Weakly Casting
This week I had a lot of concurrent activities moving forward. I have ordered the wax and molding latex silicone, as well as some other materials for the pour. I have conducted a walk through of the process and am documenting both the process and expected timings, and I am learning if there are any tricks or tips that might make the mold making easier once those parts are on hand.
For learning to create the molds well I have watched and read a lot of different sources. Ones that contained information vital to the process or just did a great job of making the process visible are included in the references at the bottom.
Wax is surprisingly expensive. For the purposes of this current project I want to keep things as likely to succeed as I can so I am using a micro-crystalline wax that is commonly used for this type of casting. This type has properties most similar to the 3d printer filament types I would use if I am printing wax patterns or whole wax trees. I intend at some point to explore the ability to create my own filament, but for now I want to keep the process as close to identical as I can. Understanding the amount of wax I need to have on hand is another issue, for hollow casts it is fairly straightforward, for hollow castings I need a couple of MM space to allow for flow, complicating things a bit. I am torn between understanding the weight of wax is much less than the metal and understanding how much will be lost to the process itself, sprues, vents, ect. One reference says roughly 9 to 1 weight metal to wax, I am hoping this is roughly correct including vents and sprues.
I decided that ordering an 11 pound slab of brown micro-crystalline wax will at least be sufficient for a test run, though it may not be as much as I was hoping for for this run. Note that I don’t expect to use this wax often or at all for production, so any leftovers are best used elsewhere. The 11 pound slab isn’t that expensive at $35.55. This point of pain for me is the shipping being extortionate at $29.32. At this price point I am more interested in ensuring I collect the info I need before turning to the 3d printer. Once the wax arrives and I have an idea of the volume, I can much more easily predict what all I am going to need. It should be easy to capture photos showing the volume versus the items I intend to duplicate and provide a good visual on making sure I have enough volume of wax for the patterns I want to pour as much as having enough metal and ready crucibles to pour,.
After reviewing multiple mold making videos and reading some literature from manufacturers as well, there is not a lot I can do to simplify the mold making process. If anything it has highlighted some of the cost savings of my intended methodology to the final products. I am going to look into what additional capabilities are possible out of the print nozzles, I have a feeling there are gains to be had in employing cnc type tooling.
I am still on the fence between latex mold making material, or some of the silicone binary material as providing the best outcome. I am ordering the silicone binary molding material as well as deciding to remove figure 1, and object 1 from casting this run. Figure 1 is not something I want to risk damage to, object 1 is simply too complicated for attempting at this time. Object 1 will be the first cast attempt with the 3d printer.
Documentation is going to stay where it is for now. Centralizing it would require building out and maintaining more infrastructure than I am interested in just yet. So for now documents not directly software will remain on a Gdrive and I won’t leave it open access just yet.
Walkthrough pour was interesting. Discovered that although the process can be done by a single person it is not going to be efficient to set up safely and cheaply. I am going to see if I can get someone to work with me for a few hours for this pour both to solve a few of the issues that an extra set of hands may, as well as to get feedback on future one person set ups.
Setting up the work area will have two areas, one for handling and dealing with the oven and molds, the other the furnace and the crucibles. This part of the process is going to need at least one more walk through before I fire anything off. The mold will need to be inverted when it is first placed in the burnout furnace to allow for the wax to flow out of the mold. Flipping the mold while it is both extremely hot and extremely fragile is likely to be tricky (also the primary reason for reducing the number of castings I intend to make this run). Being able to flip, inspect, and pour the metal might not be doable in a single task before cooling creates its own needs, such as being placed back in the oven to get back to a good temperature to receive the metal.
All in all I am finding that for this manual run a lot of efficiency will not be available to me as my budget is tight as is to establish the first line process as solid as possible. I am also looking into the physical layout I will want should I move to a space dedicated for the purpose, able to handle a higher throughput without a second person needed for safe operation.
I am looking into what OSHA regs will apply for this and what additional safety items might need to be addressed both immediately and later items to be incorporated into processes, procedures ect.
Get Aaron Smith’s stories in your inbox
Join Medium for free to get updates from this writer.
All in all the week’s production was a bit disappointing. I was anticipating having more done this week, on the upside, I have been able to find more information about how to do this well the first time for almost every aspect of the project.
I am going to write a number of short papers and references for the various items I have looked into so far that need more information than is usually needed for a manual pour.
Mold Making- It appears that latex is probably the best option for great results, if you know the various particularities of the process well and intend that the molds be retained for multiple reuse.
Wax- There is a ton to know about the wax, various properties of it, how to use it, alternatives and options.
Investment- There are many varieties and types, why and when sand casting makes sense, modern investments.
Mold handling/oven- This part has taken me a bit of time to understand, I will certainly need to learn a lot more before this happens successfully.
I am considering adding a youtube channel for videos once there are thing worth videoing, I will include links once I do so.
Reference Videos that may be of interest:
https://www.youtube.com/watch?v=IRhaAQrfEkE 1280 How To Make Latex Rubber Molds For All Kinds Of Things
https://www.youtube.com/watch?v=_t4wNUnBRGA Making Latex Molds
https://www.youtube.com/watch?v=1H42C3nW_nw How to make a mold.
https://www.youtube.com/watch?v=OPIUMpiV0IY Primitive Technology: Making Iron From Creek Sand
