Even though you claimed this wasn’t the most exciting video you’ve ever made, I actually really enjoyed it. It was super helpful to learn what the issues were and how you solved them. Sort of like a basic physics lesson.
Awesome book that gives you step-by-step photos ruclips.net/user/postUgkxTNB_zFBSnTo_O1PqfVUwgi7ityw0JlKt and directions to make every day project. I can see myself making a few of these projects and giving them as housewarming and holiday gifts!
Quick suggestion from an aerospace engineer with a structures background: slacken off the tension in the bridge cables so they sag a couple of feet in the middle. It will reduce the horizontal load at the endpoints and make it more fun to play on. For example, if the weight of the bridge and people on it is 500lbs and there's a 5 degree droop from horizontal, the horizontal end loading is around 2,750lbs. If there's a 30 degree droop, the end load is around 430lbs.
That's a good point, more slack in the cables actually means less tension going on. I would guess that 12-degrees might be a good optimum, stealing from the common design goal for the angles on sailboat shrouds
I agree that the tension on the bridge should be reduced. What about expansion and contraction of the metal beams with temperature fluctuations? Could that affect the structures or the bridge?
@@adrianpaterson9904 I actually don't know off the top of my head what the thermal expansion coefficient is, but a quick Google for steel, and assuming it's around a 15' length, seems to show less than 0.1inchs over a 50 degF change.
I noticed that loosening the bridge cables was never considered. Love your You Tube videos a lot! Thumbs up from a retired general contractor of over 45 years.
I wondered the same thing. As the towers spread apart, the bridge cables came into tension. I bet loosening the bridge tension cables would have made this much easier. It is easy to be a Monday AM quarterback when you have a physics degree and aren't in the moment. Glad you found the problem before it caused a larger issue. Great video and keep them coming!
That was the idea screaming in my head from the moment he said they couldn't get the towers spread back apart. What was the thing that caused the issue in the first place. The bridge tension......
I LOVE this channel! Jason, if you had loosened the tension on the cables, your 8 hour project could have been completed much quicker. Also, the tension is still way too tight. Ultimately the excessive tension will damage the structure where the cables are attached. I suggest loosening the cables to protect the structure and to make crosing the bridge more fun. That being said, I wish I was as good a woodworker. Love the channel!
Wouldn't that have defeated the purpose? If you loosen the tension, you'll never get it back to the tension you need to make structurally sound once the beams are in place. The beams would have made the tension loose.
That bridge looked pretty tight around the 15:00 mark, where the bridge support cables preventing the towers from spreading? You could have just loosened the turnbuckles! Hindsight being 20/20 and things become obvious in a video...
Particularly because he still has to solve the problem, some others have pointed out after the last video, that the ropes of the Suspension Bridge will dig into the wood. He hasn’t used any bushings to prevent this from happening
Could you have not have used heavy duty springs on the bridge? Like the ones that hold long zip lines up to absorb the additional force applied when someone stands on the bridge.
The fix to the issue makes the cause of the issue kind of pointless. I mean the suspended bridge can now be replaced by a proper bridge using the 2 steel beams. Still nice to watch!
Maybe you should have released some tension on the bottom cables of the bridge, they look tight now, so probably stopping you moving the large tower I would probably release some tension anyway so the weather doesn't put strain on the structure, cold makes things shrink ;)
I was about to say exactly the same thing but thenI thought I should check to see if someone else already had. Nice one. Releasing the tension on the bridge should have happened before the truck being hooked, up in my opinion.
Should've taken the tension off the bridge. I bet if you'd have detached or just loosened the bridge the truck would've been able to put the tower apart. Also, you could build an angled climbing wall on the back side of the tower to anchor it down mimicking the stairs on the other tower.
This is what i ended up doing on a treehouse I built that was swaying due to the tension in the suspension bridge. I ran two 4x4 posts down from the treehouse to the ground at 45 degrees and built a net hammock/climbing net between them.
You could have replaced the suspension bridge with two wooden joists, and put the bridge planks directly on the wooden joists. The reason for a suspension bridge is to span a gap where you can't build a solid bridge. This is still a fun video. As an engineer, and a woodworker, I'm constantly getting myself out of problems that I make for myself 🙂
Pretty simple problem, side sway. Each structure needs to be strong enough to resist the loads they are designed to carry on their own. Your two tower structures don’t have any members to resist side sway. Take a look at how fire towers are designed. A couple of steel cables in the form of an X would be a a lot stronger. The steel beams have locked the two towers together, but the whole structure is still susceptible to side sway. Each tower needs to be able to stand entirely on its own, including wind and side loads. You should still do some x bracing. It might not seem like it, but your building and designing a fairly large and tall structure.
Great video In responding to a challenging situation. I worked on a project where we had a large steel cable net suspended from an existing bridge structure. In order to not overload the supporting structures we actually added slack to the cables. Only adding day 1-2% sag reduced the lateral forces on the supports by about 50%. It takes and exponential amount of force to resist the lateral loading the tighter you try to bring those cables. Seems counterintuitive but was a very simple solution.
By the time this is finished, it’ll be better designed and overbuilt than some people’s actual houses. At least the foreman will have his own place when he moves out of your house.
Another potential problem I noticed that you may want to address is where you drilled holes into the wood to run the cables through. With the tension you have on the cables, that can begin to cut into the wood. Those steel cables will start to cut into that wood like a saw. To prevent that you can just slip some steel couplers into the holes of the wood and have the cables run through the steel couples. Just get a piece of 1/2 or 3/4 inch pipe or whatever size you need to slip the cable through and for the pipe to fit snug in the hole of the wood and cut into 1 1/2 lengths or whatever the thickness the wood is and insert them into the holes and run the cable through that. That way the cables aren't eating away against the wood. You may want to file down the inside edges of the pipe so the cable tension isn't rubbing against the sharp edge of the inside of the pipe which could cause fraying to the cables.
This would be a good video for engineering students as they study the forces in catenary structures. Think of the forces in real bridges and power lines . Nice job recovering!
did you think about loosening your bridge's wires before pulling the towers appart? Because i don't know if it is an optical illusion, but while your towers now seems to be level, the post supporting your top wire for the bridge seems to be out of plomb on the video. Maybe that was what prevented you from being able to pull the towers appart and you applied enough force to pry them out... Might wanna check on that. Great video as always though!
You should have just loosened the cables of the bridge somewhat, so the big tower doesn't pull on the small tower anymore. That way the space between the towers would be bigger when pulling with the truck and the steel beams would drop into place easy. Nice build BTW.
I’m wondering if two 2x6x16’s cut to size would’ve worked just fine, rather than those awesome (but expensive) steel beams. I get that this channel has the budget to do things “overbuilt” but my first thought would’ve been “I can get a couple 16 foot 2x6’s for under 30 bucks”
A 2X6 wouldn't have been enough. 1 3/4 thickness would've warped easily. A 4X4 could've worked but a 4X6 would've been ideal. The extra money spent on bigger materials is worth not having to replace the 2X6 in 3 months and replumbing the entire structure.
LOOSEN THE CABLES ON THE BRIDGE!!! Sorry. I got so frustrated yelling at the tv that i had to comment. By the way. This is the first youtube video ive even commented on. I think.
1.Loosen cables. 2.Get towers plum and square. 3.Install braces (which should probably have some kind of cross-beam joining them together if you're going this route) 4.Tighten cables. You're route was "ugg me use truck!" and you've now got some pretty crazy torsion and tension going on throughout the structure.
Soooo...I'm guessing you never watched any of those Modern Marvel's shows talking about disasters. There's a whole show about bridge disasters. 😄 🤣 Guess that's why when the build bridges, the footings are driven very deep and are encased is a shit tonS of concrete and steel. But I can understand the thought process you might have gone through at the beginning. It's a 15' span. It's just a simple play area. I don't need an engineering degree....or do I 😁 Don't beat yourself up about it too much. No one got hurt and ya learned how NOT to do it.
Wouldn't cross bracing on the platforms have addressed the problem? Also, maybe a little bit of sag in the bridge so that there's less tension on the platforms.
Oh yeah, well, you can put in an angle brace, or you can probably ignore it. I know you're probably gonna be on it playing with the foreman, but realistically I doubt you're gonna be up there often enough to really make a lasting impact. Edit, well the cross beams will work, but now the flex is gone from the suspension bridge, kinda defeats the purpose, but it will work.
When you were fighting with trying to pull the tower out enough to slip the beam in, did you release tension on the cables? I would think by backing off the tension on the cables would allow you to pull the tower back enough to slip the beams in place then just tighten the tension again on the cables.
Great fix… now that you have that steel in place it looks like a great place to hang a relaxing porch swing between the towers or even add a hanging sleeping platform that you can put a small tent on. Thanks for sharing and would loosing the cables have given you any more ease to pull the towers apart?
I mean, there were already 4 steel cables pulling the towers together. You were fighting steel with steel, the wood was just an innocent victim here. It's a miracle nothing snapped.
You are an exemplary teacher. If you ever decided to moonlight, I’ll bet there are some construction/wood shop classes that could seriously benefit from your abilities. Teaching is much, much more than knowing how to do something or having done it. We’ve forgotten that over the past few decades. I have a son in high school who’s taking a construction class because I told him those skills are indispensable, whether he uses them in his future professional life or not. So far, they’ve done a boatload of OSHA book work, but haven’t cut a single board. They did help finish a pair of cornhole boards for one of the other classes (PE? 😮), and painted a bookcase for the library. But that’s it. Meticulous and deliberate are great qualities, but even the least entertaining of my classes (I have a master’s degree) were made exponentially better by great instructors/professors. This guy seems like he’s getting them the info, but too little of the practical - like sitting through some corporate training initiative designed less to impart information and more to limit corporate liability. Not a great way to teach. I watch your videos because I am a lifelong learner - I just dig it - because I’m interested in woodworking and want to be better at it, and because they are always entertaining even when you don’t think they are. Thank you. Seriously.
As an instructor running a high school level Diesel and heavy equipment repair program, I can say all that boring work is just as important, if not more, than the more interesting parts of the class. You can't build a house without a good foundation, and likewise, cannot teach students the rest of the material until they understand the very basics. As an example, I just gave my students a test on basic hand tools, after covering the material for a week. I then laid out 15 tools and had them identify the tools (the instruction was "what would you tell someone else if you were asking them to get you this tool to make sure they got you the right one?"). Many got a score below 80%...and no, I was not picky on the technical terms. If everyone involved in the conversation knows the same terms, then that term is good. If everyone involved calls a 1/2" drive impact socket a rock, then telling someone you need a 3/4" rock does get the correct information across. Even though I was very loose on what was required of them, I still saw many low scores. How would you expect a kid who doesn't understand basic hand tools to understand the flow path and gear ratios in a wheel loaders transmission?
@@ST-ku5ni I am an engineer, but in a completely different field so it doesn't really apply. I'm guessing he didn't want diagonal beams for the same reason he didn't want steel cables, because it's something to run into
@@WoLpH I was shocked that the original design didn't have diagonal bracing.. don't think I've ever seen a wooden tower like these built without them. Woodworkers should make engineer friends when tackling projects like this.
Lots of good comments but I found myself shaking my head as you climbed into the truck. Besides the cable tension (it's always the most obvious that we discover last) I was shocked to see the steel. I mean, 4x6 timber (even 2x would have worked in compression) would have retained the overall look. I like your willingness to share corrections as you go. Thanks for the good content and the ears look better too.
Yay! I can't wait to show this to the hubby... I won the bet! I completely called this... I'm only 3 mins into the video, can't wait to see your fix... Sorry I'm rejoicing at your oops... Thanks for the $20
Dear Mr Moth, There could be a problem where the cable threads through the uprights (36inch height) as the cable may indeed start sawing its way down the post with the movement .... I recommend passing the cable through a sheaf (piece of waterpipe?)
Jason - nice solution to a difficult problem. Practical and functional. For what it is worth, using a bottle hydraulic jack is much easier than a scissors jack. More power and more easily controlled. I replaced the scissor jack in my truck after trying to change a tire when it was raining out......
Seems like an easier and less costly option, would have been to use two 4”x6”x20’ treated beams, notched about 2.5” where the beams overhang onto both structures, spaced underneath the bridge planks, and place the bridge on top of the beams (no more springy, unsafe suspension bridge that is a slipping hazard after a light rain), and both structures are then solid, once again, eh?!?
Love this series. I'm about to adopt my 2 and 4-year old grandkids so you're giving me some good ideas. Since they're so little now they wouldn't be able to use it, which is good because they'll have probably graduated from high school before I finish it (ADHD).
I'm basically just regurgitating what a lot of other people have already said, but I really appreciate you highlighting your mistakes and explaining how you identified a solution as opposed to covering it up and pretending like it was all part of the plan. Even when it comes to woodworking, seeing mistakes really helps me to be mindful of things I likely wouldn't have given much thought to otherwise. Arguably even more importantly, seeing how you work out how to fix that mistake really comes in handy when I make mistakes of my own. I'm really excited to see the rest of this series! You should definitely do more like this! (maybe not so spread out because binging some Bourbon Moth is something I do regularly)
Appreciate you correcting a flaw and pointing it out… but honestly a 2x6 piece of wood on each side of the bridge would have been enough, all you need is a stop, they aren’t supporting a load, they are creating resistance. I would have tried that.
I appreciate the problem-solving approach you demonstrated in this video. All too often we are given a perfectly executed build but this project kept me engaged from the beginning. Thanks for sharing the successes along with the struggles.
Anyone else notice what a beautiful spot you live in? The last minute of the video showing the tall trees, fluffy clouds and blue sky is lovely. And the honesty of everyone in this community is epic. 🌞
Expensive steel beams sort of eliminated the need for a suspension bridge, but cool for kids to be able to bounce across the span. Rustic logs probably could have accomplished solving the towers pinching together, and saved a few bucks. I know, I know…who ask me anyways. Every one of my projects could be second guessed. Love your channel!
Yeah, my thought too. I mean, I don't dispute the validity of the solution, and bouncy bridges can be fun. But, yeah... That said, I feel like the option B of larger bracing for the platform structure probably actually would've worked fine, assuming the footings are properly anchored (sorry, I'm one of those dummies that didn't go watch the first "making of" video, so I don't know what the status of the footings actually is). And then the suspension bridge could be justified both recreationally and mechanically. :)
That was actually the first thing on my mind when I saw you were building that bridge but you seemed super confident about how sturdy the towers were that I just threw that thought away.
With my current age and planning to get kids: Heck - Good idea! With remembering me as a 9yr old: DON'T YOU DARE taking this new play/climb/fall opportunity away 😂🙈
I'm an amateur builder. I live in the house I built by myself. Nobody other than my wife has helped whatsoever. I've made this same mistake. I ended up learning a lot about sheer strength. Now my house is super solid even though I built the entire thing on skids. I saw at 12:09 that when you hit the beam the whole structure wobbled. It doesn't seem like much but the higher you build, it will get worse. You may want to be extra aware of that possible issue for the future. I love your videos. I'm subscribed and I'm building the same staircase for a customer, so thank you!
While Trent builds $100,000 canoes, Jason builds $100,000 treeless treehouses! Haha. But seriously though, great video as always! I look forward to them every week.
So this is where it gets tricky. The weight of the bridge and it's occupants is 100%, that part is true. Let's say that the amount of dip in the bridge is approximately .4 feet and that the load combination of the wood slats and the people is about 600 lbs. (it could be much more than that if they are jumping. Right now the bridle angle of the steel cables is 174.28 degrees. The force on a single cable is 6000 lbs, but that's a force of 6000 lbs on each side pulling inwards. Jason has two cables, so that is split between the 2 at 3000lbs on each cable pulling inwards. IF he were to have a drop in the middle of the bridge of at least 12 inches, then that load per cable drops to 2418lbs and divided by 2 is 1206lbs, more than half of what it was originally. If he had a drop of 24 inches, then it would be 1236 lbs each divided by 2 cables would be 618 on each cable attachment point. This is why when you see suspension bridges they have a dip, especially playground bridges where the shock load of a bunch of kids jumping on it can be way higher. Adding the beams in keeps the structures from pulling in, but it does not loosen the tension on the cables or the attachment points. There is still 3000 lbs or more on each attachment when someone walks across.
I'm an architect who watch your videos to learn woodworking...generally feeling dumb as quality work is hard to master. This time though, I would've given you a few tips beforehand...brace those stilts!
I am a big fan of yours! Look forward to your videos every week (even over my geek stuff). Two things; first, with a few close calls, perhaps it's time to institute HARD HATS? Second, since you have effectively increased the overall structural integrity with the steel beams👍🏽would you consider adding a loft to the structure? Literally taking it to the next level. Love the posts.
A more *aesthetically appealing* and *technologically fascinating woodworking effort* would have been to design and build *cantilever trusses* across the span - that would have put *both* your woodworking and structural skills on full display - both strong AND pretty!
For the NEXT time you have to do this.... ratchet winches are your friend. My buddy and I demo'd an 80' x 40' 150 year old barn in Sacramento to salvage the redwood beams and tin some years back. Because it the city had built up around it, there were fences less than 3' from two sides of it. We hooked 3 ratchet ratchet winches to anchor points opposite the fences and pulled it toward the opposite corner - we were able to make the entire building lean away from the fences - then cut into the principal posts and slowly winched the whole thing until it collapsed with no damage to the surrounding buildings. Yeah... super safe. But it worked. Pulling the treehouse a few inches would have been a breeze.
Please go back and fix the cable connections! The cable clamps are on wrong, there aren’t enough of them, you need thimbles at the turn back at the eyebolts. If there was enough force to move the tower, you have enough to damage the cable.
All these comments about what he should have done...my first thought was how the beams will be used to walk across! I will however agree with any comment about loosening the cables a bit though. Less force and more fun! Looking good Jason!
Yep, was thinking a nice slide on the other end. Imagining running up the stairs, across the bridge and a bar across the entrance to the slide. Grab that and whip down. Oh to be a kid again. Cool build though. And I see it would be larger than the current footprint so not sure if something is in the way down there.
I actually thought a slide at the large end with the same sides as the stairs would have done the same job that the stairs are doing on the small end. But hey, the steel beams work so all good.
Thank you for showing a very common theme in anything DIY. Something that shouldn’t take long and seems very “SIMPLE” turns into a big headache, consumes a bunch of time and requires so good old fashioned ingenuity.
It's been some time since I calc'd a catenary, but the more level you drive the bridge, the higher the stress on the upper decks, pulling them together. You may not have seen the end of this yet: time and stress equal "creep", the deformation of materials. A solution: support the bridge from the steel beams, even if only in a couple/three places. That will relieve the tension on the cable/wood interfaces. Enjoyed the video, as always. While you've come up with a lot of innovative techniques, we all might keep in mind that this kind of construction is millennia old, and the conventional techniques are "conventional" because they've proven their worth. But I gotta admit to the fun!
Load Paths! This could also have been fixed by adding bracing to the structures it self. The load paths are still not complete down to the footings, adding the HSS sections is one way to 'close' the loop. Next time reach out the community for a quick "peer review", would love to give some advice in the design stage that could have prevented this. Looks good non the less! Love the videos.
Running the cables through the 2 platforms and then at say 45+ degrees down on each side , to a suitable concrete anchor will reduce the lateral tension.
attaching the end of cables to the ground under the beams it would minimize the horizontal vector of force depending to the pressure over the bridge,so if you put more pressure you get more horizontal force minimizing .
I think I would have added a diagonal anchor to the other side instead. You are right in a single cable would be dangerous. So I think I would have installed a slide. I mean it would serve as an alternate escape route incase the small tower was not able to be used for egress.
Thank you so much for showing a mistake and the fixing of it. Single biggest problem with build videos is not showing the issues that arise and the problem solving.
Through most of the video... Me: Dude, you just need a wooden beam and a car jack to force those things apart. BMW: So then I got a wooden beam and a car jack... Me: HA! Now, you need to secure the ends of the beam before you jack it, or you might hurt yours... BMW: And the beam fell down, so I secured the ends to prevent it from happening again. Me: HA! Later... BMW: This bridge makes it really easy to twerk. Me: No. NO. NOOOOOOOOOO!!!!!!!!!!! SUGGESTION: On the opposite side of the large tower, install a couple of diagonal boards like stair stringers. Only don't put stair on them - put a cargo net on them for kids to climb. Or a slide. Or both! Also, a steel ship's ladder coming off the large tower would make another great option.
You kept saying that many of us said that may of us claimed that you'd overbuilt these. Well, I guess that shows how smart we are! HA. Who looks silly now?!?!?! wait...............no
Why didn't you put 45 deg. bracing in the corners. You had flex from lack of bracing and the 45 deg. bracing would more than likely take care of it or most of it anyway. No offence to the beams, but you have taken away the look of the suspended bridge. Just a thought.
....it would have been much more of a shame if they died...... that is DRY, dark humour. I like! I think this video is just as interesting as the others. Solving problems is just as educational as building without problems. 👍👍👍
The moment you said what the nature of the issue was -- the suspension bridge -- I knew what the problem was -- you've built framework boxes with no real 3-d interaction -- e.g., an angled member that ties the structure up in three directions rather than each connection tied in 2 directions**. In other words, it does not handle shear forces at all. All it needs is some angled connections between the different support beams -- ideally one connection at an angle between each leg, plus one across to the "catty corner" leg. I'm only 2:15 into the vid... let's see if I'm correct. OK, @ 6:25 -- you are VASTLY underestimating the increase in stability which a single angle brace -- not even a full X, and not one enclosing the whole structure -- i mean a single brace at about 20-30° at the top of the four/six support beams of each structure connecting it to the adjacent beam ... especially if you added one more connecting one catty-corner to the other, again, at about 20-30°. That thing would be like the whole thing was on a solid bulk of GRANITE rather than the flexible structure you have. Believe me -- try this yourself -- build a small 4-sided frame -- a drawer without a bottom. Now apply lateral stress and notice how easily it deforms when you push at the top while holding the bottom still. NOW take that same thing, attach a thin little piece of 1x¼" TRIM MOULDING from one corner to the next, and see what a massive difference it makes in the rigidity of the whole thing. Add two of them in an "X" from each of the catty-corners to the other, and that thing is going to be a flinkin' ROCK. I have seen this happen with boxes, and the rigidity it offers is nothing short of amazing to me, and I *know* it does it. You can -- and no doubt have -- done what you decided, but it kind of defeats the purpose of the suspension bridge in the first place, to my lights. And it still leaves the entire structure susceptible to shear forces, though with the staircase that should be mitigated in at least that direction. I am suspecting that, once you have the treehouse up, you will see that thing swaying a lot in the non-stair direction in a major windstorm, as it applies lateral force against the walls of the structure which are perpendicular to the stair axis. When you get a big windstorm, go out and see what it is doing. I am betting you it will be swaying notably in that direction. ALWAYS create structural members in three dimensions, not just two. That's kind of what your short-angles (I believe the term is "knee braces") do, but they aren't long enough to really make it rigid. The cross-bracing does not even need to be substantial -- a single 2x4 or even a 2x2 would have an amazing affect on the rigidity of the structure. Also, note that plywood sheathing effectively does this same thing -- it just uses a big solid piece rather than a thin piece. OK, @ 12:15 -- it appears to me as though you actually twisted the 6-pole structure somewhat, too, since the bridge is much closer to one corner of the structure. That is, it's not just leaning, it's leaning more on the side where the corner bridge is connected near than it is on the opposing corner. Makes a kind of sense, if you look at the physics of the forces involved. ====== ** Yes, nominally, the floors go in 3 directions so that shear isn't going to be an issue for that. But the support beams have no such interactive element.
Homeschool Mom of 10 so I don't have access to metal beams. Is there a way to build from beginning to make suspension bridges off platforms built around actual trees? Trying to replicate a bit of Lord of the Rings Lothlorien Elve area with 4 platforms built at varying heights on stilted footings that wrap around existing trees, joined by suspension bridges. The trees are the standard tall skinny trunks all over middle Tennessee
Great job, admittedly I was one who said it was over engineered .. as far as size of lumber used. which is still true, its great but it is! Smaller lumber could have been used. and proper cross bracing would of helped or solved this issue as well. and simple 2x6 or 4x4 wood would have accomplished the same thing as the industrial overkill 4x4 steal tubing. lol when I say proper cross bracing, I mean you have corner cross bracing which is ok for things up top, but when you have a 8 ft tall structure that weights about 2500+ lbs, you need full top to bottom cross bracing. Like building bridges you don't just see a cross brace on corners, they go the length or height of the span in that section. when designing structures or Planes in my job. you want maximum strength with minimum weight. Now overkill on a child's play-set is all good and isn't hurting anything of course other than wallet.
Edit: he literally just did what I mentioned below. Should have kept watching before commenting! 😂 At least we had the same idea! 👍 Another way to span the gap could be to use a 4x4 shorter than the gap, by about a foot or so, and use a car jack between the 4x4 and one of the structures, to slowly spread the two structures apart. Like how they jack up a house when it’s sagging, but horizontally. Hanging/lifting the 4x4 could cause some issues but it was just a though that popped in my head.
2 года назад
It's a way to solve a problem.😂 Now with those overkill beams you might as well make a solid bridge instead. 🤔 Also some diagonal berms stretching from top to bottom would have worked too. (without those overrated beams)😉 Just looking at bridge constructions or scaffolding and googling this stuff would have helped too or just asking the community. 😉
STEEL CABLES WILL NOT STRETCH! The real problem in installing the beams is that you are getting a huge amount of resistance from the cables. Looking down the bridge plane you can see it is nearly flat. The top hand rail cables are about as far as yhey can go as well. Loosening the bottom cables would have made it a lot easier. At least you got it done!
Man... You really screwed up!! But hey, you fix it! Nah lol I'm joking, it was cool seeing how you went about fix the issue you where having! Great work. Well done
Even though you claimed this wasn’t the most exciting video you’ve ever made, I actually really enjoyed it. It was super helpful to learn what the issues were and how you solved them. Sort of like a basic physics lesson.
Awesome book that gives you step-by-step photos ruclips.net/user/postUgkxTNB_zFBSnTo_O1PqfVUwgi7ityw0JlKt and directions to make every day project. I can see myself making a few of these projects and giving them as housewarming and holiday gifts!
Quick suggestion from an aerospace engineer with a structures background: slacken off the tension in the bridge cables so they sag a couple of feet in the middle. It will reduce the horizontal load at the endpoints and make it more fun to play on. For example, if the weight of the bridge and people on it is 500lbs and there's a 5 degree droop from horizontal, the horizontal end loading is around 2,750lbs. If there's a 30 degree droop, the end load is around 430lbs.
Agreed. The cables need some slack! Basic free body diagram.
That's a good point, more slack in the cables actually means less tension going on. I would guess that 12-degrees might be a good optimum, stealing from the common design goal for the angles on sailboat shrouds
I agree that the tension on the bridge should be reduced. What about expansion and contraction of the metal beams with temperature fluctuations? Could that affect the structures or the bridge?
@@adrianpaterson9904 I actually don't know off the top of my head what the thermal expansion coefficient is, but a quick Google for steel, and assuming it's around a 15' length, seems to show less than 0.1inchs over a 50 degF change.
Yeah, as a structural engineer I couldn't even watch enteirly the first video about the bridge without losing it.
I noticed that loosening the bridge cables was never considered.
Love your You Tube videos a lot!
Thumbs up from a retired general contractor of over 45 years.
I wondered the same thing. As the towers spread apart, the bridge cables came into tension. I bet loosening the bridge tension cables would have made this much easier. It is easy to be a Monday AM quarterback when you have a physics degree and aren't in the moment. Glad you found the problem before it caused a larger issue. Great video and keep them coming!
Exactly what I was thinking! 👍👍
They were fighting the cable tension exactly
That was the idea screaming in my head from the moment he said they couldn't get the towers spread back apart. What was the thing that caused the issue in the first place. The bridge tension......
Yeah, at least loosen the cable when you're spreading the towers :)
I LOVE this channel! Jason, if you had loosened the tension on the cables, your 8 hour project could have been completed much quicker. Also, the tension is still way too tight. Ultimately the excessive tension will damage the structure where the cables are attached. I suggest loosening the cables to protect the structure and to make crosing the bridge more fun. That being said, I wish I was as good a woodworker. Love the channel!
Why didn’t you take the tension off of the cable? Would’ve fit easier without so much drama. Otherwise too kewl. Greetings from Gera, Germany
Frank, you are acting too much like German 😂 it’s good to lighten up and enjoy a little drama 🎭 🤠🇫🇮
@@finntexbuild4809 I use to live in Grants Pass and built my kids something similar. Gotta love it
Wouldn't that have defeated the purpose? If you loosen the tension, you'll never get it back to the tension you need to make structurally sound once the beams are in place. The beams would have made the tension loose.
@@sherespawns8373 After Insertion then retension the cables.
Could you have taken tension off the bridge cables first then used your ute to pull the house easier?
Seems so obvious to me! Could have gotten the job done in no time. Spent all my time shouting at the video to release the tension in the cables!
Me too
Yeah- I’ve been yelling this the whole time I was watching!!! Release the tension!!!
Same here 😂
Yup
That bridge looked pretty tight around the 15:00 mark, where the bridge support cables preventing the towers from spreading? You could have just loosened the turnbuckles! Hindsight being 20/20 and things become obvious in a video...
Don't know if it will cause any issues structurally, but you could weld some handle bars on the bottom of those beams to make a sort of jungle gym
Turn one into one of those zip handles that you see on play structures now.
Particularly because he still has to solve the problem, some others have pointed out after the last video, that the ropes of the Suspension Bridge will dig into the wood. He hasn’t used any bushings to prevent this from happening
Could you have not have used heavy duty springs on the bridge? Like the ones that hold long zip lines up to absorb the additional force applied when someone stands on the bridge.
The fix to the issue makes the cause of the issue kind of pointless. I mean the suspended bridge can now be replaced by a proper bridge using the 2 steel beams. Still nice to watch!
but what fun would that be? no suspension bridge, no bounce.
@@johnrhoades1776 would still be funnier than dropping out on day 1, don't you think?
Maybe you should have released some tension on the bottom cables of the bridge, they look tight now, so probably stopping you moving the large tower
I would probably release some tension anyway so the weather doesn't put strain on the structure, cold makes things shrink ;)
I was about to say exactly the same thing but thenI thought I should check to see if someone else already had. Nice one. Releasing the tension on the bridge should have happened before the truck being hooked, up in my opinion.
Did you think about loosening the cables. In trying to open up the span, you are fighting the cables. Looking forwarding to the house building.
That was my thought aswell
Dido
Me too
I thought the same
I was shouting that at my phone
Should've taken the tension off the bridge. I bet if you'd have detached or just loosened the bridge the truck would've been able to put the tower apart.
Also, you could build an angled climbing wall on the back side of the tower to anchor it down mimicking the stairs on the other tower.
Yep. Also, climbing wall is a great idea!
Or a slide for the kids to slide down.
This is what i ended up doing on a treehouse I built that was swaying due to the tension in the suspension bridge. I ran two 4x4 posts down from the treehouse to the ground at 45 degrees and built a net hammock/climbing net between them.
Dude honestly, seeing you make mistakes reminds me that I have a chance at being good in the woodworking world. You’re still the man.
You could have replaced the suspension bridge with two wooden joists, and put the bridge planks directly on the wooden joists. The reason for a suspension bridge is to span a gap where you can't build a solid bridge. This is still a fun video. As an engineer, and a woodworker, I'm constantly getting myself out of problems that I make for myself 🙂
Lol exactly this doesn't make sense at all but fun content nevertheless
But then it wouldn't bounce at all, losing a lot of the appeal of the bridge.
Pretty simple problem, side sway. Each structure needs to be strong enough to resist the loads they are designed to carry on their own. Your two tower structures don’t have any members to resist side sway. Take a look at how fire towers are designed. A couple of steel cables in the form of an X would be a a lot stronger.
The steel beams have locked the two towers together, but the whole structure is still susceptible to side sway. Each tower needs to be able to stand entirely on its own, including wind and side loads. You should still do some x bracing. It might not seem like it, but your building and designing a fairly large and tall structure.
I agree with this. I think X bracing would solve the problem by itself. Just have to direct the load back into the concrete footers.
Great video In responding to a challenging situation. I worked on a project where we had a large steel cable net suspended from an existing bridge structure. In order to not overload the supporting structures we actually added slack to the cables. Only adding day 1-2% sag reduced the lateral forces on the supports by about 50%. It takes and exponential amount of force to resist the lateral loading the tighter you try to bring those cables. Seems counterintuitive but was a very simple solution.
By the time this is finished, it’ll be better designed and overbuilt than some people’s actual houses. At least the foreman will have his own place when he moves out of your house.
Another potential problem I noticed that you may want to address is where you drilled holes into the wood to run the cables through. With the tension you have on the cables, that can begin to cut into the wood. Those steel cables will start to cut into that wood like a saw. To prevent that you can just slip some steel couplers into the holes of the wood and have the cables run through the steel couples. Just get a piece of 1/2 or 3/4 inch pipe or whatever size you need to slip the cable through and for the pipe to fit snug in the hole of the wood and cut into 1 1/2 lengths or whatever the thickness the wood is and insert them into the holes and run the cable through that. That way the cables aren't eating away against the wood. You may want to file down the inside edges of the pipe so the cable tension isn't rubbing against the sharp edge of the inside of the pipe which could cause fraying to the cables.
This would be a good video for engineering students as they study the forces in catenary structures. Think of the forces in real bridges and power lines . Nice job recovering!
Lol. I assumed you just hadn't fitted these yet. Why wouldn't you use wood beams. 🤷🏼♂️
did you think about loosening your bridge's wires before pulling the towers appart?
Because i don't know if it is an optical illusion, but while your towers now seems to be level, the post supporting your top wire for the bridge seems to be out of plomb on the video. Maybe that was what prevented you from being able to pull the towers appart and you applied enough force to pry them out... Might wanna check on that.
Great video as always though!
You should have just loosened the cables of the bridge somewhat, so the big tower doesn't pull on the small tower anymore. That way the space between the towers would be bigger when pulling with the truck and the steel beams would drop into place easy. Nice build BTW.
Jimmy DiResta posted a video 30 minutes earlier and I chose to watch your one first. Consider that a win. ;)
I’m wondering if two 2x6x16’s cut to size would’ve worked just fine, rather than those awesome (but expensive) steel beams. I get that this channel has the budget to do things “overbuilt” but my first thought would’ve been “I can get a couple 16 foot 2x6’s for under 30 bucks”
A 2X6 wouldn't have been enough. 1 3/4 thickness would've warped easily. A 4X4 could've worked but a 4X6 would've been ideal. The extra money spent on bigger materials is worth not having to replace the 2X6 in 3 months and replumbing the entire structure.
Cross members was the simple fix here. In that aspect 2X6's would've done nicely. It would've completely changed the look he was going for though.
LOOSEN THE CABLES ON THE BRIDGE!!!
Sorry. I got so frustrated yelling at the tv that i had to comment.
By the way. This is the first youtube video ive even commented on. I think.
1.Loosen cables.
2.Get towers plum and square.
3.Install braces (which should probably have some kind of cross-beam joining them together if you're going this route)
4.Tighten cables.
You're route was "ugg me use truck!" and you've now got some pretty crazy torsion and tension going on throughout the structure.
Soooo...I'm guessing you never watched any of those Modern Marvel's shows talking about disasters. There's a whole show about bridge disasters. 😄 🤣
Guess that's why when the build bridges, the footings are driven very deep and are encased is a shit tonS of concrete and steel.
But I can understand the thought process you might have gone through at the beginning. It's a 15' span. It's just a simple play area. I don't need an engineering degree....or do I 😁
Don't beat yourself up about it too much. No one got hurt and ya learned how NOT to do it.
Wouldn't cross bracing on the platforms have addressed the problem? Also, maybe a little bit of sag in the bridge so that there's less tension on the platforms.
Cross bracing!!!!!!!!!!
Oh yeah, well, you can put in an angle brace, or you can probably ignore it. I know you're probably gonna be on it playing with the foreman, but realistically I doubt you're gonna be up there often enough to really make a lasting impact.
Edit, well the cross beams will work, but now the flex is gone from the suspension bridge, kinda defeats the purpose, but it will work.
When you were fighting with trying to pull the tower out enough to slip the beam in, did you release tension on the cables? I would think by backing off the tension on the cables would allow you to pull the tower back enough to slip the beams in place then just tighten the tension again on the cables.
Great explanation of the problem! That is helpful for me as a future treehouse tower and bridge builder.
Did you really need 4x4 steel tubing to make the braces. I think 4x4 lumber would have worked out just as well. I hate to think what that tubing cost.
Great fix… now that you have that steel in place it looks like a great place to hang a relaxing porch swing between the towers or even add a hanging sleeping platform that you can put a small tent on. Thanks for sharing and would loosing the cables have given you any more ease to pull the towers apart?
I mean, there were already 4 steel cables pulling the towers together. You were fighting steel with steel, the wood was just an innocent victim here. It's a miracle nothing snapped.
You are an exemplary teacher. If you ever decided to moonlight, I’ll bet there are some construction/wood shop classes that could seriously benefit from your abilities. Teaching is much, much more than knowing how to do something or having done it. We’ve forgotten that over the past few decades. I have a son in high school who’s taking a construction class because I told him those skills are indispensable, whether he uses them in his future professional life or not. So far, they’ve done a boatload of OSHA book work, but haven’t cut a single board. They did help finish a pair of cornhole boards for one of the other classes (PE? 😮), and painted a bookcase for the library. But that’s it. Meticulous and deliberate are great qualities, but even the least entertaining of my classes (I have a master’s degree) were made exponentially better by great instructors/professors. This guy seems like he’s getting them the info, but too little of the practical - like sitting through some corporate training initiative designed less to impart information and more to limit corporate liability. Not a great way to teach.
I watch your videos because I am a lifelong learner - I just dig it - because I’m interested in woodworking and want to be better at it, and because they are always entertaining even when you don’t think they are. Thank you. Seriously.
As an instructor running a high school level Diesel and heavy equipment repair program, I can say all that boring work is just as important, if not more, than the more interesting parts of the class. You can't build a house without a good foundation, and likewise, cannot teach students the rest of the material until they understand the very basics. As an example, I just gave my students a test on basic hand tools, after covering the material for a week. I then laid out 15 tools and had them identify the tools (the instruction was "what would you tell someone else if you were asking them to get you this tool to make sure they got you the right one?"). Many got a score below 80%...and no, I was not picky on the technical terms. If everyone involved in the conversation knows the same terms, then that term is good. If everyone involved calls a 1/2" drive impact socket a rock, then telling someone you need a 3/4" rock does get the correct information across. Even though I was very loose on what was required of them, I still saw many low scores. How would you expect a kid who doesn't understand basic hand tools to understand the flow path and gear ratios in a wheel loaders transmission?
I assumed you were going to add a few diagonal cross beams to the towers... but this definitely works as well ;)
A lot of armchair engineers here, and this was the best comment and best solution. (Maybe you are an engineer as well, lol) I am not. Enjoy your day!
@@ST-ku5ni I am an engineer, but in a completely different field so it doesn't really apply. I'm guessing he didn't want diagonal beams for the same reason he didn't want steel cables, because it's something to run into
@@WoLpH I was shocked that the original design didn't have diagonal bracing.. don't think I've ever seen a wooden tower like these built without them. Woodworkers should make engineer friends when tackling projects like this.
Lots of good comments but I found myself shaking my head as you climbed into the truck. Besides the cable tension (it's always the most obvious that we discover last) I was shocked to see the steel. I mean, 4x6 timber (even 2x would have worked in compression) would have retained the overall look. I like your willingness to share corrections as you go. Thanks for the good content and the ears look better too.
Yay! I can't wait to show this to the hubby... I won the bet! I completely called this... I'm only 3 mins into the video, can't wait to see your fix... Sorry I'm rejoicing at your oops... Thanks for the $20
Wood across that distance would compress and bend I assume? The black looks nice with the wood I think you failed upward 👍
Wood would have been totally fine... Those steel beams are a ridiculously over the top solution to this problem.
wood would have been fine.
@@GreganDunn his kids are going on this
@@CoveringFish would be plenty strong with just wood. Kids would be totally safe! The steel is complete overkill.
Dear Mr Moth, There could be a problem where the cable threads through the uprights (36inch height) as the cable may indeed start sawing its way down the post with the movement .... I recommend passing the cable through a sheaf (piece of waterpipe?)
I commented similar a few weeks ago. Protect them holes!!!
Good point, could maybe cut a U-shaped piece of PVC and shove it in there so the cable wears the PVC out which is replacable.
Jason - nice solution to a difficult problem. Practical and functional. For what it is worth, using a bottle hydraulic jack is much easier than a scissors jack. More power and more easily controlled. I replaced the scissor jack in my truck after trying to change a tire when it was raining out......
Seems like an easier and less costly option, would have been to use two 4”x6”x20’ treated beams, notched about 2.5” where the beams overhang onto both structures, spaced underneath the bridge planks, and place the bridge on top of the beams (no more springy, unsafe suspension bridge that is a slipping hazard after a light rain), and both structures are then solid, once again, eh?!?
Love this series. I'm about to adopt my 2 and 4-year old grandkids so you're giving me some good ideas. Since they're so little now they wouldn't be able to use it, which is good because they'll have probably graduated from high school before I finish it (ADHD).
I agree, start now since this is a big project.
I'm basically just regurgitating what a lot of other people have already said, but I really appreciate you highlighting your mistakes and explaining how you identified a solution as opposed to covering it up and pretending like it was all part of the plan. Even when it comes to woodworking, seeing mistakes really helps me to be mindful of things I likely wouldn't have given much thought to otherwise. Arguably even more importantly, seeing how you work out how to fix that mistake really comes in handy when I make mistakes of my own. I'm really excited to see the rest of this series! You should definitely do more like this! (maybe not so spread out because binging some Bourbon Moth is something I do regularly)
I saw this happening in the last video. Soz, should of said something. Love these videos and not a hater 😘
Appreciate you correcting a flaw and pointing it out… but honestly a 2x6 piece of wood on each side of the bridge would have been enough, all you need is a stop, they aren’t supporting a load, they are creating resistance. I would have tried that.
Cross bracing on the structures would of prevented this😂
Since you have a fabricator friend, you should have him make a set of drop down monkey bars to attach to the beams.
Not a huge fan of the beam solution but, you could have gone with wood instead of steel.
I appreciate the problem-solving approach you demonstrated in this video. All too often we are given a perfectly executed build but this project kept me engaged from the beginning. Thanks for sharing the successes along with the struggles.
Anyone else notice what a beautiful spot you live in? The last minute of the video showing the tall trees, fluffy clouds and blue sky is lovely. And the honesty of everyone in this community is epic. 🌞
You've pretty much had every idea I had to get the towers apart. But I would have used some bedliner on the beams to help prevent rust.
Expensive steel beams sort of eliminated the need for a suspension bridge, but cool for kids to be able to bounce across the span. Rustic logs probably could have accomplished solving the towers pinching together, and saved a few bucks. I know, I know…who ask me anyways. Every one of my projects could be second guessed. Love your channel!
Yeah, my thought too. I mean, I don't dispute the validity of the solution, and bouncy bridges can be fun. But, yeah...
That said, I feel like the option B of larger bracing for the platform structure probably actually would've worked fine, assuming the footings are properly anchored (sorry, I'm one of those dummies that didn't go watch the first "making of" video, so I don't know what the status of the footings actually is). And then the suspension bridge could be justified both recreationally and mechanically. :)
Budget wise, that's what i thought too.
I mean, wooden beams will do the exact same thing, heck, they even used a beam to spread the towers...
Why not use 4x4 pressure treated wood, it would be much less expensive and blend in with the existing material.
Think of it as a clothes line or power line. You need slack. You have it tensioned too high. You could solve 90% of the prob by giving it slack
Can you do a fireman's Pole on the opposite side?
That was actually the first thing on my mind when I saw you were building that bridge but you seemed super confident about how sturdy the towers were that I just threw that thought away.
Yeah, same. Engineering math classes for the win!
Might want to put some kind of barrier in so the little ones won't be tempted to walk the beam.
With my current age and planning to get kids: Heck - Good idea!
With remembering me as a 9yr old: DON'T YOU DARE taking this new play/climb/fall opportunity away 😂🙈
My first thought was “I want to walk across the balance beam!”
Disclaimer: "no expense was saved in the making of this tree house".
Really liked seeing how he engineered a solution to the problem
Did you think to loosen the bridge cables?
I'm an amateur builder. I live in the house I built by myself. Nobody other than my wife has helped whatsoever. I've made this same mistake. I ended up learning a lot about sheer strength. Now my house is super solid even though I built the entire thing on skids. I saw at 12:09 that when you hit the beam the whole structure wobbled. It doesn't seem like much but the higher you build, it will get worse. You may want to be extra aware of that possible issue for the future. I love your videos. I'm subscribed and I'm building the same staircase for a customer, so thank you!
While Trent builds $100,000 canoes, Jason builds $100,000 treeless treehouses! Haha. But seriously though, great video as always! I look forward to them every week.
Bravo Jason you succeeded, it wasn't easy 😊, nothing to do with the table at Rubio
So this is where it gets tricky. The weight of the bridge and it's occupants is 100%, that part is true. Let's say that the amount of dip in the bridge is approximately .4 feet and that the load combination of the wood slats and the people is about 600 lbs. (it could be much more than that if they are jumping. Right now the bridle angle of the steel cables is 174.28 degrees. The force on a single cable is 6000 lbs, but that's a force of 6000 lbs on each side pulling inwards. Jason has two cables, so that is split between the 2 at 3000lbs on each cable pulling inwards. IF he were to have a drop in the middle of the bridge of at least 12 inches, then that load per cable drops to 2418lbs and divided by 2 is 1206lbs, more than half of what it was originally. If he had a drop of 24 inches, then it would be 1236 lbs each divided by 2 cables would be 618 on each cable attachment point. This is why when you see suspension bridges they have a dip, especially playground bridges where the shock load of a bunch of kids jumping on it can be way higher. Adding the beams in keeps the structures from pulling in, but it does not loosen the tension on the cables or the attachment points. There is still 3000 lbs or more on each attachment when someone walks across.
I'm an architect who watch your videos to learn woodworking...generally feeling dumb as quality work is hard to master. This time though, I would've given you a few tips beforehand...brace those stilts!
Great Explanation and verry elegant solved Problem 🙂 Wish you Luck with all your Projects.
You mean to tell us you put grandma in danger????🤣🤣🤣🤣
Kids todays word of the day is RACKING, also know as lateral force, say it with me RACKING!
I am a big fan of yours! Look forward to your videos every week (even over my geek stuff). Two things; first, with a few close calls, perhaps it's time to institute HARD HATS? Second, since you have effectively increased the overall structural integrity with the steel beams👍🏽would you consider adding a loft to the structure? Literally taking it to the next level. Love the posts.
A more *aesthetically appealing* and *technologically fascinating woodworking effort* would have been to design and build *cantilever trusses* across the span - that would have put *both* your woodworking and structural skills on full display - both strong AND pretty!
how about when you finish the build you plant a tree in a pot and place it onto the deck. then you have a treeless treehouse tree.
For the NEXT time you have to do this.... ratchet winches are your friend. My buddy and I demo'd an 80' x 40' 150 year old barn in Sacramento to salvage the redwood beams and tin some years back. Because it the city had built up around it, there were fences less than 3' from two sides of it. We hooked 3 ratchet ratchet winches to anchor points opposite the fences and pulled it toward the opposite corner - we were able to make the entire building lean away from the fences - then cut into the principal posts and slowly winched the whole thing until it collapsed with no damage to the surrounding buildings. Yeah... super safe. But it worked. Pulling the treehouse a few inches would have been a breeze.
Please go back and fix the cable connections! The cable clamps are on wrong, there aren’t enough of them, you need thimbles at the turn back at the eyebolts. If there was enough force to move the tower, you have enough to damage the cable.
All these comments about what he should have done...my first thought was how the beams will be used to walk across! I will however agree with any comment about loosening the cables a bit though. Less force and more fun! Looking good Jason!
I can't be the only one who thought maybe there would be a swing set, some form of slide or a zip line on the end to help hold the structure plum.
Yep, was thinking a nice slide on the other end. Imagining running up the stairs, across the bridge and a bar across the entrance to the slide. Grab that and whip down. Oh to be a kid again. Cool build though. And I see it would be larger than the current footprint so not sure if something is in the way down there.
I actually thought a slide at the large end with the same sides as the stairs would have done the same job that the stairs are doing on the small end. But hey, the steel beams work so all good.
Thank you for showing a very common theme in anything DIY. Something that shouldn’t take long and seems very “SIMPLE” turns into a big headache, consumes a bunch of time and requires so good old fashioned ingenuity.
It's been some time since I calc'd a catenary, but the more level you drive the bridge, the higher the stress on the upper decks, pulling them together. You may not have seen the end of this yet: time and stress equal "creep", the deformation of materials. A solution: support the bridge from the steel beams, even if only in a couple/three places. That will relieve the tension on the cable/wood interfaces. Enjoyed the video, as always. While you've come up with a lot of innovative techniques, we all might keep in mind that this kind of construction is millennia old, and the conventional techniques are "conventional" because they've proven their worth. But I gotta admit to the fun!
Mechanics of materials! This brings me back to engineering math in uni.
those beams would make great anchors for some swings
Load Paths! This could also have been fixed by adding bracing to the structures it self. The load paths are still not complete down to the footings, adding the HSS sections is one way to 'close' the loop. Next time reach out the community for a quick "peer review", would love to give some advice in the design stage that could have prevented this. Looks good non the less! Love the videos.
He mentioned that as a possibility at the beginning but decided to go with that instead.
Running the cables through the 2 platforms and then at say 45+ degrees down on each side , to a suitable concrete anchor will reduce the lateral tension.
attaching the end of cables to the ground under the beams it would minimize the horizontal vector of force depending to the pressure over the bridge,so if you put more pressure you get more horizontal force minimizing .
I think I would have added a diagonal anchor to the other side instead. You are right in a single cable would be dangerous. So I think I would have installed a slide. I mean it would serve as an alternate escape route incase the small tower was not able to be used for egress.
Thank you so much for showing a mistake and the fixing of it. Single biggest problem with build videos is not showing the issues that arise and the problem solving.
Those beams would be a perfect place for a couple of swings, just like you planed it, right? 😃
Looks like grandma is lucky to be alive 😂
Through most of the video...
Me: Dude, you just need a wooden beam and a car jack to force those things apart.
BMW: So then I got a wooden beam and a car jack...
Me: HA! Now, you need to secure the ends of the beam before you jack it, or you might hurt yours...
BMW: And the beam fell down, so I secured the ends to prevent it from happening again.
Me: HA!
Later...
BMW: This bridge makes it really easy to twerk.
Me: No. NO. NOOOOOOOOOO!!!!!!!!!!!
SUGGESTION: On the opposite side of the large tower, install a couple of diagonal boards like stair stringers. Only don't put stair on them - put a cargo net on them for kids to climb. Or a slide. Or both! Also, a steel ship's ladder coming off the large tower would make another great option.
Great work! The steel is overkill, but I’ve been looking for some to overkill a few projects of my own
You probably could have used pullies and snatch blocks to increase leverage for the truck idea.
You kept saying that many of us said that may of us claimed that you'd overbuilt these. Well, I guess that shows how smart we are! HA. Who looks silly now?!?!?! wait...............no
Why didn't you put 45 deg. bracing in the corners. You had flex from lack of bracing and the 45 deg. bracing would more than likely take care of it or most of it anyway. No offence to the beams, but you have taken away the look of the suspended bridge. Just a thought.
....it would have been much more of a shame if they died...... that is DRY, dark humour. I like!
I think this video is just as interesting as the others. Solving problems is just as educational as building without problems.
👍👍👍
The moment you said what the nature of the issue was -- the suspension bridge -- I knew what the problem was -- you've built framework boxes with no real 3-d interaction -- e.g., an angled member that ties the structure up in three directions rather than each connection tied in 2 directions**. In other words, it does not handle shear forces at all. All it needs is some angled connections between the different support beams -- ideally one connection at an angle between each leg, plus one across to the "catty corner" leg. I'm only 2:15 into the vid... let's see if I'm correct.
OK, @ 6:25 -- you are VASTLY underestimating the increase in stability which a single angle brace -- not even a full X, and not one enclosing the whole structure -- i mean a single brace at about 20-30° at the top of the four/six support beams of each structure connecting it to the adjacent beam ... especially if you added one more connecting one catty-corner to the other, again, at about 20-30°. That thing would be like the whole thing was on a solid bulk of GRANITE rather than the flexible structure you have. Believe me -- try this yourself -- build a small 4-sided frame -- a drawer without a bottom. Now apply lateral stress and notice how easily it deforms when you push at the top while holding the bottom still. NOW take that same thing, attach a thin little piece of 1x¼" TRIM MOULDING from one corner to the next, and see what a massive difference it makes in the rigidity of the whole thing. Add two of them in an "X" from each of the catty-corners to the other, and that thing is going to be a flinkin' ROCK. I have seen this happen with boxes, and the rigidity it offers is nothing short of amazing to me, and I *know* it does it.
You can -- and no doubt have -- done what you decided, but it kind of defeats the purpose of the suspension bridge in the first place, to my lights. And it still leaves the entire structure susceptible to shear forces, though with the staircase that should be mitigated in at least that direction. I am suspecting that, once you have the treehouse up, you will see that thing swaying a lot in the non-stair direction in a major windstorm, as it applies lateral force against the walls of the structure which are perpendicular to the stair axis. When you get a big windstorm, go out and see what it is doing. I am betting you it will be swaying notably in that direction.
ALWAYS create structural members in three dimensions, not just two. That's kind of what your short-angles (I believe the term is "knee braces") do, but they aren't long enough to really make it rigid. The cross-bracing does not even need to be substantial -- a single 2x4 or even a 2x2 would have an amazing affect on the rigidity of the structure.
Also, note that plywood sheathing effectively does this same thing -- it just uses a big solid piece rather than a thin piece.
OK, @ 12:15 -- it appears to me as though you actually twisted the 6-pole structure somewhat, too, since the bridge is much closer to one corner of the structure. That is, it's not just leaning, it's leaning more on the side where the corner bridge is connected near than it is on the opposing corner. Makes a kind of sense, if you look at the physics of the forces involved.
======
** Yes, nominally, the floors go in 3 directions so that shear isn't going to be an issue for that. But the support beams have no such interactive element.
Homeschool Mom of 10 so I don't have access to metal beams. Is there a way to build from beginning to make suspension bridges off platforms built around actual trees? Trying to replicate a bit of Lord of the Rings Lothlorien Elve area with 4 platforms built at varying heights on stilted footings that wrap around existing trees, joined by suspension bridges. The trees are the standard tall skinny trunks all over middle Tennessee
Great job, admittedly I was one who said it was over engineered .. as far as size of lumber used. which is still true, its great but it is! Smaller lumber could have been used. and proper cross bracing would of helped or solved this issue as well. and simple 2x6 or 4x4 wood would have accomplished the same thing as the industrial overkill 4x4 steal tubing. lol when I say proper cross bracing, I mean you have corner cross bracing which is ok for things up top, but when you have a 8 ft tall structure that weights about 2500+ lbs, you need full top to bottom cross bracing. Like building bridges you don't just see a cross brace on corners, they go the length or height of the span in that section. when designing structures or Planes in my job. you want maximum strength with minimum weight. Now overkill on a child's play-set is all good and isn't hurting anything of course other than wallet.
Edit: he literally just did what I mentioned below. Should have kept watching before commenting! 😂 At least we had the same idea! 👍
Another way to span the gap could be to use a 4x4 shorter than the gap, by about a foot or so, and use a car jack between the 4x4 and one of the structures, to slowly spread the two structures apart. Like how they jack up a house when it’s sagging, but horizontally. Hanging/lifting the 4x4 could cause some issues but it was just a though that popped in my head.
It's a way to solve a problem.😂
Now with those overkill beams you might as well make a solid bridge instead. 🤔
Also some diagonal berms stretching from top to bottom would have worked too. (without those overrated beams)😉
Just looking at bridge constructions or scaffolding and googling this stuff would have helped too or just asking the community. 😉
STEEL CABLES WILL NOT STRETCH!
The real problem in installing the beams is that you are getting a huge amount of resistance from the cables. Looking down the bridge plane you can see it is nearly flat. The top hand rail cables are about as far as yhey can go as well.
Loosening the bottom cables would have made it a lot easier.
At least you got it done!
Man... You really screwed up!! But hey, you fix it! Nah lol I'm joking, it was cool seeing how you went about fix the issue you where having! Great work. Well done