Pneumatic bondage rack

Ideas and instructions how you can make your own bondage toys.

Pneumatic bondage rack

Postby Riddle » 27 Aug 2012, 10:15

Here is information regarding my latest creation: a spread-eagle pneumatic self-bondage rack. This is an update to the previous iteration, a self-bondage sawhorse. This permits a 4 to 6 point medical restraint to be automatically controlled.

EDIT: Previous thread here viewtopic.php?f=7&t=1796

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The wooden frame is local sized lumber bolted together to duplicate a sheet of plywood and allows the steel wrist latches to be mounted at waist level (or anywhere matching holes are drilled). The 3 center boards are covered with a blanket when the black chest and torso straps are used. Otherwise, an oriental bed set covers the frame nicely and makes for a comfortable bed.

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The steel plates were purchased prior to making latching with the sliding bolts but were difficult to shape... After only 4 years, the 1 1/4 inch slit for the restraint loop was finally hand-filed to function. Starting with a string of closely spaced drilled holes, a small file set was used to cut and shape the slit. The black sliding bar was purchased locally with the oval slits already formed. These latches are sturdy with no flex or give.

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This image shows the timer, pneumatic valves, air tank, wiring, battery, and switch.

The timer is started and shut off using the wired remote power switch (white wire). When powered on, the timer waits 1 minute before powering the solenoids through a MOSFET and starting a 1 hour count down. After reaching 0, it powers off the solenoids and continues to count zero until power is gone. This uses an arduino ardweeny, an led display driver ic, and 2 led 4 digit displays. The 12V battery powers the timer and solenoids. The timer draws 200 to 300 mA depending upon how many segments are lit.

With this iteration, metric air lines are coupled to my original valves with a needle-valve on the valve output line at the "T" fitting. The needle valve controls air flow to the latches and slows piston speed down to something reasonable. Quick release air couplers allow the orange air lines going to each latch to be easily disconnected for storage. The supply air tank is from an international suspension air bag company (fire & stone) purchased for its reasonable price ($45) and low capacity (1/4 gallon, ~1 ltr). This tank may be ordered from EU, AU, and US online retailers. A standard upright bicycle pump can fill it to top pressure quietly and quickly which allows 1 to 2 latch cycles.

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The timer circuit close up. Neither pretty nor nicely enclosed, yet it is functional. Since the battery, wood, and most of the bolts will be recycled soon due to a pending life event, this is good enough for now.
Last edited by Riddle on 28 Aug 2012, 13:37, edited 1 time in total.
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Re: Pneumatic bondage rack

Postby bound_jenny » 27 Aug 2012, 11:10

Nice work! :D

Jenny.
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Re: Pneumatic bondage rack

Postby lj » 27 Aug 2012, 15:52

Is there a power-fail release ? for example, a solenoid valve held closed by power-on that would release all air in the cylinders and reservoir when the battery runs flat?

an interesting idea :-) A pal of mine has done a lot of stuff like this, though in the partnered bondage situation and for his website http://bondage-engineering.com (not a commercial site, as such, so I'll put the link )
be a switch, double the fun :-)
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Re: Pneumatic bondage rack

Postby Riddle » 28 Aug 2012, 13:30

bound_jenny wrote:Nice work! :D

Thank you Jenny.


lj wrote:Is there a power-fail release ? for example, a solenoid valve held closed by power-on that would release all air in the cylinders and reservoir when the battery runs flat?

Battery power is required to hold air cylinder pressure but not air tank pressure. The air circuit is 12V hold, power-fail release, and pressure-fail release.  Single acting cylinders (pressure extend, spring return) operate the dual-spring-release latches (80 psi to extend). Valves dump all air cylinder side pressure when either valve is in the normally open position.  The valves are two way types (common, normally open, and normally closed ports) like a double throw relay and are operated in parallel. The air tank pressure stays on normal release but dumps out if the valves get into opposite positions due to either a mechanical or electrical failure.

Please see the following thread for further details of the air system parts.
viewtopic.php?f=7&t=1796


lj wrote: and for his website http://bondage-engineering.com  (not a commercial site, as such, so I'll put the link )

Thank you for the reference source.
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Re: Pneumatic bondage rack

Postby Riddle » 08 Sep 2012, 09:16

I was surprised to figure out this setup is not completely escape-proof. Both finger-tips and heels can touch the ground enough to move the frame millimeters at a time until a hand is in the timer box. Moving the ankle restraints up and onto the long boards made it more difficult to move but still possible. The final bondage session lasted 6 minutes shy of the hour and a half set time. The next iteration will not have this flaw...

Debating on using the latches on either an elevated chair or a regular queen bed starting in November. Any suggestions?
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Re: Pneumatic bondage rack

Postby kobal1 » 08 Sep 2012, 13:34

Thanks LJ for the mention.
i would like to add my bit and although im not a fan of self bondage without precaution, i can cite a case of situation wher it went horribly wrong.
But that said. you might want to look at a PLC for the timer and they are pretty simple to programme, if i can, anyone can and the good thing is if they loose power they fail safe.
and a fail safe could easily be introduced by switch or noise if needed

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http://bondage-engineering.com
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Re: Pneumatic bondage rack

Postby OrgasmAlley » 18 Nov 2012, 17:27

That's a great design! I had a good laugh at your description of a way out, as well... what is your fix?
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Re: Pneumatic bondage rack

Postby Riddle » 18 Nov 2012, 21:27

OrgasmAlley wrote:That's a great design! I had a good laugh at your description of a way out, as well... what is your fix?

Riddle wrote:Since the battery, wood, and most of the bolts will be recycled soon due to a pending life event, this is good enough for now.

Due to unrelated factors, shortly after the pictures were taken, all 2 meter boards were cut in half to fit into a dumpster with the other boards. All bolts except for those used on the latches went into the metal recycling bin. The latches, air line, and valves made it safe through the mail to my new location. Now, I need to start over to build a frame to hold the latches. This time, I am thinking of either installing the latches into chair arms or into a wooden queen size bed frame. Either way, no more touching the ground.

The fix for escaping that frame could have been merely elevating it about 6 inches so that there was no longer a way to touch the ground. However, this is now a "could have been" idea. Plywood here sold in 4'x8' sheets is cheaper than buying boards 8 foot long and making an entire frame. Yeah, no more metric lumber sizes (and associated cost)!
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Re: Pneumatic bondage rack

Postby OrgasmAlley » 19 Nov 2012, 18:37

Sorry, I certainly missed entirely your line about disassembling it! Adapting to a chair should be interesting. I like your idea of a small hand-filled tank as a cost-effective way to briefly power pneumatics... should anyone else be following this approach, they might consider a simple 2 liter soda bottle which will easily hold 120 PSI and costs next to nothing.
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Re: Pneumatic bondage rack

Postby bound_jenny » 20 Nov 2012, 00:45

OrgasmAlley wrote:a simple 2 liter soda bottle which will easily hold 120 PSI and costs next to nothing.


:shock: :shock: :shock: Ummm... that's about the pressure where it explodes into lovely plastic shrapnel and makes a horrendous racket in the process (re: Mythbusters)... Tone that down to 80, and.... better yet, find a safer pressure vessel!!!!

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Re: Pneumatic bondage rack

Postby Riddle » 24 Nov 2012, 19:18

bound_jenny wrote:
OrgasmAlley wrote:a simple 2 liter soda bottle which will easily hold 120 PSI and costs next to nothing.

:shock: :shock: :shock: Ummm... that's about the pressure where it explodes into lovely plastic shrapnel and makes a horrendous racket in the process (re: Mythbusters)... Tone that down to 80, and.... better yet, find a safer pressure vessel!!!!

Jenny

I second Bound Jenny's stern warning to not use soda bottles! They are not not safe for pressures beyond storing soda.

Pressure vessels must be tested at twice the working pressure and measured for deformation. One Dr. Pepper 20 ounce held pressure for half an hour before the bottom blew out and made a steel tipped rocket in my bedroom...
The expense and headache required to then connect the soda bottle to an air system will easily put the total cost over $30 dollars which actually makes it more expensive than buying a 5 gallon inflation tank designed to be filled like a tire, hold 125 psi, and already has an output hose.
OrgasmAlley wrote:I like your idea of a small hand-filled tank as a cost-effective way to briefly power pneumatics...

The small (1/4 gallon) tank was not cost-effective... That tank was chosen to be extremely small and easily placed out of site, but it's price was $25 more than the cheapest air tank. Amazon has a 1 gallon tank listed for $20 that would be ideal for a manual pump setup. My total cost was about $100 including the $45 air tank, $20 pump, $10 145 psi pressure relief valve, and other fittings. An inflation tank and a bicycle pump would be most cost-effective and labor-intensive.
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Re: Pneumatic bondage rack

Postby Sir Cumference » 30 Nov 2012, 21:10

An empty powder extinguisher is a very nice pressure vessel, and typically is tested to 30 bars and have a workingpressure around 15 bars.

If pumped to just 8 bars with a normal compressor or a bike pump, the safety margin is more than adequate.



Make sure to clean it thoroughly before using it. The powder can ruin any mechanical or electronic part it contacts.
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Re: Pneumatic bondage rack

Postby Riddle » 27 Jun 2020, 08:49

All of the pictures are no longer hosted on imageshack. Some of the pictures are available on Fetlife.

https://fetlife.com/users/109950/pictures

I will try to reproduce some of the images in the future.
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