Week 8 - Moulding and Casting¶
Design parameters: +1.6mm thickness 60mm * 60mm *8mm 2.5D Base with round edges
The Principle of Moulding and Casting¶
Moulding and casting are two fundamental processes in manufacturing and art. Moulding involves shaping a material by placing it into a hollow container (mould) that has the desired shape or by drilling it using a fine milling machine. The material is usually in a liquid or pliable state and solidifies to take the shape of the mould. Common materials used in moulding include plastics, metals, and ceramics. Casting on the other hand is a process where a liquid material is poured into a mould and allowed to solidify. Once solidified, the mould is removed, leaving a cast object. This process is commonly used with metals, but can also be used with other materials like concrete, plaster, and resins, which is what we were told will be using in Fab Lab Academy.
Applications
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Moulding: Commonly used in the production of plastic products, automotive parts, toys, and household items.
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Casting: Widely used in the manufacturing of metal parts, sculptures, jewelry, and industrial components.
Moulding my Design with a Fine Milling Machine¶
Fine milling machines are used to create precise moulds from materials like metal, plastic, or wood. The high precision of these machines ensures that the moulds have intricate details and tight tolerances, which is crucial for high-quality moulding.
So I chose to make a letter stamp with my name since I love sending letters the old-fashioned way to my friends :) I want it to be a signature at the end of letters because I’ve always wanted to perfect my signature in letters while writing Love, Sara.. So I decided to do exactly that! With a pretty flower next to it that will be connected to my name. Let’s walk through the steps I took:
1.Design
First I created a detailed CAD model of my mould in .STL format. Although it was supposed to be very simple since it’s just a signature stamp, I really suffered to make it perfect according to the parameters we were told to follow.
Design Parameters: A minimum of 1.6 mm thickness, dimensions must be 60 mm * 60 mm * 8 mm in a 2.5D format, with a round edged base.
Issues Encountered¶
Super Narrow Thickness
I first used Cuttle.xyz to do my design, but I couldn’t quite control the letter thickness using their fonts and the shapes they had didn’t offer much variety. After doing my design I imported it to Fusion 360 to try and change the thickness of the parameters.. But they were too many and I couldn’t control them well. As you can see below after extruding the letters they were too narrow for the drilling bids to go through (minimum of 1.6 mm) so I had to change something about it without compromising the beauty of cursive fonts.
Extruding Font in Fusion 360 I had some issues with fonts on fusion because they weren’t extrudable.. I did some research and came up with the tutorial below that instructed me I needed to FIRST create a base sketch and then choose it as a face to add text on and THEN the text will be extrudable.
Going back to scratch
So I moved to Fusion 360 and downloaded my own fonts, imported some vector flowers to include. Still, the letters were too narrow for the drilling bid to go through and I had to go the hard way and do everything from scratch. I designed my own letters one by one while trying to mimic the font I liked but keeping track of each letter thickness, and came up with this design that I somewhat compromised for because cursive letters were too narrow and the flowers I previously chose were also too detailed to be drilled by a 1.6mm bit.
This is what I thought would be the final design lol:
However, after uploading it to the drilling machine software ang getting ready to start after setting up all the settings and proceeding to the start button, the software showed me how will it be printed, and the flower I put was narrower than the smallest bid we had.. So I went back to designing another shape and this time I used Tinkercad because my instructor Duaa compiled all of my classmates’ designs into one and she was already using it and we were both tired to start a new design from scratch :(
So I started looking for an object other than flowers because the ones I had in mind were too detailed, I ended up choosing a camel; because it resembles my Arabian roots and environment. I wanted my letters to convey a flavor and a sense of culture for the receiver because sometimes I mail my international friends abroad. I picked out a simple camel and Duaa helped me turn it into an outline using Inkscape. This was the design on Tinkercad:
However AGAIN we encountered another issue on Tinkercad with my text because somehow it wasn’t connected right at the bottom of the base. So Duaa instructed me to isolate the text and the camel and create a separate base. I went back to Fusion360 and created a simple round edged base and exported it to Tinkercad.
Casting with Silicone¶
First I prepared my mould and materials. Stirring stick like a wooden or plastic stick works well. Mixing Containers must be clean and disposable, because once that silicon sticks into anything, IT ISN’T COMING OFF (i.e Duaa’s abaya rip lol). I also had the silicone parts A and B close and handy because they can react very quickly once mixed.
Carefully measured equal parts of silicone A and B. The ratio is usually 1:1, but check the manufacturer’s instructions to be sure.
Then I mixed the silicone by pour both parts into the mixing container. Stirred thoroughly for about 3 minutes, ensuring the mixture is uniform. Scraped the sides and bottom of the container to avoid unmixed portions.
I slowly poured the mixed silicone into my mold. Starting from one corner and letting it flow to avoid trapping air bubbles. I tapped the mold gently on a flat surface to help release any trapped air bubbles and used a wooden skewer to pop out any bubbles left.
Lastly I had to alllow the silicone to cure for the recommended time, 24 hours. Duaa kept it for me in a dust-free environment to avoid contamination (in the drawers).
Demolding¶
Once cured, I carefully removed the silicone casting from the mold. For the finishing touches I trimmed off any excess silicone or flash with a sharp cutter.
3D Printing a Stamp Handle¶
Finally, I created a handle to glue the silicone stamp into so that it’d be easier to use. I decided to write on the sides the name and slogan of my cookie business Cookie Codes just in case I start using it to stamp my orders lol.
https://docs.google.com/document/d/186WN7jQR-awvqYc_pqp820IxycKKrmYaYDcl_m1yDik/edit?pli=1
Our machine is MonoFab Roland SRM-20 SRP player software to generate a toolpath for our design