Washers, bearings and stop pins: role and use in cutlery

In the manufacture of a folding knife, the visible parts - handle, blade, guard - catch the eye. But it's often the quality of the internal components that determines longevity and comfort of use. Washers absorb friction between metal surfaces and protect handles from mechanical wear. Bearings transform laborious opening into a smooth, precise movement. Stop pins ensure that the blade stops in the right place when opening, protecting both the mechanism and the user.

Properties and technical features

These components are machined to tight tolerances to ensure a precise fit in the handle housings.

Washers

Available in stainless steel, brass, bronze or copper, washers for folding knives slide between the blade and handle to reduce lateral play and direct friction. Their thickness, generally between 0.3 and 1 mm, determines the final play of the mechanism. A washer that is too thick creates slack; a washer that is too thin no longer plays its role as a shock absorber. The choice of material also influences the visual appearance if the washer is visible in the open position.

Bearings

Bearings - ball or needle bearings - replace or complement washers in top-of-the-range knives. They enable one-handed opening with a fluidity that washers alone cannot match. Thinner needle bearings are ideal for narrow-handled designs. Ball bearings offer better radial load distribution. In both cases, the quality of the steel and the precision of the machining are decisive.

Stop pins

The stop pin is the mechanical stop that stops the blade in the open position. Without it, the blade can overshoot the balance point and force the spring or pivot. Available in stainless steel, titanium or brass, stop pins take the form of cylindrical pins to be fitted into a hole drilled in the handle. Their diameter and length must correspond exactly to the dimensions of your design.

How to choose washers, bearings and stop pins?

The right choice depends above all on the type of knife you're making and the level of finish you're aiming for.

• Simple folding knife or slip joint: brass or stainless steel washers are sufficient in most cases. They are easy to adjust and replace.
• Liner lock or frame lock: bearings provide superior operating comfort and are justified on knives intended for regular use or for sale.
• Automatic or assisted deployment knives: high-precision ball bearings and titanium stop pins are preferred to absorb dynamic opening stresses.
• Aesthetic criteria: if the washer is visible in the open position, gilded brass or copper offer a much-appreciated handcrafted look. Polished stainless steel is ideal for contemporary designs.

If in doubt about dimensions - inside diameter, outside diameter, thickness - please contact us with the dimensions of your pivot before ordering.

Mercorne and cutlery hardware: a rigorous selection process

For over 34 years, Mercorne has offered a selection of assembly components tested and validated by professional cutlers. Each reference of washer, bearing and stop pin available in this catalog has been evaluated in our workshop before being offered for sale. Our bearings are delivered in protective packaging to avoid contamination or deformation during transport. Free delivery on orders over €90, shipment within 24 hours, returns accepted within 15 days.

Frequently asked questions about washers, bearings and stop pins

What's the difference between a washer and a bearing for a folding knife?

The washer is a simple flat piece that reduces friction and play between blade and handle. Bearings, on the other hand, contain rolling elements (balls or needles) that reduce friction even further, enabling smoother, lighter opening. Bearings are more efficient, but also more expensive and more demanding to install.

How to choose the right washer thickness?

The ideal washer thickness depends on the desired clearance between blade and handle. A zero or near-zero clearance gives a tight, precise mechanism; a greater clearance makes for a smoother opening, but can create side-to-side wobble. Most cutlers work with washers of between 0.5 and 0.8 mm, then refine to size.

Are stop pins interchangeable between knife models?

No. The diameter and length of the stop pin must correspond exactly to the dimensions of your design. A stop pin that's too short won't perform its function as a stop; too long and the blade may not close properly. Always measure the housing before ordering.

Can I use bearings on a liner lock knife I've already started?

Yes, provided the handle is designed to accept bearings. If the pivot housing has been sized for washers, it will generally be necessary to mill a deeper or wider housing to accommodate the bearings. This is a common operation, but requires precise tools and, if possible, a drilling template.

Which material to choose for washers: brass, stainless steel or bronze?

Stainless steel offers the best resistance to corrosion, and is suitable for knives intended for wet or marine use. Brass is softer, providing better protection for surfaces in contact - ideal if the blade or handle is made of a softer alloy. Bronze is intermediate, appreciated for its golden hue and good wear resistance.