OK, I’m going to ask: Just what are you making this time? You always seem to come up with interesting DIY projects.
I was keeping this is a secret because I was going to try and get a patent but there is so much prior art and so many expired patents on it already I decided not to bother with a patent and just build it for my grandson and myself and maybe sell a few. This is a bellow used for strength training. It is a push/ pull device. I started playing with it decades ago but never followed through. One of the biggest problems with air devices that don’t use compressors is that air compresses to much before a target resistance is ever reached By going over 100 sq inches it keeps the pressure very low and eliminates or reduces the compression to a little more than 10% which is basical just a slight cushion effect on each push pull. The larger size also solves the problem of a vacuum collapsing the bellow. I use a heavy material and steel rings all around it so I only get a minimal collapse effect. One of the biggest problems was controlling air flow. smaller sizes let the air out oo quickly and are hard to adjust. This larger size is not sensitive to small changes in vent size and makes adjustments very easy. It is an extremely pleasant work out because it doesn’t push back and the operator pushes as hard or as soft as he likes. He controls his speed by opening or closing the vents. I have had many pleasant surprises with it. Less reps are needed because each push is so pure. I think it has real potential.
So the same exercise effect as the many commercial machines available that use something akin to automotive shock absorbers as the resistance source.
But those are compact and unbreakable while your invention is bulky & fragile even if commercially produced.
But yes, as @Chronos said, you do have some very interesting and inventive ideas. I enjoy engaging with them whether they are wise or more toward cockamamie.
Thanks for sharing this one.
Small doesn’t work well for a number or reasons I have already pointed out. My device is not fragile at all. I am making it bullet proof. Cyl are very fragile, they don’t tolerate even the smallest dent or leak. Shock absorbers are what inspired the idea. They don’t compare. Thats why almost all air machines use compressed air to regulate resistance. My first prototype was a 6" cyl like a shock absorber and I found it to be not very effective or at least not close to optimal performance. The first patents on this came out in the 1960’s and people have been playing around with it for decades. They just don’t work very well. Air doesn’t have much mass to work with so you simply need more air.
If you have the tools.
I recommend a round plywood end. Just that might suffice if you coat the outer edge with silicone and use a hose clamp. If the fabric slips in the clamp, a length of thick gauge solid wire or double sided tape under the hose clamp may bite / stick the fabric in more securely. I am curious how you have made a sturdy air tight seam in the fabric that will withstand constant movement.
I had guessed a bellows. But no idea of the use.
Maybe this?