Ken's Dream CNC Router Machine

Cheaply - Quickly - High Performance, you can choose the two you prefer. Many decisions involve making trade-offs between Cost, Schedule and Capability and this is one of them.

Machine Type: The main choice here is a movable X-Y table or movable gantry configuration. I have concluded that movable gantry machines are the dominant configuration, especially for machines with larger cutting capacities. My preference is a movable gantry. With that decided the question of single or dual gantry motors needs to be considered. I had an informative email exchange with Ahren Johnson of CNC Router Parts. He indicated that his rule of thumb is that gantries wider than 2 feet benefit from a dual drive system (where each side of the gantry has a drive line). As width increases the tendency for the gantry to rack between the ways increases. Narrower gantries (2' or less) can be driven well with a single centered drive line. So this decision is dependent on the machine size chosen.

Cutting Area: I have concluded that a minimum of a 2' x 3' cutting area will suffice for most projects I currently have in mind. I plan to machine the profile and contours of bolt-on guitar necks with the machine. Bass guitar neck blanks are approximately 34 inches in length so this should just fit in a machine with a 3' capacity.

Size: This of course is related to the cutting area required. In my case I have very limited shop space so although I might like a bit larger machine to accommodate larger projects in the future space constraints dictate that the best choice would be a bench top sized machine.

Moreover, I live in a typical suburban housing tract in Temecula, CA. The city of Temecula has stringent noise ordinances. Currently my use of hand and table routers is intermittent. You do a setup, turn on the screaming banshee, make a cut or two. Turn the little screamer off. Rinse and Repeat. Things will be different with a CNC Router. A roughing and finishing cut on a complex 3D carving might run for an extended time. This could be more than even easy going and tolerant neighbors could take. The smaller the machine is the easier it will be to enclose it to reduce the noise level. The noise issue may also warrant looking into a true milling spindle with VFD.

Another aspect of size is the router spindle itself. My envisioned uses will require more than a trim router can handle and less than a 3 hp big boy. I have always liked my versatile and venerable Porter Cable 690. This class of router would be adequate.

Tolerance: My primary use for the router will be profiling wood and plastic material, and possibly engraving brass. Precision and repeatability within a few thousandths of an inch would be adequate for my purposes.

Materials and Tools: My shop is setup primarily for woodworking. With the correct saw blade I can cut aluminum material, but I am not setup for steel fabrication. I have a pedestal drill press but I would prefer that components be supplied pre-drilled, especially if close tolerances are required. Jobing out some fabrication work would be an option for a small number of components. I like, no I love, many forms of wood, but it is not my first choice for a machine tool material. A bolt-together aluminum machine would be my first choice.

Given my tendency to start and not finish things I would be wise (know thy self) to go with a complete kit rather than attempting a build-from-plans project, even though the cost may be more. Remember the three options? You get to choose any two. For a given level of performance I can choose lower cost (more DIY) or a quicker schedule (less work and time on my part).

Budget: Thanks to a small windfall I have been able to set aside the funds needed to do this project. My goal is to have a functioning system, the controller, machine and basic software for $3K. I am willing to spend more if warranted, however this is my first foray into CNC. I do not consider it to be a 'now or never' situation to build the ultimate machine. This is a learning experience and there are more than a few participants in the CNC forums that are on their 2nd or 3rd build. If this project goes well I may eventually scale up in size and capability, if and when I have the good fortune to have a dedicated shop space.

For those who think: Wow, 3 grand for a tool! I may have more to say about this, but for now I will just say that for me this project will result in more than a CNC Router. It is adding to what can be referred to (by Thomas Sowell and others) as my 'human capital'. A topic that my daughters are probably tired of hearing about from me.

How about you? What do you think of my decisions? What kind of CNC Router would you build? Leave a comment.