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I should not be surprised when somebody like Bessey brings new thinking and function a very old design but I was and they did. I promise to have more faith in them in the future.
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Bessey Auto-Adjust Toggle Clamps

Making an old idea a bunch better

Text, photos and video by Tom Hintz

Posted – 8-22-2011

I have been using toggle clamps for decades and have been fighting their deficiencies the whole time. Until now toggle clamps always had to be adjusted when the stock thickness changed even a little bit. Many of them would flex, bend or pop open unexpectedly if you approached their comparatively low pressure and size capacities. While I have used toggles in my woodworking forever the folks at Bessey tell me that the metalworking world uses them quite a bit more. That bit of info from Bessey corroborated what I was hearing in my email so I decided to put this review on www.newmetalworker.com.

The Basics

The Bessey Auto-Adjust Toggle Clamps are great examples of what the big kid on the clamping block can do when they apply their world-class engineering to the task. Keep in mind that Bessey is also a major player in worldwide steel design and manufacturing and are not shy about putting high-end materials in their clamping products.

The Bessey Auto-Adjust Toggle Clamps are adjustable in ways other toggles just can’t match. The Bessey Auto-Adjust Toggle Clamps do have the up and down adjustable contact point that can also be moved in and out on the arm on the vertical models. That screw is heavy, very well made and stays locked when you tighten the nut down. This contact point adjusting screw locks with one nut on top rather than how many other clamps do it with one nut on top and another below the arm. Notice that all of those components are made from thicker, tougher steel than all others I have seen. Flex just is not going to be an issue.

The contact disks (left) are on an easy to adjust threaded shaft and feature a swivel and removable non-marring cover. Everything on these clamps is heavy duty (right) including the steel used to make them.
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The contact point on the Bessey Auto-Adjust Toggle Clamp is a free swiveling steel disk that can handle the remarkable pressures these clamps are capable of generating. The swivel allows the clamp to get a better “seat” on material that may be less than perfectly flat. A snap-on, snap-off, non-marring cover for the contact point is included with each Bessey Auto-Adjust Toggle Clamp. This cover lets you work with sensitive materials without marking them up when clamped.

Bessey also used heavy-duty pivot pins at all of the joints to further insure long, flex-free service. These pins and the material used around them is a favorite place to cut costs on the lower priced toggles. I have looked at the actual difference in price (on the street, not the suggested retail) between the “bargain” versions and the Bessey Auto-Adjust Toggle Clamps and that makes trying to save that little money a dumb idea.

The base of each Bessey Auto-Adjust Toggle Clamp has heavy steel flanges with slotted and round holes to give you lots of mounting options using ¼”-diameter (M6) fasteners. The bases are large enough to give the Bessey Auto-Adjust Toggle Clamps solid footing yet they do not take up extra space. The flanges are still large enough to use locking clamps and pliers to hold them in place if the job requires it.

The Bessey Auto-Adjust Toggle Clamps have a large, ergonomically designed operating handle that is easy to use even with gloved hands. This handle is easier to work than you might suspect, in part because of the adjustable pressure capability and the auto-adjusting mechanism.

Adjustable Pressure

This simple screw (left) adjusts the pressure. Somewhere amongst the pivots I suspect is the engineering that Bessey came up with to make this happen. This box-like portion of the clamps (right) slides back under pressure and is part of the Auto-Adjust system. Again, I don't claim to understand just how it works but I do know that it does work.
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A simple screw at the base of the operating handle allows you to dial in the amount of clamping pressure (within the listed range) to be applied. A locking nut on the screw prevents it from changing during use. This is part of the auto-adjust capability in that the pressure you set remains constant as the Bessey Auto-Adjust Toggle Clamps conforms to the material size. The ability to regulate the clamping pressure can make many tasks in the shop easier and faster.


The real bit of wizardry built into the Bessey Auto-Adjust Toggle Clamps is their ability to clamp different thicknesses without needing adjustment. The mechanism compensates for the material size (within its range) as the operating handle is pushed yet doesn’t change the amount of clamping force being applied. I know that the bodies of the Bessey Auto-Adjust Toggle Clamps do slide rearwards when thicker material is encountered but after that I just am not sure how this auto-adjust system does what it does. But, it does and it does it every time.

If you have fought with the mortal toggle clamps, having to adjust the contact point whenever the material size changed the Bessey Auto-Adjust Toggle Clamps will be a valuable new tool in your shop. Once you get used to the auto-adjust feature I suspect that regular toggle clamps just won’t matter anymore.


The STC-HH50 has a horizontal clamping arm with 1-¾-inches of clamping capacity with a clamping pressure range of 25 to 550 pounds of force and a holding force of 700-lbs. The STC-HH70 is also a horizontal toggle clamp but with a taller base that gives it up to 2-1/2-inches of clamping capacity. It is capable of generating 25 to 550 pounds of clamping force with a holding force of 700-lbs.

The STC-IHH25 is an inline style clamp with a 1-inch capacity variation. The STC-IHH25 has a clamping for range of 25 to 550-pounds and a holding capacity of 700-pounds.

In the Shop

The operating handles (left) are nicely shaped to make them easy to use and comfortable. The mounting flanges on all of these clamps (right) give you lots of options for putting these clamps where you need them.
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The only part of using the Bessey Auto-Adjust Toggle Clamps that takes any time at all is getting used to setting the pressure screw to generate the grip that you want. And that takes a whole ten minutes or so of experimentation. I have gone long periods of time without adjusting the Bessey Auto-Adjust Toggle Clamps at all because the setting carries over to other stock sizes all on its own.

The other part of using the Bessey Auto-Adjust Toggle Clamps that takes any brainpower is positioning them for your job. You might have to tweak the contact point screw for some jobs but that goes quick and the one-nut locking makes keeping that setting a snap.

I have tried all of the mounting options that I can think of from simply clamping the Bessey Auto-Adjust Toggle Clamps in place to drilling holes and using bolts with wing nuts to secure the clamp to a piece of metal that I can clamp in whatever position I need. Here again, a little bit of experience and you will get the feel of how you like mounting the Bessey Auto-Adjust Toggle Clamps for your type of work. The mounting options that Bessey provides will cover any temporary or permanent job you have.

All of the adjustments that I made initially stayed right there until I intentionally changed them. I like that kind of consistency but with the Bessey Auto-Adjust Toggle Clamps it goes even further because of the auto-adjust feature. More often than not I can place a Bessey Auto-Adjust Toggle Clamp where I need it for the next job and never have to disturb the adjustments from the previous job because it handles material variations so well.


Video Tour

The Bessey Auto-Adjust Toggle Clamps are exceptionally well made and obviously meant to last a very long time in even busy shop environments. Despite the obviously complicated engineering behind the auto-adjust feature these clamps are very easy to use. The clamping power they generate means that they will hold your materials solidly.

With street prices of $21.25 for the STC-HH50, $22.50 for the taller STC-HH70 and $23.50 for the inline STC-IHH25 (8-19-2011) the Bessey Auto-Adjust Toggle Clamps are well worth the extra few bucks they may cost as compared to lesser brands that are sold for those who want cheap first and quality later. In case you haven’t figured it out yet saving a few bucks up front always winds up costing more later when the cheapies work like cheapies and you wind up stamping around the shop saying things of which your mother would not be proud. I have tried that scheme many years ago and have the Bessey Auto-Adjust Toggle Clamps in my shop because even I can learn.

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