Tested parallel-jaw clamps
Ask any woodworker if he or she would like more clamps, and the answer will undoubtedly be a resounding "Yes!" Then follow up with "Which kind?" and they'll likely want parallel-jaw clamps. These sought-after clamps have sturdy bars that resist flexing, deep jaws that close up parallel, and the mass and ruggedness to better clamp flat workpieces and case assemblies. They come with premium price tags, as well.
To find the best of the bunch, we brought together eight models—including a brand new design for the venerable Bessey K Body—to compare in head-to-head testing. The good news: You can't really go wrong with any of them, but some will improve your time in the shop. Download a chart of our complete parallel-jaw clamp comparison.
We tested each clamp in 2' and 4' versions where possible. (Although five models actually measure 50" between jaws, for clarity and convenience we simply refer to them as 4-footers.) One clamp, the Yost K5000 series, tops out at 36", which we tested.
Parallel proves true for all
We measured the ability of each clamp's jaws to close against workpieces and yet remain in the same plane. Five models (Bessey K Body Revo, Bessey K Body Revo Jr., Irwin, Jet, and Peachtree Woodworking) closed up with perfectly parallel jaws. The remaining three clamps canted outward by 1⁄16 " or less under pressure, which we found acceptable.
With almost every clamp, we discovered more deflection in the bars than in the jaws. Both Bessey K Body models, along with the Irwin, Jet, and Yost K5000 clamps, deflected the least. As long as the jaws remain parallel, an assembly should remain flat when clamped, provided you don't knock it back down onto the bar with a mallet.
The force is strong in these
A well-made joint typically requires about 100 pounds of clamping force to pull it tight. But there will be times when more force is needed, such as when clamping thin strips to a form for bent laminations. Even in those more-demanding applications, most of these parallel clamps will work fine.
To compare clamping force among the test clamps, we had 10 woodworkers of various ages "max out" each clamp, measuring the force with a hydraulic ram, and then averaged the results. As you can see in the chart below, all the clamps can achieve sufficient force to do any typical assembly job in the shop, so don't hang your buying decision on maximum force alone.
To add grip to slick or too-small clamp handles, apply strips of adhesive-backed traction tape.
Instead, check out the ergonomics, which can suit people differently. For example, testers with large hands preferred the large-diameter handles on the Bessey K Body Revo, Irwin, and Jet clamps, with the Irwin handles favored most because they're slightly elliptical rather than perfectly round. But Irwin's finer threads require about twice as many handle turns to create similar clamping force. Smaller hands might get better results on the smaller handles, such as those on the K Body Revo Jr., Peachtree, and Yost K5000 models. And some handles, with a combination of plastic and rubber inlay, become slick as you begin to max out the clamping force.
Two clamps, the Lee Valley Ehoma and the Yost K7000—virtually identical except for color and branding—have handle systems that helps you crank up the force, as shown above. You can also gain added leverage with the Bessey K Body Revo clamps, shown below. These methods prove helpful for anyone with limited hand strength.
Jaw slide should work for you
With each clamp, the tail jaw is fixed to the bar, while the other jaw slides the length of the bar. On the best models, the jaw slides easily, yet grabs the bar when it's time to apply force. The Bessey K Body models (above) and Jet (below) work best in this regard. All three have thick, sturdy bars with serrated top edges that the sliding jaws engage without backsliding when positioned against a workpiece or assembly. The Irwin and Yost K5000 clamp bars lack serrations, and the jaws grip easily enough, but over time problems can arise. In our tests, the Irwin jaws marred the bar (below), and the Yost bar's paint coating peeled off, creating a less-than-smooth slide.
More features you may (or may not) find helpful
- Rear feet. Each of the clamps has a support foot at the end of the bar. All the feet can be removed, allowing you to reverse the sliding jaw and use the clamp as a spreader.
- Bar pads. All but the Irwin, Jet, and Peachtree clamps come with a pair of removable plastic supports that straddle the bar to prevent glue contact. Nice idea, but we found they can cause workpieces to misalign, especially during panel glue-ups. Plus, they can be easily misplaced when not used on the clamps. When steel and moisture combine with wood, stains often result in the wood. Glue stains are reduced or eliminated when using the clamp bar pads. But without them, four clamps resisted staining better than the others, with the Peachtree and Yost K5000 clamps producing stains that required planing or scraping to remove.
- Jaw sleeves. The same clamps that have bar pads also have replaceable sleeves that provide a non-marring barrier between the harder jaws and the workpieces. These work fine, but they slip off frequently and become scratched or worn over time, needing to either be replaced or discarded.
- Trigger release and measured bar. Jet's clamps employ a unique trigger-style sliding-jaw catch that we really like. It keeps the jaw from sliding along the bar when you don't want it to, and it's easy to activate. And the bars are numbered in inch increments, making it easy—before adding your workpieces—to set the jaws near the position you'll need for clamping.
Clamp down on your budget and spring for the leader As we said earlier, there were no duds in this group, but one clamp rose to the top: the Bessey K Body Revo. It earns Top Tool honors. This clamp works great at all the clamping chores we performed and comes in nine lengths.
But if you need to hold to a tighter budget, opt for the Peachtree Woodworking clamps, our Top Value. These clamps cost $10–$20 less per clamp without sacrificing meaningful performance.
Bessey K Body Revo
Bessey K Body Revo Jr.
Lee Valley Ehoma