Shaft Clamp With Keyway vs Without Keyway

The standard EP-SCS shaft clamp is plain-bore, while keyway K dimensions are listed for most models from 10 mm bore upward. A keyway should be requested because the machine interface requires it, not because a keyed collar is automatically “better” than a plain one.

The correct choice depends on what the collar is expected to do and how the shaft itself is designed. A collar used only as an adjustable axial stop may not need a keyway, while a keyed assembly needs the mating key and shaft geometry to be defined together.

Plain-Bore Collar

A plain-bore collar uses the split clamp to grip around the shaft and can serve as a stop or locator when the machine design supports that role. The configuration is simple and avoids introducing a keyed feature that the shaft may not need.

For setup references and adjustable stops, the ability to loosen and reposition the collar can be more important than adding a keyway. The buyer should still confirm bore fit, envelope and screw access.

Keyed Collar

A keyed request adds an interface feature that must relate to the mating shaft and key. The K dimension shown in the EP-SCS chart is a collar-side reference, but it does not by itself define key width, depth, tolerance or the complete shaft-side geometry.

Send a shaft drawing or the relevant key/keyway dimensions with the RFQ. That prevents the collar from being quoted around an incomplete interface description.

Which EP-SCS Models List K?

When a Keyway May Be Unnecessary

If the collar is only establishing an axial reference and the machine does not require a keyed relationship, adding a keyway can introduce avoidable complexity. The plain-bore configuration keeps the interface focused on shaft diameter and clamping position.

Do not use a keyway request as a substitute for explaining the actual duty. If torque transmission or another functional responsibility is involved, describe that system requirement explicitly.

When to Send a Drawing

Send a drawing whenever the keyway must line up with an existing shaft feature, when the collar is part of a retrofit, or when the surrounding space is tight. Include the measured shaft, preferred EP-SCS model, quantity and the collar’s intended role in the assembly.

Ordering Checklist

• EP-SCS model or required bore.
• Shaft diameter/tolerance.
• Key width and shaft-side keyway geometry when applicable.
• Quantity and application.
• Maximum OD/width if the machine envelope is restricted.