Written by Jody Muelaner
Strap clamps, also known as band clamps, resemble the ratchet straps used to tie loads down — such as on a vehicle’s roof rack or a truck bed. The webbing strap is placed around an assembly and tightened, applying pressure to joints.
Strap clamps are often fitted with four corner guides, for use in a rectangular arrangement. The guides prevent the corners of the parts from being crushed when the load is applied, enabling the straps to slide freely so that an even pressure is applied to the assembly.
Special purpose clamps may have guides in other configurations.
Stramp clamps are also often used to apply pressure while bonding joints in woodwork or when welding joints in fabrication.
Different mechanisms may be used to tighten these strap. The most common is a screw that’s incorporated into one of the four corner guides. In this arrangement, the straps are first pulled tightly by hand before being locked off with cams on either side of the screw. The screw is then used to draw the cams away from the corner guide, causing the strap to tighten around the assembly.
Straps are most commonly made of a textile webbing material, with the guides and clamp body made of plastic. Some heavy-duty strap clamps use metal banding instead of webbing and may be referred to as band clamps.
Ratcheting load straps can be used as strap clamps if they’re the only available option. In this case, the corner guides may also be easily fashioned from scrap material — and, ideally, a polymer with little friction.
An even simpler way of improvising a strap clamp is to tie a loop of webbing or rope around the parts to be clamped and then insert a bar that can be wound to twist the loop, causing it to tighten. The bar can then be tied off to prevent loosening.