13. Molding and Casting: Angel, Noah, Kathryn, Jenna¶
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Milling - Noah¶
Part of the group work was to compare different methods of making molds. Our lab has 2 methods, 3d printing and milling, and everybody choose to 3d print their individual mold. For the group work, I milled out my own mold out of machining wax, which has a good guide for the othermill here.
File Preparation¶
For some reason, importing stl’s onto bantam tools software didn’t work, so I had to find a different method. For this, I remembered what Dr. Gershenfeld had said a long time ago about Mods. Learning mods took way too long, as searching for mods, or even mods community edition usually just gave video game mods. I eventually found this fab academy page for electronics production that described how to use mods to make PCB’s with a specific milling machine my lab doesn’t use. Through trial and error, I eventually found that on the mods page
right click -> programs -> open program -> G-code -> mill 3d stl.
After loading that program, I loaded my stl file. Be careful when exporting that stl from whatever software you use that it is a Binary STL using inches as units. If not, it will make 1mm equal to an inch and the website will crash trying to compile such a large model. I took that STL and put it into the
After importing the file, I went to the Mill raster 3d block and clicked calculate. in that block, theres also a really important setting called “stepover”, which would be easier to understand if it was just called “quality”. Basically, the lower it is, the longer your mill will take, but the better it will look.
After calculating with a stepover of .5 (rough pass) and .2(finishing pass), I took the files it
Random file fix¶
Because im using the program for general milling machines, it didn’t follow some standards for othermill. the main problem was that it added in G54 to the start of the gcode. this changed offsets, but is Not supported on the othermill machines. In order to fix that, I simply deleted that line from the gcode files it exported. If you dont delete that, the othermill software gives you a giant warning about it not milling where you want it, then it won’t mill where you want it.
Othermill¶
After getting the good gcode files, I sent them to the computer connected to the mill. I loading in a 1/8th ballnose for both passes, as my lab doesn’t have 1/8th straight for the roughing pass. In the software itself, I only changed offsets to make sure that it milled on my wax, then started the mill. The rough pass took 10 minutes a 1.5 inch square basically, and the finishing took twice as long to cut with twice the detail.
Post Milling¶
After milling, I spent a bit sanding down the face. Due to the fact that we didn’t have that straight bit, there were very small but visible channels going down the machine.
Molding¶
For the mold, we followed the same processes we did for our individual mold. We did end up using a different material, just because it was already out for another persons mold. We also used the quick release spray to create a layer between the wax and the molding material, which would make getting it out easier.
Milling + Molding result¶
Milling Advantages¶
- Wider range of materials: When using 3d printing, your limited to almost always plastics, but resins on a sls are also possible.
- Accuracy: A well tuned milling machine can surpass even the best accuracy of a 3d printer.
- Surface Finish: Thanks to the ability to due a finishing pass, you can make something on a milling machine that doesn’t require any manual post processing