A couple of years ago I bought a pair of Urko 32″ HiPer bar clamps from Amazon. I gave them a quick test when they arrived, and promptly sent them back.
I understand that some clamps might be purposely angled slightly, such that at strong clamping pressures the jaws are put under tension and reach parallel alignment.
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But these jaws, in my opinion, then and now, seem to be too off-parallel, at least for the not steel-hard materials I wanted to use them on. Maybe they’d be fine for clamping something to an I-beam.
In my quick test with scrap material, the clamps dug in, and I wasn’t able to achieve high enough clamping pressure to reach parallel alignment.
Their “application” image on Amazon showed 2 pieces of rectangular steel tubing stock being clamped together.
Since both clamps had similar jaw angles, I assumed that the clamps were simply far too heavy duty for what I wanted to use them for. Or maybe they were both defective.
It would take a LOT of force to correct those jaws into being parallel. Or maybe I was wrong about the clamps. I could never determine if the problem was with my expectations, or the clamps.
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Would you consider these clamps to be too crooked, or perfectly designed?
BikerDad
Crooked. It looks like then they cleaned the casting lines off the face of the jaw, they didn’t get it square. While a bit of out of parallel is okay, even desired, that’s just too much. I can’t imagine that the bar would bow enough to bring that square, and it’s even less likely to get enough movement out of the jaws to do it.
Yadda
I agree, poor quality control.
ca
That seems reasonable for an F-clamp capable of “3,700 pounds of clamping force”.
Nathan
does that screw end have a hex on it for you to tighten with a wrench – because you aren’t getting 3500+ lbs on that with the little cross bar.
If however you are able to crank on it and clamp into 3500 lbs that slight angle might not matter – and it’s not for wood – way too much clamp for wood if that’s the rating.
However it does appear to be missing 2 rubber or whatever pads. That I would want on there even if clamping metal pipes. Would be interesting to see. Where they cheap perhaps
Stuart
Urko is not a cheap brand. They were on my radar for a while, and I snagged then when the price dropped to $22 apiece.
This was all around 6 and a half years ago.
Allen
In order to become parallel with added pressure wouldn’t that move the work ?
All mine have a a swivel foot I guess.
Chad Brink
All of my “F” clamps have a ball socket swivel pad on one side to allow for self alignment. I don’t see how any clamp without some sort of give could be expected to align due to varying degrees of tension placed on them.
fred
It may be a defect – but as you apply clamping pressure – wouldn’t the moving arm tent to tilt downward and outward – pivoting a tad on the bar? How’s your Spanish – have you talked to the engineers at Urko? Or the importer (Anglo American Tools) ?
I have some Urko cantilever clamps (404C and 424C series) – but not these – so I can’t compare to mine.
Fran
On a 32″ clamp, no matter what brand or style, the bar will bend quite a bit at anything approaching 400-500lbs. At a couple thousand pounds, those pads would align to produce solid pressure.
That said, I think the pads should be much closer to parallel than your photo indicates.
The strongest I-beam clamps I’ve ever used that were over 28″ long still bent when applying a good amount of twist to the handle. It’s a symptom of the design of a long(ish) bar.
fred
BTW – I see that Bessey has stepped in to offer a few new (to them) styles of clamps – once made by Pony-Jorgensen. I-Beam clamps are one of them:
http://www.acmetools.com/shop/tools/bessey-ibeam36
taras
One thing to consider is are both jaws “out of square” evenly between the two? Does a perpendicular line from the bar bisect the jaw angles? If so, then it may be the anticipated flex was accounted for in the design. If one is out more than the other, or just one, then maybe it’s a defect?
Koko the Talking Ape
That is a thought. Hm.
But on the other hand, it wouldn’t matter in use. The bar flexes, not the two jaw castings (I imagine). So if the angle is only in one casting, that means the bar will simply be slightly out of parallel with the workpiece (assuming a rectangular workpiece.) It might be easier to make the head casting square and build the angle into the sliding casting.
And yes, it seems like too much angle.
Whiskey and wood
They make all of their piston clamps in two models, one with a fixed head, and one with an articulating ball joint head, for different applications. If the model ends in P, it’s a fixed piston, if it ends in PA, it’s articulating. i believe the fixed head ones are designed for higher pressure metal clamping.
Whiskey and wood
The model shown on Amazon that you linked to is 403-P
Stuart
Yes, it had a fixed pad and piston-based forwarding system. I had still expected it to clamp true on a parallel workpiece.
Whiskey and Wood
That’s why I was pointing out that the different head styles are for different purposes. Every clamp that’s not a parallel clamp is made with and “angle of compensation” for flex at the pressure range it’s designed to be used at. A clamp with a 3700 pound pressure rating shouldn’t be parallel at 100 pounds, if it was, then it wouldn’t be parallel at 3700 pounds (without and unreasonably sized bar). The articulating head is designed for irregular surfaces, jigs, etc. and would make up for this. It will clamp parallel on a parallel surface at 3700 pounds of pressure, I don’t think it’s fair to disparage a tool for expecting it to work a certain way under circumstances it wasn’t designed for. If you look at their website, there isn’t a single photo of any clamps in this line being used for anything other than large, industrial metal fabrication.
Stuart
I’m not disparaging it – my intent was to throw this out for discussion to help finally determine if this resulted from a defect with the product, or that my expectations were off.
This was all 6-1/2 years ago.
Tim
The clamps we use at work have a slight inward angle like this.
I always assumed it was to ensure whatever you were clamping didn’t pop outwards with too much pressure.
ACalz
maybe it has to many shims or the metal shims that help release it from the bar are to thick. If it had one less shim maybe the lower jaw would move a little more out and down and it would align itself with the top.
Ed
Every European style f clamp We have from various manufactures including Urko and Piher has jaws like that, They work fine there’s nothing wrong with them.