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.
Advertisement
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:
Advertisement
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)
Piher Clamps
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.
First Thoughts
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?
BonPacific
I’m struggling to think what the use-case is for 2000lbs of clamping force on a woodworking clamp. If you need that much force, there’s something *very* wrong with your glue-up. Maybe it’s for steam-bending or bent lamination? The speed would be more important in those circumstances.
Matt
I can’t imagine too many woods that would stand that kind of force without indenting the surface. Technically these are impressive, but I’d be worried about over-clamping delicate surfaces.
fred
Generally you don’t need much beyond light (maybe 125 to 150 psi.) gluing pressure for flatsawn pine – but rock maple needs a lot more – maybe 1000 to 1200 psi. Oak, Poplar, Walnut, Cherry etc. are in between. Probably better to err on the side of a bit less pressure than more .
Using clamping cauls to spread out the forces – is often a good idea.
BTW – we always found that the needed clamping pressure for quartersawn hardwoods was about half what you needed to get a good joint with flatsawn stock. – And of course you never get a good joint with just glue on endgrain.
As you point out you never want to crush the wood fibers along the joint line – or have so much squeezeout that the joint is starved for glue
Stuart
You don’t need to use these clamps at their highest capacity.
I’ve found that, with clamps, higher capacity means greater strength and rigidity.
Even if I need say 500 lbs of clamping force, I’d rather use a clamp capable of 2000 lbs than one capable of 500 lbs or slightly higher.
It also suggests that these clamps are easier to tighten up, whereas you might be grunting and struggling to get smaller clamps to comparable clamping pressure.
BUT I would be careful to check that the jaws were parallel. As mentioned in a below comment about my Urko experience, some clamps might be designed to exert a lot of force before they adjust to a parallel orientation.
Since these clamps were designed for woodworking applications, that’s probably not a concern – I hope.
Benjamen
To be honest the only woodworking use I could think of with that much pressure was being too lazy to flatten surfaces and forcing them to bond, but both Stuart and fred bring up some good points.
The other two were maybe metalworking and using the clamp like a one ton press.
RKA
Bessey also makes F style piston clamps. The model numbers start with PZ. They generate over 1000 lbs of force which is more than you need for this style of clamp imho. You can get them on zoro with a 25-30% coupon but some will be back ordered for a bit (waiting on a few right now actually). Search for rapid action lever clamp. These are new to me, I liked them because they won’t turn the work piece as you clamp down, which can be a nuisance if glue is lubricating mating surfaces.
Fred also linked to a Spanish manufacturer starting with the letter O that makes these (in the giant clamps thread on the discussion forum). I can’t recall the name right now. They looked really nicely made but availability in the US is almost nil. Bessey is a far better option.
fred
I might have linked to Urko clamps also made in Spain:
https://www.amazon.com/URKO-URHP403P40-HiPer-Clamp-40-Inch/dp/B0015DIM56/ref=sr_1_1?ie=UTF8&qid=1471621611&sr=8-1&keywords=urko+clamp
I like the bar-profile on the Urko clamps a bit better than a flat bar for rigidity and strength.
RKA
Yeah that’s the one I was thinking of, thanks Fred! Amazon had one of each size in stock which is strange.
fred
Yep – and quite a bit pricier than the Rockwell ones
Stuart
I ordered a pair of Urko clamps from Amazon once, and the jaws would never parallelize, resulting in marred wood. I returned them.
It was their URHP403P32 HiPer Clamp clamps, capable of 3,700 lbs of force. I mostly ordered them because I needed longer clamps and they were on sale.
fred
In a production environment – fast and repeatable clamping often relies on hydraulics not manual clamping. Machines called clamp carriers do the work for panel clamping etc. If interested take a look at Doucet, Holytek, Quick Machinery and James Taylor (not the singer).
We had a manual panel clamp station – suitable for a small cabinet shop. Nice because it worked in a vertical orientation – taking up less floor space. A home shop enthusiast could build their own version with pipe clamps or long bar clamps.
Benjamen
That’s a good point about parts being slippery because of glue. it’s like trying to clamp two ice cubes, any pressure other then straight the joint will slide.
I guess I wasn’t thinking about that when I wrote it. I rarely use F-Clamps for the primary clamp anymore, I’ll use bar clamps or in my last project my new parallel jaw clamps. The F-clamps (and the pipe clamps) com out when I’ve run out of the expensive clamps.
fred
About the pieces slipping about – for things like table top glue ups – its good to clamp in 2 directions. The parallel jaw clamps pull the panel together along the glue lines. Then you can sandwich the panel together with some straight flat stock on each side clamped with your F-Clamps. Some waxed paper will prevent the squeeze-out from sticking.
I guess if you were a wooden boat builder you might have hundreds of F-Camps – but for edge-gluing panels, table tops etc. the parallel jaw clamps (especially since the Bessey ones went off-patent) have mostly replaced them – but shorter ones are good for the chores I described above – and certainly for clamping things down to your benchtop
Drew M
I sort of like the handles… that’s about it.
Michael
I would have to handle one before I would layout hard earned money.
Albert Lee
I laminate a few timber post in my semi commercial workshop, I have a pneumatic press table but I dont use it to laminate my timber post, to obtain the amount of pressure required on the post (cross sectional area of 14cm x 180cm), it will require a lot of force, say 8kg/cm2(110psi), thats 8 x 14 x 180 = 20160kg/197769N
A standard SMC 125mm bore ram can exert 11100 N at 0.9MPa, 197769/11100 = 18 ram required.
A standard SMC 125mm/100 stroke ram cost about $1000 NZD, thats about 630 EURO, 18 of these clamps will cost about 18000NZD/11340 EURO.
I endup buying 10 Urko Clamps (about $1480NZD/930Euro) and will be using them in conjunction with Record T bar clamps, I will be making my own cauls to get the best use out of the Urko clamps.