6 Best Steel Shims For Sensor Leveling Pros Use

Precision leveling is the silent difference between a machine that runs for a decade and one that vibrates itself into an early grave. When sensors are misaligned due to an uneven foundation or shifting support, the data integrity drops and maintenance costs spike. Using high-quality steel shims ensures a rock-solid base that won’t compress or deform under heavy load. A professional job always starts with a perfectly level plane.

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Precision Brand Slotted Shims: Best Overall Value

Precision Brand slotted shims serve as the industry standard for general mechanical alignment. The U-shaped design allows for quick installation around existing mounting bolts without requiring total fastener removal.

These shims are manufactured to tight tolerances, meaning a 0.020-inch shim actually measures 0.020 inches. On a job site where time equals money, avoiding the headache of mismatched thickness saves significant labor hours.

Reliability remains their strongest suit for standard motor and sensor mounting tasks. While they aren’t the cheapest option on the market, the consistency in thickness prevents the cumulative error that often occurs with cheaper, stamped alternatives.

Artus Steel Shim in a Can: For Custom Fit Jobs

The Artus shim kit provides a selection of various thicknesses packaged in a convenient, durable container. This setup proves ideal for field technicians who frequently encounter varying gaps that cannot be predicted before arriving on site.

Having an organized kit eliminates the habit of grabbing whatever scrap metal is nearby to bridge a gap. Using improper materials, like thin aluminum flashing or wood, creates a “soft foot” that will inevitably lead to sensor drift or bracket failure.

These kits keep the workspace orderly and ensure that every technician has the right tool for the job. Investing in a pre-packaged kit reduces the inventory management burden while keeping high-precision components protected from moisture and debris.

McMaster-Carr Stainless Shims: Top Corrosion Pick

Stainless steel shims are mandatory in environments exposed to moisture, chemicals, or coastal air. Standard carbon steel shims will oxidize rapidly, creating rust expansion that can actually throw off the level of a sensitive sensor.

McMaster-Carr offers a wide catalog of 300-series stainless options that resist corrosion indefinitely. In a harsh industrial plant or an exposed exterior mounting location, these shims maintain their structural integrity without fusing to the base plate.

Selecting stainless is an insurance policy against future maintenance headaches. While the upfront cost is higher, the ability to adjust or remove these shims years later without them crumbling into flakes justifies the investment.

Martin Slotted Shim Kits: The Pro’s Go-To Set

Martin shims are engineered for heavy-duty applications where precision must be maintained despite vibration and thermal expansion. Their kits feature a distinct color-coding system that allows technicians to identify thickness at a glance.

This visual shorthand is invaluable when working in tight, dark, or cramped enclosures where measuring every shim with a micrometer is impractical. The heavy-duty steel used in these sets handles high clamping forces without deforming.

For contractors handling large-scale commercial installations, these kits provide a repeatable, professional standard. Consistency in assembly creates a uniform installation process, which is essential for ensuring that every sensor in a network performs identically.

Grainger Labeled Shim Stock: For Easy ID On Site

Grainger provides shim stock that comes clearly marked with thickness identification directly on the metal. When precision is critical, losing track of which shim is 0.005 and which is 0.010 is a common source of error.

Labeled stock eliminates the guesswork and the potential for human error during the final tightening phase. Having the identification visible reduces the need to pull bolts out to verify measurements if a sensor happens to be out of spec.

Professionals prefer this for projects requiring custom-cut shapes to fit irregular sensor bases. It serves as a reliable, high-quality base material that keeps the documentation of the installation as clean as the mechanics.

All-Spec Pre-Cut Shims: For Repetitive Tasks

All-Spec specializes in standardized shapes that fit common mounting footprints found in factory automation and precision sensing. If a project involves installing fifty identical units, using pre-cut, perfectly slotted shims is the only efficient path forward.

These shims minimize waste and maximize installation speed. Because they are pre-cut, the technician avoids the sharp edges and burrs often found on custom-cut sheet metal, which can cause minor misalignment if they aren’t deburred properly.

Consistency is the ultimate goal in repetitive assemblies. Using these uniform parts ensures that the torque values remain consistent across every mounting point, preventing uneven pressure that could stress the sensor housing.

How to Correct Soft Foot With Steel Shims

“Soft foot” occurs when one of the mounting feet of a machine or sensor does not contact the foundation plane correctly. This creates a spring effect, leading to misalignment during operation and eventual bracket cracking.

Identify the gap by loosening each mounting bolt one at a time and using a feeler gauge to measure the distance between the foot and the base. Once the clearance is determined, slide the appropriate thickness of steel shim into the slot.

Never use more than three shims at a single mounting point. If more are needed, the base plate requires professional shimming or machining to create a proper contact surface.

Steel vs. Stainless vs. Brass: Pick Your Shim

The choice of material depends entirely on the operating environment and the potential for galvanic corrosion. Carbon steel is perfectly adequate for climate-controlled indoor environments where cost is a primary factor.

Stainless steel is the requirement for any environment subject to humidity, washdowns, or outdoor exposure. It prevents the seized bolts and rusted shims that complicate future adjustments.

Brass serves a niche role in applications where spark prevention is critical or where the shim needs to be softer than the mounting material to prevent surface galling. Always match the shim material to the base and the bracket to avoid electrochemical reactions.

Slotted vs. Solid Shims: When to Use Each Type

Slotted shims are the professional choice for 90% of sensor leveling tasks. They allow for installation and adjustment without the need to fully remove the mounting bolt, which saves significant time in tight quarters.

Solid shims are reserved for permanent installations where the bolt is installed after the shim is placed, or where vibration is so severe that any opening in the shim is considered a structural weakness. Use solid shims when you want to minimize the number of points of failure in the stack.

Always prioritize the slotted design for ease of maintenance unless the spec sheet explicitly demands a full-contact solid ring or square. The trade-off is slightly less contact surface, but the gains in maintenance efficiency are massive.

Reading Shim Markings: Thickness Explained

Precision shims are manufactured to strict engineering standards, often marked in thousandths of an inch. Understanding that a 0.005-inch shim is effectively the thickness of a thick sheet of paper is essential for fine-tuning.

Most professional kits use color-coding to denote thickness, which acts as a quick-reference guide. If the markings are worn off, use a high-quality micrometer to verify the thickness before installing.

Never stack too many thin shims, as this creates a “sandwich” effect that can lose rigidity over time. Aim for the fewest number of shims possible to reach the desired height, as this creates the most stable foundation for your sensor.

Choosing the right shim is about more than just filling a gap; it is about establishing a permanent, level foundation that allows sensors to function without internal strain. By prioritizing material quality and correct thickness, any installation will gain years of reliable service. When in doubt, lean toward stainless steel and pre-cut kits to ensure speed and longevity on every job.