shimstock
Stock (material) suitable for making shims; often in the form of sheets of metal, plastic, or wood of various thicknesses, ready to have pieces cut out of them as needed.
shimstock: pre-cut material for gap-filling shims
Shimstock is raw material supplied in sheets, rolls, or strips, ready to be cut into individual shims. Unlike custom-fabricated shims, shimstock comes in standard thicknesses and materials, allowing a shop floor or service technician to cut pieces on demand rather than order them in advance. It is the industrial equivalent of keeping stock plywood or sheet steel: you buy it in bulk and machine or shear what you need.
The most common shimstock materials are cold-rolled steel (for load-bearing applications), aluminum (where weight matters), and phenolic or fiberglass-reinforced plastic (for electrical isolation or corrosion resistance). Thicknesses typically range from 0.003 inches (0.076 mm) up to 0.125 inches (3.175 mm), sold in increments of 0.001 to 0.010 inches depending on the grade. Rolls are usually 24 to 48 inches wide and wound on cores for easy dispensing; sheets come in standard sizes such as 24 by 36 inches.
A technician or machinist cuts shimstock to fit a specific gap using hand shears, a bandsaw, or a punch press, depending on the material hardness and required edge quality. Speed and simplicity matter: rather than wait for a custom shim, you cut one from stock in minutes. This is especially valuable in field assembly and maintenance, where unexpected gaps emerge during installation or wear reveals clearance problems.
Tolerances and selection
Shimstock thickness is not held to tight tolerances; typical variation is plus or minus 0.002 to 0.005 inches within a single roll or sheet. If a job requires thickness accuracy better than that, individual shims are ordered from a shim supplier. For stacking multiple layers to reach a target dimension, the cumulative tolerance must account for the variation in each layer. The material's hardness, yield strength, and surface finish affect how well it distributes load and resists creep under sustained pressure.
The name reflects its industrial function: stock kept on hand for making shims. It is distinguished from a finished shim by its raw form and from general-purpose sheet stock by its availability in the thin gauges and material choices that shimming demands. Purchasing shimstock in bulk reduces cost per piece compared to ordering custom shims, making it the standard choice for manufacturing facilities and service depots that handle alignment, leveling, and gap correction regularly.