The Fastener Trap
Every machinist has met the buyer who says: just use a standard bolt. And usually they are right — standard fasteners from a distributor cost cents. But our RFQs keep bringing in parts like an M10 washer with a 0.02 mm thickness callout, a thread-locking screw in 316 with a custom head, or a family of bolts in a size no catalog carries. That is when CNC machining stops being a fallback and becomes the only option.
When Machining Beats the Catalog
- Non-standard size or thread pitch — the catalog simply does not have it
- Special material — 316L, 4140 heat treated, titanium, or brass for corrosion or conductivity
- Tolerance callouts — standard fasteners are made to loose commercial tolerances; precision fits need machining
- Small quantity — cold heading has a high minimum and long tooling lead time; 100 machined bolts are fast
- Custom head geometry, locking features, or one-piece assemblies with threads on both ends
Cold heading is the right process for 50,000 standard screws. For anything special — and any quantity below a few thousand — CNC turning of fasteners is faster to start and cheaper in total once you count tooling. We have turned families of 4-5 bolt variants in one program family, sharing the setup, which is exactly how a mixed fastener kit should be priced.
Threads: Cut, Rolled or Machined
Machined fasteners give you a choice the catalog does not: cut threads versus rolled threads. Cut threads (single-point or thread milling) are standard for small batches and give good accuracy. Rolled threads are stronger — the cold working compresses the grain structure — and are the default for anything load-bearing in production. For a prototype or a 100-piece run, cut threads are perfectly fine; just say if the thread is structural so we can spec the right process.
Material Choice Changes the Price More Than Anything
| Material | Best For | Watch Out |
|---|---|---|
| 304 stainless | General corrosion resistance, washdown | Galling on threads under load |
| 316 stainless | Salt, chemicals, marine | More expensive, harder to machine |
| 4140 Q&T | High-strength structural bolts | Needs heat treat after machining |
| Brass / copper alloys | Electrical, non-magnetic, decorative | Softer — strip threads easily |
| Titanium | Aerospace, weight critical | Expensive, slow machining |
Washers and Pins Are Fasteners Too
Precision washers with thickness tolerances, dowel pins with ground diameters, split pins, sealing washers with rubber bonded in — these all show up in RFQs and all benefit from machining when tolerance matters. A stamped washer is fine for a general spacer; a washer that sets a bearing preload needs machined faces and a real flatness spec. Same logic: catalog when you can, machine when the number matters.
If your fastener has a drawing instead of a catalog number, send it over — non-standard threads, custom heads and special materials are exactly what we machine every week.
Locking Features and Plating: The Details Buyers Forget
Two fastener details cause more field failures than thread strength: missing locking features and wrong plating. If the screw must stay put under vibration, machined fasteners can carry a thread-locking patch, a prevailing-torque feature, or a nylon insert — none of which exist in a standard catalog part. And plating is not decoration: zinc protects in wet environments, black oxide is for dry indoor use, nickel resists chemicals. Say where the fastener lives and how it is loaded, and the material and finish spec writes itself. A fastener with the right locking and plating outlasts a stronger fastener with the wrong surface.
Frequently Asked Questions
When does it make sense to machine fasteners instead of buying standard?
When you need a non-standard size, a special alloy, tight tolerances, custom geometry, or a quantity below a few thousand. Cold heading only wins at high volume with standard specs.
Are machined threads as strong as rolled threads?
Rolled threads are stronger because cold working compresses the grain. Cut threads are fine for prototypes and low loads; specify if the fastener is structural.
Can you make a custom bolt family in one order?
Yes — variants of the same family share programming and fixturing, which cuts the setup cost per variant. Tell us the full family up front.
What materials are available for custom fasteners?
Stainless 303/304/316, 4140 and other alloy steels, brass, copper alloys, titanium, and more. Material spec drives most of the price difference.
What is the minimum quantity for machined fasteners?
There is no hard minimum. A 50-piece special bolt run is routine; the per-piece price is higher because setup is spread over fewer parts.