CFBSO Self-Clinching Blind Standoffs (Carbon Steel)
Heat-treated carbon-steel blind self-clinching standoff, zinc clear finish — pressed flush into sheets from 0.040 in. (1.0 mm) up to Rockwell B-80, unified #4-40 to #10-32 and metric M3 to M5, closed threaded end controlling screw penetration, with per-thread mounting geometry and steel-standoff performance rows.
Last updated: 2026-11
Specifications
CFBSO is the heat-treated carbon-steel member of the blind self-clinching standoff series: press it into a plain hole in sheet metal and the panel cold-flows into the clinching feature, locking the standoff in place flush and non-rotating — no reaming, deburring or welding first. "Blind" means the far end is closed: the standoff still fixes the spacing, but its internal thread stops the mounting screw at a controlled depth instead of letting it run through, so the screw cannot protrude behind the panel or bottom into enclosed hardware. The catalog rates CFBSO for panels of Rockwell B-80 hardness or less — the most permissive of the three series — and most sizes come in two body diameters (small-body 440-style and large-body 6440-style codes). A typical designation reads CFBSO 6440-10: carbon-steel blind standoff, large body, #4-40, length code -10. For the stainless and aluminum counterparts see the CFBSOS and CFBSOA pages; for the generic metric BSO/BSOS/BSOA ladder see the blind standoff family page, and for the through-threaded counterparts of this same catalog the CFSO series page.
| Series | CFBSO — heat-treated carbon steel, zinc clear finish; installs into panels of Rockwell B-80 hardness or less (the most permissive of the CFBSO/CFBSOS/CFBSOA series) |
|---|---|
| Threads | Internal 2B per ANSI B1.1 (6H per ANSI/ASME B1.13M for metric): #4-40, #6-32, #8-32, #10-32; M3 x 0.5, M3.5 x 0.6, M4 x 0.7, M5 x 0.8 |
| Minimum sheet thickness | 0.040 in. (1.0 mm) and up |
| Length ladders | Inch .312–1.062 in. (length codes -10 to -34 by thread), tolerance +.002/-.005 in.; metric 6–25 mm (codes -6 to -25), tolerance +.05/-.13 mm |
| Unified geometry, small body (sampled) | #4-40: A .166 +.003/-.000, H .165 +.000/-.005, C .187; #6-32: .213 / .212 / .250; #8-32 and #10-32: .281 / .280 / .312 |
| Unified geometry, large body (sampled) | #4-40: A .213, H .212, C .250; #6-32: .281 / .280 / .312; #8-32 and #10-32: .281 / .280 / .312 |
| Metric geometry (sampled) | M3: A 4.22 +.08/-.00, H 4.2 +.00/-.13, C 4.8; large body 5.41 / 5.39 / 6.4; M3.5: 5.41 / 5.39 / 6.4; M4: 7.14 / 7.12 / 7.9; M5: 7.14 / 7.12 / 7.9 (mm) |
| Trailing minimum columns (sampled) | Two trailing "Min." columns align positionally with the through-series table's minimum-edge-distance and minimum-sheet entries: #4-40 small body .23 in. edge / .040 in. sheet; large body .27 / .040; #6-32 and up .31 / .05; metric M3 6.0 mm / 1.0 mm, M3 large & M3.5 6.8 / 1.0, M4 & M5 8.0 / 1.27 — the printed sub-headers did not survive text extraction (see evidence note) |
| Effective thread depth (blind) | T minimum ladder .156 / .187 / .25 / .375 in. (3.2 / 4.0 / 5.0 / 6.5 / 9.5 mm) across the length ladders; the per-length assignment is not recoverable from the text layer — the metric ladder matches the effective-thread-depth ladder published on the BSO/BSOS/BSOA family page from a second collected source (see evidence note) |
| Part number structure | CFBSOS 6440-10 = series CFBSOS, body code 6 (large body), thread code 440 (#4-40), length code -10; small body uses body code 4 |
| Performance (steel standoff, .060 in. 5052-H34 aluminum sheet) | 440 group: 1100 lbs installation, 160 lbs pushout, 11 in.-lbs torque-out, 280 lbs pull-through; 6440/632: 1700 / 300 / 25 / 280; 8632/832/1032: 2400 / 400 / 45 / 580 |
| Performance (steel standoff, .060 in. cold-rolled steel sheet) | 440 group: 2200 lbs installation, 225 lbs pushout, 19 in.-lbs torque-out, 330 lbs pull-through, max tighten 4.75 in.-lbs; 6440/632: 3300 / 420 / 35 / 380 (max tighten 4.75, 8.75); 8632/832/1032: 4000 / 560 / 75 / 700 (max tighten 8.75, 18, 32) |
| MOQ / lead time | Not owner-confirmed for this family — confirmed at quotation |
Materials
- Heat-treated carbon steel, zinc clear finish (CFBSO)
Ordering & documentation
Documents
Shipments are backed by Mill Test Certificate (MTC), Dimensional Report, Salt Spray Test Report on request, with full batch traceability from raw material to finished product. Quality management follows the owner-confirmed compliance list: ISO 9001:2015, RoHS, REACH. Exact document sets are confirmed on the order.
Quotation
- The fastener family (CFBSO Self-Clinching Blind Standoffs (Carbon Steel)) plus the standard designation from your drawing — DIN / ISO / JIS / ASTM / ANSI, or a drawing for custom parts.
- Size (diameter and length), thread type (metric or inch), property class or grade, and coating or finish.
- Quantity per size and your target delivery date.
- Destination country, and any required documents (for example a mill test certificate) so the quote includes them.
Sample & supply
Minimum order quantities and lead times for this family are confirmed at quotation — send your sizes, grades and quantities on the RFQ and the quote will carry a firm schedule. Sample availability is confirmed with the quotation.
Storage & shipping
Parts are packed for export and shipped factory-direct to buyers in Europe, Asia, the Americas and the Middle East. Store fasteners dry and protected until installation, and keep coated parts in their packaging until use; specific packing and preservation requirements can be stated on the order and confirmed at quotation.
Frequently asked questions
When does a CFBSO blind standoff beat a through-threaded CFSO?
Choose the blind CFBSO when the screw must not pass through or protrude behind the panel: the closed end stops the screw at a controlled depth, which matters for enclosed assemblies, stacked boards, or a finished back face. The through-threaded CFSO from the same catalog is the choice when you want the screw to run through and engage beyond, or a mating part to bolt onto the far face. Both install into the same panel minimum (0.040 in.) and share the same thread range; the blind series gives up nothing in panel hardness rating (CFBSO is rated for HRB 80 or less, same ladder as CFSO).
What do the performance figures for a CFBSO include?
The collected catalog's performance table covers all six standoff series and splits by standoff material; the CFBSO rows are the steel-standoff rows. In 0.060 in. cold-rolled steel sheet, the large-body #4-40 group (6440) reaches 3300 lbs installation force, 420 lbs pushout, 35 in.-lbs torque-out and 380 lbs pull-through, with a maximum recommended tightening of 8.75 in.-lbs; in 0.060 in. 5052-H34 aluminum the same group shows 1700 / 300 / 25 / 280. These are tested figures at that sheet thickness for that standoff material — ask for the row of your exact thread, body and sheet at quotation.
What should an RFQ for CFBSO blind standoffs state?
State the series (CFBSO carbon steel — or CFBSOS stainless / CFBSOA aluminum if the panel or corrosion requirement points there), thread size (for example #10-32 or M4 x 0.7), body size (small or large), nominal length L, sheet material, thickness and hardness, and quantity per size — plus destination country. For a blind standoff also state the required effective thread depth and the maximum permitted screw penetration. Commercial terms are confirmed at quotation.
Request a Quote
Get factory-direct pricing from the manufacturer.
What to include in your inquiry
- ✓ Standard and property class (e.g. DIN 912, ISO 4762, class 8.8) — or a drawing for custom parts.
- ✓ Sizes, lengths and thread type (metric or inch).
- ✓ Quantity per size and your target delivery date.
- ✓ Destination country, plus any coating or finish requirement.
- ✓ Any documents you need with the shipment (e.g. mill test certificate) so the quote includes them.
- ✓ Your inquiry goes straight to the factory team by email and gets a reply within 24 hours.
- ✓ Factory-direct pricing
- ✓ Standard and custom specifications
- ✓ Factory-direct export to buyers in Europe, Asia, the Americas and the Middle East
- ✓ Full fastener family support