Choosing the Correct Air-Cooled Spindle for Your CNC Router
Choosing the correct spindle is an important part of building or upgrading a CNC router. The spindle affects the tooling you can use, the amount of cutting power available and the type of work your machine can comfortably handle.
Air-cooled spindles are a popular choice because the cooling system is built directly into the spindle. There is no need for a water pump, coolant reservoir or cooling pipes, making installation simpler and reducing the number of components that need to be maintained.
CNC Online offers air-cooled spindle options from 400W through to 3.5kW, with different power ratings, collet systems and mounting styles available.
Air-Cooled Spindle Comparison
| Spindle | Collet | Max Speed | Body Style | VFD / Power Setup | Best Suited To |
|---|---|---|---|---|---|
| 400W | ER11 (1mm–7mm) | 12,000 RPM | Round | 48V DC power supply | Small CNCs, engraving and light cutting |
| 1.5kW | ER11 (1mm–7mm) | 24,000 RPM | Round or Square | 1.5kW H100 Mini recommended; 1.5kW YL also available | Small to medium CNC routers |
| 2.2kW | ER20 (1mm–13mm) | 24,000 RPM | Round or Square | 2.2kW H100 Mini recommended; 2.2kW YL also available | General-purpose CNC routing |
| 3.5kW | ER20 (1mm–13mm) | 24,000 RPM | Square | 4kW H100 Mini recommended; 4kW HY also available | More demanding routing and milling |
400W Air-Cooled Spindle
The 400W Air-Cooled Spindle is designed for small CNC routers, engraving machines and hobby CNC builds.
It uses an ER11 collet system, with metric collet sizes available from 1mm to 7mm, reaches speeds of up to 12,000 RPM and operates from a maximum of 48V DC.
Unlike the larger air-cooled spindle range, the 400W spindle does not use a VFD. Its speed is controlled by adjusting the DC voltage supplied to the spindle.
It is well suited to:
- Engraving
- PCB machining
- Small wood projects
- Plastics
- Light routing
- Compact DIY CNC machines
For a smaller CNC that does not require the additional power or weight of a larger AC spindle, the 400W is a practical entry-level option.
A matching 400W 48V 8.3A Power Supply is also available from CNC Online.
1.5kW Air-Cooled Spindle
Moving up to 1.5kW provides considerably more capability for general CNC routing.
CNC Online offers both a 1.5kW Round Air-Cooled Spindle Kit and a 1.5kW Square Air-Cooled Spindle Kit. Both use an ER11 collet system, covering metric cutter shank sizes from 1mm to 7mm, and operate at speeds of up to 24,000 RPM.
The round spindle has a 65mm diameter body and mounts using a matching 65mm spindle clamp. The square version provides an alternative mounting configuration for machines designed around a square spindle body.
The 1.5kW spindle is well suited to:
- Wood and MDF
- Sign making
- Engraving
- Plastics
- Furniture components
- General CNC routing
For a small to medium CNC router where larger ER20 tooling is not required, 1.5kW offers a good balance between spindle size, capability and cost.
2.2kW Air-Cooled Spindle
For customers looking for a more capable general-purpose spindle, the 2.2kW Air-Cooled Spindle is our main all-round recommendation.
It operates at speeds of up to 24,000 RPM and uses an ER20 collet system, covering metric cutter shank sizes from 1mm to 13mm.
The move from ER11 on the 1.5kW spindle to ER20 on the 2.2kW is an important difference. ER20 gives you access to a wider range of tooling and allows larger cutter shank sizes to be used.
CNC Online offers both a 2.2kW Round Air-Cooled Spindle Kit and a 2.2kW Square Air-Cooled Spindle Kit.
The round version has an 80mm diameter body and uses a matching 80mm spindle clamp.
Typical applications include:
- Woodworking
- MDF and cabinetry
- Signage
- Plastics
- Composites
- Aluminium machining
- Furniture manufacturing
- General CNC production work
For someone building a capable CNC router that will be used for a variety of materials and projects, the 2.2kW ER20 spindle provides an excellent combination of power and tooling flexibility.
3.5kW Air-Cooled Spindle
The 3.5kW Air-Cooled Spindle is the largest air-cooled option in the current CNC Online range.
It has a square-body design, uses an ER20 collet system with a metric range of 1mm to 13mm and operates at speeds of up to 24,000 RPM with a maximum operating frequency of 400Hz.
The spindle is rated at 10A and is paired with a 4kW VFD.
It is designed for more demanding CNC routing and milling applications, including:
- Hardwood machining
- Larger woodworking projects
- Plastics and composites
- Aluminium machining
- More demanding routing
- CNC milling applications
The current CNC Online 3.5kW spindle kit can be paired with either a 4kW H100 Mini VFD or a 4kW HY VFD, with the H100 Mini being our recommended option.
More spindle power is not automatically better for every CNC machine. The machine frame, gantry, Z-axis, linear motion components and electrical system all need to be suitable for the larger spindle.
ER11 vs ER20 – What's the Difference?
The collet system determines the range of cutter shank sizes the spindle can hold.
The 400W and 1.5kW air-cooled spindles use ER11 collets. CNC Online's metric ER11 range covers 1mm to 7mm, making it well suited to smaller cutters, engraving tools and general routing work.
The 2.2kW and 3.5kW air-cooled spindles use ER20 collets. CNC Online's metric ER20 range covers 1mm to 13mm, giving you a wider tooling range and the ability to use larger cutter shanks.
If your work mainly involves smaller cutters and engraving, ER11 may be all you need. If you want greater tooling flexibility or expect to use larger cutters in the future, ER20 is the better option.
This is one of the main reasons the 2.2kW spindle is such a strong general-purpose choice.
Round vs Square Spindle
Round and square spindles can both provide excellent CNC performance. The main difference is how they mount to the machine.
Round Spindles
A round spindle uses a separate spindle clamp.
CNC Online's current round air-cooled options include:
Round spindles are popular for custom CNC builds because the clamp provides some flexibility when positioning the spindle vertically.
Square Spindles
Square spindles mount using the spindle body and are suited to machines designed around this mounting configuration.
CNC Online currently offers square air-cooled options in:
The choice between round and square should therefore be based mainly on your machine design and mounting arrangement, rather than assuming one style is automatically more powerful or accurate.
Which VFD Should You Choose?
The 1.5kW, 2.2kW and 3.5kW air-cooled spindles require a Variable Frequency Drive (VFD). The VFD controls spindle operation and speed and must be correctly matched to the spindle being used.
For a new spindle and VFD setup, we recommend choosing the H100 Mini VFD option where available. It has a compact design, a wide operating frequency range and is available in power ratings to suit the 1.5kW, 2.2kW and 3.5kW air-cooled spindle setups.
| Spindle | Recommended VFD | Alternative |
|---|---|---|
| 400W | 48V DC power supply | No VFD required |
| 1.5kW | 1.5kW H100 Mini | 1.5kW YL |
| 2.2kW | 2.2kW H100 Mini | 2.2kW YL |
| 3.5kW | 4kW H100 Mini | 4kW HY |
H100 Mini VFD – Our Recommended Option
The H100 Mini VFD is our recommended choice for most new CNC spindle installations.
It has a compact, space-efficient design and supports a frequency range of up to 650Hz. The current H100 range includes 1.5kW, 2.2kW and 4kW 220V options suitable for the air-cooled spindle combinations covered in this guide.
The wider VFD frequency range does not mean that a spindle should be run beyond its rated speed. The spindle's specified maximum RPM and frequency must always be followed.
YL VFD
The YL Series remains a suitable alternative for the 1.5kW and 2.2kW air-cooled spindle kits. CNC Online stocks both the 1.5kW YL VFD and 2.2kW YL VFD.
HY Huanyang VFD
The 4kW HY Huanyang VFD is available as an alternative VFD option for the 3.5kW air-cooled spindle setup.
What Comes in an Air-Cooled Spindle Kit?
The exact kit contents depend on the spindle and whether it has a round or square body.
1.5kW Round Kit
The 1.5kW Round Air-Cooled Spindle Kit includes:
- 1.5kW air-cooled round spindle
- 1.5kW H100 Mini VFD or 1.5kW YL VFD
- 65mm machined aluminium spindle clamp
- 7-piece ER11 collet set (1mm–7mm)
1.5kW Square Kit
The 1.5kW Square Air-Cooled Spindle Kit includes:
- 1.5kW air-cooled square spindle
- 1.5kW H100 Mini VFD or 1.5kW YL VFD
- 7-piece ER11 collet set (1mm–7mm)
Because the spindle has a square mounting body, a separate round spindle clamp is not required.
2.2kW Round Kit
The 2.2kW Round Air-Cooled Spindle Kit includes:
- 2.2kW air-cooled round spindle
- 2.2kW H100 Mini VFD or 2.2kW YL VFD
- 80mm machined aluminium spindle clamp
- 13-piece ER20 collet set (1mm–13mm)
2.2kW Square Kit
The 2.2kW Square Air-Cooled Spindle Kit includes:
- 2.2kW air-cooled square spindle
- 2.2kW H100 Mini VFD or 2.2kW YL VFD
- 13-piece ER20 collet set (1mm–13mm)
3.5kW Square Kit
The 3.5kW Air-Cooled Spindle Kit includes:
- 3.5kW air-cooled square spindle
- 4kW H100 Mini VFD or 4kW HY VFD
- 13-piece ER20 collet set (1mm–13mm)
For a new CNC build, purchasing a complete spindle kit is usually the simplest option because the main spindle, VFD, collet and mounting components have already been matched together.
Which Air-Cooled Spindle Should You Choose?
| If You Need... | Recommended Spindle |
|---|---|
| Small hobby CNC, engraving or PCB work | 400W |
| Smaller general-purpose CNC router | 1.5kW |
| Best all-round balance of power and tooling | 2.2kW |
| More demanding routing or milling | 3.5kW |
For most general-purpose CNC router builds, 2.2kW is the option we would recommend first because it combines useful spindle power with the greater tooling flexibility of ER20.
A compact CNC may be better suited to a 400W or 1.5kW spindle, while a larger and sufficiently rigid CNC intended for more demanding work may benefit from the 3.5kW option.
Air-Cooled or Water-Cooled?
Air-cooled spindles are a good choice when simple installation and lower cooling-system maintenance are priorities. Because cooling is built into the spindle, there is no external water pump, coolant reservoir or cooling pipework to install.
Water-cooled spindles may be preferred where lower operating noise and water-based cooling are important.
If you are still deciding between the two systems, read our Air-Cooled vs Water-Cooled Spindle Guide .
Find the Correct Spindle for Your CNC
The correct spindle depends on your CNC machine, the materials you plan to cut, the tooling you want to use and the type of work the machine will perform.
CNC Online stocks air-cooled spindles, VFDs, spindle kits, ER11 and ER20 collets, spindle brackets and related CNC components for new CNC builds and machine upgrades.
Choosing the correct spindle, VFD and tooling combination from the beginning gives you a CNC setup that is properly matched to the work you actually want to do.
Need Help Choosing?
Every CNC setup is different.
If you are unsure which air-cooled spindle is correct for your machine, tell us the CNC router you are building or upgrading, the materials you plan to machine, your required tooling and how the machine will be used.
CNC Online South Africa can help you choose the air-cooled spindle, VFD and supporting components that best suit your application.
Email: sales@cnconline.co.za
WhatsApp: 073 352 8930