What I Do with a CNC in My Shop

Here’s a glued up leg and apron assembly for a sofa table being milled with a CNC router.

Here’s the big picture: A CNC is a digitally controlled router that cuts from its highest to its lowest point in three dimensions over the entire area of its bed. What would any woodworker do with that capability? It turns out you can do quite a lot. Below are some of the things I use a CNC for in my woodworking shop. Obviously, these are simple examples and they’re also potential topics for future articles and blog posts. There’s a lot to cover.

Pattern Cutting

As mentioned before, I’ve been using a CNC to cut patterns for a long time using an outside CNC services to do the work. It works great. If you’re willing to do the needed 2D CAD or even Adobe Illustrator drawings, I can’t recommend it enough. Perfect patterns.

Material Preparation

I flatten and surface boards that would be too awkward or large for a jointer. I thickness plane boards that can’t fit through my planer. CNCs have been a great tool for working on large slabs of wood.

Use the Built-in Precision

I take advantage of CNCs high level of precision for certain needs. Even simple tasks sometimes need precision. For example, if I need a series of holes that need to be precisely laid out and sized, the CNC sometimes does this better than other techniques.

Part Making

Part making is probably the best use of a CNC in a woodworking shop. And it’s a straightforward process once you learn how to do it. I regularly use a CNC to cut wood parts, except for the rectilinear parts — if you have the tools, it’s just easier and faster to use a table saw and miter saw for parts with straight lines. The results from cutting CNC parts are even more accurate then I’ve gotten with patterns and shaping. And, because the tool is machining a rigidly held board, I can cut even the most delicate of details without breaking the wood. Bonus: sometimes the CNC is a great assistant. While the CNC is cutting parts I can be working on something else.

Details

The CNC has been great for adding details to woodwork. I use what’s referred to as engraving routines to add cove cuts, bevels, grooves or other precision detail that normally might have to be carved into parts. Certainly hand tools can do this but there are some situations where the added precision and control is a real advantage. It’s also a great tool for adding lettering, figures to panels and other carving details.

Joinery

I use a CNC for some kinds of joinery that would be difficult to do accurately in other ways. I regularly use two techniques/tools for mortise-and-tenon joinery (Leigh FMT or Domino) and sometimes a mortiser. As great as these tools are, sometimes they can’t accurately put a mortise right where you need it. On the edges or ends of a board is usually not a problem. But, in the middle of a larger surface is challenging. The CNC puts a joint anywhere you like. That’s very handy.

Another example of how I use a CNC as a joint making tool is a kind of a twofer. If you’re already using the CNC to cut parts that ultimately need mortises, why not just cut the mortises at the same time?

Finally, a CNC router offers the potential for kinds of joinery we’ve never seen before. No matter the tool or method, we’ve been doing joinery pretty much the same way for thousands of years successfully. The value of millennia of experience is that we know exactly why and how joints work and why they can fail. The point is we understand the engineering. So let’s apply what we know and maybe rethink the entire of idea of joinery. The possibilities are exciting and it’s something I’m seriously exploring.

Jigs and Fixture Making

I regularly use a CNC for making jig and fixture parts. It’s particularly handy if you need dedicated clamp cauls for an unusually shaped project or other task-specific tools.

Plywood Cutting

I know it’s a strange topic to bring up on a woodworking blog but sometimes plywood is a very useful material. Cabinets are obvious, but there’s a lot of other things you can make out of sheet goods, particularly if you have a CNC handy. I’ve made, chairs, stools, tables, tool boxes and all kinds of things with plywood. Parts are joined together with a whole range of joints developed for the task that pretty much snap into place. And, there are great plans out there for CNC owners. Many are free and well designed.

Cutting Materials Other Than Wood

I had never cut aluminum or plastics before I got a CNC. Now I use it to machine aluminum for jigs that need metal parts. Same with polycarbonates and plastics. Depending on the machine’s rigidity, many machines can cut soft metals. I have friends with CNCs that use them to cut brass or aluminum parts for furniture. As you can imagine cutting metal is not the same as wood. You  use different procedures, tooling and techniques.

Carving

I regularly use a CNC to add features that would normally be carved by hand or done with elaborate jigs or router setups. It’s great for tasks like carving a seat for a stool or a chair, tapering a bevel or a progressive round over the length of a table leg, for example. Many things are possible if you can work in 3D in CAD software and have CAM programs that support 3D operations and learn how to carve with a CNC.

Next I’ll explain how I accomplished certain woodworking tasks before I had a CNC and what’s changed since.

— Tim Celeski