0.01mm Concentricity Diamond Knurled Adjusting Wheel in 303 Stainless Steel for Instrument Panels

This is the adjustment wheel on the front of an instrument or machine control panel. An operator grips the diamond knurl and turns it; the wheel drives a shaft through its bore or pushes an index pin through a set screw hole. Three characteristics make it feel right in the hand and work reliably on the panel.

The knurl must be a clean diamond pattern without double-tracking, because a doubled knurl looks like a defect and feels rough. The crests must be deburred, because a burr on a knurl is a cut waiting to happen on an assembly line. And the knurl must run concentric to the bore within 0.01 mm, because a wheel that is 0.03 mm eccentric visibly wobbles against a panel scale.

1. Drawing and knurl review. We check knurl pitch, wheel diameter, face width, bore fit, set screw position and the index line requirement, then quote within one working day.
2. Material verification. 303 stainless bar is checked against the mill certificate. 303 is the default because its sulfur content gives clean knurl crests; 304 or 316L are used where corrosion resistance matters more than formability.
3. Blank preparation. The bar is sawn, faced and turned to the knurl blank diameter, which is smaller than the finished knurl OD by roughly 0.3 to 0.4 mm because knurling displaces material outward rather than cutting it.
4. Knurling. The diamond pattern is formed with a straddle knurling tool at a feed matched to the knurl pitch, so each revolution indexes into the previous one. A mismatched feed is what produces double-tracking and a smeared pattern.
5. Facing and boring after knurling. Faces and bore are machined after the knurl, because knurling pressure distorts a thin wheel. Finishing the bore last also removes any ovality the knurl induced.
6. Chamfers and set screw hole. Faces are chamfered, and the radial set screw hole is drilled and tapped with live tooling in the same clamping so it is clocked to the index line.
7. Crest deburr and passivation. Knurl crests are brushed to remove the fine fin left by the forming tool, then the part is passivated and dried.
8. Inspection. Knurl pitch and pattern checked optically, bore gauged for size and roundness, knurl OD runout measured against the bore on a CMM, then a first article report with the batch.

Knurling is a forming operation, not a cutting one. The tool presses the blank and lifts material into the tooth form, so the finished outside diameter is larger than the blank. If the blank is turned to the finished size, the tool has nowhere to displace material, the teeth overwrite each other and the result is the double-tracked surface that customers reject on sight.

The practical rule is to leave 0.15 to 0.2 mm of radial material for the knurl to raise, and to match the feed to the pitch so each revolution seats into the previous tooth. On a thin wheel, the same pressure can also close the bore, which is why the bore is finished after knurling and not before. Both of those decisions are made at the drawing stage, not at the machine.

Wheel diameter, knurl pitch and type, face width, bore fit, set screw position, index marking and material grade are all built to your drawing. One piece is a normal order with no tooling charge and no setup fee, and the prototype follows the same knurl and inspection plan as a batch. If the wheel is too thin for the knurl pressure you specified, our engineer flags it before the bar is cut.

• NDA before files. Mutual non-disclosure is signed before drawings or samples are released, covering geometry, volume, end use and customer identity.
• No public reference. Confidential wheels never appear as samples, catalogue items, website photos or trade fair parts.
• Separated cell. Sensitive work runs with named operators and project-coded programmes.
• Partner control. Passivation suppliers receive process specifications only.

Dongguan Changxinda Precision Technology Co., Ltd has machined custom parts since 2008. The plant runs turn-mill centres, CNC lathes with live tooling, and four-axis and five-axis machining centres. It employs 90 to 102 people under ISO 9001:2015, serves more than 200 customers, exports 50 to 60 percent of output, and records annual sales of USD 10 to 20 million.

• Dates in writing. Prototypes 3 to 6 working days; batch orders 10 to 16 working days after drawing approval.
• Repeat orders skip setup. Programmes, knurl tools and gauges stay on file.
• Bar stock on hand. Common 303 and 304 diameters are stocked.
• Early notice. If material, knurl tooling or passivation threatens the date, you are told before the date is missed.
• Dispatch evidence. Photos, inspection report and packing list before shipment.

• Consumer Electronics: phone, tablet and laptop housings, heat sinks, camera brackets, VR/AR headset structural parts, smart wearable shells
• Automation & Industrial Equipment: automation fixtures, jigs, module frames, transmission sliders, motor mounts, sensor housings, conveyor line parts
• Semiconductor & Vacuum Equipment: vacuum chambers, vacuum fittings, precision equipment bases, thermal isolation and insulation parts, inspection fixtures
• Medical Devices: surgical instrument bases, diagnostic instrument housings, endoscope components, aesthetic device structural parts (medical-grade aluminum and stainless steel)
• Automotive: new energy motor housings, battery end plates, sensor brackets, lamp structural parts, tuning parts, hydraulic valve blocks
• Aerospace & UAV: aircraft structural parts, drone frames, landing gear parts, avionics instrument housings (lightweight precision parts)
• Optics & Photonics: optical lens barrels, lens mounts, light source heat sinks, camera module brackets, inspection optical benches
• Communications: 5G heat dissipation cavities, filter parts, signal adapter structural parts, telecom equipment housings
• Robotics: robot arm joint parts, robot bases, reducer housings, AGV structural parts
• Instrumentation: test equipment housings, precision gauge bases, flow meter parts, laboratory equipment accessories

Each wheel is bagged with desiccant, seated in a foam tray so knurl crests cannot rub against each other, and packed in a five-layer export carton marked with part number, quantity and batch code. Sea freight ships on fumigation-free plywood pallets; neutral cartons are available.