CNC Plotter -- Part 1

It has been a long time since I want to build my own CNC machine. I love to make things, and so I like making things that make things. School's laser cutter is a beefy workhouse, but I can only access it three days a week at specified hours, and that's definitely not enough. I want my own machine.

So here is the plan: build a small-scale 2D CNC routing system, with a third control channel that can do different jobs (laser, pen, spindle...).

After some search, here is one that caught my eye:
PCB Plotter

PCB plotting is a function that I really want to have on my system. Recently I have started doing PCB designs, and it would be nice to have a 30min-turnaround home made PCB prototyping platform.

The the capability of homemade CNC, especially with budget under $500, cannot compete with real commercial CNC machines. What I expect out of my machine is that it can draw lines and shapes on a paper/PCB bare board, can drill holes with acceptable accuracy and precision, and can do some light carving jobs.

Unlike the PCB Plotter shown above, I'm going to use a single-rigid body design for my machine, so that the stiffness is good enough to ensure fine line drawing. The chassis will be made out of 0.5 inch acrylic sheet, since that's the strongest material that I can cut shapes out of.

NEMA17 stepper motors will be used, and the transmission will be timing belt. The lead screw system is too slow for me and the extra force is just beyond the scope of this system.

The software used for this system will be GRBL; this is a nice open source CNC drive software that are perfect for homemade CNC and 3D printers.

This blog is mainly the general discussion of the system. Next part will be the dicussion of CAD design and assembly of this thing. The design is already done. For your curiosity, here is what it looks like in CAD:

model assembly