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Top-roped Cross

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Some of you may recall my blathering about living in a city with an active BDSM community. But only very occasionally do I get a chance to prowl the local club on a Saturday night, and never before with my new best-toy Cruxie! :)

Been workin' on Cruxie off and on for over a year, and just this weekend the perfect opportunity arose to complete all outstanding tasks and take her downtown for a show-off. Spent 20 minutes hangin' on her once set-up, and now that the kit is complete I'll be bringing her along to semi-regular Thursday mixers. While folks seemed politely impressed in her full debut, I was a bit surprised she not get any takers on my offer of a 'free ride'...:(

One woman said with a smile 'Sorry, I wasn't raised Catholic'. :D Had to admit she got me figured there!

No theological discussion intended, only curious to see if its a fairly common denominator in our crux-fetish community....

Straw poll: Were you raised Catholic? :eek:

Cheers!
Sir Nob


Cruxie Photo Notes:

1. The complete kit, less suspension cuffs. Will post separately about cuffs shortly. A very grainy photo in the evening dusk, literally just before packing up and heading out for the club.
2. Unistrut 6-hole t-connector, crossbar not yet attached. All bolts, nuts & washers are 1/2" steel
3. Cuff attach point: 2-hole connector with 1/2" forged-steel eyelet and stainless-steel snap-link.
4. Rated, new climbing rope and hardware -- pulley, belay device & carabiners.
  • To keep the base simple (and transportable), this T-cross is top-roped from another 1/2" forged-steel eyelet in the center of the T to a hard-point directly above.
  • Pulley is suspended from the hardpoint using a rated carabiner, and the rope is anchored through the belay device.
  • Belay device (Petzl Grigri) is attached to a hardpoint on the nearby sidewall also with a rated carabiner. The belay device allows the rope to be tensioned without slipping, and released quickly if needed.
5. 'Erection Hinge' and adjustable-angle footrest detail. Actually took Cruxie to a Thursday night gig about 6 months ago, and received some good design feedback. Like 'How would you get someone down if they passed out?' This hinge and the rope belay feature are the result.

6. A most generous seat. Far more generous than any slave-girl deserves -- but hey, I was sitting on it tonight!


crux_1a.jpg crux_2a.jpg crux_3a.jpg crux_4a.jpg crux_5a.jpg crux_6a.jpg
 
Sure, it's certainly very convenient for "Crucifixion'Pic-nic"...but, why are you
amazed that woman dont agree to try it?
Woman is "romantic", she prefers the contact with the wood, to rasp her shoulders, her buttock, against a natural and noble material...;)
Perhaps you could envisage a piece of wood , situated on the back of the victim?
 
Woman is "romantic", she prefers the contact with the wood, to rasp her shoulders, her buttock, against a natural and noble material...;)
Perhaps you could envisage a piece of wood , situated on the back of the victim?
Not only women...
I was thinking the very same thing: "The eye is eating as well", so while it is functional, it lacks the the view of a classic wooden cross... made from aged wood.
 
Yes, as an incurable tree-hugger (Tree-hugger too)​
the feel of rough bark against bare skin,​
the thought "how many tormented bodies have rubbed against this before mine?"​
is a big attraction of the old wooden whipping-post,​
and the same must be true for the Cross​
and other Instruments of Torture​
 
The practical issues of getting your kit to the club. LOL!
Fishing kit bags do great to carry whips and so (always great fun to see people carry this into a building with no water in miles around), but of course transporting the big kit can be an issue. Unloading a full size cross from the back of your car on a public parking (or taking it on or off the roof-rack) can draw, well, questions.
During the run-up to Easter you can of course say it is for the dress reherarsal of a passion play. This time however strikes as a bit out of season.

In any case I agree that steel is not a material I would use for a cross.
And I wasn't even raised as a catholic.
 
Aye, I hear ye. And I have wrestled with the aesthetics issue.

In the end, safety won.

Unlike actual cruxecution -- where no one either really cared much or perhaps found it amusing if the patibulum or sedile fell off or the crux tipped over -- Cruxie is a serious fetish toy designed as safe as I can make her for adult BDSM play:
  • Super-strong and widely adjustable, to accommodate from the petite to the extra-large-size player:
    • Adjustable-height and easily-replaceable sedile
    • Adjustable-position backboard. This is composite plastic now, but I like Messa's idea of replacing it with a plank of rough lumber. ;)
    • Adjustable-height and angle footrest
    • Adjustable-width wrist-cuff points
    • Channel steel provides simple, secure mounting for future features like ankle-chains or an electrostim console
  • Quick and easy set-up or break-down using a ratchet wrench
  • Ability to lower an unconscious or otherwise helpless player safely using the top-rope and hinge.
Now if this were a permanent crux in my back yard (anyone have suggestions on what to tell the neighbors?) I agree that all-wood design is the way to go. But wood drys and splits over time, and just isn't as dependable as steel when you start putting hinges on it and beating it up with repeated set-ups and tear-downs.

While I lamented earlier that no one took me up on a free ride offer, I really wasn't all that disappointed. Am most optimistic I'll get plenty of takers over the coming months, and I'll be sure to keep you posted...:cool:
 
Aye, I hear ye. And I have wrestled with the aesthetics issue.

In the end, safety won.
Don't underestimate the strength of wood! A 10*15cm (4*6) wooden bar is stronger than your steel construction... and by far!
Set up / tear down can be defeated using metal insets and machine bolts.
Drying of the wood isn't really any issue or it would not be used to build houses!

I should transport my "crux construction thread" out of CruxFoundation to here, but intend to wait until I can show it installed in my new dungeon.
Anyhow, here some images how I did it:

(wooden cross, large steel ground platform with hinge that is standing safely, winch to erect the cross...)

Please note that I am also concerned about the small foot of your cross. I don't think it stands as safely as it should.
Mine has a 1 by 1m footprint if it can be anchored to the ground (bolted to the floor), otherwise it is 2*2m. Think of a victim jerking on your cross...
 

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Nice work Fan, but you've a permanent installation.

No doubt wood is everyone's preferred 'aesthetic' choice (mine too!), but I just don't have a handy panel van to haul around 8-foot 4x6's! :) My 6' steel crossbeam channel has an allowable bending moment of 423 ft-lb (safety factor of 2.5), which calculates to a maximum 140lb hanging from each end -- in other words, sufficient capacity for a 280 lb player. So the steel channel is as strong as it needs to be, and provides a simple way to quicky adjust wrist-cuff connection points.

As for the 'tippiness' -- well, that's why it's called a 'top-roped cross'. It's anchored to a hard-point directly above with rated climbing rope and hardware.

And it works great, I verified that myself last night... unfortunately the club doesn't generally allow photos, but I may be able to get one of the full assembly sometime 'off-hours'.

Cheers!

PS: My arms and legs are a bit stiff today, just 20 minutes was a pretty good workout!
 
...
My 6' steel crossbeam channel has an allowable bending moment of 423 ft-lb (safety factor of 2.5), which calculates to a maximum 140lb hanging from each end -- in other words, sufficient capacity for a 280 lb player./
...
The load bearing capacity of a cantilever with an open cross section is usually determined by elastic failure (a.k.a tripping), I do not know the exact properties of the profiles you use, but I suggest you do not rely too much on specifications but do a sound testing before use in the real.
Sorry if I sound pecky, but I have seen a few too many cases of failure due to unexpected 'out of plane' bending.
*** Takes off teacher's hat and congratulates you with the project.:D
 
Nice work Fan, but you've a permanent installation.
Not at all, that's the purpose of this construction: It works also on a sandy beach and it is easily disassembled and assembled.
PS: My arms and legs are a bit stiff today, just 20 minutes was a pretty good workout!
:D :D :D ;)
 
Not at all, that's the purpose of this construction: It works also on a sandy beach and it is easily disassembled and assembled.

:D :D :D ;)

Well, 'easily' is a relative term...:) 'Easily' for me translates to 1) 10 minutes to grab sub-assembled parts from garage and throw in car 2) 10 minutes to transport parts into club from car 3) 10 minutes to bolt sub-assemblies together and secure the top-rope -- ready to play!

Don't get me wrong, Fan, your design is awesome -- did you weld the frame yourself?

Your steel base frame looks capable of resisting a large bending moment (probably 10x or more of the cantilevers), while my design decision to use the top-rope was made specifically to avoid building such a structure. Both designs 'work' and are safe for the player, but mine requires an overhead hard-point (which I have available down at the club) while yours has the flexibility of 'free-standing' anywhere.

Do you have any photos you can share of it fully-assembled and 'occupied'?

Cheers!
 
Well, 'easily' is a relative term...:) '
I used to transport half my dungeon once a month to a club, believe me I know what transportable means.
The patibulum is held by 3 machine bolts.
The stipes is bolted to the metal base with 6 bolts.
Attaching the base (without winch and whipping post for fair comparison) is another 12 bolts
So it probably takes more than 10 but less than 30 mins to assemble on site.
But it's more stuff to carry.
did you weld the frame yourself?
Yes
Your steel base frame looks capable of resisting a large bending moment (probably 10x or more of the cantilevers), while my design decision to use the top-rope was made specifically to avoid building such a structure.
Wanting to use a winch (to not be depending on a helper crew to erect the cross with victim) plus the "design requirement" to be able to use it on a sand beach made this necessary.

Do you have any photos you can share of it fully-assembled and 'occupied'?
!
Well, minor design flaw, it is 5cm too high for my existing dungeon :D :D :D
I set it up once at the workshop, without taking pics.
As said, I'll provide that once the new dungeon (1m higher!) is in a "presentable" state ;)
 
The load bearing capacity of a cantilever with an open cross section is usually determined by elastic failure (a.k.a tripping)...

The published 'allowable' bending moment and other load factors, from the Unistrut Engineering Catalog, have a safety factor of 2.5 based on the known physical properties of steel and the geometry of the part in question. A safety factor of 2.5 means the allowable load would need to be increased by a factor of 2.5 before approaching elastic failure.

Cruxie is as strong as she needs to be, but ever-mindful of safety I am aware that one of the greatest risks is inadequately or improperly tightened bolts. Thus I will always be doing the assembly and final check-out myself, prior to any playtime.


Cheers!
 
The published 'allowable' bending moment and other load factors, from the Unistrut Engineering Catalog, have a safety factor of 2.5 based on the known physical properties of steel and the geometry of the part in question. A safety factor of 2.5 means the allowable load would need to be increased by a factor of 2.5 before approaching elastic failure.
Please note that you should be using a factor of 5 and more, 2.5 is aerospace industry!
Having said so, steel has a "friendly" failure mode of bending and not failing catastrophically, so it will not be dangerous.
Bolts as you say are a bigger concern, don't use cheap bolts made in China ;)
 
GOOOOD! So you can see how Messa is suffering on your cross!:eek:

You're right about that M! After 20 minutes my spotter released one wrist, and I was too stiff to reach over and unclip the other one!

Will see if I can work-up to an hour or more over the next few months...

;)
 
Please note that you should be using a factor of 5 and more, 2.5 is aerospace industry!

The SF of 2.5 is approached as the weight of the player increases to 280lb and the wrist-attach points are moved to the very ends of the crossbar. Am not anticipating cruxing many of this weight and wingspan -- for me, 180lb man with attach-points about 12" inboard, the safety factor I'm almost certain will pencil-out in excess of 5 -- but those calculations will have to wait 'till later as I gotta run!

Thanks for your critical feedback -- it is an important part of a sound design process!
 
...
2.5 is aerospace industry
...
FAR25 says 1.5 :D
5 is general for ropes and stuff, and relates to breaking strength. Steel indeed has great inherent safety because there is yet another factor 1.5 or so between yield and breakage.

Never mind, always good to hear people are savy in structural matters.

It is the thick of the french revolution. A priest, a count and an engineer are bound for the guillotine. When they are driven to the village square the mob is roaring! Justice will be done, and blood will flow for sure.
The priest goes up first. The executioner pulls the rope, the blade falls and blocks one inch above the priest's neck. They try agian; same failure. On the third try the machine also fails. The priest is set free.
Then the nobelman goes up the scaffold, and for him also the machine fails three times so they set him free too.
Then the engineer is sent up. While they bend him forward, he looks at the guide rails and shouts: ' Hey, wait a minute! I think I see what is wrong!'
 
FAR25 says 1.5 :D
5 is general for ropes and stuff, and relates to breaking strength. Steel indeed has great inherent safety because there is yet another factor 1.5 or so between yield and breakage.
Well, I would not want to hang from a FAR25 rated cross unless it has frequent NDT inspections and unless the supplier is FAR25 rated as well and unless there has been a detailed study on actual forces exerted by jerking victims ;)
Even a factor of 5 already is a stretch because the loads largely are unknown ;)

But we all are in agreement that Nard's steel profile is safe enough. ;)
(I'll not start another debate about the hinge ;) )
 
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