Simple improvement on the Electonic timer padlock

[alobazombie]

Many threads exist about this kind of cheap electronic timer padlock:

Electronic Timer Device Time Lock

and in nearly all of them a complaint is made about the cheak plastic housing. I own a couple of these and indeed they feel like the cable could be ripped out of the lock without difficulty.
As a result I never use these kinds of locks to secure anything that might come under tension, which limits the ties I can do with this lock.

Today I came up with a ridiculously simple device that can bypass this problem. I'm not sure if this kind of technique has aeady been posted here.

Materials:
-The lock
-A- small-medium chain of any length you like
-A heavy-duty ziptie

plus pliers and side-cutters


The idea is to use the timer padlock to lock a loop of chain without transferring the tension load on the locking mechanism itself. Create a flat loop with the ziptie that can be slid inside two chain links as shown:
   
   

The chain links and ziptie need to be appropriately sized so that  the ziptie strip itself can barely slide through the chain links but the locking square thingy cannot.

The final step is to lock the timer padlock inside the loop so it cannot slide out the other way unless the padlock is removed first:
   


When the loop of chain is subject to tension,  the upper chain link closest to the padlock wire will compress the wire against the ziptie, placing no load on the padlock body. The ziptie itself is subject to tension and shearing forces, and thus becomes the new "weakest link".
I haven't made any load tests yet, in any case I believe it could be plenty strong enough for many selfbondage applications.

As a safety plus if the timer lock fails to open, you can now use a pair of side cutters  to cut the ziptie loop in addition to the padlock wire.


EDIT:

There may be some difficulties in sliding the padlock wire out of the ziptie when the whole thing is under tension, the metal endpoints of the wire can catch the zip-tie links.
If the zip-tie is thick and wide enough to just barely fit inside a chain link, it will pivot slightly under tension from the links but not enough to choke the padlock wire. The wire can then be slid out with some work.

In any case this definitely requires at least one hand to unlock (but so does the padlock)

[Tinker D]

What a brilliant idea.
This is a great idea, except for one detail.

At each end of the cable, there is that small peice of steel that holds the cable to the lock body. Like a shackle. With the chain in tenchion, can that cable fully slip through the zip tie? Or will the end of the cable part hang up in the zip tie?

[alobazombie]

What a brilliant idea.
This is a great idea, except for one detail.

At each end of the cable, there is that small peice of steel that holds the cable to the lock body. Like a shackle. With the chain in tenchion, can that cable fully slip through the zip tie? Or will the end of the cable part hang up in the zip tie?

Thank you! That's a really good point you make.

I just did a test with a long piece of chain hung from a pull-up bar , looped down to ankle-level an back up so I could slide my foot in and put some weight on this device.

Under load the short end of the chain will pull the zip-tie loop down, pivoting arount the link of the other side of the chain. Since it's a thick zip-tie there isn't much room to do this inside the chain links so it's a limted movement.
The zip-tie loop must then be long enough to allow for this motion while not gripping the padlock cable so hard that it's impossible to slide out. 

In my case it definitely didn't slide out easily, but it wasn't too hard to push the ziptie loop apart enough to let it through. Mind you, my hands were not tied and, most importantly ,they were not tied under tension from this very chain, so it may turn out to be more difficult.
I plan on doing a session tonight and will report.