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Coach Screw Pilot Hole Sizes

This article provides a comprehensive analysis of coach screw pilot hole sizes and guides you with selecting the appropriate pilot hole size for M6, M8, M10, and M12 coach screws DIN 571. 

The purpose of drilling pilot holes is to create a guide for the screw, ensuring that it can be inserted easily and securely into the material without causing any damage or compromising its integrity.

In this article, you will find detailed charts that show the minimum pilot hole size you should use before using your coach screw to ensure secure and efficient fastening.

While there is a standard guide of the required coach screw pilot hole size being half the thread diameter of the screw for softwood and three-quarters of the thread diameter when used with hardwood, it is important to consider factors such as the thickness and composition of the material and adjust your pilot hole accordingly. 



For materials with low density or softness, a smaller pilot hole diameter may be sufficient to provide adequate grip and prevent splitting or damage. Conversely, denser or harder materials may require a larger pilot hole diameter to accommodate the screw's threads without causing undue stress.

Please note that these recommendations are intended as a starting point and should be adjusted according to specific coach screw applications.


Coach Screw Pilot Hole Chart

The chart below provides recommended diameters for pilot holes for coach screws. These recommendations are based on extensive testing conducted by experts in the field to ensure that the pilot holes.

The recommended drill hole sizes vary depending on the type of material being drilled, such as wood, metal, or concrete. These recommendations should be used as a guide for wood, but should be adapter for tougher materials accordingly. 

Metric Size Thread Diameter Minimum Softwood Pilot Hole Size Minimum Hardwood Pilot Hole Size
M6 6mm 3mm 4.5mm
M8 8mm 4mm 6mm
M10 10mm 5mm 7.5mm
M12 12mm 6mm 9mm


what size pilot hole 


M6 Coach Screw Pilot Hole Size

The recommended pilot hole size for an M6 coach screw is 3mm when used with softwood and 4.5mm-5mm for hardwood.  

M8 Coach Screw Pilot Hole Size

The required pilot hole size for an 8mm thread diameter M8 coach screw is 4mm when used with softwood and 6mm for hardwood.  

M10 Coach Screw Pilot Hole Size

The minimum required pilot hole size for an M10 coach screw with a 10mm thread diameter is 5mm when used with softwood and 7.5mm-8mm for hardwood.  

The M10 coach screw is a commonly used fastener in construction and woodworking applications, known for its strength and durability. 

As M10 and above are commonly found in heavy duty applications, it’s important to consider using a larger pilot hole when drilling into harder materials like metal or concrete to prevent splitting or cracking of the material.

M12 Coach Screw Pilot Hole Size

The required pilot hole size for an M12 coach screw with a 12mm thread diameter is 6mm when used with softwood and 9mm for hardwood.  

To assist with this decision-making process, a table has been provided below that outlines minimum recommended pilot hole sizes for different materials:

Material Minimum Pilot Hole Diameter
Softwood 8mm
Hardwood 10mm
Plywood 6mm
Chipboard 6mm
MDF 5mm


M12 coach screw with 12mm thread diameter


Frequently Asked Questions

What are the Recommended Pilot Hole Sizes for Coach Screws of Different Sizes?

The recommended pilot hole sizes for coach screws of different sizes depend on various factors such as the material being drilled into, the diameter and length of the screw, and the specific application.

As we mentioned earlier, you should use the guide of at least half the thread diameter for softwood and three-quarters of the thread diameter for hardwood. A larger pilot hole is recommended for stronger materials.

Can I Use a Larger Pilot Hole Size Than Recommended for Coach Screws?

Using a larger pilot hole size than recommended for coach screws may compromise the structural integrity of the connection, but a larger pilot hole also reduces the risk of materials such as concrete splitting when inserting the screw.



By following the pilot hole size chart for M6, M8, M10, and M12 coach screws, you can be sure that your coach screw will fit securely with minimal risk of splitting or weakening the wood.

Don't underestimate the importance of selecting the correct pilot hole size for your coach screws!

Want to know more about coach screws? You can learn about the history of coach screws here.

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