3D printing is pretty exciting, but it is best for making prototypes. I decided to find ways to easily make copies of my designs.
1) The easiest way is to 3D print one master, build a box around it, mix and pour silicone around it to make a mold. Then you pour resin into that mold to make a copy. The silicone is expensive and tends to get bubbles. The resin is fairly expensive and tends to get bubbles. Bubbles are the enemy. I probably need to build a box that sucks a slight vacuum.
2) I started working on plastic injection, and built an inexpensive machine in my garage. It melts plastic pellets and extrudes them into a mold when I pull hard on the lever.
a) You need a metal mold to inject the plastic into.
b) To make a good product, you need about 5,000 pounds of pressure, and I was getting about 500.
Making metal molds for plastic injection:
I have bought a device that melts some metals. I am working with lead-free pewter right now, but it is too expensive.
I can 3D print a mold, press it into foundry sand, and then pour pewter into it. I then have a pewter mold that will not dissolve when I push hot plastic into it.
The most difficult aspect right now is mastering Fusion 360 so that I can design parts and molds. Temporary problem.
I want to make the molds out of zinc or aluminum, which my device will not melt.
Plastics melt at about 450 F, and so does pewter. Not a good choice for a mold. Zinc melts at 787 F, a good choice and much cheaper. Aluminum at 1221 F.
So my partner Marsh Wildman built a forge for $50 and posted it on his YouTube channel. I bought it and will start melting zinc soon.
Better injection machine:
We need more force. We will probably go with hydraulic power.
We have seen a machine that does this, and the cost for it is $23,000. We figure that we can build it for under $1500, maybe under $1000. I expect that after we get it working, we could sell such units for about $3000 to $5000.
I think that there are a lot of people out there that would like to move up to short run manufacturing. Make a mold in your back yard and then crank out 1000 plastic pieces to sell online.
Oh, also plan to make pewter and zinc injectors. Once I have aluminum molds, I can do that.
An aluminum mother mold, inject zinc to make a mold, sell the zinc molds to people that want to do plastic injection.