JLCMC Blog

Selection Principles

2-Bolt vs. 4-Bolt Flange Bearing Units: Selection Differences That Matter

Key Takeaways Housing geometry and space: A two-bolt flange bearing unit normally uses an oval or diamond-shaped housing, making it ideal when the mounting face is narrow or access is limited. Bolt count vs. capacity: A four-bolt flange bearing unit normally uses a square housing suited for wider interfaces, but bolt count alone does not establish the unit's load capacity. Machine interface priority: Choose the housing pattern based on the machine interface first. Then verify shaft size, published loa......

Oct 08, 2026

Fasteners & Hardware

Threaded Standoff vs Spacer: What Is the Difference?

Key Takeaways Threaded standoffs provide both spacing and threaded attachment points, making them ideal for modular assemblies and PCBs. Spacers are unthreaded sleeves that work with through-bolts to maintain gaps in clamped assemblies, offering a simpler and more economical solution. The right choice depends on the load path, assembly sequence, material, and service environment - not just appearance or catalog naming. A threaded standoff and a spacer can look almost identical on a workbench. Both cre......

Sep 30, 2026

Fasteners & Hardware

How to Choose a Threaded Standoff for PCB and Mechatronic Assemblies

Key Takeaways Select the right configuration: Choose male-female, female-female, or male-male thread configurations based on the two mating interfaces and the intended assembly sequence. Treat height as a tolerance stack: Standoff body length must satisfy clearance, electrical, thermal, and connector requirements across the full tolerance range, not just the nominal dimension. Verify thread engagement: Check male thread length against tapped-hole depth and upper screw length against usable female thre......

Sep 30, 2026

Power Transmission

How to Choose a Shaft Coupling: Rigid vs Beam vs Jaw vs Universal Joint

Key Takeaways Shaft Coupling Basics: A shaft coupling transmits torque between driving and driven shafts while accommodating misalignment, vibration, and thermal expansion. The core choice is between rigid (zero flexibility, maximum torque density) and flexible (misalignment-tolerant, vibration-damping) designs. Four Primary Types: Rigid couplings offer zero backlash but require perfect alignment; helical beam couplings provide precision motion for light-duty drives; jaw couplings deliver versatile vi......

Sep 30, 2026

Bearings & Housings

Sealed vs Shielded Bearings: What 2RS and ZZ Mean

Key Takeaways Suffix definitions: ZZ commonly means metal shields on both sides. 2RS commonly means seals on both sides, often contact seals. Always confirm the exact definition in the manufacturer's catalog. Design difference: A metal shield typically uses a non-contact clearance or labyrinth path at the inner ring, while a contact seal uses a sealing lip that contacts the mating surface, directly affecting contaminant exclusion and friction. "Sealed" variations: "Sealed" does not always mean "contac......

Sep 30, 2026

Fasteners & Hardware

Threaded Standoff Guide: Types, Sizes, Materials and Applications

Key Takeaways Thread configuration first: Choose female-female, male-female or male-male based on how both sides of the assembly attach — thread config is the most practical way to classify a threaded standoff. Body length is the critical dimension: Standoff length refers to the distance between supporting faces, not total physical length. Reading the wrong length causes incorrect mounting height or screw bottoming. Material affects more than strength: Brass, stainless steel, carbon steel, aluminum an......

Sep 29, 2026