What Is A CNC Machine For Wood?

All hobbyist carpenters have, at some point, found themselves frustrated with a project.  This is especially true of projects requiring intricate detail and duplication, even more so if you are pressed for time.  And it’s here that the CNC machine bursts into the humble wood shop, offering its helping hand of precision.

Simply put, a CNC machine is a computer-controlled plunge router.  The user can set up a cutting path, or template, on a computer and then send that template to the CNC machine.  The CNC machine will execute the template by guiding a cutting router bit across the workpiece.

Definition Of CNC Machines

Have you heard that you can turn your plunge router into a large planer by building a two-axis jig?  Well, you definitely can.  The idea is to create a tray or housing for your router and attach it to a sled, allowing you to slide it back and forth.

You then mount that sled onto another set of rails perpendicular to the sled.  These allow you to slide the whole sled side to side.  In this way, you can now precision route an area as big as the total travel of the sleds.  Here’s a video showing the process: https://www.youtube.com/watch?v=E_s8WCMu0GQ

This jig allows precise cutting by fixing the router onto a plane.  Now, imagine if you could build a similar jig but have the whole thing motorized and controlled by a computer.

This is precisely what a CNC, or “computer numerical control,” is.  It translates data from a drawn template into an exact cutting path and then instructs the machine to cut along that path.

However, in the case of a CNC machine, the cut path is on three axes.  This means that it cuts not only front-to-back and side-to-side but also up and down to cut deeper or shallower.

For extremely complicated jobs, there are CNC machines that use five axes.  In addition to the three above, the router can tilt side to side, and the actual work surface can also turn.

Types Of CNC Machines

Like most carpentry tools, CNC machines come in various sizes and types.  However, the most common CNC machines include a router, plasma, and laser machines.

Router CNC Machines

If you want a machine for carpentry, then a router CNC is the way to go.  Like a router, it cuts or drills wood using a spinning bit.  This means all the versatility of different router bits applies to this machine.

Using different bits, you cut and carve textures and chamfers into your workpieces, and you’re not limited to simple straight cuts.

Plasma CNC Machines

Plasma CNC machines replace the router with a plasma cutting torch.  These torches use compressed gas ionized through electricity, turning it into a super-hot plasma.  This plasma is so hot that it can cut through just about anything.

However, as you can likely imagine, it isn’t a great option for woodwork unless you plan on having a BBQ on the ashes of your workpiece.  For this reason, it is mostly used in cutting through metal.

Laser CNC Machines

Where plasma cutters use ionized gas, laser cutters utilize high-power optical laser beams to cut through the material.

The benefits of using a laser machine are that you can cut through many different types of material, including wood, without needing the fire department.  They are also extremely accurate.

Although you could use a laser machine for wood, you need to be aware that your cut will have a deep black scorch line, and you can’t cut all the various chamfers like you can with a router machine.

You also won’t be able to cut quite as deep as you can with a router machine.

The Benefits Of Using A CNC Machine

As you can imagine, there are as many benefits to a CNC machine as use cases.  However, in reality, four primary benefits apply to all users.

Increased Accuracy

The first benefit of a CNC Machine is its precision.  If you instruct your CNC machine to make a cut between points one and two, you can bet it will make the cut exactly as you asked.  However, some errors creep in, and we’ll look at those later.

Increased Productivity

When hand carving an intricate piece, it’s hard to get it perfect.  And it’s nearly impossible to duplicate it exactly.  This is not the case for a CNC machine.  Because the machine uses computer data to guide the cut, duplication is accurate.

This duplication, coupled with precision, means that a CNC machine can vastly improve productivity in a shop, depending on how it is used.

Reduced Wastage

When you are working with rare and expensive wood, wastage can be a big stress inducer.  Every scrap you waste is a cost to you.  Fortunately, because CNC machines are so accurate, you reduce material waste.

Provided that your machine and workpiece are set up correctly, and nothing breaks, you shouldn’t have any waste apart from what absolutely must be removed.

A CNC Machine Is Generally Safer

Because the sharp spinning-bit-of-death is controlled by a computer, it is generally safer to use than a router.  Obviously, this benefit only applies if you keep your digits away from the cutting area.  If you touch the work area while the machine works, just remember that the computer can’t differentiate between bone and wood.

Common Applications Of CNC Machines For Woodworking

At this point, your next logical question should be, “that sounds great, but what can I do with it?” And the answer is that there isn’t a lot that can’t be done with it.

Furniture Production

CNC machines are fantastic at producing furniture.  In fact, if you partner with a three-axis router CNC machine with a CNC lathe, you can build just about anything using a computer.  Obviously, your limitation is the size of your CNC cutting surface.

For example, if you need to build a chair, the backrest with its spars and armrests can all be cut using a CNC machine.  The legs can be turned using a CNC lathe.  In fact, if you have wood boards wide enough, you can even cut the seats with the machine.

Then all you are left with is an IKEA situation of “some assembly required.”

Cabinetry

Cabinetry is an area where CNC machines really shine.  Cabinetry requires two things that a CNC machine was made for: precision and duplication.  As a result, each shelf, drawer, bracket, and door can be made intricately and accurately.

This means that you will not only spend less time in the wood shop, but job site assembly will also be a lot quicker.

General Carpentry

There are plenty of general jobs around your shop where a CNC machine could become your new best friend.  From drilling precise holes to edging shelves.

You can even fit a knife into a CNC machine to cut paper templates.  In other words, your CNC machine is really only limited by its size, the material you are working with, and your imagination.

Here is a comprehensive video of some of the uses of a CNC machine: https://www.youtube.com/watch?v=NWDrWbCbI3s

What Are The Drawbacks Of A CNC Machine

Before you assume that the CNC machine is the absolute perfect wood shop tool of flawless consistency, you should know a few hard facts.

A CNC Machine Will Only Do What You Tell It

The benefit of having a machine that does exactly as it’s told can also be a big drawback.  If you tell your CNC to make a bad cut, the machine won’t know to fix your poor instruction and will make the cut exactly as you asked.

This means that there is going to be a reasonably steep learning curve for you.  You will need to learn to use computer-aided design software (CAD) and use it with the same pin-point accuracy you want from your CNC machine.

Just be prepared to make mistakes because you will make many in the beginning, and some of these mistakes can be extremely costly.

This also applies to how well you set up the cutting surface.  For example, if you place the board skew or if the board moves during the cutting process, you will fill your swear jar very quickly.

A CNC Machine Is Still A Machine

Every machine is flawed, and this applies to a CNC machine as well.  There are a lot of nuts, bolts, pullies, motors, and other moving parts involved, and each of those parts has a life expectancy.

The more you use your machine, the quicker the parts will age and eventually fail.  Unfortunately, losing just a nut could cause a vibration in the machine, instantly messing up a workpiece.

So don’t expect a CNC machine to toddle along without needing love and care.  You will need to do regular maintenance repairs if you don’t want your projects to like they were made by a left-handed two-year-old with scissors.

CNC Machine Are Expensive

Much like 3D printing, some affordability advancements have been made in the hobbyist sector of CNC machines.  However, these machines are usually small and unlikely to cope with the workload of a busy garage wood shop.

They could be a good option if you want to dip your toe into the unknown.  Still, if you hope to do any actual woodwork, you will need a proper CNC machine:  and a proper CNC machine is expensive.

For a basic machine, you can expect to pay between $5,000 and $10,000.  That price goes up to between $25,000 and $50,000 for a mid-tier machine, and a high-end machine can skyrocket to $150,000.

Conclusion

A CNC machine is a spinning, router-like motor that moves along three axes and is guided by a computer.  The computer translates graphical instructions from the user into cutting paths for the CNC machine.  This makes a CNC highly accurate and perfect for detailed work and duplication.