At Smallhouse Models, we make dollhouse furniture using a furniture design process that is different than the traditional process. Traditionally, miniature artisans make everything by hand. To get repeatable parts, they use molds or jigs. To fit pieces together, they often rely on a filing tool to shave off a little here and a little there.
At Smallhouse Models, we incorporate power tools and computer control of those tools. We cut out pieces of our furniture using a CNC router. CNC stands for Computer Numeric Control. A CNC router is a router controlled by a computer. The computer positions the router to make the cuts. With our set up, we have control to within 0.001 of an inch! This level of detail is extremely useful for making tiny things such as dollhouse furniture. Each piece is cut identically to the previous piece, which standardizes the process and ensures end-product quality.
Of course, before the CNC router touches wood, we need a furniture design and computer instructions for cutting.
It all starts with an idea. First a piece of furniture is researched. This usually means looking at different styles of that furniture and deciding what aspects we like or dislike, or if those styles give us any new ideas. All chairs have the same basic design – they have a seat, legs, and a back – and they are all recognizable as chairs. However, the styling of each chair can be vastly different. Some chairs have straight backs, others have curved backs, some have arms, some are padded, others are cushioned. Tons of differences! What task the chair will be used for also helps to determine what it will look like. Armchairs are very different than dining chairs.
After we have some initial furniture design ideas, the next step is to draw. Most designers draw by hand, while others are more comfortable using a pen on a tablet. The important thing is to transfer the idea from the designer’s head onto paper or computer file, where someone else can see it. Even if a designer has to act as his/her own ‘someone else,’ having a drawing to look at is very different than just thinking what it will look like. Designs get tweaked, improved, scrapped, and started over again until they are ‘just right’.
With a Computer
The next step is translating the furniture design into 3D in the virtual space of a computer running CAD software. CAD is “computer aided design”. We use Sketchup software simply because it is quick to learn, intuitive to use, and easy to design in quickly. In the past before CAD, designers would make physical mock ups of their designs. While we still do this, we do less of it now because it’s much easier and faster to make changes to a computer model than it is to change something on a real model.
Part of this step is breaking down the design into component parts. While it works perfectly well for 3D printing to have an entirely solid single piece, we work with flat wood stock (similar to real lumber) so all parts need to be flat. It is not that hard to break something down into flat sides. It’s very similar to the kindergarten lessons of folding and unfolding paper cubes, or how 3D puzzles start with flat pieces and lock together to create a structure.
The next step is to import the model into the CAM software. CAM means Computer-Aided Manufacturing. Some programs do both CAD and CAM. Ours does not, so we export the file or sometimes just redraw the components in the CAM software. We use Vectric’s VCarve Pro because that is what came with our machine. There are many different options available for CAM softwares, and they all have their pros and cons.
With the flat component pieces in the CAM software, the next thing to do is to apply toolpaths to them. Toolpaths are just what they sound like. They are the paths that the tool (the router) takes while it is cutting out the pieces. There are many intricacies to proper toolpaths. This is one place where our skill and artistry shows through. You can’t just press ‘go’ on the machine and watch something come out perfectly. We program how we want the machine to behave. We tell it how fast, how deep, what vectors (lines) to cut along, and what bit to use. These variables affect how smooth the pieces come out, how efficiently we can run, how long the pieces take to create (which directly affects price), what kinds of details we can include, and other things like that.
Another thing to take into consideration when creating the toolpaths, is the bit. We get different results if we use larger or smaller bits. As an example, larger bits are used for ‘roughing’ passes. They remove a large amount of material (wood) from the blank very quickly, but they are not suited for doing detail work because often the bit is larger than the detail needed. As an analogy, you can’t very well use hedge clippers to trim your nails; you need a smaller tool for the job.
After all the toolpaths have been created, the files are exported in G-Code, which is a very simple file containing coordinates and simple instructions that are understandable to the software running the router. Sample instructions are: turn on the router, turn off the router, move here, move there. If you open a G-Code file in Notepad, you will see coordinates, such as 0,0,0 followed by 4,1,2 and so on. These coordinates are X, Y, Z directions: X means left or right, Y means forward or back, Z means up or down. So the above coordinates tell the router to move to the origin, then move 4 inches to the right, 1 inch back, and 2 inches up. The router will then cut a perfect straight line between those two places: the origin, and 4,1,2. The next set of coordinates will be the destination where the router needs to go next.
Securing the Material
With the G-Code files, the process of actually cutting out the pieces is rather straightforward. We load the file into the computer that runs the machine, and secure the board to the table. Securing the board to the table is a major issue for all CNC setups. For our situation, we secure the board to the table with a vacuum table system that we created.
We cut on both sides of our board blanks, so that finished pieces have features on both sides of the wooden sections. It is extremely important to get everything to line up properly when cutting on both sides, so again, we created a registration system to solve this issue.
If we are testing out a new piece, the next step would be to evaluate how well everything was cut out and fits together, make notes on areas we can improve, fix the toolpaths based on the notes, and try another run. When we cut out a finalized piece, everything is already perfect and the pieces are identical to other previously cut finalized pieces.
Furniture Design Finishing
The final thing to do with a piece once it is cut out, is a bit of hand touch ups. The pieces are held onto the board with small tabs, and these need to be broken off and sanded smooth afterwards. Once the piece is smooth, next comes the oil. Of all the many different oils and waxes available to furniture craftsmen and miniaturists, we use Danish Oil. Trial and error has helped us find the best oil for our furniture pieces. Once the pieces are dry, we glue them together, let them dry, and the piece is finished! It is ready for packaging and then is sent off to stores and happy dollhouse hobbyists. Bet you had no idea how much went into the furniture design of something so small and simple, right?