Upgrading Your CNC Machine

With our machine now working well, it’s time to consider what improvements we can implement to add to its functionality and make it work better. With some common components, we can improve our machines’ performance and extend their capabilities. In addition, there are several add-ons that can be easily acquired or fabricated.

In this chapter, we will cover the following upgrades:

• Adding end-stops so that our machine can home itself and not require us to set the origin.
• Adding a Z probe so that we can define the starting point on any surface.
• Giving your machine an emergency STOP switch so you can prevent problems from getting worse without having to rely on the computer and risk lag when telling your 3018 to stop. This is also important if you intend to operate the machine untethered from a computer.
• Introducing the ability to carve and cut on a rotary axis.

We will also upgrade your 3018 to be able to operate as...

Installing end-stops

If your machine has no way to home unless you set a specific origin, then you have no guarantee that your toolhead will always start at the exact same position as the origin every single time. Consider this scenario: you move your toolhead to a specific location on your surface, set that as the origin (in the software), and then start a cutting job. In the process, your machine gets jammed while moving. You then stop the machine and try again, starting by telling the machine to home. However, the machine thinks it is where it should be, but in fact isn’t. Consequently, when it tries to backtrack and return to what it thinks is the origin, it will instead reposition the toolhead somewhere else altogether. This problem is also encountered when you need to cut the same object multiple times. Having to keep setting the origin manually can get tedious and will make it annoying to re-attempt a job because you have to mark the origin you select somehow and bring...

Emergency stop switch

The purpose of this switch is to bring everything to an immediate stop in the event your toolhead is about to damage something or go beyond its cutting borders (or any other emergency). It doesn’t matter what sort of switch it is, but it must have a way to positively break the circuit. I personally like big red push buttons such as the one you see here on my machine:

Figure 6.10 – My E-Stop switch, mounted right on my 3018’s frame

You can find these on Amazon or similar sources for very little. They will have three terminals but are wired with two wires. My controller board has a two-pin terminal for this switch, but if yours does not, wire it to your connector to the board (the live, i.e., positive wire). Do not wire it directly to the plug to the wall as that would be dangerous. Install the switch somewhere easily accessible from any angle on the board. The reason I like the big red button is that you cannot...

Installing a Z-probe

Irrespective of your end-stops, your end mills are going to be of different lengths and if you replace the spindle with the drag knife or pen holder, then the starting point for machining (i.e., where you set Z = 0) will change. This is why I like to have some sort of Z-probe to set the top limit of my Z-axis with every job. That’s the job of the Z-probe. You can buy these just about anywhere, and they look something like the following:

Figure 6.11 – A Z-probe just as it comes out of the packaging

On my controller, there is a connector for this, and there should be one for yours as well. This is where your connector will go. My Z-probe did not come with a connector, but you can make a suitable connector using a jumper wire or a suitable two-pin connector for your board. I find that using a probe is my preferred way to “zero” my end mill and toolhead. The procedure is very simple after you have wired in a...

Adding a rotary axis

One of the neatest things with this type of CNC machine (and others like it) is to cut or carve a round surface. In our applications so far, we have been operating on the X-Y plane. However, a very simple upgrade will allow us to add the ability to work around a surface instead of just on it. There are two ways to do this: make your own rotary axis, or just buy one. In this chapter, we are going to cover a unit you can buy, while in a later chapter, we will discuss fabricating your own. The rotary axis replaces your Y-axis, allowing the toolhead to move in the X direction, but your workpiece will rotate while that is happening. The nice thing about all this is that you can carve/cut with the spindle, engrave and cut with the laser, and draw with the pen. A rotary axis is therefore a very useful upgrade. In this section, let’s quickly discuss the setup and then look at the impact on the G-code. We will do a deeper dive into working with a rotating workpiece...

Plotters and drag knives

Upgrading the 3018 to be able to make precise drawings or cut vinyl, cardboard, and paper mechanically is the least complicated modification you can make to your 3018. For the most part, you are replacing the spindle (temporarily) with something to hold a pen/sharpie or a blade. The rest is controlled by the software and G-code. Consider: If you have no traversal in Z other than to raise or lower the toolhead, your drawing is rendered entirely in 2D (no depth to worry about), so it is reasonable to think that your 3018 can draw and cut using the same software. You would just have to work on the process of raising and lowering the toolhead where appropriate.

While these modifications are certainly simple enough and absolutely reversible, you should know that the machine will appear to operate slowly. This is because the 3018s use leadscrews in all axes and those are meant to move a heavy toolhead at a reasonable rate for cutting. In the case of these upgrades...

Summary

So far, we’ve covered mostly mechanical upgrades to our 3018. There are more that we should cover, but they are very quickly becoming projects of their own. The first one we want to cover next is adding a laser and discuss what the impacts are on our operations when we do. The other project is to review how we can further improve our rotary axis. However, from our work in this chapter, we now have a machine that can home to the same place every time, a way to accurately zero our Z-axis, and a way to stop the machine in an emergency, and our machine can now double as a plotter and drag knife, albeit a slow one.

You will have noticed the utility of having access to a 3D printer due to my by-now multiple references to Thingiverse and similar sites. This is because there is a wealth of information there that you can lean on. I try very hard to not reinvent the wheel, especially with designs. I might modify a design, but if I can use it as is, so much the better. Definitely...