What is a 4Axis CNC Router?
For the most part, the principals of 4th Axis use with a CNC Router on wood are much the same as the more metal-focused 4th axis articles that have come before. We’ll focus on how it all looks on a CNC Router as well as common applications for the 4th Axis on a CNC Router. You will find that one of the makes for a very versatile cnc machine!
You can mount a typical 4th axis on a cnc router machine table and go to town:
The goal of 4th axis woodworking is typically engraving or columns…
The goals of 4th Axis woodworking are often a little different. You seldom see 4th axis as a way to access more sides of the part without more setups or as a way to machine more parts in one setup through indexing. CNC Routers already have lots of XY area and don’t need a 4th axis to create more area. In fact their limited Z clearance would make it hard to use one for the purpose anyway.
Most 4th Axis woodworking is about continuous indexing in order to do round work such as engraved cylinders of columns for various kinds for architectural work:
This sort of thing is called ornamental turning work, and in fact, it is common to refer to the 4th Axis as a “Lathe Attachment” in the CNC Router world.
Here’s a video showing one of my favorite style lathe attachments which involves mounting the 4th axis permanently alongside the table:
A 4th Axis installed on a CNC Router…
The video shows a lot of the typical pineapple and other shapes common to ornamental turning. Slinging the workpiece alongside the table allows for quite large work to be done and gets away from the Z-travel limitation that many router tables have.
CNCZone has some neat pictures of a DIY lathe attachment for a CNC Router:
His solution for low backlash gear reduction was to build a “gearbox” using timing pulleys to slow down his stepper motors. Clever!
What Kind of CNC Machining Do They Do?
Here’s a video of some 4th axis work on a CNC Router to create a gunstock. Very cool work:
Some great how-to tips in this video of making a gunstock with a 4th axis…
One of the most exacting and beautiful uses for CNC 4th Axis Woodworking is inlay work, particularly for custom guitars, pool cues, and similar work. Seeing a cnc machine doing this kind of art is always amazing to me!
Custom pool cues made with CNC…
How about cutting a Tiki:
CNC Router Machine cutting a Tiki…
How Can I Program this kind of CNC Machining?
The easiest way to program is to use CAM software that supports 4 axis cnc. Not every CAM package supports it, and those that do often force you to pay more to get the 4 axis cnc support.
How Should I Choose a 4 Axis CNC Router?
There are a few considerations to keep in mind when choosing a cnc router to do 4 axis cnc work.
First, its controller must support a rotary axis. Not all of them do. It needs to have both the necessary g-codes and the ability to hook up a rotary axis. The g-codes enable motion on the rotational axes (a axis, b axis, or c axis) in addition to the normal three axes (x axis, y axis, and z axis). 4 axis cnc moves may involve any combination of up to 4 of these axes.
The machine will include either an a axis or b axis depending on how its configured, but not both at the same time. Lastly, the units for the rotational axis are typically degrees.
Second, does it have a rotary axis available for purchase? If not, you may have to build one. A 4 axis cnc is a fairly exotic add-on for the average desktop cnc router, so you may not be able to purchase one for most low-end cnc routers.
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Bob is responsible for the development and implementation of the popular G-Wizard CNC Software. Bob is also the founder of CNCCookbook, the largest CNC-related blog on the Internet.