Stainless angle in an Australian warehouse is two families pretending to be one. There is hot-rolled (or otherwise mill-produced) equal and unequal angle, usually in a dull HRAP finish. There is folded sheet angle, cut and bent from 304 or 316 to a drawing — the product the old Alltrade page called custom cut and folded angle.
They both look like an L from across the shed. They do not do the same job. One carries a published profile. The other is a custom-cut blank with a radius where a structural root would be. Mixing them because both are “angle” is how a kitchen trim becomes a lintel in someone’s head.
This essay sits in the custom-cut and sections map. If the shape is a U, read channel versus folded channel. If it is a strap, you wanted flat bar.
Mill angle
Common legs run through the small architectural sizes (20, 25, 30, 40, 50 mm) up into heavier sections. Thickness is independent of a sheet rack. Finish is often No. 1 / HRAP: pickled, dull, honest. Grade is usually 304; 316 exists and should be named if the angle lives near salt.
Uses: ledgers, frames, lintel-adjacent work that an engineer has actually sized, brackets that need a known profile. This is closer to flat bar than to a splashback. The mill product has a root, a consistent fillet, and a stiffness the folder will not invent from 1.2 mm sheet.
You buy a catalogue size. You do not invent a 37 mm × 22 mm because a tile rebate is 37 mm. If the rebate is odd, you are in folded territory — or you pack the mill size. Edges are mill edges, not furniture. Deburr if a hand or a hose will find them.
Equal versus unequal legs
Equal angle has two matching legs: 25 × 25, 40 × 40, 50 × 50, 75 × 75. It is the default for frames and for brackets that sit square on a wall and a shelf. Unequal angle has two different legs: 40 × 20, 50 × 25, 75 × 50, 100 × 75. It exists so one leg can hide on a face while the other carries a fixing, a drip, or a ledger.
Write both numbers. “Fifty angle” is a conversation, not a specification. Write the thickness as a third number. Write which leg sits against the wall if the two legs are different — otherwise the installer will guess, and the guess will be wrong on every second bay.
The words equal and unequal describe geometry. They do not promote a 1.5 mm fold into a structural section. On a wall trim, an unequal fold (long face, short return) is often the honest detail. On a frame an engineer has sized, use the mill profile in the software. Do not swap them to win a nest.
Common mill sizes
Merchant lists move. These are sizes Australian trades actually say. They are not a stock promise or a price list.
| Legs (mm) | Typical thickness (mm) | Equal or unequal | Shop-floor use |
|---|---|---|---|
| 25 × 25 | 3, 5 | Equal | Brackets, door frames, plant stands |
| 40 × 40 | 3, 5 | Equal | General fabrication, bench frames, guards |
| 50 × 50 | 5, 6 | Equal | Heavier frames, engineered brackets |
| 75 × 75 | 6, 8 | Equal | Work an engineer has actually sized |
| 40 × 20 | 3 | Unequal | Reveals, drips, one-sided fixings |
| 50 × 25 | 3, 5 | Unequal | Ledgers with a slim visible edge |
| 75 × 50 | 5, 6 | Unequal | Frames that hide one leg |
Lengths are typically 6 m on heavier sections. Custom-cut the bar to the job.
Folded sheet angle
This is a custom-cut blank with one bend. You choose alloy, finish, thickness and two internal legs. The old catalogue’s useful constraint: a smallest internal leg around 10 mm, with a radius at the fold. A 1.2 mm No. 4 304 angle as a wall trim is a good product. A 1.2 mm angle as a beam is a fiction.
Uses: edge trims, corner guards, light frames, kitchen returns. Grain on a No. 4 should be decided before the fold or the two legs will disagree in the light.
Thickness comes off the sheet chart, not a bar list. 1.2 mm and 1.5 mm are the everyday architectural folds. 3 mm sheet angle is still sheet, still a radius, still not a hot-rolled 50 × 50 × 5.
Fold limits and the radius
The folder has a minimum internal leg. Historic Melbourne notes put that number near 10 mm internal (about 12 mm external) on angle. Thicker sheet needs more flange. A 3 mm fold with a 10 mm internal is a banana.
The radius eats dimension. Internal 40 × 40 is not external 40 × 40. Say which you measured. If the angle has to sit inside a channel, draw both. Springback is real on austenitics. A 90° on the drawing is a conversation with the operator, not a keystroke.
How to specify
- Mill angle: “50 × 50 × 5 mm, 316, HRAP, 3.0 m.”
- Folded: “304, No. 4, 1.5 mm, 40 × 20 internal, grain along 40, 1800 long, ±2 mm.”
Say internal or external. The radius eats dimension. If the angle has to match a channel, draw both. Add the environment: “316, coastal, drain the heel” beats a mood board. 304 versus 316 still decides the alloy. Indoor kitchen angle can be 304. A balcony drip in Bondi should not be.
Name the finish. HRAP is dull. No. 4 is brushed. Match a seen bench or accept a contrast. Folded length tolerance is the old shear number: around ±2 mm unless you paid for another process.
Welding, cutting and dressing
Mill angle welds like other 304/316 bar. Use the matching filler, keep carbon-steel tools off the face, and treat heat tint as damage on anything that will see chlorides. The welding 304 and 316 essay is the briefing; this page will not invent amps.
A folded sheet angle is thin. A continuous fillet along a 1.2 mm return will wave the face. Stitch where hygiene allows. Clamp.
Cut mill angle with a dedicated stainless blade. A carbon-steel disc leaves iron in the cut. Protecting stainless during install applies to a bundle on a rusty rack as much as to a filmed splashback. After a weld or a heavy grind, passivate. Polishing the bead pretty is not the same job.
Corrosion and pairing
A 316 folded angle held on with A2 screws is a 304 stain at the hole. Outdoor angle follows the same alloy rules as 304 versus 316. Indoor kitchen angle can be 304 and should be cleanable — no open grit pits on a food upstand.
The heel of an angle is a dirt shelf if you install it upside down as a drip. Water sits, salt sits, tea staining starts in the internal corner. Drain it, or accept a wash programme from the coastal care essay. Do not bleach the stain off; cleaning without chlorides is the method, not a steel-wool pad.
Dissimilar metals still apply. Carbon-steel brackets behind a stainless angle will rust onto the back face. Isolate or match.
If you need a strap or a bent ear, start with flat bar. If you need a U, you wanted channel. The fabrication and care hub covers the weld, the film and the wash. Specify family first — mill or folded — then legs, thickness, alloy, finish. An L is a silhouette, not a specification.