casting coal with epoxy resin and silicone molds

by:Keyuan     2020-07-13
Epoxy is a great thing.
Since it is almost combined with anything, you can mix it with particles of almost any material and end up with a substance that can be formed or cast into whatever shape you want.
With this in mind, I am interested in forming relief panels with a material that does not seem to be able to form this shape-coal.
In this note, I will outline the process of 3d modeling relief, processing the front of the foam, creating silicone molds from the front, processing coal into powder, and casting the last piece with epoxy resin.
There are a lot of ways to model reliefs, but I\'ll introduce here my preferred approach to using Rhino.
First, run the Heightfield command.
Heightfield will use grayscale input images to drive the creation of the relief, where the light color defines the high point and the dark color defines the low point.
Select the image from which you want to generate the relief.
Next, set your origin.
You will be asked to enter the length of the height field.
Set the length of the required relief.
You then need to set the number of sampling points, the total depth, and the required geometric output.
The sampling point defines how well the output surface meets the color of the image.
Try this setting until you find a solution that meets your needs.
I prefer to output the mesh with vertices at the sample position, as this will allow you to create a fairly high sample rate without interrupting your computer.
Initially you will get a jagged mesh, but it is possible to smooth this mesh using the free WeaverBird Plugin
Command with wbCatmullClark-
A mesh subdivision algorithm.
You can repeat this command on the grid until you reach the level of smoothness you want.
In order for the model to be toolpathized, you need to export the mesh and bring it into the CAM software of your choice.
Alternatively, you can create relief directly in some CAM software.
ArtCAM has this ability, and it may make sense to explore this if you plan to use relief frequently.
You can use the grayscale images outlined above, or import other 3d models, ArtCAM converts them into relief, and direct modeling can be painful if you work in a reUrethane bubble a lot --
This is what we really need to make silicone molds.
It is light weight, uniform, relatively affordable, the machine is easy and beautiful, and has a range of sizes and densities to meet the needs of your specific project.
You can be taller.
Density Polyurethane Foam from multiple sources, it has several names, so you may need to do some search to find the supplier that makes the most sense to you --
Probably the one closest to you.
You can order through McMaster
Carl, if you\'re in a hurry.
Freeman manufacturing and supply company produces in RenShape\'s name in various sizes and densities.
Better yet, they include a variety of processing guides for the types available.
If you are using foam with lower density (15 lb. /cu. ft. or less)
The cutting depth is shorter than the cutting length of the drill bit, and you may skip the rough machining process completely to get almost the same result.
The possibility of this soft material damaging the machine is low.
This can greatly save processing time.
You can read the general procedure for casting silicone in the last instruction I wrote.
However, one of the key differences here is that I used a tin
Compared with platinum, based on siliconebased one.
Polyurethane foam can inhibit the curing of Platinum
So I don\'t want to take this risk because silicone rubber is very expensive.
I built a small box to hold the foam front and left some space on it and I would pour the silicone there.
I could have sealed the foam with some sort of spray finish, but I haven\'t bothered since the material I\'m going to cast (coal dust)
There will be no resolution and details like plaster or pure resin casting.
As instructed by the manufacturer, I mixed parts A and B together.
It may not be necessary, but I decided
Inflate the silicone using a vacuum chamber.
When the silicone is ready, I pour it into the mold at the lowest point.
It is important to resist the urge to spread it when pouring, but to let the silicone slowly spread and find its level.
This will help prevent any airbag from forming in the mold.
The video here only shows the first pour, and it took about 5 times to get to the necessary level.
For this reason, it\'s good to have a silicone with a long jar-life.
I am mainly limited by the size of the available mixing containers, but it is also good to mix only what is needed for my mold and avoid wasting expensive materials.
Warning: coal dust can be very dangerous.
Google image search will provide relevant images for terms such as \"pollution\", \"explosion\" and \"Black Lunch.
In fact, coal mine dust explosion is one of the biggest mine disasters in history.
For these reasons, please be careful with the use of protective devices to reduce dust exposure, minimize total dust in the air and stay away from any possible ignition source when using the material.
In addition, ensure adequate protection is used when mixing the resin.
Epoxy is a skin-sensitive agent, so be especially careful with skin contact when the resin is in an uncured state.
Due to the brittle nature of coal, it is not difficult to produce dust.
In fact, if you happen to know any blacksmith or anyone who runs coal
Forge, who is fired, you may be able to accumulate enough dust for a meaningful project.
They might be more than happy to get rid of it than deal with it in other ways.
If you need to make Dust yourself, the first step is to get some coal.
I ordered my coal from Metropolitan coal and received it about a week later.
How you determine that processing coal will depend primarily on the fineness and total volume required.
If I need a lot of dust, I might develop a more automated method of dust generation.
However, since I only need a small bucket, I decided to handle the dust generation process manually. With a 10 lb.
Sledding, I was able to divide the coal into smaller, more manageable parts.
These things are then treated in a small blender to dust that I want to make.
Using the mold I created in the previous step, I was able to pour the dry coal mixture into the mold and measure if it was enough to cast my parts.
Once I mixed the whole batch of dust with epoxy until the coal looked a little damp.
You don\'t want to add too much, otherwise the resin will be more visible in the final panel, giving everything a \"plastic-y\' appearance.
After the coal and epoxy are fully mixed, I pour the mixture into the mold.
The rest is as simple as you think.
I level the coal in the mold and make sure that everything is packed to prevent the gaps in the mold.
To make sure that the dust is tightly packed enough that the epoxy can glue everything together, I cut a piece of plywood into the exact size of the final panel, and use it to apply even clamping pressure on the entire panel.
I stuck everything in and let the epoxy cure.
I used a very slow 24 hour epoxy curing that gave me the most working time on powder coal.
Although I have not used any special mold release agent on silicone or plywood mold box, I have not encountered any problems either
Molding, so if you don\'t use too much epoxy in the mixture, release may not be necessary.
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