Third Time’s the Charm

 In our last official lab session, we started the production run of the pyramids. We were hoping to get a little over 100 translucent pyramids by the end of lab, but unfortunately ran into a couple of problems along the way. 

First, we didn’t know how to get translucent parts that would be an even color across the entire run. We decided to use half the weight of the colored resin instead of mixing in the full 2.5 g. When we started the run, there was still some leftover resin in the BOY from our body run, so the pyramids were coming out a burgundy color instead of translucent red. We ran a couple of parts and some purging cycles so we could start to see what the pyramid would look like if it came out the right color. 

Before purging the remaining black resin from the first body production run

Along with the incorrect color, the sprue was also getting stuck in the cavity mold almost every cycle. We added more threads to the core side and bumped up cooling time to 30 seconds, but it was still catching. After inspecting a couple of the sprues, we noticed a possible misalignment of the cavity mold, so for a quick fix, we stuck a piece of paper under the MUD insert and got a couple of parts to come out without catching. Unfortunately this successful streak only lasted around 15 parts before the problem returned.

Over the weekend, we were able to come into lab to finish our production run, as we had only made 35 working pyramids. Using alignment pins seemed to resolve the issue of the sprue getting stuck. Between our official lab and Saturday, we tested the newly soldered PCBs with the LEDs and were surprised by how bright they are and that they are visible under the opaque white cover, so we determined that the pyramids didn’t need to be translucent for the LED effect to work. This also made it easier to produce identical parts since the level of translucency was no longer a concern. 

Some of the color variations of the pyramid

Even not producing translucent parts, we got some color variation across the run, which we were able to get back in control after running a couple of purge cycles. We finished our production run and ended up with 125 pyramids of the correct color. It was noticed on closer inspection that there was a slight misalignment of the molds, since the ledges on one side of the pyramid were larger than the other, but they are still able to catch on the white cover and not fall out while the yo-yo is spinning.

Molds post production run with some off color pyramids

Production Run: 57 and counting