How and which one to choose a CNC milling machine spindle

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Perhaps you are planning to upgrade your existing machine or are building a new router from scratch and need a good spindle for your hobby CNC machine.

In this guide, I have compiled a list of the best CNC spindles available in the market today.

Choosing the best CNC spindle for your machine will depend on the hardness of the materials you want to machine and the speed at which you need to do it. You can read a more scientific, theoretical approach to spindle selection in the article on spindle selection

If you don't have the time or patience to manually change the tool, you can opt for an automatic tool change (ATC) spindle, but it is more expensive compared to regular spindles.

The factors I considered when compiling this list were power output, spindle build quality, collet size, and cooling system.

I sorted them by power output, starting with the low power spindles and working my way up to the 4kW spindle.

At the end of this article, I discussed the factors to consider when choosing a spindle for your CNC.

1.5KW Water Cooled Spindle Kit

1.5KW Water Cooled Spindle Kit

1 & 220v 1.5kw ER16 water cooled spindle 4 bearings 80x220mm

1 & 220v 1.5kw 1000Hz inverter/VFD

1 & 80mm spindle bracket/holder

1 & 220v 75w water pump and 5m pipes

The balance between quality and power is what you get with the G-Penny machine 1.5KW ER16 spindle kit.

The spindle has a diameter of 3.14 inches and can be mounted to a CNC router using the included clamp.

This spindle kit includes a 1.5kW ER16 spindle, 80mm clamp and 220V VFD.

You can increase the speed of this motor up to 24,000 rpm at 1.5 kW power using a 220V power supply. But can only rotate clockwise. The speed can be changed using the variable frequency drive included in the kit.

However, the lowest stable speed you can achieve with this kit is 6000 RPM. You can use another VFD to reduce the speed.

The spindle has a pre-installed ER16 collet and can hold tools in the range of 0.02-0.354 in. (0.5-9 mm) with 0.002 in. runout.

This is a water cooled spindle made of stainless steel. The pump and cooling pipes are included in the kit. This spindle is suitable for engraving and cutting wood, aluminum and other soft materials.

The kit includes spindle, 220V 400Hz variable frequency drive, 220V 80W water pump, 16ft pipe.

CNC Spindle Motor 2.2KW

CNC Spindle Motor 2.2KW

A complete CNC spindle kit for your new CNC build that can cut soft materials is what you get with this CNC spindle motor kit.

The spindle weighs 5 kg, and the entire kit weighs about 10 kg and includes the spindle motor, VFD, water pump, 16-foot water pipes, 2.75-inch dust brush, 13 ER20 collets, and 10 drill bits.

You can also buy a spindle without a kit by contacting the seller by email.

You can install the spindle on any frame that can accommodate a 3.14-inch diameter spindle. The kit comes with ER20 collets and has a runout of 0.0002 inches, which is pretty good accuracy.

You can change the spindle speed from 0 to 24,000 rpm using a variable frequency drive that provides 2.2 kW of power. The VFD supplied with the spindle speed control kit is a 220V, 0-400Hz unit.

The CNC machine spindle is water cooled and comes with a 220V submersible pump, making it suitable for long-term operation.

The spindle, VFD, and water pump together can draw about 15A of current, so you may have to provide the appropriate breakers to set it up.

The connectors used are aircraft type plugs and provide good waterproofing.

Well-labeled wires, documentation and videos will guide you through the installation process. There are also plenty of videos on Youtube about setting up these spindles to help you along the way.

Design and technical features

Main components of the technical specifications:

• power;
• shaft rotation speed;

Milling spindle

Data on the power of the installation allows you to determine the material suitable for the job.

Yes, for:

• plywood, chipboard, MDF, plastics, a power of 800 W is sufficient;
• wood, textolite, soft alloys - 1.5 thousand W;
• stone, steel - 3 thousand W.

Knowing the speed of rotation allows you to set the operating mode of the machine, taking into account the characteristics of the material.

CNC Spindle Motor 4kw

CNC Spindle for CNC machine 4 kW

This spindle weighs around 8kg and is a sturdy spindle. Its size is 100 mm.

With this spindle, you get an ER20 collet that accepts tools with shaft diameters ranging from 0.039 to 0.512 inches and has a runout of 0.0004 inches.

HongYang also produces ER11 1.5KW, ER25 4KW, ER32 7.5KW spindles, all of which are available on AliExpress

You can change the spindle speed from 1 to 24,000 rpm. To control the spindle speed, you need to connect it to the VFD.

It is rated at 220V, can produce 4kW of power and draw a maximum current of 10A at 400Hz.

The spindle is water cooled and can be used for routing or engraving wood, stone and soft metals such as aluminum.

These spindles are quiet and well balanced, providing good stability when working at high speeds.

The construction material is durable and can last a long time.

Selecting the type of cooling

Cooling of the rotation zone is required to increase service life. There are two types.

Water (liquid)

Differences:

• They are very quiet - the liquid flows almost silently. But at the same time there is another loud sound from the movement of the impeller.
• The presence of a circuit that includes a system of tubes, a container, and a pump. It is necessary to constantly monitor the moisture supply and its temperature.
• Can operate at low speeds.

Air

Distinctive features:

• Strong and not the most pleasant sound.
• Chips may fly away under the influence of a jet of air.
• It is necessary to clean the shirt where metal particles become clogged at regular intervals.
• It is required to monitor the temperature very carefully; ideally, install a sensor with a signal, because the entire device is very sensitive to overheating.

As a result, we recommend using the air option when working with soft materials, but when the workpiece is made of durable metal, it is better to use liquid cooling.

Which spindle to use for steel machining

Generally, steel machining requires low RPM (compared to the RPM of aluminum and wood) and high power of a CNC spindle.

The ability to machine steel also depends on the rigidity of your machine and the tools you use. For steel, it is recommended to select a spindle with high power at low speeds.

The forces acting on the tool and therefore on the spindle are greater when machining hard materials such as steel.

It is advisable to choose a spindle with a steel body, rigid structure and ceramic bearings. Ceramic bearings can withstand more beating than metal ball bearings.

The power and speed of a CNC router spindle is also determined by the type of machining operation you are going to perform.

For example, drilling steel requires more energy than milling or turning steel.

Typically, when processing steel, the milling speed is 50% higher than the drilling speed.

In the case of turning, the speed can be 100% higher than when drilling.

For businesses that need to do heavy production work, I highly recommend ATC spindles over regular CNC spindles.

Bearing adjustment

No matter how good the technique was initially, over time it loses its positive qualities. Problems with bearings are inevitable during long-term operation. Even earlier they appear due to overloads and vibrations. Ignoring this point risks not only poor processing quality, but also equipment damage. You can adjust the bearings (or rather, their clearances) on cantilever milling cutters using approximately the same scheme:

• introduction of the mandrel;
• touching the cylindrical protrusion with an indicator pin;
• swinging the spindle with a mandrel in the support;
• marking the largest deviations of the indicator (they should be no more than 8-10);
• if exceeded, adjust according to the instructions.

Factors to consider when choosing a spindle for your CNC router

Size and weight.

The size of the motor determines whether it can be installed correctly on your CNC router. It is also important to consider the shape of the spindle as there are cylindrical and square spindles.

Make sure your CNC router frame is strong enough to support the weight of the spindle. In stepper motors, the axes must have sufficient torque to handle the weight of the motor.

Speed ​​and power

Spindle speed determines the range of work you can do. For example, cutting soft materials requires low speed because large pieces of material can be cut off easily.

In the case of metals, cutting large pieces of metal is difficult and therefore the amount of material removed in one pass is significantly reduced.

To achieve high cutting speeds, you will have to increase the spindle speed to make more cuts per minute.

Spindle power is another limiting factor for your projects. A spindle with sufficient power can ensure smooth cutting and prevent damage to the workpiece. On the other hand, a spindle without sufficient power can cause it to stall.

Cooling type

Very high RPM spindles tend to heat up quickly, so it is important to ensure the spindle is properly cooled.

The most common types of cooling available for spindles are air cooling and water cooling. Water has a higher heat capacity than air and therefore can remove more heat from the engine. It is better to use distilled water instead of regular water to avoid damaging the spindle.

Air-cooled spindles generally have better torque characteristics than water-cooled spindles due to their design. But air-cooled spindles produce more noise than water-cooled spindles.

In general, water-cooled spindles last longer and provide better accuracy than air-cooled spindles.

The main problem when operating a water-cooled spindle is the influence of climatic conditions. Because in cold weather, water can freeze and prevent the spindle from rotating.

Water cooling is preferred over air cooling if the spindle is used for extended periods of time.

Speed ​​control

The low power spindle can be controlled by PWM (Pulse Width Modulation) motor drivers.

VFD (Variable Frequency Drive) is preferred for high-power spindles as it provides better control and stable performance.

It is necessary to select the correct VFD for your spindle. An incorrect configuration can immediately damage your spindle. Make sure the voltage, current and spindle frequency ratings match your VFD (if you already have a VFD).

You can also control the spindle speed using a controller that runs your stepper motors. I talk about GRBL CNC Controllers in detail here - Best GRBL CNC Controllers for Hobbyists.

Basic device parameters

All equipment of this type is divided not only by design, but also by a number of indicators that should be taken into account both when choosing a ready-made option and when assembling the system yourself. The most important factors are the following:

Power The engine for a wood milling machine must provide the necessary performance for a particular type of work. Naturally, it is better when there is a certain reserve of power, but if you constantly perform simple work that does not require large energy costs, then an overly efficient motor will cause constant excessive consumption of electricity. Type of design Below we will look at the main options, and you will need to choose the type of layout that suits you best. which best suits your needs and needs

It is important to clearly understand what kind of work you will be doing, so that later it does not turn out that you need another version of the device. Quality of equipment Price should in no case be the main criterion when choosing; in addition to low quality, such options are also characterized by low performance indicators. The service life of cheap samples is short, and often in the event of a breakdown, finding the necessary spare parts for wood milling machines of unknown origin can be very, very difficult Availability of necessary communications If you want to perform certain work on an ongoing basis, then you need to make sure that you have at your disposal there was a room with sufficient area, it was also necessary to make a dust removal system

An important factor is the operating voltage of the machine; if it is 380 Volts, and you do not have an appropriate line, then the cost of supplying it may be more expensive than the equipment itself

Industrial portal-type CNC equipment allows you to perform almost any wood processing work