Caldwell Model SCSM Locking Screw Plate Clamp

Locking Screw Plate Clamp – 1-Ton Capacity for Single Plate Turning and Bench Work

The Renfroe Model SCSM is a locking screw-type lifting clamp designed to handle single steel plates through a full 180-degree rotation arc — from horizontal to vertical to horizontal. With a rated capacity of 1 ton (2,000 lbs) and a lightweight 12-lb body, it is built primarily for bench work applications where controlled plate turning is required. It accommodates plate thicknesses up to 0.75 inches and attaches securely via a screw-handle mechanism. This clamp is manufactured by J.C. Renfroe & Sons, Inc., an internationally recognized leader in lifting clamp design and production.

Unlike cam-style or gravity-actuated clamps, the SCSM uses a positive-locking screw handle that must be manually tightened before lifting, giving operators direct control over clamping force during bench-level turning operations. This makes it especially well-suited for lower-volume, precision-oriented work where deliberate attachment and removal are priorities over rapid cycling.

Key Features & Benefits

180-Degree Rotation Arc

The SCSM is specifically engineered to turn a single plate from horizontal to vertical to horizontal through a full 180-degree arc. This capability is essential for fabrication and assembly bench work where plate orientation must be changed without repositioning the entire workpiece.

Positive-Locking Screw Handle

The screw handle requires deliberate manual tightening to secure the clamp before a lift, ensuring the clamp cannot engage or disengage unintentionally. This positive-lock design also allows easy removal of the clamp once the plate has been set, reducing handling time at the bench.

Lightweight Construction

At just 12 lbs, the SCSM is a lightweight tool that minimizes operator fatigue during repeated attach-and-release cycles typical of bench work. Its compact dimensions — with a clamp height of 6.62 inches and overall height of 9.19 inches — make it easy to maneuver in tight work areas.

Integrated Swivel Shackle

The clamp includes a swivel shackle with an inner width of 1.69 inches and shackle thickness of 0.62 inches, providing a secure connection point for rigging. The swivel allows the load to hang plumb during the turning operation without binding the rigging connection.

Common Applications

Single Plate Turning on the Bench

The SCSM is primarily designed for bench-level plate turning, allowing fabricators to rotate a steel plate from flat to vertical to flat in a single controlled lift operation.

Steel Plate Repositioning

Used to reorient steel plate stock during fabrication or assembly processes where changing plate face orientation is required before welding, cutting, or further processing.

Light Overhead Lifting of Steel Plate

With a 2,000-lb rated capacity, the clamp can be used for short-distance overhead movement of steel plate in shop environments when connected to a hoist or crane via a flexible rigging connection.

Compatible Materials

• Steel plate (flat, single-plate lifts only)

Product Documents

• Download Catalog
• Download Manual
• Lifting Clamp Survey Report
• Lifting Tool Inventory and Maintenance Form
• Minimum Recommended Clamp Inspections
• Renfroe Repair Kits Catalog

Application Instructions

Before Every Lift

1. Read and understand the Operator's Manual (OM 311-SCSM) before putting the clamp into service.
2. Visually inspect the clamp before each lift per the inspection instructions in the manual. Do not use a clamp that has been overloaded or shows signs of damage.
3. Confirm the plate thickness does not exceed the 0.75-inch maximum jaw opening.
4. Confirm the load does not exceed the 1-ton (2,000 lb) rated capacity.

Attaching the Clamp

1. Position the clamp jaw on the edge of a single steel plate. Do not lift from the bottom of a plate stack.
2. Tighten the screw handle firmly to lock the clamp onto the plate before applying any lifting force.
3. Connect rigging to the shackle using a flexible connection between the crane and the clamp shackle. Do not attach the clamp directly to the crane hook. Do not use a heavy flexible connection.
4. Ensure the load is balanced before lifting. Use an adequate number of clamps if required for balance.

Performing the Plate Turn

1. During the turning operation, keep the edge of the plate opposite the clamped edge in contact with a supporting surface (such as a factory floor or bench) at all times.
2. Do not allow the load on the clamp to exceed one half of the rated capacity during the turning operation.
3. Rotate the plate smoothly through the 180-degree arc (horizontal to vertical to horizontal) without side-loading the clamp.
4. Do not lift over workers or safety areas during any phase of the operation.

Removing the Clamp

1. Once the plate is resting on a stable surface, release tension on the rigging.
2. Back off the screw handle to release clamping force and remove the clamp from the plate.
3. Inspect the clamp after the lift and complete any required inspection documentation.

Technical Specifications

Safety Data Summary

Safe Handling

• Lock the clamp closed before lifting any load. Do not lift with the lock in the open or "Lock Open" position.
• Do not lift over workers, safety areas, or personnel at any time.
• Do not use a connection that may release the clamp during a lift.
• Do not attach the clamp directly to a crane hook — always use a flexible connection between the crane and the clamp shackle.
• Do not use large-capacity clamps to lift light loads; use the correct clamp for the job.
• Do not overload the clamp beyond its 1-ton rated capacity.
• Do not use a clamp that has been overloaded.
• Do not side-load this clamp.
• Do not lift more than one plate at a time.
• Do not lift plate from the bottom of a plate stack.
• Do not lift a plate horizontally with a vertical lift-only clamp; use the correct clamp type for horizontal lifts.
• Do not alter, grind, weld, or modify the clamp in any manner.
• During turning operations, the load on the clamp must not exceed one half of rated capacity.
• During turning operations, the opposite plate edge must remain in contact with a supporting surface.
• Use only RENFROE replacement parts to ensure proper operation.
• Inspect the clamp before and after every lift per the instructions in the Operator's Manual.

Frequently Asked Questions

Q: What is the maximum plate thickness this clamp can handle?
A: The SCSM has a maximum jaw opening of 0.75 inches, so it is limited to plates up to 3/4 inch thick.

Q: Can this clamp be used for horizontal lifting of plate?
A: No. The SCSM is a vertical turn/lift clamp intended for single-plate turning and vertical lifting. Do not use it to lift plate horizontally — use a clamp rated and designed for horizontal lifts.

Q: What is the maximum load allowed during the plate turning operation?
A: During the turning operation, the load on the clamp must not exceed one half of the rated capacity (i.e., no more than 1,000 lbs during the turn), and the opposite plate edge must remain in contact with a supporting surface throughout.

Q: Can this clamp be attached directly to a crane hook?
A: No. Always use a flexible connection between the crane and the clamp shackle. Do not attach the clamp directly to the crane hook, and do not use a heavy flexible connection.

Q: Are replacement parts available for the SCSM?
A: Yes. The SCSM has serviceable sub-assemblies including the Shackle (SCSM-1), Screw & Handle Assembly (SCSM-2), Screw Cup & Spring (SCSM-3), and Swivel Jaw & Spring (SCSM-4). Refer to the Renfroe Repair Kits Catalog for available parts.

Q: What inspections are required before using the SCSM?
A: A visual inspection must be performed by the clamp operator before and after every lift. Additional timed inspections are required based on the clamp's service class. Printable inspection forms are available for download in the Product Documents section above.