Magdalena Milly Assignments Final Project

12 Molding and casting

This week's assignment is to review the safety data sheets for each of your molding and casting materials, make and compare test casts with each of them, compare printing vs milling molds and design a mold around the process you'll be using, produce it with a smooth surface finish, and use it to cast parts.

Group assignment: Moulding and Casting

The documentation for our group assignment from the Barcelona node can be found here.

Lessons Learned

A "Doña Lechuga" treat

For this week's assignment I really wanted to try out the food safe silicon. Thanks to @Carolina, @Emily and the visual mind of Microsoft AI Image generator we have a running gag about our lab's very own superhero: "Doña Lechuga", a salad throwing supervillain, that gives mean people e-coli. Thus my goal for this week was to create a lettuce leaf mould and want to cast it in chocolate afterwards.

dona

Design the final piece

Initially I started to draw the lettuce piece freehand in Rhino and adding "Eat your greens" or "Mangia Lettuga" in letters to the shape, but wasn't really happy with the look and the letters would take forever to mill. For that reaseon I decided to take some inspiration from freepik.com and craft the lettuce shape in 2D in Rhino. to get the 3D shape I used Loft.

rhino design

Create the mold

I followed @Julia Leirados advice to start thinking about the final shape i wanted to create: a chocolate treat with engraved letters. To reach the engraved letters I would create a two-sided mold from Ferris File-A-Wax. Unfortunately initially I "forgot" one crucial step - the silicon mold. So I had a perfect model in Rhino that was the other way around, which I realized once I opened Modela Player 4 and it could not generate the toolpath.

rhino fail

Secondly I had forgotten to measure the block, so I needed to scale the model down to fit the 149,4x88,5 cm block of wax.

rhino sketches

Thanks to @Mahe, @Adai for the help on figuring it out. I roughly followed these steps to create the mold, with some detours on the way:

rhino blender

I prepared the whole file to fit the 1/8 inch endmill and had changed the font to "Doña" only to fit with this endmill, but eventually it only worked with the 1/16. Due to this I had to increase the size of the accent and for time reasons we did it in Blender. Thanks @Adai!

Please find the final file here.

Create the toolpath in MODELA Player 4

Because Modela player 4 only runs on Windows I used our labs pc to create the milling toolpath for the Roland SRM 20, our labs milling machine.

modela 4

Open Options/Add/Remove Tool and add tool and name it significantly (Tool Name). Choose the Tool Type, in my case Square and select High Speed Spindle as Tool Material. In oder to enter the collet's measurement in mm, convert inch to mm (e.g. 1/8 inch = 1:8x25,4 = 3.175mm). Open Cutting Parameters and choose Modeling Wax. Hit Set Parameters to calculate the parameters (calculated parameters can be trusted). And finally click Register to save the parameters.

Next add a new cutting process:

I checked the toolpath with the Preview Option, which gives you a little animatio of the cut and very importantly the cutting time. Last but not least save the .rpn files to the cloud to be able to open them from the machine's pc.

Mill the waxform

In order to mill the wax the process is very similar to milling a pcb board, which I described in detail in Electronics Production Week.

milling flat

On the first attempt, when I launched my file the end mill was cutting air, because the block was not completely straight. So I had to reset the Z - keep in mind to do that at the lowest part of the block.

Second learning was to keep in mind the cut depth, when setting the spindle in order not to crash the collet holding the spindle into the block, when it cuts the edges. Thanks @Daniel Mateos for the hint!

milling

After 1,5 hours the rough cut was done and I launched the X finishing milling. After another 1,5 hours I was satisfied with the quality and and I could clean it from the scraps with air compression and start to create the silicon mold.

Cast the silicon mould

I teamed up with @Carolina to prepare the food save silicon Easyl 940-FDA Pink. Keep in mind to work in a save environmet, which means to wear gloves, double check the working time of the silicon (30 min in our case) and keep paper and wooden sticks close by. We roughly followed these steps to create the silicon mold:

silicon prep silicon degas

We cured the silicone over night and than put it in the oven for 4 hours at 100° to make the silicon truly food save.

A final chocolate treat

chocolate in mold

The first time I tried the mold, I was lazy and wanted to avoid the granny way of melting chocolate in the hot water without butter, but learned my lesson because the chocolate did not harden. On the second try I made the effort and it worked out fine. Mangia lechuga!

chocolate treats

Lessons Learned