6 Best Brass Shims for Leveling Machinery Worth Using

When machinery isn’t level, vibration kills precision and shortens the lifespan of critical components. Getting that foundation dialled in requires materials that won’t compress or corrode under heavy loads. Brass shims are the gold standard for this task because they offer the perfect balance of malleability and structural integrity. Selecting the right shim set saves hours of frustration during installation and ensures the long-term stability of the equipment.

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Precision Brand Slotted Shim Kit: Best Overall

Precision Brand kits are the industry standard for a reason. These slotted shims are pre-cut to fit standard bolt diameters, making them ideal for rapid alignment tasks where downtime must be kept to a minimum.

The uniformity of these shims is what sets them apart. When aligning a motor to a pump or a high-speed fan, any variation in thickness across a stack leads to binding and uneven load distribution. These are manufactured with strict tolerances that prevent that kind of mechanical stress.

For the contractor who keeps a variety of machines running, this kit is the baseline for professional alignment. It eliminates the need to cut and punch stock on the fly, ensuring that the bolt hole fits correctly every time.

McMaster-Carr Brass Shim Stock: Top Pro Choice

McMaster-Carr is where professionals go when they need absolute certainty in material quality. Their brass shim stock is available in a vast range of thicknesses and dimensions, providing the precision needed for unique machine footprints.

This is the preferred choice for legacy equipment or custom-built setups where standard slotted shim dimensions don’t align with unconventional mounting bolts. The material is consistent, burr-free, and holds its shape perfectly when torqued down.

Choose this when the scope of work involves high-stakes machinery where the margin for error is measured in thousandths of an inch. It requires a bit more labor to cut to size, but the trade-off is a custom, exact-fit shim.

Martin Slotted Slotted Shim Pack: Heavy-Duty Champion

Martin provides a more rugged take on the slotted shim. These are designed to withstand significant compression without deforming, making them suitable for heavy-duty industrial machinery.

The thickness range is particularly useful for heavy-base motors that require significant height adjustments to achieve coupling alignment. Unlike thinner shims that might ripple or pinch when tightened, these maintain their structural profile.

If the job involves large-frame motors or heavy vibrating equipment on a concrete base, prioritize this brand. Their durability ensures that once the alignment is set, the machine stays locked in place for the long haul.

AccuTrex Brass Shim Roll: For Custom Sizing

When the job requires shimming an entire baseplate or creating a custom gasket-style shim, a roll is the only practical solution. AccuTrex supplies high-quality brass rolls that allow for precise, continuous coverage.

Using a roll allows for the creation of oversized shims that provide better surface contact area under a machine foot. This is a critical consideration for distributing the load effectively across a larger mounting surface, reducing the risk of point loading.

Buy this when standard pre-cut shims are either too small or the wrong shape for the project. It is the most economical choice for contractors who perform regular maintenance on a fleet of varied equipment.

Dayton Brass Shim Assortment: Great Value Pick

Dayton offers a comprehensive assortment that serves as an excellent starting point for any shop. These kits cover a broad spectrum of sizes, providing enough variety to handle most common alignment tasks encountered in a typical week.

The quality is solid enough for general-purpose applications where extreme high-precision aerospace tolerances aren’t required. It is an affordable way to ensure that any necessary height adjustment can be addressed immediately without waiting for specific parts to arrive.

This is the “truck kit”—keep it on hand for those moments when a machine needs a quick adjustment on-site. It balances cost and utility, making it a staple for the well-prepared contractor.

Trinity Brand Shim Kit: Solid Budget Option

Trinity delivers a no-frills shim kit that gets the job done without inflating the overhead. These are perfectly functional for smaller jobs, light machinery, or hobbyist projects where standard alignment is sufficient.

While they may not possess the same level of finish as premium brands, the brass material is still corrosion-resistant and reliable for standard shimming duties. They serve well for those who need a base kit but do not want to invest in high-end industrial inventory.

Use this for general shop repairs or initial setup where you plan to upgrade to more specific thicknesses once the machine is permanently leveled. It provides the necessary function at a lower entry price point.

Why Brass Shims Beat Steel for Most Machines

Brass is softer than steel, which allows it to conform slightly to uneven surfaces, creating a better seal and contact area. This reduces the likelihood of the machine rocking or losing its alignment as bolts are tightened.

Furthermore, brass is highly resistant to corrosion in industrial environments where lubricants, coolants, or moisture are present. Steel shims can rust over time, which not only degrades the shim but can cause the bolt hole to seize, making future maintenance a nightmare.

While steel has a higher load-bearing capacity, brass is sufficient for the vast majority of machinery alignment tasks. The ability to prevent rust and conform to the substrate makes it the superior choice for long-term installation.

Slotted vs. Solid Shims: Which Do You Need?

Slotted shims are the go-to for alignment jobs because they can be slipped over a bolt without fully removing the fastener. This saves significant time and effort, especially when working on heavy motors that are difficult to lift.

Solid shims are preferred for permanent, final installations where the machine will not need adjustment for a long time. Because they surround the bolt entirely, they offer better vibration resistance and total surface support for the machine foot.

Assess the machine’s maintenance schedule before choosing. If it is a piece of equipment that will require seasonal alignment checks, stick with slotted shims to minimize maintenance labor.

How to Properly Stack Shims to Avoid Soft Foot

“Soft foot” occurs when a machine base is not uniformly supported, leading to frame distortion when the mounting bolts are tightened. To avoid this, never stack more than three or four shims under a single foot.

Use the thickest shims at the bottom of the stack and the thinnest at the top. This layering technique provides a stable, pyramid-like structure that is less likely to slip or “walk” under the force of vibration.

Always ensure the total surface area of the shim is larger than the foot of the machine being supported. If the shim is smaller than the foot, the baseplate will eventually deform or flex, causing the equipment to fall out of alignment.

Measuring and Installing Shims for Alignment

Accurate shimming starts with a clean surface. Scrape away any paint, rust, or debris from the machine foot and the baseplate, as even a small bump can throw off a precision measurement.

Use a high-quality feeler gauge to measure the gap under each foot before introducing any shims. Once the shim is in place, re-check the gap; if the bolt tension causes the gap to close further, the shim is likely compressing and needs to be replaced with a harder material.

Finally, always torque mounting bolts in a cross pattern to ensure even pressure across all feet. A properly leveled machine should show no change in alignment when the final torque is applied.

Choosing the right brass shims is a fundamental step in ensuring your machinery runs smoothly and stays productive for years to come. By selecting the correct material and following proper installation techniques, you eliminate the vibration and mechanical strain that lead to premature equipment failure. Rely on these quality options to keep your installations square, level, and built to last.