Simfix field journal
For DIYers and the tradeLatest guide: 5 October 2026
The Fix
Straight answers on stainless steel fixings. Which grade, which size, which head, and how to fit it so it stays fixed.
Door 1
Doing it yourself?
Weekend job, one-off repair or your first deck. Start here and get it right first time.
Door 2
On the tools every day?
Spec it fast, buy in the right pack size and keep the job moving.
The workbench
Tools that do the measuring for you
Size Guides
Read and measure any size
What M8 x 30 means, how to measure the one you have, plus spanner, hex key and drill sizes.
Size it
Converter
Metric or imperial?
Convert mm and inches, and compare metric threads with UNC, UNF and BSW sizes.
Convert it
Fresh off the bench
The latest guides
Fault finder
What's the problem?
Pick the question closest to yours. Each ticket opens the guide or tool that answers it.
- No. 01 Grade Should I use A2 or A4?
- No. 02 Thread Is it metric or imperial?
- No. 03 Shape Which head or drive is this?
- No. 04 Coastal Is it going near the sea?
- No. 05 Timber What goes into treated timber?
- No. 06 Metals Can stainless go into aluminium?
- No. 07 Fitting Why do stainless bolts seize?
- No. 08 Fitting How tight should it be?
- No. 09 Drilling What pilot hole for a self-tapper?
- No. 10 Spec What do DIN and ISO numbers mean?
- No. 11 Packs When is a trade pack worth it?
- No. 12 Size How do I measure the one I have?
The parts shelf
Every guide, sorted into bins
Bin 01
Materials and corrosion
Grades, coastal use, mixing metals
Bin 02
Sizes and standards
Reading sizes, threads and specs
Bin 03
Fitting and installing
Torque, seizing and pilot holes
Bin 04
Buying smart
Packs and quantities
On the job
Fixings sorted by the job you're doing
Back issues
Every guide from The Fix
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Metric vs Imperial Fasteners: How to Tell Them Apart
How to tell metric from imperial fasteners, why they never mix, and size charts for UNC, UNF, BSW, BSF and BA threads...
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How to Stop Stainless Steel Bolts Seizing: Thread Galling Guide
Prevent stainless steel thread galling with clean parts, low speed, correct lubrication and matched torque. Includes warning signs and removal advice.
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Stainless Steel Screws in Aluminium: Galvanic Corrosion Guide
Use stainless screws in aluminium without avoidable galvanic corrosion. Learn when the pairing is safe, when to isolate it and which grade...
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Stainless Steel Bolt Torque Chart: A2-70, A4-70 and A4-80 Explained
Dry tightening torque chart for A2-70, A4-70 and A4-80 metric stainless bolts from M3 to M20, with lubrication and preload guidance.
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Self-Tapping Screw Pilot Hole Size Chart for Aluminium and Plastic
Choose a starting pilot hole for 3.5, 4.2 and 4.8 mm stainless self-tapping screws in aluminium and compatible plastics, with practical test...
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Best Screws for Treated Timber and Decking: Grade and Size Guide
Choose stainless screws for treated timber, decking and outdoor structures. A2 vs A4, screw sizes, pilot holes and corrosion mistakes explained.
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Fastener Head and Drive Types: A Visual Glossary
Pan, countersunk, button, hex, socket, cup square - what each fastener head type looks like, what it's used for, and which drive...
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DIY vs Trade Pack: When to Buy Bigger
How to decide between a DIY pack and a Trade pack of fasteners. Cost-per-unit, storage, common-stock items, and when bulk pays off.
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Marine-Grade Fasteners: A Complete Buying Guide
Marine grade fasteners are A4 (316) stainless steel. This guide covers when you need A4, when A2 is enough, and what to...
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DIN, ISO and BS Standards Explained for Fasteners
What DIN, ISO and BS standards mean for fasteners, and why they matter. Quick reference to the most common standards on the...
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304 vs 316 Stainless Steel: A2 vs A4, Which Grade Should You Use?
A2 and A4 are the fastener names for 304 and 316 stainless steel. Use A2 indoors and inland; use A4 near the...
The trade counter
Still stuck? Ask at the counter.
Tell us what you're fixing, what it's going into and the size if you know it. We'll help you find the right part.