Allen-Bradley ControlLogix 1756-A chassis screw size
M4 / M5 · length not stated in the sources
Allen-Bradley ControlLogix 1756-A chassis takes M4 and M5 metric screws. None of the sources we found gives an exact length, so measure the original before you order.
There are 2 separate fitment records for it, including M4 or M5 Phillips screw with flat and star washer for the chassis grounding lug (M4) and M5 alternative to M4 for the grounding tab (Rockwell lists M4/M5 as #10/#12 equivalents) (M5).
Head and drive, as the sources state them: Phillips drive.
2 of the 2 records are marked confirmed, drawn from 1 source (literature.rockwellautomation.com).
M4 means a 4 mm nominal diameter with a 0.7 mm thread pitch. Imperial look-alike: #8-32 (4.17 mm) — the standard US PC/rack screw, close but not the same.
Allen-Bradley ControlLogix 1756-A chassis screw specifications
One row per fitment record. Head, drive are shown only where the source states them; pitch is the ISO coarse pitch for the thread.
| Thread | Length | Pitch | Head | Drive | Where it goes | Status |
|---|---|---|---|---|---|---|
| M4 | not stated | 0.7 mm | not stated | Phillips | M4 or M5 Phillips screw with flat and star washer for the chassis grounding lugwasher / flange face | Confirmed |
| M5 | not stated | 0.8 mm | not stated | not stated | M5 alternative to M4 for the grounding tab (Rockwell lists M4/M5 as #10/#12 equivalents) | Confirmed |
Fitment records and sources
M4 or M5 Phillips screw with flat and star washer for the chassis grounding lug
pitch 0.7 mm · tap 3.3 mm · clearance 4.5 mm · PH2 / Torx T20
M5 alternative to M4 for the grounding tab (Rockwell lists M4/M5 as #10/#12 equivalents)
pitch 0.8 mm · tap 4.2 mm · clearance 5.5 mm · PH2 / Torx T25
How to check the screw before you buy
- Check the strength class stamped on the head (8.8, 10.9, A2-70) and replace like for like.
- Diameter: across the threads an M4 screw measures about 4 mm with calipers (usually a hair under). This device also uses M5, so measure each screw rather than assuming they match.
- Pitch: 0.7 mm from one thread crest to the next (14.29 crests per centimetre). A thread pitch gauge or the pitch-gauge tool settles it in seconds.
- Length: measure from under the head to the tip for pan, button, wafer and cap heads; countersunk (flat) heads are measured overall.
- Driver: the source names a Phillips drive. For comparison, standard M4 heads take PH2 (Phillips) or T20 (Torx), or a 3 mm hex key.
- Tightening: no device-specific torque is published in these records. The site's general figure for M4 is about 2.0-3.0 N·m into metal threads and 0.8-1.4 N·m into plastic bosses; snug it up and stop.
Common mix-ups with M4 / M5
- Grounding/earth-stud screws on hazardous-area (ATEX/IECEx) gas detectors are commonly M4 even though the enclosure body uses larger threaded glands — don't extrapolate the earth screw size to the whole unit.
- Some rackmount KVM switch kits pair M4x10 bracket-to-rack screws with M3.2x4.5 bracket-to-chassis screws (non-standard M3.2, not a true M3), so kits are not fully interchangeable with generic M3/M4 hardware.
- Commercial washer-extractor cabinets mix DIN 933 (hex head, full thread) and DIN 84A (slotted pan/cheese head) M5 screws for different panels on the same machine line, so a single family/brand isn't consistent across all fasteners.
- GoPro also uses M5 for its classic two-prong mount thumbscrew and buckle system, while smaller GoPro chassis screws are commonly Torx-driven without a confirmed metric thread in available sources — don't conflate the mount thumbscrew size with internal chassis screws.
More in Industrial & Machinery
The same screw also fits
Devices whose records share a thread with Allen-Bradley ControlLogix 1756-A chassis, closest length match first.
- Melco EMC 1 Embroidery Peripheral (textile printing/embroidery machinery) also M4
- DeWalt D51430 / D51431 pneumatic nailer also M4
- Milwaukee cordless tool (service bulletin 54-26-2590) also M4
- Makita DHS680 165mm cordless circular saw also M5
- Needle plate screw for Bernette/EverSewn/Necchi/Singer industrial-style sewing machines also M4
- Schneider Electric Altivar 312 drive also M4
- SICK sensor mounting accessories also M4
- ABB random-wound motor terminal boxes (ACS580 drive systems) also M4
Questions about Allen-Bradley ControlLogix 1756-A chassis screws
- What size screw does Allen-Bradley ControlLogix 1756-A chassis use?
- M4 for M4 or M5 Phillips screw with flat and star washer for the chassis grounding lug; M5 for M5 alternative to M4 for the grounding tab (Rockwell lists M4/M5 as #10/#12 equivalents).
- How long are the screws in Allen-Bradley ControlLogix 1756-A chassis?
- None of the sources states a length. Remove one screw and measure it from under the head to the tip (overall for a countersunk head).
- What is the thread pitch of an M4 screw?
- 0.7 mm (coarse), which is the standard pitch for M4 machine screws; a 0.5 mm fine pitch exists but is uncommon. The tap drill is 3.3 mm and the normal clearance hole is 4.5 mm.
- What screwdriver do I need for Allen-Bradley ControlLogix 1756-A chassis?
- The source lists a Phillips drive. Standard M4 heads otherwise take PH2 (Phillips) or T20 (Torx), or a 3 mm hex key.
- Can I use an imperial screw instead of M4?
- No. Imperial look-alike: #8-32 (4.17 mm) — the standard US PC/rack screw, close but not the same. Use a true M4 screw so it does not cross-thread or strip the hole.