Jack Bolt - Design for Disassembly

Jack bolt design for removing interference-fit parts (positioning, quantity, thread protection)

While designers visualize assembled parts, experienced engineers first consider 'how will this come apart?' Without thoughtful disassembly features, maintenance teams resort to hammers and chisels, risking part damage. The solution: Jack Bolts.

1. What is a Jack Bolt?

Not for fastening, but for pushing parts apart. Threaded holes positioned to accept bolts that, when tightened, push against a surface to gradually separate tightly fitted components.

2. When to Use Jack Bolts

Interference Fits: Tightly fitted housings and covers
Heavy Flanges: Large parts seized by weight and friction
Corrosion-Prone Areas: Outdoor equipment where moisture or heat causes seizing

3. Design Guidelines

Positioning: For circular parts, use 3 holes at 120° intervals for stability. Minimum 2 holes (180° apart) to prevent tilting during extraction.
Surface Protection: Protect soft materials (aluminum) at contact points with hardened washers or flat-ground bolt tips to distribute pressure.
Thread Size: Match assembly bolt size so workers can use the same wrench for both assembly and disassembly.

💡 Expert Advice
"Design completion is measured by maintainability, not just assembly. Adding jack bolt holes takes 10 seconds but saves maintenance teams 5+ hours and prevents costly part damage. Want field techs to thank you? Never forget the jack bolts."

Jack Bolts — US Industry Common Use

Jack bolts (machine leveling bolts, foundation alignment bolts) per ASME B18.6.7M and SAE J492 are common in US industrial machinery installation. Cast-iron-bottom jack bolts with hardened steel plates distribute load on concrete foundations. Vibration-isolation jack bolts (Vibrostop, Tech Products) replace plain jack bolts in machine tool installations to reduce floor-transmitted vibration.

Concrete Anchor Combinations

Most US machine installations combine drop-in concrete anchors (Hilti HKD, Simpson Strong-Tie) with jack bolt + leveling plate stack. The drop-in anchor takes uplift; the jack bolt sets elevation. ACI 318 governs concrete anchor design. For temporary installations or rental equipment, leveling pads (Vlier, J.W. Winco) avoid concrete drilling — limited uplift capacity but quick setup.