Need help with building a pulley system to lift my HBOT on a platform

[meadow_wind]

Right now you're at 2:1 mechanical advantage

That would mean 50% of the weight right? Which should be more or less 27 lbs. But it feels so much heavier than that! I tried the heavy-duty gloves and gave it my best shot: I failed at lifting it to the ceiling, I only got halfway there and I gave up. I don't understand...
I will buy a ticker rope tomorrow and try again, then update with the results.

I wonder if the placement/distance of the double pulley at the end of the system makes a difference?
And the angle at which I pull the rope?
Right now I'm stuck against the wall and I was debating if I should rotate the setup 180 degrees to have the hook near the door, that way I would have more maneuver.
Thanks for the Amazon link. I looked up local hardware stores and they don't have it.

 

[iamthatis]

Instead of suspending it, you could consider building a loft?

You could get 8 foot 2x4s, cut them so that they reach just above the door frame, and then mount the platform you already have onto the legs.

It would mean you have to reach that high to get the HBOT every time, do you think you could lift down 35 lbs regularly?

Based on your photos, it looks like you have enough space for a loft, although you may need to move the shelf with clothes on in shown in post #5 on the left.

You could try a simple design like this:

How to Build a DIY Wood Workbench: Super Simple $50 Bench

This DIY workbench is simple enough and cheap enough that you can make it in a morning, and yet it's big enough for serious woodworking and hobby projects.

www.familyhandyman.com

However, it's usually a good idea to not just use horizontal fasteners (screws) to secure any load. The strongest design is supporting from the weight from the bottom with laminated legs and 'aprons'. Like this:

Easy DIY Garage Workshop Workbench | Ana White

Pin For Later!

www.ana-white.com

Except you don't need the bottom shelf.

This plan above could use a bit of a change. Here's what I would do (but I'm not an engineer nor a carpenter):

I'd delete the bottom bit below the red line. You could skip the stubby legs, as you don't need a bottom shelf, and have your stabilizer aprons directly along the floor.:



The other thing about these pics is to change the orientation of the aprons to fit your storage space. They could all be in the orientation of the green check mark, giving a free path.


This is basically what I did to fit the HBOT in my bedroom, I built a loft bed to fit the machines under it.

Anyways, something to consider if the pulleys don't work.

 

[nicklebleu]

Currently you have two pulleys and two ropes, if I am correctly understanding your current setup. You could change that easily to a one rope pulley system that should reduce the weight further: One rope going from ceiling left -> pulley left on bottom frame -> pulley left on ceiling -> pulley right on ceiling -> pulley right on bottom -> pulley right on ceiling -> wherever else to get it out of the way.

 

[meadow_wind]

Currently you have two pulleys and two ropes, if I am correctly understanding your current setup. You could change that easily to a one rope pulley system that should reduce the weight further: One rope going from ceiling left -> pulley left on bottom frame -> pulley left on ceiling -> pulley right on ceiling -> pulley right on bottom -> pulley right on ceiling -> wherever else to get it out of the way.

Actually, I have 3 single pulleys and 1 double pulley and use a 2 rope system like the white/blue schematic I pasted earlier.
I took it from this video: www.youtube.com/watch?v=1g0JnWUMxJw
They seem to lift something light though...

So the 2 rope system does not reduce the weight as much as a single rope system?
I've seen a 1 rope system, but it would require a 4th single pulley.

This is basically what I did to fit the HBOT in my bedroom, I built a loft bed to fit the machines under it.

Anyways, something to consider if the pulleys don't work.

Thanks for the idea. I was starting to consider it out of despair lol
I can still lift 35 lbs so that should not be a problem. My dad is good with woodwork so he'll understand your sketches.

 

[Cosmos]

So, have I understood you correctly: you intend to have the chamber on that pully system plus your own body weight, 5 days a week?

If so, I have a number of concerns with that concept/design to begin with:

- Have you carefully calculated/considered if the sealing (which looks like wood!?!) can support the required weight with the used anchors? And the anchors themselves, can they hold that weight in such material? Don’t underestimate what weights you are talking about here!!! The Chamber + body weight + quite some more everytime you move or want to get in or out of it. And that 5 days a week… In other words: What you have constructed and thought about looks pretty dangerous to me!

- Have you tried to go in and out of that chamber on a floor? As others said/warned, even doing that on the floor is pretty difficult for most people (with metal frame in it!). And you want to do it on a freely swinging platform?

 

[Jacques]

And you want to do it on a freely swinging platform?

I think the platform is just to store the unit when it is not in used.

 

[meadow_wind]

So, have I understood you correctly: you intend to have the chamber on that pully system plus your own body weight, 5 days a week?

No, the platform is just for storage for when the chamber is not in use. It is meant only for the chamber and the cushions. The 3 heavy electrical units are to remain on the floor. I wouldn't dare try the chamber on a swinging platform, although it could be an interesting circus act

 

[Cosmos]

No, the platform is just for storage for when the chamber is not in use. It is meant only for the chamber and the cushions. The 3 heavy electrical units are to remain on the floor. I wouldn't dare try the chamber on a swinging platform, although it could be an interesting circus act

Thank god! Then I think it is a cool idea.

 

[Tuatha de Danaan]

A luxury version, would be using a wench.

Sorry, couldn't resist. has the meaning of wench the same meaning as it has here in the UK. Makes me think the standard version in a blow-up doll. Hope I'm not barred from the forum for this.

 

[Glenn]

A luxury version, would be using a wench. But they can be costly .

Yes a luxury version indeed. Something like this? Just pulling your leg...

wench /wĕnch/

noun​

1. A young woman or girl.
2. A woman servant.
3. A promiscuous woman or a prostitute.

 

[Olivierlejardinier]

That would mean 50% of the weight right?

The mechanical efficiency of the sytem must be accounted for, plenty of pulleys calculators online, this one states :

μ = mechanical efficiency of the system (equal to one for an ideal friction-less system, a fraction less than one for real-world systems with energy losses due to friction)

Maybe an experienced mariner could give you advices on how to place the pulleys to achieve an easier lift...

 

[Ina]

What I would change in your design
- The ceiling pulleys need to be rigid, nearly colinear (spaced with the distance between the centers of the double pulley) and very close to the ceiling so the string does not jump, like in the original picture.
- The double pulley at the end (next to the wall) needs to be alligned with the right of the the second nearest puley. The first nearest pulley needs to be alligned with the centre of the double pulley. Therefore, first, set the doube pulley then the first and second pulley, using laser levels.
- The strings need to be parallel !! , both on the ceiling and downwards. Pick a matrial that does not twist or unravel.
- Calculate and cut the string so it has equal segments as required, for the bottom triangles. For the rest you can trim the pulley strings using a level on the platform.
Summary:
- 2x deep groove, rigid pulleys for upward mounting
- 1x deep groove double pulley for lateral mounting. IdeaI, it would be framed in a corner bracket. If not, you can use a wooden bracket, providing that you use the same width wood interface for the ceiling mounting.
- approx 10m of nylon line, no more than 4 mm diameter, if you use pulleys as per original design. Ideally the diameter of the string should be 80% of the pulley groove depth.

The pulleys you used, are potentially moving around 270 deg and thus cannot provide tension and the required geometry for a movement designed in on plane on an up or down direction.
The string you used is too thin to allow stability for your base when lifting or lowering.

Good luck!

 

[aragorn]

- Have you carefully calculated/considered if the sealing (which looks like wood!?!) can support the required weight with the used anchors? And the anchors themselves, can they hold that weight in such material? Don’t underestimate what weights you are talking about here!!!

I second this concern. If the total weight is around 30kg(?) you need to get the bolts in the ceiling secured in more than just wooden panels. What’s on the other side of those panels?

I’d also recommend using thicker rope and a winch with a secure locking option. If that thing comes crashing down on your head, it could be fatal.

 

[meadow_wind]

What I would change in your design

Thank you for such detailed advice!

plenty of pulleys calculators online, this one states :

Great find, thanks!

you need to get the bolts in the ceiling secured in more than just wooden panels. What’s on the other side of those panels?

We screwed the wooden board to the ceiling with 3 anchors of 85 lbs. Next, we screwed the pulley attachment points into the wood, but the eyelet screw is very long and goes into the ceiling. (This might be awkwardly written because it's a translation made with Google)

 

[Ina]

Thank you for such detailed advice!

Actually, Thank You! I have been thinking of ways on how to store our Thule car roof box, and the initial system you found is the simplest and most elegant.