A Step-by-step Guide To DIY Mini Lathe CNC Conversion

Like most modern equipment, machine tools have improved and shrunk in size over the years. Despite technological advances and affordability, most small lathes do not have CNC capabilities. 

Most hobbyists cannot purchase a CNC lathe because the machines are either too expensive or too large. A CNC Lathe conversion kit is a convenient workaround for small shops or hobbyists with a little more time on their hands.

What is a CNC conversion kit?

A typical CNC conversion kit for an older lathe comprises a number of new components as well as installation instructions. Motors and other new hardware will allow the lathe to move automatically along the X, Y, and Z axes. There is also a new control unit and software. 

Some conversion kits will be comprehensive, including complete electronics packages with a control unit and programming software. Others are far more basic, consisting of the motors and other hardware required to make the machine CNC-capable but lacking the complete control packages.

Is CNC conversion the right choice for you?

If you have a smaller shop with tried-and-true machines that are now obsolete, CNC conversion kits are an excellent way to expand your capabilities without incurring the expenses of a new machine. You’ll have the capabilities of a genuine CNC machine – not a poor imitation – and the dependability of your old workhorse after conversion.

Of course, CNC conversion kits are ideal for the home hobbyist as well, allowing them to upgrade their existing machine at a low cost and experiment with CNC programming, g-code, CAD, and all other aspects of CNC machining.

What tools are required for a DIY CNC conversion?

There are some additional machining tools that you will need to purchase to convert your existing lathe into a CNC lathe machine. Because the tools on your older lathe may not be capable of advanced lathe operation, your CNC lathe will be inefficient.

Mechanical components for CNC lathe operations

When converting your manual lathe to CNC, replace existing mechanical components, such as lead screws, with a pair of ball screws and double nuts.

We recommend replacing these mechanical components because lead screws on a lathe machine have backlash and are incompatible with CNC operations. Ball screws, on the other hand, have very little to no backlash and are an excellent choice for the drive of a CNC lathe machine.

And, while you may have to purchase ball screws and double nuts separately, in addition to the conversion kit, this isn’t always the case. This is because many manufacturers include these components as part of their lathe CNC conversion kit package.

Electrical components for your CNC lathe machine

When purchasing a lathe CNC conversion kit, you will also need to buy some electrical components required to control CNC machining. 

To begin, you should purchase a high-quality controller, limit switches, stepper drivers, and mechanical probes to effectively control your machine’s X, Y, and Z movements. The spindle control comes next, and if you want to control the RPM manually with buttons, we recommend purchasing a VFD.

Finally, you’ll need a computer at the other end of the controller to run the CNC software and send commands to your lathe machine. Once you’ve purchased the computer, you can install and run various CNC software, ranging from Mach3 to GRBL to LinuxCNC.

How to convert your existing lathe with a CNC conversion kit?

The conversion procedure varies depending on the lathe machine and conversion kits. But, in general, here’s what the entire process entails:

1.Mechanical retrofitting of your lathe

The first step in CNC conversion is mechanical retrofitting, which requires you to disassemble the entire lathe before installing the conversion kit. It’s also not as simple as simply replacing the components because disassembly and reassembly involve dealing with large and complex machine parts.

To begin, remove each axis of your lathe and replace the lead screws with ball screws in each axis. You cannot manually remove your machine’s Z axis because it can weigh a thousand pounds. As a result, we recommend using an engine hoist to easily pick up and move the axes.

In addition, your lathe may be screwed to the floor with nuts and bolts that you must remove. When each axis is removed, the CNC components can be added individually.

Attaching stepper motors to your machine’s axis is the next step in lathe CNC conversion. During this process, ensure that the stepper motor can handle the heavy weight of the Z axis. After you’ve attached the stepper motors to the X, Y, and Z axes, you’ll need to reposition them.

There’s more to mechanical retrofitting 

You must square up the Z axis and ensure it is perpendicular to the work table before you can use the lathe machine. This procedure, known as tramming of the lathe, is carried out with a tramming indicator.

If the lathe isn’t properly trimmed, you can shim the column and adjust its leaning using the metal sheets under the machine’s base. Once you’ve finished tramming the column, you should do the same for the spindle, ensuring it’s not tilting. Your lathe machine is now ready to use after tramming on both the column and the spindle.

2. Electronics installation to enable CNC on your lathe

After mechanical retrofitting, electronic components must be installed to enable the CNC lathe on your machine. Before you begin installing electrical components on your machine, you must first install stepper motors on each axis.

To begin, you’ll need to install a control system for the stepper motors. The control system, you see, is the most important component of your machine because it allows the lathe to be computer-controlled rather than hand-operated.

Aside from the control system, you should buy various other electrical components for the lathe. An unregulated DC power supply, three limit switches, and two probes are also included. 

In addition, we recommend that you purchase three stepper motor drivers to power your lathe’s stepper motors.

Following that is the controller for your benchtop CNC lathe, which you should carefully select because it must be compatible with CNC software. You can, however, use it if the CNC control packages are compatible with Mach3, LinuxCNC, or GRBL. This is due to the fact that these are the most commonly used CNC programs, and many popular lathe conversion kit brands include them in their kit package.

Spindle retrofit to effectively use a CNC lathe conversion kit

The spindle system must be retrofitted for an effective CNC conversion of your lathe.

So, if your lathe has a gear-driven spindle motor system, you’ll need to change it to a belt drive system. A belt drive lathes CNC conversion kit, for that matter, will be suitable for converting your lathe machine.

You should also buy a VFD motor controller suitable for the spindle motor to control your machine’s spindle. Manual buttons on VFDs are typically used to increase or decrease the spindle’s RPM. 

Wrapping it up

The best project you can do for your machine shop is a DIY mill CNC conversion; all you need is the correct conversion kit. While CNC conversions may appear hard, if you’re familiar with milling machines, you can easily convert them to CNC.

Check out our items if you’re looking for a mill conversion kit. We have the best CNC conversion kits available on the market from world-class manufacturers.