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Left Hand Thread Hex Bolts & Set Screws
Compare your fastener to our visual size guide to confirm size, pitch and length.
Match your spanner / socket AF (across-flats) to the size it fits - our reference chart covers every metric and imperial size we stock.
Left hand thread (reverse thread) hex bolts and set screws are used in applications where standard right-hand-thread fasteners would loosen under operating conditions. Examples include pedal cranks on bicycles, rotating shafts whose direction of motion would unscrew a right-hand bolt, fan and blower hubs, and cutting tools where the rotation direction matters.
They look identical to standard hex bolts except the thread spirals the opposite way — tighten anticlockwise, loosen clockwise. Suppliers will typically mark left-hand thread fasteners with a small "L" or notch on the head to avoid confusion.
MATERIAL AND FINISH
A2-70 G304 Stainless Steel — The only specification stocked. largely non-magnetic — A small degree of magnetism from work-hardening during manufacture is normal.
GRADE
A2-70 — The standard stainless grade.
Sizes: M4, M5, M6, M8, M10 and M12 metric coarse — left hand thread.
Thread system: Metric Coarse, Left Hand Thread.
Standard: DIN 933 (fully threaded set screw form).
All left-hand bolts must be paired with left-hand nuts — see our left-hand thread nuts page. Refer to our Technical PDF's Library for thread engagement and clamp data.
WHY AUSTRALIA TRUSTS BOLT & NUT
With 15+ years selling fasteners online from Brisbane, we hold over 25,000 stock lines and 200 million pieces — 98.75% of online orders placed before 1pm leave same day. Save more as you buy more — we offer up to 13 price breaks plus 3 spend-tier discounts. Read our customer reviews or get in touch if you need help picking the right bolt.
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Reverse-thread hex set screws that tighten anticlockwise - for rotating shafts and assemblies where a standard right-hand thread would work loose. A2-70 G304 stainless, M4 to M12 metric coarse.
TECHNICAL RESOURCES
Key charts and specification sheets: Specs - Left Hand Hex Set Screw Metric Coarse Stainless G304 DIN933 · Imperial vs Metric Strength Chart · Bolts Markings
For the full library, see our Technical PDF's Library.
