In my attempt at designing and building UAS, one of my greatest challenges is the manufacturing facilities I have available. Having come from university, where the facilities were fantastic: many 3D printers, laser cutters, foam cutting, an entire workshop where all I needed to do was send them a drawing of what I needed to now, where all I really have access to is a 3D printer and a laser cutter which is about 40 minutes away it means that a lot of thought needs to be put into not only what I design but how I'm going to build it.
Not only that, but I am severely lacking the physical space to even purchase any additional machinery. I am lucky enough that my parents are tolerating big sheets of foamboard everywhere, but I think filling their garage with a laser cutter would be a touch too far.
This means that anything I do make has to be fairly small, or at least have the ability to pack up into a small space. This essentially rules out building or buying a CNC mill, as taking it apart and reassembling it every time I need to mill a wing would take too long.
So, my idea is to build a CNC hot wire foam cutter. I could build a manual one, and use templates however for that I would need to drive to the laser cutter to cut out the templates. Also this will be my first time building a CNC machine and it would develop my skills.
The goal of this project will be to design and then build a hot wire CNC foam cutter. This will allow me to cut wings out of blocks of foam, achieving better profiles than I can achieve by folding foamboard, as well as allowing me to construct larger wings more easily. This will have the following objectives:
The second goal of the project is to design the machine to be small, or at least to have the ability to be disassembled rapidly.
For this project, I am assigning a budget of approximately £300. This includes the wire, all construction materials (extruded bar, fasteners, plywood etc) and all electronics except for those I already have. This means all motors, drivers, power supplies will be included in the cost but if it can be controlled using an Arduino or Raspberry Pi then that will not be included.
Unlike the first iteration of my fixed wing aircraft, I will allow the use of the laser cutter. However, use will be limited to when absolutely necessary and only when multiple parts need to be cut.
The cutter will have to satisfy the following requirements:
The cutter must have the ability to pack up small. To that end, I am setting the requirements that:
Both sides must be independent. What this means is that during storage, they can be placed either next to each other, or potentially different locations.
Despite being independent and connected only by the wire, this must not impact the stability of the machine. Any wobble in the machine would directly impact the quality of the resulting wing.
The time taken to set up the machine should be less than half an hour. Including setting up the table I will use, aligning the sides of the machine and making all connections. Likewise, taking the machine apart again should also only take half an hour.
The plan is to build a 4 axes cutter. This will likely limit me to only using this machine to cut the wings and stabilisers, and not fuselages. This is something I am willing to accept as I can print fuselages on my 3D printer—this is the method we used in university, and whilst it was far from perfect it worked well enough. Well enough for it to not be worth adding rotation into the mix at least!