ISO 7050 Cross Recessed Countersunk Head Tapping Screws (Form C)
ISO 7050 cross recessed countersunk head tapping screws, Form C — ST2,2 to ST6,3 — the flush power-tool sheet-metal screw, with the collected recess sizing, Type H/Z driving ladders and the duplicated l = 38 mass rows carried verbatim.
Last updated: 2026-11
Specifications
ISO 7050 mates the power-tool cross recess to the flush countersunk head: csk-prep the hole, drive with a No. 1/2/3 Phillips-class bit, and nothing stands proud of the sheet. The collected ladder runs ST2,2 to ST6,3 with the flush head geometry (dk nominal=max./min. 4,3/4 up to 12,4/11,97; approximate head height k; countersink edge radius r 0,8 → 2,4), the cross-recess No. ladder (1/1/2/2/2/2/3/3), and the Type H and Type Z driving rows — m depth gauges (approx. 2,5 → 7,1 and 2,4 → 6,7) plus the source's "Penetration deptd" min./max. limits per size. The length ladder runs l 6,5 to 38 with approximate mass columns, and it carries a source defect the table flags: the l = 38 row is printed twice, once with mass cells from ST5,5 onward and once from ST4,8 — both rows carried verbatim, not de-duplicated, so read the pair as the source's own two-panel mass capture. Note what the head does not carry: the raised member's f/rf crown rows are absent here (that is ISO 7051). Property class, material and finish are not tabulated — per RFQ.
| Standard | ISO 7050 — cross recessed countersunk head tapping screws, Form C |
|---|---|
| Size range | ST2,2 – ST6,3; parenthesised (ST3,9) is the source's non-preferred marking |
| Head diameter | dk nominal=max. 4,3 → 12,4 mm (min. 4 → 11,97); k approx. 1,3 → 3,8 |
| Cross recess | No. 1 (ST2,2/ST2,9), No. 2 (ST3,5–ST4,8), No. 3 (ST5,5/ST6,3) |
| Recess driving data | Type H m approx. 2,5 → 7,1 / Type Z m approx. 2,4 → 6,7; penetration min./max. per size |
| Length ladder | l 6,5 – 38 with approximate mass per thread; source prints the l = 38 row twice (flagged verbatim) |
| Material / finish | Not tabulated by the collected specification — per RFQ |
| Attribute | Limit | ST2,2 | ST2,9 | ST3,5 | (ST3,9) | ST4,2 | ST4,8 | ST5,5 | ST6,3 |
|---|---|---|---|---|---|---|---|---|---|
| P | 0,8 | 1,1 | 1,3 | 1,3 | 1,4 | 1,6 | 1,8 | 1,8 | |
| a | max. | 0,8 | 1,1 | 1,3 | 1,3 | 1,4 | 1,6 | 1,8 | 1,8 |
| dk | nominal=max. | 4,3 | 5,5 | 6,8 | 7,5 | 8,1 | 9,5 | 10,8 | 12,4 |
| dk | min. | 4 | 5,2 | 6,44 | 7,14 | 7,74 | 9,14 | 10,37 | 11,97 |
| k | approx. | 1,3 | 1,7 | 2,1 | 2,3 | 2,5 | 3 | 3,4 | 3,8 |
| r | max. | 0,8 | 1,1 | 1,4 | 1,5 | 1,6 | 1,9 | 2,1 | 2,4 |
| Cross recess | No. | 1 | 1 | 2 | 2 | 2 | 2 | 3 | 3 |
| Type H m | approx. | 2,5 | 3 | 4,2 | 4,6 | 4,7 | 5,1 | 6,8 | 7,1 |
| Type H Penetration deptd | min. | 1,02 | 1,4 | 1,62 | 2,03 | 2,11 | 2,59 | 2,95 | 3,33 |
| Type H Penetration deptd | max. | 1,32 | 1,7 | 2,12 | 2,53 | 2,62 | 3,1 | 3,53 | 3,91 |
| Type Z m | approx. | 2,4 | 2,9 | 3,9 | 4,1 | 4,3 | 4,7 | 6,2 | 6,7 |
| Type Z Penetration deptd | min. | 1,1 | 1,48 | 1,6 | 1,85 | 2,05 | 2,64 | 2,72 | 3,38 |
| Type Z Penetration deptd | max. | 1,35 | 1,73 | 2,06 | 2,31 | 2,51 | 3,1 | 3,18 | 3,84 |
| y max. | Type C | 2 | 2,6 | 3,2 | 3,5 | 3,7 | 4,3 | 5 | 6 |
| y max. | Type F | 1,6 | 2,1 | 2,5 | 2,7 | 2,8 | 3,2 | 3,6 | 3,6 |
| l nominal | Type C min. | Type C max. | Type F min. | Type F max. | ST2,2 | ST2,9 | ST3,5 | (ST3,9) | ST4,2 | ST4,8 | ST5,5 | ST6,3 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 6,5 | 5,7 | 7,3 | 5,7 | 6,5 | 0,14 | 0,242 | ||||||
| 9,5 | 8,7 | 10,3 | 8,7 | 9,5 | 0,2 | 0,35 | 0,548 | 0,658 | 0,775 | 1,1 | ||
| 13 | 12,2 | 13,8 | 12,2 | 13 | 0,27 | 0,476 | 0,722 | 0,88 | 1,02 | 1,45 | 2,11 | 2,53 |
| 16 | 15,2 | 16,8 | 15,2 | 16 | 0,33 | 0,584 | 0,871 | 1,07 | 1,23 | 1,75 | 2,49 | 3,07 |
| 19 | 18,2 | 19,8 | 18,2 | 19 | 0,692 | 1,02 | 1,26 | 1,44 | 2,05 | 2,87 | 3,61 | |
| 22 | 21,2 | 22,8 | 20,7 | 22 | 1,17 | 1,45 | 1,65 | 2,35 | 3,26 | 4,15 | ||
| 25 | 24,2 | 25,8 | 23,7 | 25 | 1,32 | 1,64 | 1,86 | 2,65 | 3,65 | 4,69 | ||
| 32 | 30,7 | 33,3 | 30,7 | 32 | 2,35 | 3,35 | 4,56 | 5,95 | ||||
| 38 | 36,7 | 39,3 | 36,7 | 38 | 5,34 | 7,03 | ||||||
| 38 | 36,7 | 39,3 | 36,7 | 38 | 4,52 | 6,45 | 8,82 |
- Row 10 (38): The source prints the l = 38 row twice — first with mass cells from ST5,5 only, then again with mass cells from ST4,8. Both rows carried verbatim (row indices 8 and 9 here), not de-duplicated.
Materials
- Material and finish specified per RFQ — state the host sheet (the countersink cone needs thickness) and plating; case-hardened steel is the standard tapping body
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 (ISO 7050 Cross Recessed Countersunk Head Tapping Screws (Form C)) 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 quantity is 10,000 pieces. Stock items run 3–7 days. Quantities or variants outside the standard range are confirmed at 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
Why does the collected length table show two l = 38 rows with different mass cells?
Because the source prints it that way. In the captured page the l = 38 trade-size row appears twice: the first instance carries approximate-mass cells beginning at ST5,5, the second beginning at ST4,8. That is a capture/printing artifact, not two different screws — l 38 has one set of Type C/F length limits (36,7/39,3 on both rows, identical). The batch discipline here is verbatim-plus-flag: both rows are carried exactly as the source prints them with a table note, rather than silently merged, so any future re-check against the live page can see what the capture held. If you are reading the mass columns for a shipping estimate, the safest read is the union of the two rows (ST4,8 through ST6,3 populated, no conflicting values — the overlapping ST5,5 cells agree across rows where both print). The duplicate is documented on the page's table note; geometry is unaffected. Material and finish remain per RFQ.
Related knowledge
- Thread-Forming vs Thread-Cutting vs Thread-Rolling Self-Tapping Screws: What the Evidence Settles on Base Material
- Screw Family Selection by Base Material: Wood, Machine and Self-Tapping Threads, Engagement and Coating
- Hex Bolts vs Socket Head Cap Screws: What the Evidence Settles on Strength, Clearance and Cost
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