Bar Clamp Strength - Hardwood VS Softwood VS Steel 

The real heros are the clamps holding the clamp down.

"Absolutely nothing!' Thanks for a laugh this morning!

Wow! Motorised tests!

Your clamps and explanation is absolutely spot on - Thanks John !! My take on clamps are more or less the following: If anyone should require more clamping force than they can get out of any of these clamps .... their preparation and/or jointing sucks !!

Great video, John. I think the lesson that a lot of the folks who ask about clamping strength need to learn is that there isn’t a strong enough clamp to make up for bad joinery. I include in the term “bad joinery” long grain butt joints that aren’t straight. Scott

Thanks for the clear explaination for where does the strenth come from! Very impressive for beginners like me.

I'm going to have to challenge you on something that requires lots of testing and measuring because I love these videos.

More in the blog entry I wrote to go with this: ibuildit.ca/blog/how-strong-are-wooden-bar-clamps/ Plans for my bar clamp: ibuildit.ca/plans/wooden-bar-clamp/ Here's a video showing me testing a similar clamp until it breaks: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-hvgk3p2lZH0.html You can help support the work I do in making these videos: Plans for sale: ibuildit.ca/plans/ Support this channel on Patreon: www.patreon.com/user?u=865843&ty=h Did you know I have other RU-vid channels? My main channel: ru-vid.com More videos on my second woodworking channel: ru-vid.com My home reno channel: ru-vid.comHome Website: ibuildit.ca/ Facebook: facebook.com/I-Build-It-258048014240900/ Instagram: instagram.com/i_build_it.ca/

Thanks for the video.

I had never thought about the clamps adding a bend to wood before. I guess it's good I only do woodwork as a hobby.

Just finished making 6 of your wooden K style clamps :-)

I liked your qualitative result of "strong enough". Thanks for looking at this from a practical perspective. As you said, there are a lot of factors in choosing the best clamp, including rigidity, axial strength, clamping force, weight, cost, hardness (when the clamp hits the workpiece, which one dents), durability, cosmetics, ease of use, and more.

Excellent video 👍, I made several from 2x4s and 1x pine that were just over 8 feet long to glue up a project that was nearly 8 feet and they supplied adequate force for the joints. I was too cheap to buy pipes long enough for the job! I think it was less expensive too.

Interesting experiment. Probably the most relevant comment you made was in regard to the panel following the flex of the clamps and putting clamps on the other side to counter that flex. As far as clamping strength is concerned, if that is even a concern, the joint of the fixed jaw is the weak point. Even at that joint most of the pressure is along the sheer plane of the bar. Of course, if the work piece is held towards the end of the jaw, there will be more pressure giving at a right angle to the joint which would cause it to fail more readily. As you said, these clamps are for gluing up wood, so excessive pressure isn’t necessary, just use more clamps. I have been thinking about making some of these and now using cheap spruce 2x4s gives me incentive to try it. Thanks, John.

Your pine and ash clamps work well because you used 'handpicked' wood for the bars; straight grain, fault free, no run-out etc. Probably far more important than the actual species, which you mentioned. Also the reason that construction lumber has to conform to a certain grade. So does your bar clamp bar, and even an icecream stick, to perform its funtion. Subscribed.

What about used wooden hockey sticks? It's laminated hickory, with the grain going the right way. It does have flex though.

Cool, John! I should try clamping a bathroom scale with one of my clamps to see generally what sort of force I apply when gluing up something. I have seen deflection in the thin metal bar clamps I use.

I wonder how strong it will be when it is made from 2 or 3 layers of pine with the grain all in the same direction. But seeing this video I also wonder why bother.

I don't have a wide selection of lumber to choose form in my shop and my budget is $0. I just remember your advice about knowing the limits of the materials you are using and knowing what you need from them. I try not to over engineer or overbuild. 99% of what I do ends up on a shelf after I'm done, lol.

Having built ten of these clamps, it is not the flex that would concern me with soft wood, it is the teeth/notches. I wonder if they could fracture under heavy load or even just round over with repeated use. In hardwood though, this design is fantastic!

I wonder how much it would deflect with say, a Ford Pinto. Good chuckle video.

I think the deflection shows clamping force. The bar wants to be straight which is what applies the force. Now that we see they're all close, the question become which clamping head can provide the force needed to bend the bar.

What about using that composite decking (it's pretty much plastic infused into wood), or would it be the same a using plywood?

I've always wondered how these would hold up using hard woods commonly available at the big home centers, like red oak, poplar, or maple (which I think is "soft maple"). Just getting to the nearest hardwood lumber yard is a 2 hour round trip and 3 - 4 gallons in gas. The nearest home center is less than a half hour round trip and only a half gallon of gas. That way, I'd actually have time to build the clamps the same day.

I offer my solution to bendy timber bars on clamps again, just saw the piece through the greater cross sectionaldimension,lengthways, flip one piece end for end and glue back together with whatever brand of urea formaldehyde you have lying about. If left for a few days this stiffens timber up a fair bit.

Definitely noticed a deflection when you lifted that saw motor! What do 'the viewers' expect from clamps? You said yourself they're quite capable of doing what is sensibly expected of them. Given the cost of clamps, I'm seriously choosing your clamp design over many others, using 'make-do' rigs is all very well, but for speed and accuracy I rate your design - heck, seen you using them often enough!

I think what this shows is that most people will be perfectly fine with the softwood, there's very little reason to spend the extra on the hardwood

Maybe old growth trees are stronger then new growth because of the "old man strength" conundrum. How old were these trees John!?

Altho i made some out of 1 1/4 plywood about 2 years ago and have had no problems at all

hey! where is some movie speech fragment at the end? oh u

Like the beard!

What are these people trying to clamp up? If you have to put so much pressure, on any clamp, to bring a joint together that it's in danger of breaking the clamp, maybe you need to look into your jointing technique, rather than stronger clamps.

I have plenty of maple in my kiln if anyone is near me in the pac nw you can have some.

I notice, like mine, there's more grey in that beard than years past. Beware the Hernia when lifting table saw motors! :)

I love watching your videos they are always packed full of ideas and make me think, but wouldn't it have been better to actually compare or demonstrate the clamps true virtues by loading them up so you could have compared tensile strength or compressive strength. I would be more concerned about the "tooth" stripping a chunk of wood off the bar or the locking mechanism failing instead of the bar having catastrophic failure. I realize one clamp could exert a hundred pounds of pressure while another clamp could strip a tooth and fail at 1/4 the pressure. Why compare the bar ridgidity when the teeth or locking mechanism are more likely to fail than the bar? Just curious.

Just for giggles John, will you do a test to see at what point the jaws/bar would fail under extreme clamping pressure. For glue ups, you would never need that kind of pulling force but I've used my 3/4" pipe clamps to move steel for welding and large wood framing members for alignment. As said, that amount of force would be unnecessary for most cases, it would certainly put to rest any doubts as to the strength of your design. My bet is that they will go far beyond the clamping strength needed.

Is the idea that the tensile strength is not really that relevant because these bend over long lengths?

The purpose of clamps in joinery is to simply hold the surfaces in contact until the glue bonding occurs and solidifies and not to offset poor surface preparation. If you need more than moderate force to close the gap then maybe, just maybe the pre-glue up joinery work hasn’t been completed. I believe that the excess force applied to close a large gap is captured in the wood and could manifest itself in some other form.. The “Get a Bigger Hammer” mentality has no applicability in finer wood joinery IMHO. My comments are related to finer woodworking and not more coarse work where mechanical fasteners might also be employed...... Not directed at you John......you’re way ahead of me......

When I think about the strength of a clamp, I'm thinking about the clamping force it can generate, not how much it would deflect if a heavy weight was hung on it. For normal glue-ups, that's not a whole lot of force needed. Too much clamping force will squeeze too much glue out weakening the joint. Another job that I use clamps for is forcing a recalcitrant joint together during glue up, and for me, the more force the clamp can generate, the better. The times that is an issue is when I took a "short cut" and skipped test fitting it with a dry assembly. Someday I might learn, but don't count on it. Time go get a bigger hammer.

Confused John weight is same as clamping ,thinking no

The 3/4-in pipe is a lot stiffer than the 1/2-in pipe. If it were part of the test, it would have won for sure.

5 + 9 =..... Still very nice clamps , no doubt they all performing Well. Love these video's

I see this demo is good for making a visual comparison between three materials and showing they are all adequate. I think that's what you're trying to show at least. I'm not an engineer, but isn't this test minimally useful since the bar needs to resist tensile deformation while clamping. I'd think the metal would be *much* stronger than wood in this way. What I'd liek to see is some test of the strength of the clamping pressure. Maybe just try clamping your bathroom scale and see what kinds of forces you can match before deflecting a certain amount?

Hard wood and soft wood are not directly related to their strength. It is annoying they were labeled that way, when it just creates confusion. For instance, Balsa is a hard wood, yet is one of softest(in strength terms) woods out there.

Woodworking academia going on here. And if your interested in more wood engineering search for the free usda forestry service publication: Mechanical properties of wood Ch.4 Wood handbook : wood as an engineering material. David W. Green et. al.

What it proved ?? rope burn is to be avoided.

A stiff hardwood 🤣, sorry too many innuendos to keep up.

I enjoy your videos ,but this test of clamp bending in your your test wasn’t appropriate, the clamps tensile strength needed testing. As a clamp tightens down on the wood between the two end brackets on the clamp the wood in the clamp is put in compression and the clamp pole/shaft holding the clamp brackets is put in tension. Your soft or hard wood clamps should work fine since the compression Involved in wood clamping is not that mush So consequently the tenson REACTION within the clamp pole/shaft is minimal . I also Concur with a previous comment that I would be a little concerned about putting to much stress of the teeth portion of the wood clamps. PS the Steel clamp is far away stronger in compression,Tension and even in bending.The fact that it bent more than the wood has more to do with its shape [the structural term is “moment of inertia“.The other structural Property differential between wood and steel is their Modulus of elasticity [wood is 1,600,000 and steel is 26,000,000] . Just a point of fact, Steel cables In the case of precast concrete and steel rebar in the case of Poured concrete add the tensile strength

Thanks for teaching me absolutely nothing lol

Bar none.

Learning absolutely nothing can be enjoyable.

If it proves nothing so why do the test?

lol 30 pounds