However, some of the lab techs assured me that the edges of my cubes were sufficiently thick to withstand me pulling away forcefully at the supports with pliers.

I also decided to add a brim build plate adhesion, so that my object wouldn’t move around when being printed.

STEP 3: 

My print took on the Ultimaker 3 took ~ 37 minutes, and came out looking like this:

As you can see, the supports are pretty small, and since I would be using diagonal pliers, I thought that it would be pretty difficult to get them out without scratching the surfaces of my cubes/causing some accidental damage.

STEP 4:

My theory was correct! Tearing the supports out of each of the 4 FDM objects took around 30 minutes each, and almost gave me Carpal Tunnel (ouch!). It also proved very very difficult to remove the supports inside the cubes cleanly, especially within the smaller 2 cubes, and the ring part.

I also employed the use of the ultrasonic cutter, to try and straighten out some of the inner edges of the cubes that had some leftover residue from the support that I couldn’t fully pull out. This ended up good in some places, but I found it pretty difficult to keep the cutter straight, and at some points it cut into the actual edges of the cubes.

Also, trying to squeeze the diagonal cutters inside of the cube tended to result in me scratching the edges of some of the cubes, leaving a bit of a rugged finish, even with some sanding post-processing, which sometimes caused some unpleasant discoloration in the filament material.

Here’s a picture of one of the 4 finished products:

The cubes rattle well when dangled, which is nice.

STEP 5:

As I mentioned, I tried to do some sanding on the flat edges of the cubes, but it was pretty ineffective, and many times led to making the object uglier. I also tried to use a file for the inside, but none of them were small enough to avoid hitting the other edges of the cubes when used.

STEP 8:

Here’s a picture of how it came out:

STEP 11:

Here’s how it looked after I took out the supports using pliers:

Final Gumballs (!!!) :

I found the supports for the SLA print to be way easier to remove. With that being said, there were also the extra post processing steps specific to the SLA printer that had to be undergone before actually removing the supports, which definitely took more cumulative time than the post-processing of the FDM prints.

COST CALCS:

Labor: $35

Assuming my labor is worth $10/hr. I spent around 3.5 hours (not including waiting for my prints) post-processing my 3D printed objects.

Raw Materials: $25.24

According to https://all3dp.com/fdm-vs-sla/, 1 kilo of FDM resin is ~$25. This is the smallest amount of FDM resin I could find being sold at a time.

According to 3DprinterOS, the PLA filament is super cheap, and costs ~$.06/print.

Machine Time: $50

According to https://www.shapeways.com/model/upload-and-buy/9893335, each print of this item in versatile plastic (substitute for PLA plastic, as its the cheapest) is $5.

The SLA Plastic cut costs $30 per print.

TOTAL COST: $50.

Since the services at shapeways covers labor costs, raw materials costs, and machine time costs all in one mine(and is most likely cheaper than renting out a spot in a maker space, along with the cost of the pure raw materials you would need to buy, and accounting for the cost of your own labor), I decided to go with the cost of that service alone.