--- title: "Steel Drilling Services — Accuracy, Standard Sizes, Quotes" description: "How contract steel drilling works: the accuracy a drilled hole holds, standard clearance-hole sizes for bolted connections, and EN 10204 traceability." canonical: https://steelequivalents.com/services/steel-drilling language: en robots: index, follow og_type: website type: service-detail language_alternates: en: https://steelequivalents.com/services/steel-drilling.md cs: https://steelequivalents.com/cs/služby/vrtání-oceli-na-zakázku.md de: https://steelequivalents.com/de/dienstleistungen/lohnbohren.md es: https://steelequivalents.com/es/servicios/taladrado-de-acero.md fr: https://steelequivalents.com/fr/services/perçage-acier.md hu: https://steelequivalents.com/hu/szolgáltatások/acél-fúrása.md it: https://steelequivalents.com/it/servizi/foratura-acciaio.md nl: https://steelequivalents.com/nl/diensten/staal-boren.md pl: https://steelequivalents.com/pl/usługi/wiercenie-w-stali.md pt: https://steelequivalents.com/pt/serviços/furação-de-aço.md ru: https://steelequivalents.com/ru/услуги/сверление-металла.md tr: https://steelequivalents.com/tr/hizmetler/çelik-delme-hizmeti.md zh: https://steelequivalents.com/zh/服务/钢材钻孔加工.md ja: https://steelequivalents.com/ja/サービス/穴あけ加工.md ar: https://steelequivalents.com/ar/خدمات/حفر-الحديد.md ko: https://steelequivalents.com/ko/서비스/천공-가공.md pt-br: https://steelequivalents.com/pt-br/serviços/furação-de-aço.md hi: https://steelequivalents.com/hi/सेवाएं/स्टील-ड्रिलिंग-सेवा.md content_hash: sha256:9733af63d2ed1f23b6e31a64ea2ac9135ae6c1dfe53c0fc2fb9f8715be2099f6 generated: 2026-09-24 --- > **Machine-readable Markdown rendering.** This is a Markdown representation of a web page, > served for AI agents and crawlers as a token-efficient alternative to the full HTML. > Full interactive HTML version: https://steelequivalents.com/services/steel-drilling > Canonical URL: https://steelequivalents.com/services/steel-drilling > Available languages: en, cs, de, es, fr, hu, it, nl, pl, pt, ru, tr, zh, ja, ar, ko, pt-br, hi > Change detection: `content_hash` is the SHA-256 of this document's Markdown body — everything > below this block, whitespace-trimmed, excluding the front-matter. Compare it to detect a real > content change; `generated` moves on every render and is not a change signal. ![Steel Drilling](/images/uploads/b18f3f07-00f3-46a8-a858-093077252678/drilling-service-steel-beam-drilling-line-carbide-bit-1920x1080.jpg) Category # Steel Drilling Steel drilling: achievable accuracy, standard hole sizes and what a quote needs Drilling is putting a round hole through or into steel to a specification — you send a drawing, a shop supplies the finished part. This page covers what a drilling operation actually delivers: the accuracy a plain drilled hole holds against what needs a follow-up operation, the clearance-hole sizes structural bolted connections are built around, and what a provider needs from you before quoting. ## What drives the price - Material thickness - Hole diameter - Hole depth - Number of holes - Tolerance requirement - Steel grade - Thread requirement ## What to send for a quote - A drawing with the hole pattern - Diameters and required tolerances - Depth — through-hole or blind - Whether the holes need to be threaded - Grade or material number - Quantity - Whether you need an inspection certificate - Delivery address and required date ## Traceability and EN 10204 certificates - 2.1 - 2.2 - 3.1 - 3.2 Standard for steel purchases: 3.1 The certificate belongs to the material, not to the hole. Drilling does not create an EN 10204 certificate — the real question is whether traceability survives the operation, and how the drilled parts are marked or batched so that it does. Standard-defined Source: EN 10204 defines inspection-document types. ## Standard clearance holes for bolted connections EN 1090-2 | m12 | 14 mm | Standard-defined | | |---|---|---|---| | m16 | 18 mm | Standard-defined | Source: EN 1090-2, Table 11 | | m20 | 22 mm | Standard-defined | Source: EN 1090-2, Table 11 | | m24 | 26 mm | Standard-defined | Source: EN 1090-2, Table 11 | EN 1090-2 sets the standard clearance-hole diameter for a given bolt size in structural steelwork — the hole is deliberately larger than the bolt to allow assembly. ## Standard drill sizes DIN 338 DIN 338 defines the diameter and length series for standard jobber-length HSS twist drills — the base reference range a drilling shop works from. Standard-defined ## Achievable accuracy A twist drill on its own typically holds IT10 to IT13 — a coarser tolerance grade than a machined fit. Confirm the achievable grade with the provider for your diameter and material. Fits that need H7 or H8 — bearing seats, dowel holes — are not held by drilling alone. They need a reaming or boring pass after the hole is drilled. ## Services What accuracy can drilling achieve? Drilling alone typically holds a tolerance grade of IT10 to IT13 — coarser than a machined fit, but enough for clearance holes, fixing holes and general fabrication. A precision fit such as H7 or H8, for example a bearing seat or a dowel hole, is not something a twist drill delivers on its own: the hole is drilled undersize first and then reamed or bored to size. We do not publish an exact micrometre tolerance table here — we could not trace one to a verified primary standard — so ask your provider for the achievable tolerance on your diameter and material. What is a bolt clearance hole and how is it sized? For bolted structural connections, EN 1090-2 sets the standard clearance-hole diameter for each bolt size: an M12 bolt gets a 14 mm hole, M16 gets 18 mm, M20 gets 22 mm, and M24 gets 26 mm. The hole is deliberately larger than the bolt so the connection can be assembled and aligned on site. What information do you need for a quote? Send a drawing with the hole pattern, every diameter and its required tolerance, the depth — through or blind — and whether the holes need to be threaded. Add the grade or material number, the quantity, whether you need an inspection certificate, and the delivery address and date. Those eight things turn an enquiry into a firm price rather than a range. Standard shops work from the DIN 338 diameter series for their drills; if you need a size outside that series, say so up front. Can I send my own material to be drilled? Drilling customer-supplied material is common practice, but whether a given shop accepts it, and on what terms for liability and traceability, varies by provider. Ask before shipping, and if the material carries an inspection certificate, ask in the same message how the drilled parts will be marked so traceability survives the operation. Do I get an EN 10204 3.1 certificate? EN 10204 defines inspection document types 2.1, 2.2, 3.1 and 3.2, and 3.1 is the usual buyer default in steel procurement. But drilling does not create a certificate — the certificate belongs to the material. What matters is whether traceability survives the drilling operation, and how each part is marked or batched so it stays linked to its heat. Ask the provider that directly. What is the difference between drilling and reaming or boring? Drilling with a twist drill produces a hole to roughly IT10 to IT13. Reaming and boring are follow-up operations that take a pre-drilled hole down to a tighter grade such as H7 or H8, which drilling alone cannot hold. If your fit needs that precision, say so in the enquiry — the shop will drill undersize first and finish to size afterwards. Is there a minimum order quantity? There is no industry-wide minimum order quantity for drilling; it varies by provider. Some will drill a single part, others price small quantities in a way that makes them impractical. Ask as part of your enquiry rather than assuming. What is the lead time? No general lead time can be stated honestly — it depends on the provider, the hole pattern, the quantity and their current load. Ask for a committed date with your quote instead of planning around a norm that does not exist. Can the holes be threaded? Threaded holes are a normal request, and the thread size and depth belong on your drawing alongside the through-hole diameter. Thread requirements vary too much by application for us to state a general figure here, so put the exact thread callout in the enquiry rather than relying on a default. Is there a limit to how deep a hole can be drilled? There is a widely repeated rule of thumb that standard twist drilling is practical up to roughly three to five times the hole diameter before deeper holes need pecking cycles or specialised gun drilling. We could not trace this to a citable standard or a named supplier commitment, so we are not stating it as fact. For a deep hole, give the provider the depth and diameter and ask directly whether standard drilling reaches it. What is the difference between a drilled hole and a laser- or plasma-cut hole? Drilling removes material mechanically with a rotating cutting edge and produces a round hole with no heat-affected zone. Thermal processes such as laser or plasma can also pierce a hole, but they leave a cut edge rather than a machined bore and are not held to the same tolerance grades. For a hole that needs a specific diameter tolerance or a bolted fit, drilling — with reaming or boring if the fit is tight — is the usual choice. What does drilling cost? Drilling is not priced from a single rate, so any figure quoted here would mislead. What drives it is material thickness, hole diameter, hole depth, the number of holes, the tolerance you require, the steel grade, and whether the holes need threading. 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