When standard catalog fasteners do not fit your design, you need custom bolts. Non standard bolts can solve clearance issues, weight limits, special materials, or unusual assembly methods. However, many purchasing teams only send a short email like “need M16 special bolt, please quote” and then spend weeks going back and forth on details.
A clear, structured request saves time for both sides. It also reduces the risk of production errors, shipment delays, and performance problems in the field. This article explains how to request non standard bolts correctly, which information your supplier really needs, and how to prepare drawings and documents that support smooth production.
1. When Do You Really Need Custom Bolts?
Before preparing a detailed request, it is worth asking whether a standard fastener can already solve the problem. Standard bolts designed according to common standards such as ISO hex bolts, structural heavy hex bolts, or typical flange bolts cover a large portion of applications. Using standard items usually means shorter lead time, lower cost, and easier replacement.
You should consider non standard bolts when:
- Standard diameters or lengths do not match your design.
- You need a special head shape, such as low-profile, anti-tamper, or integrated washer head.
- The shank needs a special unthreaded length, groove, or cross hole.
- The material or coating must match a specific temperature, corrosion, or strength requirement that standard items do not offer.
- You need special small packing, pre-assembled washers or nuts, or kitting that standard stock cannot provide.
If you are not sure, you can send your current design and ask your supplier whether a standard hex bolt, structural bolt, or screw from their catalog (for example https://linkworldfast.com/product-category/bolts-nuts-washers/ or https://linkworldfast.com/product/hex-bolts/) can be adapted with minimal changes. In many projects, a small drawing adjustment avoids a fully customized part.
2. Key Information Your Supplier Needs for Custom Bolts
When you really need a custom design, your inquiry should provide a complete picture of both the part and the application. A good way is to structure your email or RFQ according to the points below.
2.1 Basic geometry and dimensions
Start with the core geometry:
- Bolt type: hex bolt, flange bolt, T bolt, eye bolt, carriage bolt, or other.
- Nominal diameter and thread: for example M16 × 2, 5/8″-11 UNC.
- Overall length, measured from under head to tip.
- Thread length and any unthreaded shank.
- Special features: grooves, cross holes, steps, recesses, or flats.
If your design is based on a standard but modified, mention the standard as a reference. For example, “based on ISO hex bolt, but with longer plain shank” or “similar to heavy hex structural bolt, with different head height”. This helps the supplier understand the starting point.
2.2 Material and mechanical properties
Next, define what the bolt must withstand in service:
- Base material: carbon steel, alloy steel, stainless steel grade, or other.
- Property class or strength level, such as 8.8, 10.9, or stainless class.
- Special mechanical requirements such as proof load, impact toughness, or hardness range.
- Working temperature range, static or dynamic loading, and safety factors if relevant.
For example, a structural steel connection may require high-strength quenched and tempered bolts, while a chemical plant may need stainless steel or a special alloy. The more information you provide about the real environment and load, the better your supplier can suggest a practical solution.
2.3 Coating and corrosion protection
For outdoor and industrial applications, coating is as important as base material. In your inquiry, clarify:
- Whether the bolt will be used indoors, outdoors, or in marine or chemical environments.
- Preferred coating type: hot-dip galvanizing, mechanical galvanizing, zinc flake coating, electroplated zinc, or others.
- Color requirements (silver, black, grey, etc.).
- Whether controlled friction is needed for torque–tension control.
If you are unsure which coating suits your environment, describe the conditions (rain, salt, chemicals, cleaning cycles) and ask the supplier to suggest options. They may propose different solutions and explain the trade-offs.
2.4 Tolerances and thread fit
Non standard bolts often involve tight tolerances or special fits. In your RFQ or drawing, indicate:
- Dimensional tolerances for head, shank, and special features.
- Thread tolerance class or fit, for example 6g or 2A.
- Any critical dimensions where you cannot accept a change.
Not every dimension needs a very tight tolerance. If you mark only the critical ones, you avoid unnecessary machining or rejected batches. This keeps the cost under control while still protecting function.
2.5 Quantity, delivery, and packaging
Suppliers need to understand not only the part design but also how you plan to buy and use it:
- Estimated annual quantity and typical order quantity.
- Whether the order is one-time project supply or long-term recurring.
- Required delivery schedule, such as multiple partial shipments per year.
- Small-packing requirements: labels, barcodes, color boxes, plastic boxes, inner bags, or mixed kits.
If you prefer the supplier to offer temporary storage and release goods in several shipments, mention that in your initial request. It helps them plan production and packing from the beginning. For example, you can refer to overall product and service capabilities at https://linkworldfast.com/products/ and https://linkworldfast.com/about-us/ to see which categories fit your project.
3. How to Prepare a Clear Drawing for Custom Bolts
A good drawing is the fastest way to make sure you and your supplier are talking about the same part. When preparing a drawing for custom bolts, try to include the following elements.
3.1 Standard views and section details
Use clear views:
- Front view showing the overall side profile of the bolt.
- Top view for head shape and any marking.
- Section view if there are internal features or complex transitions.
- Detail views for special grooves, radii, or under-head fillets.
Dimension each feature in a logical order, and avoid clutter by using section and detail views where necessary.
3.2 Complete dimension chain
Make sure the drawing includes:
- Overall length and head height.
- Across flats and across corners for the head.
- Shank diameter and thread length.
- Chamfers or radii at the end of the shank and head transitions.
- Position and size of any holes, slots, or grooves.
Do not rely on “similar to photo” or “same as sample” notes without dimensions. Photos and samples are helpful, but they should support the drawing, not replace it.
3.3 Notes on material, coating, and inspection
Add a simple notes section that covers:
- Material grade and property class.
- Coating type and minimum thickness if required.
- Surface finish or cleanliness if special.
- Critical tests, such as proof load, hardness, or salt spray hours.
If you have internal specifications or references, list them clearly. You can keep commercial terms in your RFQ email and use the drawing only for technical information.
3.4 Digital formats and revisions
When sending drawings, provide stable formats such as PDF for review and, if available, 2D or 3D CAD files. Always indicate the revision level and date. When you update the drawing, change the revision and explain what has changed. This prevents confusion about which version to produce.
4. Example: Turning a Vague Inquiry into a Clear Custom Bolt Request
To see the difference, compare these two approaches:
Vague inquiry
Need M16 special bolt for steel structure, high strength, galvanized, please quote.
This message forces the supplier to ask many questions: head type, length, coating type, strength level, whether nuts and washers are needed, and more. Lead time for quotation becomes long, and there is a high risk of misunderstanding.
Clear custom bolt inquiry
We need a non standard M16 hex bolt for an outdoor steel structure.
– Type: hex bolt with plain shank
– Size: M16 × 2, overall length 140 mm, thread length 40 mm
– Head: heavy hex style, similar to structural bolts
– Material: carbon steel, property class 10.9
– Coating: hot-dip galvanizing, suitable for coastal outdoor environment
– Quantity: 8,000 pcs per year, orders in 2 or 3 lots
– Packing: small carton boxes with labels, 50 pcs per box
– Drawing: attached PDF + STEP file, revision B
– Application: bolted joints in welded steel frame, exposed to rain and salt air
With this information, the supplier can immediately check tooling, process flow, coating line, and packing possibilities. They can reply with a concrete proposal, lead time estimation, and questions only on genuinely unclear points.
5. Communication Tips for Purchasers Requesting Custom Bolts
Technical information is important, but the way you communicate is just as critical. Here are some practical tips when working with custom bolt suppliers.
5.1 Share the application, not only the drawing
Explain where the bolt will be used:
- Indoor or outdoor, temperature range, humidity.
- Static or dynamic loading, presence of vibration.
- Contact materials (steel, aluminum, timber, composites).
- Any standards or design codes that apply.
When your supplier understands the application, they can suggest improvements such as a stronger material, better coating, or modified geometry that still fits your structure.
5.2 Ask for manufacturability feedback
Non standard bolts sometimes require machining after cold forming, special threading, or complex tooling. It is helpful to ask:
- Whether there is a simpler design that achieves the same function.
- Whether small changes in length, fillet radius, or tolerances would reduce cost.
- Whether the supplier can integrate nuts, washers, or other components into one kit.
Most experienced fastener manufacturers will point out which features drive tooling cost or cycle time. A short discussion at the RFQ stage can save significant money later.
5.3 Clarify inspection and documentation needs
If your project requires certain inspection documents, define them early:
- Basic inspection reports, such as size and mechanical properties.
- Coating thickness or salt spray test results if needed.
- Special marking or traceability for critical bolts.
Not every batch needs detailed reports, but when you do need them, it is better to agree at the quotation stage instead of after production.
5.4 Plan logistics together
Custom bolts often have longer lead times than stock items. To avoid urgent air shipments and extra cost, share:
- Your project timeline and installation windows.
- Whether you can accept partial deliveries.
- Your storage and packing preferences.
Some suppliers can produce a full annual volume, keep part of it in their warehouse, and deliver according to your schedule. You can use the contact page at https://linkworldfast.com/contact/ to discuss what is practical for your region and project size.
6. Advantages of Working with a Custom Bolt Partner
A good custom bolt partner is not just a reseller of catalog products. They combine their own cold forming capacity, machining, surface treatment, and quality inspection with a network of supporting factories. For buyers, this brings several advantages:
- One point of contact for bolts, nuts, washers, stamping parts, and other related components.
- Consistent quality and documentation across multiple part numbers.
- Flexible small packing, branding, and warehouse support for multi-shipment projects.
- Engineering support when you need advice on material, coating, or design adjustments.
For an overview of product families such as bolts, nuts, washers, screws, rigging items, and concrete fasteners, you can visit https://linkworldfast.com/products/ and related category pages. From there, you can decide which items are standard and which ones require custom design.
7. Conclusion: Make Custom Bolt Requests Clear and Efficient
Requesting non standard bolts does not have to be slow or complicated. When you provide structured information on geometry, material, coating, tolerances, quantity, and packing, your supplier can quickly understand the requirement and offer a realistic solution. A clear drawing and open communication about the application help avoid misunderstandings and redesigns.
For your next project, try organizing your inquiry as a checklist. Attach a simple but complete drawing, explain how and where the bolt will be used, and ask for manufacturability suggestions. This approach reduces risk, saves time, and helps you get custom bolts that actually fit your structure and performance targets.
If you would like to discuss specific non standard bolts, mixed fastener lists, or small packing solutions, you can explore the product range at https://linkworldfast.com/ and then send your requirements through https://linkworldfast.com/contact/ for further technical communication.