- My Forums
- Tiger Rant
- LSU Recruiting
- SEC Rant
- Saints Talk
- Pelicans Talk
- More Sports Board
- Fantasy Sports
- Golf Board
- Soccer Board
- O-T Lounge
- Tech Board
- Home/Garden Board
- Outdoor Board
- Health/Fitness Board
- Movie/TV Board
- Book Board
- Music Board
- Political Talk
- Money Talk
- Fark Board
- Gaming Board
- Travel Board
- Food/Drink Board
- Ticket Exchange
- TD Help Board
Customize My Forums- View All Forums
- Show Left Links
- Topic Sort Options
- Trending Topics
- Recent Topics
- Active Topics
Started By
Message
Engineer help- trying to recreate a pneumatic lowering device
Posted on 5/27/25 at 7:57 pm
Posted on 5/27/25 at 7:57 pm
At the 2:00 mark you see the contraption I’m trying to build. It’s from a Mark Rober video where he builds a pneumatic device that will lower someone to the ground regardless of their weight be constricting the airflow as the piston moves through the cylinder chamber.
I’ve searched online, used ChatGPT, but cannot find information on how he built this. I have a rough idea how it works. Rope routed thru pulley, into the chamber, attached to a weight the same size of the chamber and probably some type of air valve at the top to regulate how much air is pushed out, thus changing the descending speed.
However, I need some advice on what materials to use and where to source them. Is the chamber just a clear pvc? There also appear to be some metal collars on both ends. Not sure what those are. Assume they are more structurally sound than gluing on pvc end caps? I have no idea how much force/pressure would build up inside and if it blew the pvc caps off you’d have a free fall.
If I can get it figured out I plan on putting in a treehouse.
Any thoughts or ideas?
12
Posted on 5/27/25 at 8:01 pm to GoldenSombrero
Definitely wrong board 
Posted on 5/27/25 at 8:02 pm to GoldenSombrero
You’ve come to the right place
Posted on 5/27/25 at 8:02 pm to oldtrucker
quote:
Definitely wrong board
Posted on 5/27/25 at 8:03 pm to GoldenSombrero
Contact the guy and see if he will send you the specs.
Posted on 5/27/25 at 8:05 pm to UptownJoeBrown
Probably want to post this on the non-retard board
Posted on 5/27/25 at 8:06 pm to oldtrucker
quote:
Definitely wrong board
I’ve seen decent advice posted in here on rare occasions so it’s worth a shot
Posted on 5/27/25 at 8:08 pm to GoldenSombrero
Sorry my degree is in civil. If the rope isn't in equilibrium it's above my pay grade
Posted on 5/27/25 at 8:09 pm to GoldenSombrero
It's all about PSI.
Posted on 5/27/25 at 8:14 pm to GoldenSombrero
Use a larger than needed counterweight. Your air bleeder valve should be controlled by a timer, not a scale.
Posted on 5/27/25 at 8:20 pm to GoldenSombrero
Did you check the specs on the rotary girder?
Posted on 5/27/25 at 8:23 pm to GoldenSombrero
Try Harbor Frieght. They got all kinds of pneumatic shite.
Posted on 5/27/25 at 8:30 pm to GoldenSombrero
Posted on 5/27/25 at 8:57 pm to GoldenSombrero
It you have an 8 inch diameter tube with an 8 inch piston and you weigh 200 pounds you can place 4 psi on the piston.
The volumetric flow rate from a 4 psig chamber through a 1 inch diameter orifice is 591.5 cubic inches per second.
If your travel from top to bottom is 10 feet or (120 inches) you have to displace 6,031.9 cubic inches of air.
6031.9/591.5 = 10.2 sec.
Rule of thumb, 8 inch tube, 200 pound guy, 1 inch diameter orifice, rate of decent = 1 foot a second.
Rober probably has a pressure gauge in the tube and depending on the measured pressure it sends a signal to a solenoid and the solenoid opens a valve to a position depending on the pressure. It opens wide for low pressure (light kids) and hardly opens at all for fat dads. This way everyone reaches the floor at the same rate.
The volumetric flow rate from a 4 psig chamber through a 1 inch diameter orifice is 591.5 cubic inches per second.
If your travel from top to bottom is 10 feet or (120 inches) you have to displace 6,031.9 cubic inches of air.
6031.9/591.5 = 10.2 sec.
Rule of thumb, 8 inch tube, 200 pound guy, 1 inch diameter orifice, rate of decent = 1 foot a second.
Rober probably has a pressure gauge in the tube and depending on the measured pressure it sends a signal to a solenoid and the solenoid opens a valve to a position depending on the pressure. It opens wide for low pressure (light kids) and hardly opens at all for fat dads. This way everyone reaches the floor at the same rate.
Posted on 5/27/25 at 9:11 pm to GoldenSombrero
That looks like a 3/4" sanitary fitting. It's threaded on one end so it can be mounted on the homemade flange (aluminum plate). He is using that because it has smooth edge and won't cut the rope.
There is also a lot of slippage in the piston and that is why it looks like a smaller orifice than what I calculated earlier.
mcmaster.com should have everything you need.
Forget the idea that I made earlier about the solenoid valve. Rober just uses what looks like a 3/4" orifice to control the air flow and piston slippage.
You can use a basic pipeline cleaning pig for your piston. Might have to sand it down if it's too tight.
LINK
This post was edited on 5/27/25 at 9:16 pm
Posted on 5/27/25 at 9:16 pm to GoldenSombrero
[quote]pneumatic lowering device[/quote 
You mean like this? LOL, they are awesome. Used them all the time in school.
You mean like this? LOL, they are awesome. Used them all the time in school.
Posted on 5/27/25 at 9:25 pm to In The Know
quote:
Try Harbor Frieght. They got all kinds of pneumatic shite.
I have the pneumatic slide whistle.
Posted on 5/27/25 at 9:36 pm to In The Know
This thread has so much potential..
Posted on 5/27/25 at 10:29 pm to Ry_garou
quote:
This thread has so much potential..
it certainly does….potential for broken ankles….
Posted on 5/27/25 at 10:53 pm to John_V
That flange is the answer
Page 1 of 2
Popular
Back to top
Follow TigerDroppings for LSU Football News