The SG15 2RS Gothic Arch Groove Ball Bearing 5x17x8mm is a high-precision, heavy-duty linear guide track roller bearing engineered for CNC machinery, linear slide rails, camera sliders, 3D printers, and automated textile equipment. Featuring a precision-ground 90° to 120° "Gothic Arch" V-groove machined directly into its outer raceway, it provides dual-point contact on cylindrical rods and linear tracks, maximizing lateral rigidity, centering stability, and load distribution. Equipped with dual synthetic rubber contact seals (2RS) and pre-packed with long-life lithium grease, the bearing resists dust, flying swarf, and ambient moisture while providing ultra-smooth, low-friction linear movement.

Specifications

• Bearing Model / Part Number: VSG15-2RS (Also designated as SG15 / SG15-2RS)
• Bearing Type: Gothic Arch Groove Linear Guide Track Roller / Ball Bearing
• Outer Ring Profile: Precision-Machined Gothic Arch V-Groove (Dual-point contact contour)
• Groove Angle: Approx. 90° to 120° included angle
• Groove Depth: Approx. 1.25 mm to 1.5 mm
• Dimensional Standards:
  • Inner Bore Diameter (d): 5.0 mm (±0.008 mm precision ground tolerance)
  • Outer Diameter (D): 17.0 mm (±0.010 mm measured at outer rim crest)
  • Overall Width / Thickness (B): 8.0 mm (±0.012 mm)
  • Groove Center Distance: Symmetrically centered along the 8.0 mm ring width
• Mating Rail / Guide Diameter: Optimized for Ø 4.0 mm to 6.0 mm hardened cylindrical steel shafts or V-edge guide rails
• Material: High-Carbon Chromium Bearing Steel (GCr15 / AISI 52100)
• Hardness Rating: HRC 58 to 62 (Through-hardened raceways and rollers)
• Precision Grade: ABEC-1 to ABEC-3 (ISO Class Normal / P6)
• Sealing Construction: 2RS — Dual-Sided Removable NBR (Nitrile Butadiene Rubber) Contact Lip Seals
• Lubrication: Factory pre-lubricated with high-grade multi-purpose lithium-based grease
• Dynamic Load Rating (Cr): Approx. 1.25 kN to 1.40 kN
• Static Load Rating (C0r): Approx. 0.58 kN to 0.65 kN
• Operating Temperature Envelope: -20°C to +110°C
• Net Weight: Approx. 8.2 g to 9.0 g per piece

Features

• Gothic Arch Two-Point Contact: Unlike simple circular U-groove bearings that touch a rail at a single base point, the Gothic arch profile engages the cylindrical guide rod at two distinct angled contact points, completely eliminating axial play and track wobbling.
• High-Strength GCr15 Chrome Steel: Through-hardened bearing steel core and precision-honed raceways resist brinelling, surface micro-fatigue, and track groove pitting under continuous rolling loads.
• Dual 2RS Contact Lip Seals: Nitrile rubber seals actively scrape debris and protect the internal rolling elements from airborne wood dust, fiberglass particulates, metal chips, and moisture while preventing grease washout.
• Ultra-Smooth, Low-Resonance Rolling: Precision-graded chrome steel balls and balanced internal clearance provide silent, low-vibration linear motion essential for optical camera sliders and high-resolution 3D printing axes.
• Integrated Inner-Ring Extension: Precision-ground inner ring shoulders allow direct mounting against brackets and plates without the outer rotating ring rubbing against the mounting face.

Common Applications

• CNC Routers & Laser Engravers: Linear carriage guide rollers riding along hardened chrome-plated round rods (Ø 4mm to 6mm) or ground angle rails.
• Motorized Camera Sliders: Ultra-quiet, zero-backlash linear dolly guide wheels for professional cinematography and macro photography slider rigs.
• 3D Printers & Rapid Prototyping Systems: Stiff, lightweight carriage wheel assemblies for core-XY gantries, delta towers, and custom print heads.
• Textile & Embroidery Automation: High-speed reciprocating yarn guide carriers and motorized thread feeder carriages.
• Robotics & Pick-and-Place Gantry Systems: Linear motion guide wheels for pneumatic slide tables, automated sorting lines, and motorized inspection carriages.

Usage Tips

• Mating Shaft Selection & Hardness (CRITICAL):
  • Always run SG15 bearings on case-hardened, precision-ground linear shafts (e.g., WCS / SUJ2 / GCr15 with surface hardness ≥ HRC 58–60).
  • Avoid running these hardened steel bearings on soft stainless steel (304), brass, or unhardened mild steel rods. Under pressure, the bearing's hard Gothic arch edges will rapidly gall and carve deep grooves into soft guide rods.
• Preload & Eccentric Spacer Adjustment:
  • When designing a 3-wheel or 4-wheel carriage, mount at least one or two bearings using an eccentric hex spacer (bushing) on an M5 bolt.
  • Rotate the eccentric spacer using an open-end wrench to fine-tune the contact pressure against the guide rod: tighten until there is zero detectable play, but avoid over-tightening to the point where the carriage binds or feels notched.
• Fastener Clearance & Mounting:
  • Use high-tensile M5 socket head cap screws (Grade 10.9 or 12.9) to mount through the 5mm inner bore.
  • Ensure the washer or standoff placed against the inner ring has an outer diameter less than 7.5 mm to avoid making contact with the rubber seal or the spinning outer ring.
• Lubrication & Track Maintenance:
  • The internal balls and raceways are permanently lubricated inside the 2RS seals; do not attempt to wash them with solvents unless actively repacking with high-speed grease.
  • Lightly wipe the outer cylindrical guide rod periodically with a clean rag moistened with thin machine oil (ISO VG 32 or 46) to inhibit rail corrosion and reduce rolling contact friction.
• Contamination Protection: In woodworking CNC environments producing airborne sawdust, mount small felt scrapers or brush wipers in front of the bearings along the carriage plate to sweep debris off the rod ahead of the rolling contact zone.