Aluminum Extrusion L Brackets
An aluminum extrusion L bracket is a right-angle bracket that bolts into the slots of two T-slot profiles to hold them at 90°. It’s the simplest, most forgiving joint in extrusion building: no drilling or tapping, and you can loosen it to adjust or square the frame. Each bracket must match the profile size and slot width it bolts into.
L brackets by profile
| Profile | Bracket | Bolts per bracket | Nuts per bracket | Material | Source |
|---|---|---|---|---|---|
| 4040 (10 mm slot) | 90° bracket for 40 mm profile, single slot (reference: MISUMI HBLFSN8) | 2 × M8 (CBM8-20) | 2 × slot-10 M8 nuts (HNTT8-8) | Die-cast aluminum (ADC12) | MISUMI HBLFSN8 |
| 3030 (8 mm slot) | 90° bracket for 30 mm profile (reference: MISUMI HBLFSN6) | 2 × M6 (CBM6-12) | 2 × slot-8 M6 nuts (HNTT6-6) | Die-cast aluminum (ADC12) | MISUMI HBLFSN6 (catalog p. 2734) |
L bracket, corner bracket or hidden connector?
| L bracket | Hidden (internal) connector | |
|---|---|---|
| Where it sits | Outside the frame, in the corner | Inside the profile |
| Machining needed | None | Usually: tapped end or drilled access hole |
| Adjustable later | Yes: slide along the slot | Limited |
| Looks | Visible bracket | Clean corner |
MISUMI describes the bracket-vs-hidden-joint trade-off like this: brackets connect “outside the frame” and “can be moved to any position”, while blind joints are “aesthetically pleasing” but require “processing of the frame” (MISUMI 8 series catalog). See connectors for the hidden options.
Tips for square frames
- Snug every bolt first, check the frame with a square, then tighten fully.
- Brackets with a ridge (protrusion) that keys into the slot are easier to keep aligned while you tighten (MISUMI HBLFSN8).
- For a frame that people lean on, use two brackets per corner where the design calls for it. Our parts lists already include them.
Get exact quantities
Every project’s parts list counts every L bracket, bolt and nut for your exact dimensions. Each line links to a US seller. Prefer a single pre-cut kit? Buy as a pre-cut kit — join the waitlist.
Related
- T-slot nuts & bolts
- Connectors
- Corner brackets
FAQ
What size L bracket do I need for 4040 extrusion?
One made for a 40 mm profile with a 10 mm slot, plus M8 bolts and slot-10 nuts. A 40 mm bracket for an 8 mm slot will take different nuts, so check both.
How many bolts does an L bracket use?
A single-slot 90° bracket typically has one hole per leg, so two bolts and two T-slot nuts. MISUMI’s HBLFSN8 is one example (MISUMI). Wider brackets for double-slot profiles use more.
Can I use L brackets on 3030 and 4040 in the same frame?
Only with a bracket designed for that combination, and with each leg’s bolt and nut matching its own profile. Our current templates use one profile size per frame, so they never need one.
How much weight can an aluminum extrusion L bracket hold?
It depends on the bracket, the bolts, how many brackets share the load and which way the load acts, so we don’t publish load numbers for our designs.
Do I need to drill the extrusion to use L brackets?
No. L brackets bolt into the existing slots with T-slot nuts. That’s their main advantage over hidden connectors.