Making things suck¶
The second wild card thing I did was a cup box for little board game chips. For sorting and storage. The box needed a lid, so that the pieces would not fly everywhere.
I though that making a box would be about as simple as possible. The only interesting thing would just be the one valley in the box, but that should be selvable by drilling a hole at the bottom of it. To make it a bit more complex, I thought that adding an embossed design in the lid would make it a bit harder.
I used the same design for the lid that I used in the embroidery. The design could be simple, as this design has multiple small valleys that could prove problematic. I think I will first try to vacuum the design without air holes, and if they are needed, I will add them later.
For the sake of making things easy on myself early (and hard later), I made the box as male mold (some could call it positive) and the lid as female. This enabled me to just cut the lid from the box with Combine -> Cut. This decision means that the lid, which would be really easy to vacuum form, is now much harder because I introduced unnecessary valleys to it. Though those valleys could prove beneficial, as the embossed design might require me to drill it anyways.
We found some 0,5mm thick PETG plastic from a storage room, and decided to use it. According to the documentation that I was given about vacuum forming, PETG that size would require 120°C - 160°C for about 30 seconds. At my first try, the machine did nothing the plastic for the first 10 minutes. At the time, we thought it was just bad machine (which still is the case), but other things that could have affected the results are:
- The PETG sheet still had its protective wrap on it
- All the heating elements were not turned on
- The machine had no way of measuring the temperature
But after the 10-15 minute wait, the plastic seemed plastic enough, so we moved on to the vacuuming phase. We moved the heating element away from the frame, pulled the lever to insert the mold against the plastic and turned on the vacuum. Or we would have, except the insulation was busted, and the machine would not create a vacuum. Thus the only thing it did was droop a bit of plastic around the edges.
The first attempt wasn’t pretty.
Week Later¶
After new insulation arrived, and the machine was fixed, I tried again. This time I even removed the wrap around the plastic and turned all the heating elements on at the beginning. This time, the wait lasted only about 5 minutes.
The process of using the machine was not that hard. First, I needed to insert the mold into the slot reserved for it. Because I had so many valleys in my design, I was recommended to glue them on a MDF board that filled the whole bottom, and drill holes to proper positions to pull stronger vacuum in those specific spots.
Then I cut a sheet of PETG plastic to fill the tension frame, and pulled the heating cover on the plastic. Then I needed to wait until the plasstic was droopy enough. It the machine would have proper temperature gauge, I could time it better, but as is, I needed to peek into the machine a couple of times to see it the plastic had been melted enough.
This time when I pulled the pulled the lever to bring the mold up to the plastic and turned the vacuum, things seemed to happen. Then, according to the machine instructions, I pressed the vacuum separation button (which basically inverts the vacuum machine to blow air into the mold) a couple of times every 5ish seconds to remove the mold from the plastic.
But even with proper vacuum, the valleys in my molds were insurmountable. There were clear valleys in the resulting plastic shape, but not deep or angular enough to be usable as a box.
If I will test this again, I would probably make both molds male, and remove the bottom from the box’s mold. This way it could suck with full power inside the box.