Reliable, self-releasing ice lock

[marthite]

I want to share with everyone a simple ice lock:

A stem fits into a cylindrical case. When water is poured in and frozen, the two parts become inseparable.

This lock has several advantages:

1. Relatively fail-safe. It relies only on ice melting. No electronic timers, no elaborate set ups that could fail in many ways, only two simple pieces held together by ice.

2. Self-releasing. Once the ice melts, you're free. There's no need to grab a then-accessible key and release yourself from the locks.

3. Because it's self-releasing, it can be used for very tight bondage scenarios. Most other time-release methods require manual unlocking, which means you need to have enough range of motion to do the unlocking. Not here. If you attach a ratchet pulley to one end and yourself to the other end, you can pull it tight and render yourself totally immobile until the lock opens (also works well as the arm-holding part in a box tie/takate kote because you can have a really tight box tie and have the ice lock auto-release you).

4. Chaining several of them provides backup release as long as they don't all fail at the same time.

5. Mitigation of ice expansion-induced cracking (not seen in the attachment). By incorporating air pockets that don't get filled with water even if you immerse the unit in water (sort of like a flipped over canoe), water freezing into ice will have room to expand to (since air is easily compressible).

You may have seen the ice warden on Amazon, which does the same thing (minus the mitigation of ice expansion). But it sells for $100+. So if you chain 3 together (for backup release), that's $300. So where does this come in?

I spent a lot of time coming up with workable, safe designs. If we get enough interest, I can purchase a 3D printer and do a small production run for all those interested. No profits involved, just subsidizing the cost of the printer. Each can probably be printed for $1-2 in materials. Given enough interest, the per-person cost of the printer will be low as well. This is not a for-profit initiative. I'm offering this out to everyone because I want several of these locks for myself. If I use commercial services (Shapeways, i.materialise), it's going to be expensive. So the only way I can do this cheaply is getting others to join the initiative as well.

Let me know if you're interested. Feel free to suggest design modifications.

[lj]

Looks like a very interesting project.

I'm not familiar with the 3D plastics and metals now available - I've used stereo lithography commercially, but that was a few years ago when it was just getting started and the plastic we used was fine for a "proof of concept" but not strong enough for real use. I guess things have moved on !

I did make something similar when I started SB. I used a 35mm film cannister (remember them ? ) as a mould to make a cylinder of ice about 2" x 1", with a strong loop of steel rod 1/8" diameter which was frozen into the ice, and passed through a piece of slotted steel wrapped around the cannister. The loop could only escape when the ice melted, allowing the two parts to separate. It had a working time of about 2 hours as I recall.

Bear in mind that ice melts when under pressure, in my case the loop "flows" through the ice, rather than staying put until all the ice has gone. The same happens with any ice block and will apply to the OP's idea too. The set of holes in each part will help reduce this effect. The inclusion of air is a good idea, particularly if plastic is used, but I don't think it is a major issue unless the parts are so accurately manufactured that there is no gap between the two parts to allow for a bit of expansion.

Whilst it is very generous to suggest manufacturing for materials cost only, it might be a good business idea - there are a lot of SB people who would pay more ! Perhaps you could recover the cost of the printer as well?

[cooper1337]

My two - err: three - cents:
- Don't expect it to be that cheap. It will be a lot cheaper than ordering online, but 1-2$ is definitely not enough
- What are the small holes for? I mean the one on the top of the cylinder and the one near the hole for the chain. Are they for "effect number 5"?
- I suggest printing at least the inner part lying on the side. If you print it standing like on the picture, the planes will be all orthorgonal to the pulling force, which makes it easier to break.

[luanachiantelle]

I think there is no need to use a 3d printer for the inner part, it will be sufficient to drill holes in a cylinder of the right material.

I'v built myself one similar using a lathe, the only difference is that the external part has not the holes in this drawings, but only a simple cylindric chamber wider than the inner part.

It works pretty good

[marthite]

To answer some of your questions:

3D Printing
Materials. Nowadays the most popular are resins, ABS or PLA. ABS seems the most promising so far (Lego is made with ABS). As long as critical walls are kept to around 3-5mm, it should be strong enough.

Orthogonal printing. Good point about maximizing structural strength

Price per lock. Spools sell for about $35 per 2lbs. ABS density is 1.04g/mL. The lock currently uses 50mL, but let's assume 100mL to be safe. That translates to 104g = 0.23lb = $4. So $4 would be a conservative price.

Design
Two small holes (actually protrusions). They are used for alignment purposes. The small protrusion of the rod should align with the small protrusion at the top of the cylinder. This ensures the holes of the rod and case match. When water freezes, ice rods will then form along those holes, preventing the rod and case from separating.

[Jadit]

There could be small pin going to a hole on inner surface of the container. This would make it so that the inside-pipe can't rotate, and the ice-holes are always aligned.

Also you should consider the freezing process. It has to stand firmly in position while the water is inside.

[gemt]

I'm fairly sure I have seen an ice-lock like this available commercially.
My main worry would be leaking melt-water all over.
My other main concern is it may not take a lot of melt to get this free.
Once the outer edge has melted the parts will slide through each other relatively easily?

[marthite]

@Jadit:
Agreed. This design is quite preliminary. Strength/cycle testing would have to be done and other improvements would be made.

@Gemt:
- The commercially available one is $100 (although stainless steel).
- Yes there'll be leakage, but it'll be just around 5mL.
- Double outer wall with air pockets will increase melting time. So will adding your own thermal tape. I haven't tested either option (it's all in the computer for now) but I think an hour will be easily achievable, while 5 hours should still be realistic.

[marthite]

I decided to go ahead with the printer purchase. It should come in 2 weeks, and I'll let people know how the idea holds up.

[Time4Switch]

It looks like a great idea. I'll happily buy a couple.

Looking at the water leakage and timing issues, some ideas which quickly come to mind include cutting the toes off of a couple of old socks and sliding and bunching them over the device before using, and depending on its outside diameter, sliding a cut section of a water weenie (pool toy great for other uses) over it before adding the sock(s) to provide insulation.

I think the main issues durability wise would be breakage caused by side-ways forces directed at the attachment points. Keeping the attachment hole small on the plunger would reduce that aspect and the bottom "handle" might be fixed by instead incorporating a nipple with a hole through it (think pierced nipple with a loop attached). I'm not a materials engineer so I'm just thinking off the top of my head. If the material you use is the same strength of a Lego piece it probably wouldn't matter so much. I'm just throwing these ideas out as food for thought if you run into issues, not as a criticism, I love what you are doing.

I've been interested in the metal ice locks for a while and think they are way overpriced. You perfect a durable design and you could have a hit on your hands.

[bobbi]

the main concern i have for 3d printed objects is the durability. my bondage equipment needs to be super strong because if i can break it, there is no purpose.

^_^

that said, i have two of the metal icelocks from mr. s in my freezer. haven't ever used them XD lololol.

to increase time, the mr. s. ones come with neoprene sleeves. the same stuff that the beer coozies are made out of. they claim it adds another 30min to the ~2hr time.

[stefani]

I like this idea a lot. However, I feel like the whole thing could be made from some PVC pipe and caps. I would glue the cap on one end of the short PVC. and then fill the other end with water and insert the free capless end of the pvc into water filled cap and insert into freezer. All that is left is attached rings to the caps so you have a tie point on each cap. Thoughts?

[Tenderfoot88]

The main difference between this thing and the basic plumbing pipe rig is the expansion bubbles. Ice swells as it freezes, so if you fill the container, it puts strain on the PVC. If you do this enough times, the PVC will fail (though if you're doing it right, all that will happen is that your 2 lock halves will come apart sooner rather than later, and you'll need to build a new one)

I've seen a couple of good ideas for plumbing based DIY setups:

One was an image in the testing part of the forum (not sure if it's elsewhere too) of a fairly sizable post (as in holding stuff up, not adding info to the forum) with a piece missing in the middle. Put ice cubes in the bottom (capped with a mesh so water can drain), then put a metal bar (or something) in through the top part, which blocks the middle. As the ice melts, the bar slowly drops down into the lower segment where the ice used to be, and eventually unblocks the middle opening. Tie your release rope around that, and you're freed when it drops past the opening.

The other is pretty much your idea, but with the addition of running a bolt through the PVC you put into the water. Ice doesn't do friction grips well enough. It doesn't have the the ice fatigue countermeasures, but it's easy to make and it's so cheap.

Or you can shell out some more cash and get a battery powered electromagnetic lock of some kind (preferably with timer so you don't have to burn through the battery each time). At worst, you'll be waiting for the battery to die. (and if the electromagnet itself dies, it releases automatically.)

[marthite]

I made a quick prototype today with a coarse print. It seems to be working well so far. Just testing material strength and insulation properties of ABS.

[bobbi]

whoa, anon delivered!

that's actually... pretty damn cool. the rough print makes it looks like its built like a masterlocks made of layers of metal.

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