What M20 Full Thread Bolts are Used For
M20 set screws are commonly used in heavier-duty applications where a standard partially threaded bolt would not provide enough thread engagement.
Typical uses include:
- Structural steel connections
- Machinery installation and maintenance
- Steel fabrication and frames
- Timber to steel connections
- Agricultural and industrial equipment
- External installations where corrosion resistance is required
Because the thread runs the full length, these bolts are particularly useful where components vary in thickness or where precise clamping adjustment is needed.
Standards and materials
M20 set screws in this range are manufactured to:
- DIN 933 - hexagon head fully threaded bolts
- ISO 4017 - international equivalent standard
Typical characteristics of M20 DIN 933 set screws include:
- Metric coarse thread (2.5 mm pitch)
- Hex head with 30 mm spanner size
Material grades:
- A2 stainless steel (304)
- General-purpose corrosion resistance for indoor and outdoor use
- A4 stainless steel (316) - get in touch via our live chat if you require A4
- Higher corrosion resistance, suitable for marine, coastal and aggressive environments
Exact mechanical properties depend on the grade (e.g. A2-70, A4-70, A4-80), but all are suited to typical structural and fabrication use where stainless is required.
How to Choose the Right M20 Set Screw
When selecting M20 stainless steel full thread bolts, the key factors are:
Length
Choose a length that allows full engagement through all materials plus nut and washer.As a guide, allow enough thread to fully engage the nut without bottoming out.
Material Grade
Use A2 for general construction and external use
Use A4 where there is exposure to saltwater, chemicals or harsh environments
Thread type
All our DIN 933 M20 set screws use metric coarse thread (standard for general applications), ensuring compatibility with standard M20 nuts and threaded holes.
Installation
Hex heads allow tightening with standard 30 mm spanners or sockets, making them suitable for site work and high-torque applications.
Browse by Size
Within this M20 set screws range, you will find:
- Various lengths (e.g. 50mm, 75mm, 100mm and above)
- A2 stainless steel M20 set screws for general use
If you are working on a larger project or need specific grades or quantities, contact the team for support.
FAQs
What are M20 set screws used for?
M20 set screws are used in heavy-duty fastening applications where full thread engagement is required. Common uses include structural steelwork, machinery installation and fabrication.
What is the difference between a set screw and a hex bolt?
In this context, a set screw (DIN 933) is fully threaded along its entire length, whereas a standard hex bolt (DIN 931) is only partially threaded.
What does DIN 933 mean?
DIN 933 is the standard for hexagon head fully threaded bolt (known in the UK as set screws). It defines dimensions such as thread, head size and tolerances to ensure compatibility.
Should I choose A2 or A4 stainless steel?
A2 stainless steel is suitable for most indoor and outdoor applications. A4 stainless steel offers even higher corrosion resistance and is preferred for marine or harsh environments. If you require A4 stainless, please get in touch on our live chat and we can help.
What thread pitch is M20?
M20 set screws use a standard metric coarse thread with a 2.5mm pitch.
