private1
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LittleAndAlone said:Need to be careful with scaled up bouncers. Can see someone losing themselves in the fun and easily smashing their head into the top. Our bodies aren't as little as we feel inside.
Well more than a dozen various homebuilt jumpers and some repurposed "actual baby" ones and I have not once hit my head. Not once. Ever. This is an imagined non-issue.
There's also probably a dozen jumper threads on here. Always someone listing off the reasons they can't do it, me (or OCCASIONALLY a couple others) addressing all of those issues, and then silence.
My best jumper suspension so far has been 4x 160lb garage door extension springs, installed in an "X" configuration from my attic beams via 3/4" eye bolts. Steel safety cables (don't act like this is a big hurdle: THEY COME IN THE BOX WITH THE SPRINGS through the center of them, attached to a separate eyebolt at the beam end, and to the same "quick link" as the spring on the "center-of-the-X" end - this is #1 to prevent stretching the springs too far [as if 120lb me is going to overstretch 4x 160lb springs anyway, but just in case) and also to catch the "loose end" if one did manage to break.
The smallest, simplest jumper suspension is a couple of "screw eyes" into your ceiling joists. You want them to be rated SEVERAL TIMES your weight, and they have some at Home Depot with 600lb ratings. The concerns are twofold: #1- it could pull out. You address this by buying the one rated 3x to 4x what you weigh. #2 concern is they can actually *unscrew* (this is far more common than just "pulling out.") you solve this by having two of them: neither can unscrew without necessarily moving the other.
There's always a lot of concern about dynamic load, and an adult-sized weight jumping. This would seem valid, except that what most people here want to do isn't *JUMPING* at all. A child in a jumper bounces at least one half of his/her height off the floor before coming down again - often higher. Children also swing and spin. People don't want to do that - I know this, because in threads where I've discussed a lift distance of several feet (which is NECESSARY for the same actual experience a toddler-sized person in a toddler-sized jumper has) people have suggested that it is too long! Well, fine, but if the only thing you're doing is "bouncing" a foot or so (at this point you might as well just go do some calf raises) then dynamic loading is *NOT* an issue.
Go upstairs in your house. Jump. Do it again. Now come back downstairs and try to tell me the structural members holding up your downstairs ceiling (which, also hold up your upstairs floor) cannot support the weight of an adult jumping. And remember, you were just jumping from the ground: adding energy to the jump by launching yourself upward. In a jumper, the only energy in the system is from gravity itself, and is applied (relatively) gently as the spring/bungee lowers you.
Yes, an eye screw into a joist is different than jumping on a finished floor - but not MUCH. The manufacturer of the eye screw did that math when they printed the big "600 LB SWL" label on the package. The interface between the hardware and the building is warranted by the eye screw manufacturer (whose liability insurance wouldn't let them make a mistake) and for the buiding's part, the entire "force" of your assisted calf raises will also be spread to neighboring joists assuming the entire system (joists, floor, ceiling) is actually screwed together as it should be. (if not, move out, because your house is already unsafe, jumper or not)
Every thread about these things is just "I can't I can't I can't" because people prefer to talk rather than do. But you can, you can, you can. I do, I do, I do, and it works, it works, it works.
Engineering is great, but "attach something here that can hold up a few hundred pounds" falls well into the realm of the general carpentry trade.
I may apologize if my tone sounds even more harsh than "annoyed," but I'll make no apologies for seeming, and being, openly frustrated. These are fun to me. I do this a lot. It is in fact how I even came across this site to begin with. I once thought I might find others here to "compare notes" with, maybe we'd see (and I've tried to encourage) a thread discussing different designs, but all anybody actually wants to do is reinvent already-addressed "reasons" why they can't, and discourage the few who remain from trying either.
The subject comes up often enough. Try the search box. There is actually some useful information on here in previous threads..
