Introduction: Everlamp Lamp Base - CNC Mold Manufacturing
This Instructable focuses on the manufacturing of a mold for the Everlamp - a highly customizable, eco-friendly lamp designed to last a lifetime. Like it on Facebook to receive updates on when it goes for sale.
The Everlamp is not just an open-source lamp, it will also be an open-source company - these plans will give anybody the opportunity to duplicate the business model I am using. While this Instructable focuses on only one part, the instructions can easily be used to manufacture any other part.
I'm assuming you've already decided on a design for your lamp, and are now looking to manufacture it.
It took me about 4 weeks to complete the project with no prior machining experience.
The CAD files used for the part are open-source, and can be accessed below, although it's suggested that you modify them or create new ones to fit your specific needs.
A basic overview follows of how to use mold design and CAM software to control your CNC machinery for this part. A Techshop membership is a relatively inexpensive way to gain access to the machinery and software.
Expect to do a few rounds of iterating between each step, as you'll find that some future steps won't cooperate with your old plans.
~Part and Lampshade Design (covered in the previous instructable)
1. Mold Design (this makes your part)
2. Buying Endmills (cutters) and Material
3. Toolpaths for your CNC Machinery (telling the machine where to cut)
4. Actual Machining
5. Injection Molding
Step 1: Mold Design
After you've defined your part (the Everlamp in this case), you can use a CAD package with mold design software built in (such as Solidworks or Inventor) to design your mold. Techshop gives free access to Inventor, and students have free access to Solidworks online.
The key things to note here are where you're placing your runner, and the size of your workpiece, as this will reflect on the part you CNC later.
Step 2: Buying Endmills and Material
After you have your part geometry and molds figured out, the next step is to buy your endmills and material.
Enco is a great source, if you're planning on making an aluminum mold. You can get double endmills for around $6 when they're on discount.
If you're working in steel or a tougher material, you might want to go to McMaster-Carr, or at least buy the Atrax brand from Enco, as the cheap ones tend to break easily.
For material, recycled aluminum is extremely cheap, and can be cut down with horizontal band saws, and faced down on a mill or on your CNC afterwards. If you don't have the time McMaster also sells pre-cut sizes.
Step 3: Creating Toolpaths
Now it's time to go into your CAM (computer aided machining) software, to tell your machine how to use the endmills you've just purchased.
After you've set up one half of your mold, you'll need to input the orientation, tools to use, feed rates, and speeds into your software.
This part is very important as you will break endmills and/or get hurt if you don't choose the right feed rate
You can find good information online, and on some forums, but I would definitely suggest pairing it with a class. I spent a few hours browsing CNC zone by material, and type of endmill and learned all I needed.
Some basic guidelines for the endmills I used on the Tormach are in the table below. As a rule of thumb, for shorter "stub endmills" you can do deeper cuts with higher speed, but for long thin ones, stick to slower feeds.
After you've finished selecting the feeds and speeds, you just need to select the part geometries and how your tools will cut. This part can be pretty challenging as you will realize that some endmills aren't quite as great as you thought they were, and will need to buy some more. Also, there will be a lot of testing on the nice little "simulation tools." Play with this until your parts are perfect, coming out, as it will save you the time and cost of buying new material from messing up.
Step 4: Machining!
Now onto the fun part!
Here, you want to be sure to have had some previous experience, or at least taken a basic safety class before. There are a LOT of things that can go wrong if you're a first-timer
The basic flow of CNC-ing goes
1. import your toolpath info and check it in the CNC software
2. use your edgefinder to find the x and y coordinates corresponding to the origin you selected while making your toolpath.
3. make sure your endmill is firmly in the collet before putting it in the machine.
4. zero the tip of your tool to the top of your workpiece
5. watch it go.
And remember to make some awesome lamps with your new base
Step 5: Injection Molding
The injection molding with the final mold was done at Techshop's 20 ton Morgan Press.
Be sure to have cut sufficient vents along your mold to enable air to escape. About 30% of the area of your part should be sufficient; I added 8 1/4" wide slots which were about 0.005" deep.