Slightly bowed new K-clamp bars.

[mark mcfarlane]

I bought a coupe of new sets of Bessey Revo's, and 2 of the 50" bars have a slight bow in them, ~ 1/4" over the 50" length. If you place the clamps flat on a bench like you were going to glue up some panels, the bow is L-R. I'm guessing this is a non-issue, correct? I tried a little gentle knee-in-the-middle to bend them back straight, without success, but with some persistence (or weight and time) I suspect I could make them straight.

[ken masoumi]

I wouldn't let it bother me,just used them like they are perfectly straight.

[mark mcfarlane]

I wouldn't let it bother me,just used them like they are perfectly straight.

Thanks Ken.

[william watts]

The bowed bar would not allow the clamp faces to be parallel especially on wide panel glue up's. The faces slightly tilt a little under clamping pressure to move to a parallel position, in theory, but with a bowed bar no way to know without trying.

[glenn bradley]

Non-parallel clamps are not parallel clamps. Why pay for parallel clamps if that's not what you got. These things are expensive and with a reason. The fact that they were mishandled somewhere along the line is not your responsibility. Exchange them or, if parallel clamps are not what you need, return them and pick up a bunch of pipe clamps for the same amount of money as a pair of parallel clamps cost. JMHO since I hate to spend money on prime rib only to get hamburger.

[Kent A Bathurst]

Non-parallel clamps are not parallel clamps.

Eloquent, Glenn. :p I'm with you, brudda.

Except when you dis the pipe clamps - them's my faves

[Jerome Stanek]

why do some people think a little bow in a clamp should be replaced but a completely smashed grizzly tool just needs parts.

[Dan Hahr]

why do some people think a little bow in a clamp should be replaced but a completely smashed grizzly tool just needs parts.

That's funny, but true. Having had Grizzly and other Chiwanese tools, I won't stand up for their quality compared to USA made or European made stuff. I suppose they are OK for most uses. I also use a few Bessey clamps. They are really nice and straight, and I drop them all the time.

Grizzly or not, anything I pay good money for that is defective is going to cost someone else to fix or replace. Someone needs to learn how to inspect or pack or protect them better and eating the cost of them is a great tool to teach with.

Dan

[Mike Heidrick]

Beauty of a Revo is that it is modular. Have Bessey send new bars. Fixed.

Or invent the Bessey Revo BowKlamp.

[glenn bradley]

Eloquent, Glenn. :p I'm with you, brudda.

Except when you dis the pipe clamps - them's my faves

Didn't mean to dis them :). I was trying to say that for what he paid for his non-parallel parallel clamps he could have several sets of pipe clamps (I've got a dozen or so myself). More bang for the buck :).

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Beauty of a Revo is that it is modular. Have Bessey send new bars. Fixed.

Good point Mike. That would certainly be an option. I just assumed he bought them locally . . . and you know what happens when you assume . . . :D

[Bob Grier]

If I understand correctly, the bar is bent (1/4" in 50") to the side with the clamp facing up. If so, th deflection is in the weak direction of the bar and it seems to me that when pressure is applied to the clamp the bar would straighten up and not be an issue. Probably less of an issue than if you place the clamp heads 1/8" off perpendicular to your glue up. Do you set your clamps that accurately? Does it matter that much? I am sure it makes a difference but how much? If you think about it, the bow in the bar is probably less detriment to the glue up than setting the heads off perpendicular by 1/8" because the bent bar would clamp with symmetrical pressure and offset heads would not be symmetrical (perpendicular) pressure. This is hard for me to explain but I don't think a 1/4" in the weak direction is an issue but I also think you have a right to get what you pay for and the best way to maintain quality for all of us is for businesses whether the vendor or the shipper to be held accountable.

If bar is deflected in the other direction or clamp heads set off perpendicular in other direction, then that is different.

[Erik Loza]

If I understand correctly, the bar is bent (1/4" in 50") to the side with the clamp facing up. If so, th deflection is in the weak direction of the bar and it seems to me that when pressure is applied to the clamp the bar would straighten up and not be an issue....

This was my thought as well ^^^.... Does putting the clamp under tension pull the bar straight? If so, wouldn't worry about it. Be a whole different deal if there was a twist in the bar or something like that.

Erik

[Phil Thien]

Are we sure the longer bars are pre-sprung? Seems a 50" bar would want to bow when you start tightening the clamps, having a built-in bow in the opposite direction may be intentional.

I'd toss it on a piece of plywood and snug it up and check the bow again.

[Mike Heidrick]

I own the 50" Revos. They are not pre-sprung. In fact you had one heck of a deal to bend them. A simple call to Bessey will fix this. They are very good at CS.

[Randy Red Bemont]

I own the 50" Revos. They are not pre-sprung. In fact you had one heck of a deal to bend them. A simple call to Bessey will fix this. They are very good at CS.

That's what I would do.

Red

[mark mcfarlane]

If I understand correctly, the bar is bent (1/4" in 50") to the side with the clamp facing up. If so, th deflection is in the weak direction of the bar and it seems to me that when pressure is applied to the clamp the bar would straighten up and not be an issue. Probably less of an issue than if you place the clamp heads 1/8" off perpendicular to your glue up. Do you set your clamps that accurately? Does it matter that much? I am sure it makes a difference but how much? If you think about it, the bow in the bar is probably less detriment to the glue up than setting the heads off perpendicular by 1/8" because the bent bar would clamp with symmetrical pressure and offset heads would not be symmetrical (perpendicular) pressure. This is hard for me to explain but I don't think a 1/4" in the weak direction is an issue but I also think you have a right to get what you pay for and the best way to maintain quality for all of us is for businesses whether the vendor or the shipper to be held accountable.

If bar is deflected in the other direction or clamp heads set off perpendicular in other direction, then that is different.

That is correct, if the clamps are laying on the bench, as you would lay them to glue up a panel, the bow is from L-R-L, not up-down.

[Mike Heidrick]

What is your reference edge? That is an amazing bow. And two of them the same?

[mark mcfarlane]

What is your reference edge? That is an amazing bow. And two of them the same?

My previous measurements were estimate by eye. So I measured,... reference is an MFT with 4 QWAS dogs placed along the length. Held the bar up tight to two dogs on one edge of the table, measure the gap between dog and bar at the farthest dog (38" away).

My four 50" clamps varied from 1/16" to 3/16" of bow at a distance of 38", so my guess of 1/4" was probably right on. None of them were perfectly flat in this dimension, but all were straight in the other dimension.

I'm thinking this bend won't matter, you would get the exact same effect if you placed your clamps 3/16" different from the end of two boards being glued up. Anyone actually measure (really) when they are placing clamps, accurate to within 3/16"?

Anyone else care to repeat this test on their 50" Bessey K clamps?

The clamps are NOT under pressure in the photos below. I can make them straight by pushing one edge 3/16" and applying pressure.
314084314083

[mark mcfarlane]

Are we sure the longer bars are pre-sprung? Seems a 50" bar would want to bow when you start tightening the clamps, having a built-in bow in the opposite direction may be intentional.

I'd toss it on a piece of plywood and snug it up and check the bow again.

The bow is in the weak (thin) dimension of the bar. All 4 bars are perfectly flat in the strong dimension.

[mark mcfarlane]

...Good point Mike. That would certainly be an option. I just assumed he bought them locally . . . and you know what happens when you assume . . . :D

Bought from Amazon. Exchanging is a no cost affair, other than my time to drive 20 minutes to a UPS center.

[Jerome Stanek]

when you use the clamps does the bow get less from being under pressure

[mark mcfarlane]

when you use the clamps does the bow get less from being under pressure

It straightens right up, with minimal pressure.

[mark mcfarlane]

My previous measurements were estimate by eye. So I measured,... reference is an MFT with 4 QWAS dogs placed along the length. Held the bar up tight to two dogs on one edge of the table, measure the gap between dog and bar at the farthest dog (38" away).

My four 50" clamps varied from 1/16" to 3/16" of bow at a distance of 38", so my guess of 1/4" was probably right on. None of them were perfectly flat in this dimension, but all were straight in the other dimension.

I'm thinking this bend won't matter, you would get the exact same effect if you placed your clamps 3/16" different from the end of two boards being glued up. Anyone actually measure (really) when they are placing clamps, accurate to within 3/16"?

Anyone else care to repeat this test on their 50" Bessey K clamps?

The clamps are NOT under pressure in the photos below. I can make them straight by pushing one edge 3/16" and applying pressure.
314084314083

Anyone else willing o try this test on their 50" clamps? I need to make a decision today or tomorrow morning to ship back the clamps.