11 · Structural · grip & engagement
Thread engagement vs grip length on RFQs
On stone cladding brackets, structural steel splices, and heavy baseplates, “how long is the bolt?” is really two fields: grip (clamped stack after washers) and thread engagement (usable threads into nut, plate, or tap). Lock both against the controlling revision before any unit price is useful — not a warehouse length chart swap.
Define · what this RFQ is for
Use this desk when overseas buyers quote bolts, studs, or machine screws for Dashitou stone · structural · heavy nodes and the print must separate grip length (fixture + washers + isolation) from thread engagement (nut height, tapped depth, or through-thread). You own the joint design and engineer sign-off; we confirm diameter × length language, washer pack, and qty band against the controlling revision.
Pair with structural bolt class & coating (G8) when property class/finish matter, wedge anchor plate RFQ (G7) for through-plate embedment, and drawing handoff for revision lock. Then open Enquire / RFQ.
Discuss · fields that change the quote
Each row below is a desk check. Missing rows stay Open — we do not invent torque charts, proof-load tables, or engagement formulae on this public page.
Field desk · 01–06
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Clamped stack / grip Sum plate(s) + washers + isolation pads in the clamp path. Grip is not overall bolt length and not embedment into concrete.
- Email example: Grip: 18 mm plate + 2× washer 2 mm + EPDM 2 mm = 24 mm (Rev C)
- If missing: Open — do not guess stack from a shelf length
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Thread engagement target Name nut height, tapped depth, or “full nut + protruding threads” as the controlling rule. Vague “enough threads” invites dual length quotes.
- Email example: Engagement: ISO hex nut full height + 2–3 protruding pitches (buyer rule)
- If Open: mark preference or engineer note on the print
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Diameter × proposed overall length Overall length follows grip + engagement + point/chamfer — not a catalog “closest longer” guess. Partial thread vs full thread changes usable engagement.
- Email example: M16 × 70 partial thread; grip 24 mm; nut engagement per Rev C
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Washer / isolation pack Each washer and pad adds grip. Stone-on-steel stacks often need isolation — see G9. Pad brand stays buyer-named or Open.
- Email example: Stack: flat washer + buyer EPDM 2 mm under head
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Class / finish / nut set Property class and coating still matter — see G8. Nut / washer set must match the engagement rule on the same revision.
- Email example: Class 8.8 HDG + matching nut; engagement per nut height note
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Qty band & destination Mock-up joint set vs project lot; destination for packing notes. Discussion band is enough for the first reply.
- Email example: Qty band: mock-up 80 sets → project lot TBD · dest EU
What must appear on the print
- Grip or stack-up note (or explicit overall length with washer callouts)
- Engagement rule: nut height, tapped depth, or protruding-thread preference
- Diameter × length and partial vs full thread when it affects engagement
- Controlling revision — see drawing handoff
Agree · before we number
Until the following are aligned, treat any figure as discussion only:
- Controlling revision locks grip and engagement (or marks Open with a preference rule)
- No invented torque, proof-load, or “1× diameter” formulae posted as site policy here
- Washer/isolation and class/finish settled or linked (G9 / G8) in the same thread
- Samples and private-label marking only after diameter × length are clear
We do not invent certificates, plant area, or ranking badges here. Project documents that matter to the RFQ are shared privately when relevant.
FAQ · thread engagement vs grip length
Is overall bolt length the same as grip length on an RFQ?
No. Grip is the clamped stack (plates + washers + pads). Overall length also covers thread engagement into the nut or tap, plus point/chamfer. Quoting only a shelf length without stack-up often forces a resubmit.
What should I write when the engineer has not locked engagement yet?
Mark engagement Open with a preference rule (for example “full nut height + 2 pitches protruding”) on the controlling revision or in the RFQ notes. Do not ask this public desk to invent a torque or proof-load table for the joint.
Do washers and isolation pads count toward grip?
Yes. Every washer and pad in the clamp path increases grip and can push overall length. Name the pack on the print or email; stone-on-steel isolation often sits here — see the stone-on-steel RFQ desk.
Can one RFQ mix through-bolted grip joints and tapped engagement?
Yes, when zones are explicit on the BOM (through-bolt vs tapped plate). Ambiguous “M16×70 all” without joint type often splits the quote. Lock zones or mark Open with a preference rule.
What should I send so Dashitou can review length cleanly?
Open Enquire / RFQ, then email the PDF/STEP or marked sketch to shizhanhao6@gmail.com in one thread. Include grip/stack-up, engagement rule, diameter × length, washer/isolation if relevant, class/finish if relevant, qty band, and destination. Skim G7–G9 when those desks apply. No cart; no list prices on this site.
Next step
Skim structural bolt RFQ · wedge plate RFQ · RFQ checklist, then open Enquire / RFQ. Direct email: shizhanhao6@gmail.com.