Rockler has partnered with Spanish company Piher to introduce their new Rockler-branded F-clamps. These F-style bar clamps have a very unique closing mechanism. Rather than using a direct screw to close the clamping foot, the screw drives a piston foot.
Made in Spain, these new clamps can generate over 2000 lbs of clamping force. They also feature a swiveling handle so you can get more leverage on the screw when you are tightening the clamp.
The bar is made of cold rolled steel and the jaws have a throat depth of 4-3/4″. The movable jaw has a cast iron brake that won’t slip on the bar when you apply clamping force.
These clamps might look like regular bar clamps, but they’re not. Here’s a cross section.
Rather than using a single screw to drive the clamping foot, these clamps use a combination right and left-hand screw to drive a piston foot. As you tighten the clamp, this screws the larger section into the body of the jaw, while the smaller internal screw pushes the piston outwards from the jaw. The pitch of the internal screw is different from the external screw, so one turn on the clamp handle makes the piston travel farther it would have if it had just been connected to the external screw.
The piston design isn’t just about advancing the foot faster, there are some other advantages. First, the piston foot doesn’t spin as it contacts the material you are clamping. This should help reduce the chance of marring. Second, there are no threads on the inside of the jaws to muck up with sawdust and squeezed-out glue.
Rockler’s press materials say this about the design:
The double threads provide faster clamp head advancement and tightening, and the enclosed design prevents glue from clogging the threads. Additionally, the head advances without rotating, eliminating any twisting torque that might cause misalignment or marring.
Rockler is offering these clamps in three sizes: 16″, 24″, and 32″, and they’re priced at $40, $45, and $55 respectively.
It looks like they are stocking them in their brick and mortar stores, but like always, you might want to contact the store before you make the trip. If you want to pick these clamps up online you can click on the link below to activate free ground shipping on $35+ orders.
Rockler sells these clamps with a lifetime guarantee, which can be reassuring.
Activate Free Shipping (Expires August 31st, 2016, but we’ll try to update the code whenever we get a new one.)
You can also buy clamp pads for these Rockler clamps and the Piher Maxipress clamps, for $3 per set.
Buy Now (Clamp Pads)
These Rockler piston clamps are not exactly a new innovation, as Piher owns the patents and has marketed their self-branded Maxipress clamps since at least 2009.
There are a few differences between the Maxipress clamps and the Rockler piston clamps. The Maxipress clamps can generate up to 2,250 lbs of force, and have curved jaw arms. Rockler’s are straight. The clamps are also serviceable, as there is a grease port on the clamp to allow you to lubricate the internal screw threads. Finally, the upper jaw has perpendicular grooves for clamping irregularly shaped objects.
Rockler also stocks the Piher Maxipress clamps, in 16″, 24″, 32″, and 40″ lengths, and they’re priced at $48, $55, $60, and $70 respectively.
The big advantage of these clamps is that they can generate over three times the force of a normal style F-clamp — at least the 600 lb Bessey ones I own. Bessey does make a heavy duty F-clamp that can apply 1540 pounds, but these piston F-style clamps can generate even more force than that.
The other advantage is that the piston foot advances faster for every turn of the screw, even with the finer pitched threads required to get the large clamping force. There’s no question that speeding up the amount of time it takes to get a clamp in place is a good thing when you are trying to glue up an assembly.
What I think is pure marketing are the other claimed features. Normal F-clamp feet actually swivel and rotate on the screw as you apply pressure. The fact that the feet swivel also means that the edges of the material in the jaws doesn’t have to be completely parallel. Maybe rotating feet are a problem on cheaply made clamps but I wouldn’t expect it on a $40+ clamp. Or maybe it is a problem when you are generating 2000 lbs of force.
But is getting debris in the threads of a regular F-clamp really that much of a problem? I’d think you’d have just as much trouble with stuff getting inside the piston housing, although from the cross section shown above it looks fairly well guarded.
It’s also worth pointing out that the price of these clamps are in parallel clamp territory.
My untested opinions aside: Has anyone used the Piher Maxipress or Rockler clamps? Whether you have or haven’t, what do you think about their claims?