Sensor to detect lock being cut? Need ideas other than motion/camera

Seeking Advice
1

Sort of a strange inquiry here, but I’m out of ideas. I’m the caretaker of a cave that we have gated to protect the bats, only allowing occasional access to researchers…but it’s near some public woods on the edge of my property and occasionally attracts people’s attention. I have a camera and a motion sensor up, and the server sends remote alerts…but it triggers a lot. It seems to trigger more when it’s hot out, and the bats trigger it constantly. A cell service based camera isn’t an option because there’s no service out here. I’ve tried multiple different motion sensors, and they all seem to have the same issue with overtriggering even when the sensitivity is turned way way down.

Ultimately, it’s always going to draw attention from people so I don’t mind if they look in the gate…but recently I had someone try to cut their way through the gate, in the midst of a number of false triggers of the sensor, so I didn’t notice. I’ve been racking my brain for solutions, and the only one I can think of is possible attaching a glass break sensor to the gate, hidden but super close to the only place that cutting the gate open is possible. Presumably the noise/vibration of the saw would trip the glass break? We tried a fence some years ago and found that even a wooden privacy fence drew too much attention, even with the camera and all the posted signs, and people still hopped over it for a peek. It’s not like I can, or want, to run over there every time someone is innocently curious. I can, however, get there in less time then it would take to cut…if I could just have a reliable alarm alerting me to someone actually doing something bad.

Open to any advice or suggestions!

2

My basic bike locks have mega-decibel alarms when tampered with so I’m sure there will be similar out there for gates/general padlocks. Is your goal to put people off or catch them in the act? Ultimately best thing to do is keep them off your land and away from the gate

3

Janeterry said:
My basic bike locks have mega-decibel alarms when tampered with so I’m sure there will be similar out there for gates/general padlocks. Is your goal to put people off or catch them in the act? Ultimately best thing to do is keep them off your land and away from the gate

I second the bike alarms, they even have fobs to activate/ deactivate them. They are a little black box that can be secured anywhere on the gate. They trigger by motion/vibration.

4

I can think of several ideas, but a bit more information from you can help us help you even more:

  1. What model sensor and alarm hub/control panel is on site (including any extra card/wireless capabilities which might have been added)?
  2. What kind of camera is on site?
  3. Do you mind uploading a couple of photos of the current door and sensor + position to a file/photo hosting site and share?
5

Bodhi said:
I can think of several ideas, but a bit more information from you can help us help you even more:

  1. What model sensor and alarm hub/control panel is on site (including any extra card/wireless capabilities which might have been added)?
  2. What kind of camera is on site?
  3. Do you mind uploading a couple of photos of the current door and sensor + position to a file/photo hosting site and share?

Also
4.) how is the existing camera powered/ communicating with the server?
5.) who’s server? Local or cloud based?
6.) How far is the current camera from the gate?

A rough sketch showing the gate, the cave, the current camera, the nearest electric receptacle, & approximate distances in between would be useful as well

6

Bodhi said:
I can think of several ideas, but a bit more information from you can help us help you even more:

  1. What model sensor and alarm hub/control panel is on site (including any extra card/wireless capabilities which might have been added)?
  2. What kind of camera is on site?
  3. Do you mind uploading a couple of photos of the current door and sensor + position to a file/photo hosting site and share?

Just don’t dox yourself, OP

7

SophyGenesis said:

Bodhi said:
I can think of several ideas, but a bit more information from you can help us help you even more:

  1. What model sensor and alarm hub/control panel is on site (including any extra card/wireless capabilities which might have been added)?
  2. What kind of camera is on site?
  3. Do you mind uploading a couple of photos of the current door and sensor + position to a file/photo hosting site and share?

Just don’t dox yourself, OP

I’m not going to. There ain’t a chance in hell I’m posting photos, as it may be easily recognized by some people. If I didnt value my privacy+security, I wouldn’t be here asking.

8

SophyGenesis said:

Bodhi said:
I can think of several ideas, but a bit more information from you can help us help you even more:

  1. What model sensor and alarm hub/control panel is on site (including any extra card/wireless capabilities which might have been added)?
  2. What kind of camera is on site?
  3. Do you mind uploading a couple of photos of the current door and sensor + position to a file/photo hosting site and share?

Just don’t dox yourself, OP

“Yourself”? Is OP Batman? It’s a bat cave in the middle of nowhere :rofl:
Photos on hosting sites are removed after some time (can also be manually removed).
And plus in general, if someone actually has bad intentions in this subreddit (not impossible) - it would be very unuseful because everyone here is looking for suggestions on how to tightn security :grinning: , who knows what OP will install in the end?

9

Don’t put a sensor on the lock, put a sensor on the gate that detects when it’s opened.

10

Safe said:
Don’t put a sensor on the lock, put a sensor on the gate that detects when it’s opened.

But I need to know before they get the gate open…

11

Jony said:

Safe said:
Don’t put a sensor on the lock, put a sensor on the gate that detects when it’s opened.

But I need to know before they get the gate open…

Then what would a lock sensor do? If they are cutting the lock then you’d only be getting a warning like 1.5 seconds before the gate opened

12

Safe said:

Jony said:
Safe said:
Don’t put a sensor on the lock, put a sensor on the gate that detects when it’s opened.

But I need to know before they get the gate open…

Then what would a lock sensor do? If they are cutting the lock then you’d only be getting a warning like 1.5 seconds before the gate opened

For anyone to get through the gate, they’ll have to cut through a 2” thick steel rod. It’s gonna take someone some time to do.

I should have been more clear in the initial post. The lock itself, the padlock, is protected and locks what is essentially a deadbolt in place. Lock comes off and the deadbolt can slide out. Due to the way it’s designed, the lock isn’t possible to cut, nor pick(unless someone can contort themselves and do it blind while the barrel faces away from them…unlocking the damn thing with the key is a challenge sometimes), but there is a space just wide enough for a sawzall blade, torch, or if someone’s really brave, an angle grinder. Due to the direction the gate swings, that gap has to exist.

What I really need is a sensor, sorta like a glass break sensor, that will trigger to the noise or vibration from a power tool. Something that isn’t gonna go off from curious hikers touching the gate to peer in, but will should someone be making a concerted effort to get in. Someone here mentioned audible alarm bike locks, and it looks like abus makes one that triggers from motion or sound, so I’m gonna get one and just lock it to the gate as a deterrent for now.

I may also see if there’s a similar bike/motorcycle lock that’s cheap enough to merit disassembling and see if I can pay someone who’s savvy with raspberry pi stuff to rig something up. Maybe it’s possible to have the pi pickup the signal sent to the speaker on the lock and alert me somehow.

13

Jony said:

Safe said:
Jony said:
Safe said:
Don’t put a sensor on the lock, put a sensor on the gate that detects when it’s opened.

But I need to know before they get the gate open…

Then what would a lock sensor do? If they are cutting the lock then you’d only be getting a warning like 1.5 seconds before the gate opened

For anyone to get through the gate, they’ll have to cut through a 2” thick steel rod. It’s gonna take someone some time to do.

I should have been more clear in the initial post. The lock itself, the padlock, is protected and locks what is essentially a deadbolt in place. Lock comes off and the deadbolt can slide out. Due to the way it’s designed, the lock isn’t possible to cut, nor pick(unless someone can contort themselves and do it blind while the barrel faces away from them…unlocking the damn thing with the key is a challenge sometimes), but there is a space just wide enough for a sawzall blade, torch, or if someone’s really brave, an angle grinder. Due to the direction the gate swings, that gap has to exist.

What I really need is a sensor, sorta like a glass break sensor, that will trigger to the noise or vibration from a power tool. Something that isn’t gonna go off from curious hikers touching the gate to peer in, but will should someone be making a concerted effort to get in. Someone here mentioned audible alarm bike locks, and it looks like abus makes one that triggers from motion or sound, so I’m gonna get one and just lock it to the gate as a deterrent for now.

I may also see if there’s a similar bike/motorcycle lock that’s cheap enough to merit disassembling and see if I can pay someone who’s savvy with raspberry pi stuff to rig something up. Maybe it’s possible to have the pi pickup the signal sent to the speaker on the lock and alert me somehow.

Maybe you could put a vibration sensor on the fence, and play with the sensitivity so that it won’t detect wind and/or curious hikers, but will trigger for a saw.

All of the sound based stuff I know of either triggers on all sounds, or depends on an algorithm to detect specific sounds on a list, but none of them have “angle grinder” in their drop down list.

14

There are sensors that will go off when a door is opened. One part on the door, one part in the same location on the frame. I don’t know how they work, maybe a magnet or something, once they are no longer next to each other it will signal. It may not save your lock but will definitely let you know when the door is open and should not go off due to bat or human motion. I don’t know much about them and hope others will chime in with recommendations.

15

Callen said:
There are sensors that will go off when a door is opened. One part on the door, one part in the same location on the frame. I don’t know how they work, maybe a magnet or something, once they are no longer next to each other it will signal. It may not save your lock but will definitely let you know when the door is open and should not go off due to bat or human motion. I don’t know much about them and hope others will chime in with recommendations.

A magnet holds the wires either connected or disconnected. When the magnet gets too far away the circuit changes tripping the alarm.

16

Callen said:
There are sensors that will go off when a door is opened. One part on the door, one part in the same location on the frame. I don’t know how they work, maybe a magnet or something, once they are no longer next to each other it will signal. It may not save your lock but will definitely let you know when the door is open and should not go off due to bat or human motion. I don’t know much about them and hope others will chime in with recommendations.

If OP concern is about people cutting the lock and opening the gate this is a great idea.

But if they are cutting through the fence this would not help.

Alternative would be the bike locks that alarm when disturbed paired with a sensor that will alert OP when it hears it.

17

Can you post a photo of the lock? On the door?

Is it practical to enclose the lock in some sort of box. So if the box is opened, the alarm goes off? Definitely make it audible and have a sign warning of the audible alarm. If possible set it so the audible alarm goes off as soon as the box is opened. Your alert only happens if the box is open > 15 seconds.

18

ingosi said:
Can you post a photo of the lock? On the door?

Is it practical to enclose the lock in some sort of box. So if the box is opened, the alarm goes off? Definitely make it audible and have a sign warning of the audible alarm. If possible set it so the audible alarm goes off as soon as the box is opened. Your alert only happens if the box is open > 15 seconds.

The lock is already boxed in and protected. The crossbar that it holds in place is also protected…except in one sawzall blade sized spot…that can’t be hardened.

I’ll have to look into audible alarms. Possibly we can set one up that will trip after 30 seconds of vibration, and send a network alert when it does

19

Jony said:

ingosi said:
Can you post a photo of the lock? On the door?

Is it practical to enclose the lock in some sort of box. So if the box is opened, the alarm goes off? Definitely make it audible and have a sign warning of the audible alarm. If possible set it so the audible alarm goes off as soon as the box is opened. Your alert only happens if the box is open > 15 seconds.

The lock is already boxed in and protected. The crossbar that it holds in place is also protected…except in one sawzall blade sized spot…that can’t be hardened.

I’ll have to look into audible alarms. Possibly we can set one up that will trip after 30 seconds of vibration, and send a network alert when it does

What if you wrapped the thin portion where the sawall blade can go with electrical tape and then duct (not duck) tape. The aluminum stuff for duct work. Think a sawzall would short them? If they’re isolated with electrical tape then attach wires. When a short is detected: alarm.

I was initially thinking of wrapping that bar with a zigzag wire. So when the wire is cut anywhere: alarm. But getting a really thin zigzag wire would be complex.

20

ingosi said:

Jony said:
ingosi said:
Can you post a photo of the lock? On the door?

Is it practical to enclose the lock in some sort of box. So if the box is opened, the alarm goes off? Definitely make it audible and have a sign warning of the audible alarm. If possible set it so the audible alarm goes off as soon as the box is opened. Your alert only happens if the box is open > 15 seconds.

The lock is already boxed in and protected. The crossbar that it holds in place is also protected…except in one sawzall blade sized spot…that can’t be hardened.

I’ll have to look into audible alarms. Possibly we can set one up that will trip after 30 seconds of vibration, and send a network alert when it does

What if you wrapped the thin portion where the sawall blade can go with electrical tape and then duct (not duck) tape. The aluminum stuff for duct work. Think a sawzall would short them? If they’re isolated with electrical tape then attach wires. When a short is detected: alarm.

I was initially thinking of wrapping that bar with a zigzag wire. So when the wire is cut anywhere: alarm. But getting a really thin zigzag wire would be complex.

That’s actually a stellar idea. There’s no way you’d get a blade in there and not manage to tap it on the frame in the process. Would be easy to stick an isolated contact of some sort in the gap that would complete the circuit when a blade is stuck in there