Fine Pitch Bolts

Threads with a fine pitch have more threads per unit length than a standard metric coarse pitch bolt or screw. For example, an M10 coarse pitch has threads 1.5mm apart, whilst an M10 fine pitch has this figure at 1.25mm.

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These different thread pitches would be written as:

M10 - standard metric coarse pitch (1.5mm)
M10 x 1.25 - metric fine pitch
M10 x 1 - metric extra fine pitch

Matching these thread pitches and diameters between nut and bolt will ensure that the two parts are compatible.

The advantages of fine pitch threads are:

increased tensile and shear strength due to the size and depth of the fine thread, which is more apparent as the bolt/screw diameter gets smaller.
requires less torque in assembly to achieve the same pre-load.
allows for greater adjustment accuracy, and the thread finishes closer to the head.
less likely to loosen with vibration.
better for tapping into thin walled components as it needs a shorter engagement length.

The disadvantages of fine pitch threads are:

a greater susceptibility to damage.
more likely to suffer from thread galling in the case of stainless parts.
more time needed for assembly (and for any thread galling prevention).
likely to be more expensive, as they are more difficult to source.

This page features our current range of metric fine pitch bolts.
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Fastener Material Key
A2	A2 Stainless Steel - Also known as grade 304 or 18/8. A general purpose grade of stainless steel.
A4-80	A4-80 Stainless Steel - Identical corrosion resistance to A4-70 but with a higher tensile strength equivalent to that of 8.8 high tensile steel.
BZP-10.9	Bright Zinc Plated (BZP) Class 10 High Tensile Steel - A high strength non-stainless grade for screws and bolts, with a basic level of corrosion resistance.
BZP-12.9	Bright Zinc Plated (BZP) Class 12 High Tensile Steel - A higher tensile non-stainless grade for screws and bolts, with a basic level of corrosion resistance.
BZP-8.8	Bright Zinc Plated (BZP) Class 8 High Tensile Steel - The general purpose high tensile grade for screws and bolts, with a basic level of corrosion resistance.

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Hex Head Setscrews With Fine Pitch Thread DIN 961 in A2 Stainless Steel

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Hex Head Setscrews With Fine Pitch Thread DIN 961 in A2 Stainless Steel

A metric fine thread version of the common DIN 933 / ISO 4017 hexagon head set screw. Fine pitch variant screws have some distinct advantages over their coarse pitch counterparts. Size for size they are stronger than the coarse thread versions "in tension" as there is a larger stress (contact) area. They also have a larger minor diameter meaning shear is less likely. Fine Pitch set screws have less tendancy to loosen as they have a much smaller thread incline. Fine pitch bolts should be preferred if being used to adjust settings, as they give closer, more precise control. Some downsides of using Fine pitch bolts or screws are that they are slower to install, so not ideal where quick fitment and removal are required, and stainless steel variants are more likely to suffer from thread galling (see our reference section).

BZP-10.9

BZP-8.8

Socket Head Cap Screws With Fine Pitch Thread DIN 912 (ISO 4762) in A4-80 Stainless Steel

image chamfer for Socket Head Cap Screws With Fine Pitch Thread DIN 912 (ISO 4762)

Socket Head Cap Screws With Fine Pitch Thread DIN 912 (ISO 4762) in A4-80 Stainless Steel

Fine pitch screws are used in conjunction with a fine pitch threaded hole, or with fine pitch nuts which are also available on this website. The extra thread engagement gained from the finer pitch gives a more secure and stronger fitment. Used where high levels of strength are required - a fine pitch bolt has a larger stress area creating better tension than its coarse pitch counterpart, also they are less inclined to loosening through vibration due to the thread incline being smaller.

A4-80

BZP-12.9

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