What Is Shim Stock?

Shim stock is thin stock material that act as shims for various applications. Think of shims as spacers. Engineers use shim stock to verify gaps and distances, where a normal ruler or caliper would not be able to. Shim stock is also used for support, adjustment, and leveling. Example applications include setting the position of parts in tight fit applications such as Aircraft and Spacecraft.

February 29, 2024 by Kazu Fujimoto

Why Do We Need Shim Stock?

There may be times where we need to ensure the correct gap for our applications. Tools such as rulers and calipers will not be precise enough when we are dealing with gaps under 0.010″. It is handy to have shim stock laying around to use to set our gaps and distances in engineering.

How Do We Use Shim Stock?

Gaps

Take a piece of shim stock, and cut it down to size. Insert the shim stock as required to fill the gap. If you are an engineer, some of the systems that are designed will require gaps. These gaps are designed due to ensure clearances or adequate load distribution.

Leveling & Adjustment

In theory, many of the parts and appliances we deal with are perfectly straight and flat. In reality, this is not the case. Parts are produced with tolerances, and with tolerances come error. Shim stock is a great way to account for the error. Off-setting a few sheets of shim stock will save you some headache from issues such as when parts are not produced perfectly.

With variances in geometry from tolerances, we might end up with something that will be lop-sided. Think of a teeter totter as a very simple example. For a quality product, we want to ensure that where the teeter totter rests on the ground will stay flat. If a supplier makes a mistake on the flatness on the rest, shims can be used to level out the teeter totter. For this specific examples, solid shims can be used to get the desired setting, then liquid shims can be used to fill up the rest.

Real Life Applications

Furniture

The most relatable example for shim stock is furniture. Often times, we all experience moments where we buy furniture such as desks, tables, or dressers and put them together only to find that something is off. Either a table leg length is too short or long or the manufacturer drilled holes in the wrong place. Shim stock is a great way to offset incorrect distances.

Aerospace

In Aerospace Engineering, there are many complicated mechanical systems that are engineered with very little clearance. Tools such as feeler gauges are used to set distances. Feeler gauges are typically made of metal and in some cases, we need something more flexible such as paper. Aerospace deals with tight fitting clearances so flexible shims will be necessary.

Automotive

In an Automotive setting, we don’t want leaks! At some point in your life, you have likely Oil, transmission fluid, coolant are all fluids in your car that give us problems when they start leaking. Use shims to verify that all of your caps and plugs are sealed tight. This will act as an added “check” to ensure

Oil and Gas

In oil and gas, we deal with many piping systems, nozzles, elbows, and valves. A common challenge in oil and gas is manufacturing components that can withstand high operating loads, while maintaining their geometry. It is near impossible to machine parts perfectly to their specified tolerances, and in an industry like oil and gas, there are a lot of non-conformances (mistakes) on parts that come in. Examples being the nozzle centerline being too long or too short, holes being in the wrong place, or parts being out of round or not flat.

Best Shim Stock Products To Use

Precision Brand 260 Half Hard Brass – 6″ Wide x 18″ Long x 0.025″ Thick

If your mechanical system goes through a lot of vibrations, use something sturdy such as brass shims to fill up the gap. You will need something stronger than a regular pair of scissor to cut these, so make sure you have something on hand.

TTC PSS5A 14 Piece Plastic Shim Stock Assortment-5″ x 20″ Color Coded Sheets

If you’re unsure of what size to get, then you should get the entire range. The assortment contains shims ranging from thicknesses of 0.0005″ to 0.030″ to cover your specific manufacturing application. The shims are also color coded so it will get rid of any confusion regarding thicknesses.

McMaster Carr – Shim Stock

For the application in which you know the exact dimensions, go to McMaster Carr and pick out which exact shim stock you need. McMaster Carr has everything you need regarding mechanical applications such as fasteners, tools, clamps, hinges, and etc. Shim stock is no exception regarding McMaster Carr.