Computer numerical control (CNC) is the umbrella term for computer-controlled machines that translate numerical data into coordinates. These machines are typically used for precise processes in manufacturing, such as milling, cutting, routing, and so on. 3D printing itself is a CNC application.
Given the indelicate nature of their work, CNC machines tend to be large and rugged, involving fast-spinning spindles and assorted shrapnel. But what if a CNC machine could be simplified to the point that it could be mostly 3D printed?
Introducing the Mostly Printed CNC (MPCNC), a customizable CNC design by Ryan Zellars from V1 Engineering. In this case, CNC should be taken by its literal meaning as a machine controlled by computers, not limited to CNC mills (a very common type of CNC rig). This is because the MPCNC is not just another cheap CNC kit. If you’re looking for just a CNC, this is a good choice, or you can hop over to our list of the best desktop CNC routers to check out some pre-made options.
This kit is for the very DIY-inclined maker since the MPCNC is better described as a bill of materials and a design than a product. Given that, the final capabilities of the machine depend on how you choose to build it. We’ll be covering the build process in general, and then talking about the machine’s capabilities.
As the name implies, this machine is largely 3D printed and includes a conduit frame and other hardware. We’ll be covering a few details, but if you need more information, 1V Engineering provides a bill of materials and all of the specifics needed to build your own MPCNC.
First, lets take a look at the interesting aspect of this CNC: Its 1.8 kg worth of printed parts. The MPCNC uses 3D printed parts to connect the frame rails, the legs, the middle assembly, and even the tool mount. All the prints are available on Thingiverse. These parts are printable in PLA or PETG and require between 35% to 65% infill, depending on the part. However, be aware that there are three versions of these files due to the variation in conduit sizes available in different places.
The MPCNC, as mentioned, uses either conduit rails or stainless steel tubing for the frame. This includes the four outer rails for the X- and Y-axes, the two crossing rails that hold the middle piece, and the four legs. Joined by the printed parts and fastened by nuts and bolts, altogether they make for a surprisingly sturdy frame.
Of course, a frame doesn’t make for much fun by itself. The rails ride on each other via a set of bearings held together via the bolts on the printed parts. In addition, both the X- and Y-axes sport a pair of stepper motors and a single one for the Z-axis. The pair on the X and Y run together by default, but an option for individual control is available. Why run individually? Well, this allows for a very neat feature to automatically square your machine for easily repeatable and accurate results. More detail on the tech later.
Because this machine is more of a design than it is a product, a lot of the specifics are left to the user. For the most part, 1V Engineering recommends smaller builds for more accuracy and rigidity. Large builds can add mid-span supports to the frame and have a surface area as large as 1 x 1 m. That said, the recommended build size is 2 x 2 ft or 0.6 x 0.6 m. The Z-axis is dependent on the application, but in general, is significantly shorter due to the design’s limitations. As for the accuracy, that depends on the build, too. Those who want to dial their machine in can get better accuracy.
The outstanding characteristic of the Mostly Printed CNC is its adaptability. It boasts the capability of being anything from a 3D printer to a plasma cutter. Of course, being a flexible design means that many of these things may require special planning, detailed research, or additional parts. Below are some common uses of the MPCNC and things to take into account.
What if you found a machine that could make use of additive and subtractive manufacturing technology? Impossible! Well… nearly impossible. While it may not be the best application, it is possible to make a 3D printer MPCNC.
The design of the axes of the MPCNC makes it suitable as a very specific 3D printer. Due to the large double rail design, it is possible to have a large XY-plane of print space. The caveat here is the Z-axis has a limit to how long it can be before it loses accuracy. The suggested max is 1 ft.
If this machine is what you want to focus on, the main additions needed are the physical extruder and a firmware adjustment. The extruder is up to you choose, but if you need help you can inform yourself from our 3D printer extruder guide. As for the firmware, V1 Engineering provides helpful information on that and the connections.
It is worth noting that V1Engineering has a milled and printed 3D printer design as well. This may be a better alternative if all you want is a stand-alone 3D printer.
The MPCNC mill is perhaps the most common build. The MPCNC makes for a mill with decent quality and power. The main limitations of the mill variation come down to how much work you want to put into it (as can be said for any MPCNC). The mill can cut aluminum and even steel if the right amount of attention is given to the build. A large factor is the effect of size on rigidity. This isn’t to say that it can’t be large, simply that it takes more effort to make it so. Due to this, the recommended size for your first MPCNC is 2 x 2 ft.
Besides the actual building, a very important consideration for your MPCNC mill is the spindle. The recommended one is the Dewalt 660, but this, like the rest of the MPCNC, is up to you.
Moving on to the extreme end of cutting is the plasma cutter. A bit of rewiring, firmware tweaking, and a relay will turn that handheld plasma cutter into a precise machine.
This one isn’t as well documented and may require more research and ingenuity to pull off. The actual plasma cutter has to be modified in order to control it. Plus, attaching it is another matter. And, of course, consider the safety of the machine you’ll be making.
Another V1 Engineering machine should be mentioned for applications calling for work space: The LowRider CNC.
The MPCNC is a rather large machine for a laser, and such a function could even be viewed as an additional feature to your existing MPCNC build. That said, this machine can go from being a fairly precise engraver to a large laser cutter. And again, V1 Engineering has helpful tips when setting up your electronics to work with a laser.
The main work in adding a laser to your MPCNC is going to be selecting the right one for the job. This can vary from a more precise 2.5-W laser to a powerful 10-W laser (or more). You can find some helpful information in Laser Cutting – Advantages and Disadvantages.
These options are grouped together because they are rather simple to implement with almost any CNC device and even more so with the MPCNC. Some depend more on the overall build choices involved and less on a single modification, and others can be viewed as add-ons. Things like plotting and vinyl cutting are achieved with the addition of simple tools such as a pen and a drag knife. Others are more dependent on the focus of the build, such as a smaller build focused on accuracy, rigidity, and a precise spindle for a PCB etcher.
The electronics on this CNC are left up to the users, but 1V Engineering doesn’t leave you without some guidance. There are several options supported if you choose to use them, beyond that, you’ll have to depend on other resources.
The suggested boards for the MPCNC include several Ultimachine boards and the RepRap Ramps Arduino Mega shield. While both are Arduino Mega-based, the Ultimachine boards are preferred. The good news is that there are guides for both.
The guides include the process of wiring the boards to the stepper motors and adding additional tools (laser, extruder, heated bed, etc.) There’s even a walkthrough to get the dual endstop feature running. Without this feature, you have to rely on your ability to square and position your mill for every run.
Moving on to the software, the process is fairly simple. V1 Engineering provides preconfigured Marlin firmware for its suggested boards. And on top of that, flashing the firmware is as easy as loading an Arduino program with the Arduino IDE. The actual computer side of things is as easy as connecting to Repetier Host for your first set up and going onto their walkthrough of ESTLCAM.
The MPCNC is a special machine directed at the enthusiastic maker. Few other CNC machines in its class rival the MPCNC. There are many cheap CNCs, custom CNCs, and quality CNCs, but few come close to this. One other player that must be mentioned is the similar RS-CNC, but a comparison would be beyond the scope of this article.
Concluding our overview, the MPCNC’s unique design, support, and resources make this the ideal CNC for the right audience. After all, this is not meant to be a plug-and-play experience, but neither is it meant to be compared to refined products. The MPCNC is a multitool for those willing to take on its creation.
Be sure to check out V1 Engineering‘s other DIY designs: the ZenXY, the Milled/Printed 3D Printer, and the LowRider CNC.
License: The text of "Mostly Printed CNC (MPCNC): All You Need to Know" by All3DP is licensed under a Creative Commons Attribution 4.0 International License.
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