I found this fairly straight forward article regarding Mechanical Mods for the folks that have no idea what a "Mech" is and for the peeps that are interested in delving into the scary place of mechanical monsters 
found here
Mechanical Mod Guide
This guide is designed for beginners new to the world of mechanical mods.
NOTE: If you are just starting out with vaping, we don't recommend choosing a mechanical mod as your first device as these devices do not have the inbuilt safety features of our standard vaping kits and require some additional knowledge of handling and monitoring lithium based batteries.
What is a mechanical mod?
A purely mechanical mod is a very basic personal vaporiser device. It is a tube that holds a replaceable rechargeable battery and on the tube is a button that when engaged completes a circuit that delivers unregulated current to the atomizer. A mechanical mod contains no wiring or soldering, nor any electronics.
Example of a mechanical mod
Mechanical mods come in all different shapes and sizes. The following image shows aKamry KTS+ ; a telescopic mod that caters to different capacity batteries.
Why choose a mechanical mod?
A major reason some vapers choose a mechanical mod aside from aesthetics is their durability. In a typical personal vaporizer, the device is heavily dependent on electronics and if any component fails, repair is usually not possible for the average user. Some electronic personal vaporizers are also basically a disposable device in that once battery end-of-life has been reached, the battery cannot be replaced.
Some choose mechanical mods for the ability to run low resistance atomizers that cannot be run on other forms of vaping equipment; however, this is riskier than using standard resistance equipment, so requires special care.
Is a mechanical mod safe?
No lithium battery powered device is 100% safe given the amount of energy stored in what is a comparatively small battery. Electronic personal vaporizers are generally safer than mechanical mods due to their inbuilt safety features that protect against faults such as short circuits. However, good quality mechanical mod equipment in the hands of an experienced person is quite safe.
What are the risks?
Issues such as short circuits can cause a battery to discharge at such a rate that it heats up to a point of it venting and catching fire. If the vent gases cannot escape, explosion is also a possibility.
Mechanical mod safety tips
The following tips will help ensure a more enjoyable and safer vaping experience with a mechanical mod.
Acquire a multi-meter
A multimeter is a very useful device when using mechanical mods and they can be purchased from any electronics store for under $10. With a multimeter, you'll be able to monitor battery voltage and resistance of your clearomizers and atomizers and detect shorts on the mechanical mod body.
Something to note with cheaper multi-meters is the resistance reading (Ohms) may be somewhat inaccurate due to the multi-meter itself having resistance. The way to test for this is to touch the multimeter probes together and note the reading. That reading needs to be subtracted from any measurement.
Battery type and quality
Don't skimp on batteries - it's not worth saving a few dollars at the risk of your safety. Old batteries and those with a damaged outer casing or any other noticeable defect should not be used.
Also choose the right type of battery. Unprotected standard lithium-ion (ICR - lithium cobalt oxide) batteries should not be used in mechanical mods as these have a greater risk of overheating. A good quality protected ICR chemistry battery is a better choice and some would argue that IMR (lithium manganese oxide) battery chemistry is safer again due to it being less volatile.
Battery chargers
All battery chargers are not created equal and charger quality is crucial. A poor quality charger can over-charge a battery, making it unstable and greatly increasing the change of an overheating, venting or explosion scenario while in use.
A fully charged IMR battery should be somewhere between 4.15 and 4.20 volts. Much above that (4.25V) and its life will be shortened and instability becomes a concern. Above 4.5v is a recipe for disaster.
Also ensure the lithium battery charger you buy doesn't just have an Australian plug, but is also Australian electrical standards certified - many chargers being sold in Australia do not have this certification. Even with the high quality models shown above, there can be Australian approved and non-approved versions. Look for the c-tick or RCM (Regulatory Compliance Mark), which is a tick inside a circle inside a triangle.
Battery low voltage
Unlike an electronic personal vaporizer that has low voltage cut-offs; a mechanical mod will run down the battery until it is absolutely flat, which is very bad for lithium based batteries - this is where having a multimeter is very important. Even without a multi-meter, a low battery voltage will be noticeable due to a substantial decrease in vapor production. For the best experience, recharging at 3.6V is advised or as soon as you notice vapor production drops off.
Battery polarity
Ensure you insert the batteries the right way.
Battery stacking
This is another potential point of catastrophic failure and we advise against battery stacking. Use a single battery only.
Remove batteries
When not in use, it's a good idea to remove the battery - this not only helps protect against accidents, but will also prolong the life of the mechanical mod's spring.
Resistance testing
Atomizers and clearomizers should be checked when new and regularly during use to ensure a short situation has not occurred or that resistance isn't too low. For safety reasons, we recommend using atomizers and clearomizers that have a resistance no less than 1.8 Ohms - take into account the multi-meter's own resistance (if any) as described above.
To test the resistance of a clearomizer or atomizer, touch the positive probe to the center post where it emerges from the device and the negative probe to the metallic outer ring beside the post.
The mechanical mod itself should also be tested for shorting. This is achieved by removing the end cap and battery, then touching the positive probe to the positive pin of the mod and the negative probe to the body. Any reading other than the default on the multimeter indicates a problem and the mod should not be used.
Vent holes
A mechanical mod should have vent holes in the device to allow the escape of gases in an overheating event. Without venting holes, a mechanical mod is basically a hand-grenade in a battery venting situation.
Firing button lock
Most good quality mechanical mods will have a switch locking devices, which is usually engaged by spinning a small knurled wheel in an anti-clockwise direction.
All of the above appears to be a lot to have to observe when using a mechanical mod, but it all becomes automatic with time. An experienced vaper isn't one who can ignore these guidelines - if anything they pay special attention to them, knowing the potential consequences of faulty equipment.
Consider adding a fuse
Devices such as the Vape Safe have been developed for mechanical mods that are designed to trip if a short occurs; reducing the risk of thermal runaway and battery venting.
found here
Mechanical Mod Guide
This guide is designed for beginners new to the world of mechanical mods.
NOTE: If you are just starting out with vaping, we don't recommend choosing a mechanical mod as your first device as these devices do not have the inbuilt safety features of our standard vaping kits and require some additional knowledge of handling and monitoring lithium based batteries.
What is a mechanical mod?
A purely mechanical mod is a very basic personal vaporiser device. It is a tube that holds a replaceable rechargeable battery and on the tube is a button that when engaged completes a circuit that delivers unregulated current to the atomizer. A mechanical mod contains no wiring or soldering, nor any electronics.
Example of a mechanical mod
Mechanical mods come in all different shapes and sizes. The following image shows aKamry KTS+ ; a telescopic mod that caters to different capacity batteries.
A major reason some vapers choose a mechanical mod aside from aesthetics is their durability. In a typical personal vaporizer, the device is heavily dependent on electronics and if any component fails, repair is usually not possible for the average user. Some electronic personal vaporizers are also basically a disposable device in that once battery end-of-life has been reached, the battery cannot be replaced.
Some choose mechanical mods for the ability to run low resistance atomizers that cannot be run on other forms of vaping equipment; however, this is riskier than using standard resistance equipment, so requires special care.
Is a mechanical mod safe?
No lithium battery powered device is 100% safe given the amount of energy stored in what is a comparatively small battery. Electronic personal vaporizers are generally safer than mechanical mods due to their inbuilt safety features that protect against faults such as short circuits. However, good quality mechanical mod equipment in the hands of an experienced person is quite safe.
What are the risks?
Issues such as short circuits can cause a battery to discharge at such a rate that it heats up to a point of it venting and catching fire. If the vent gases cannot escape, explosion is also a possibility.
Mechanical mod safety tips
The following tips will help ensure a more enjoyable and safer vaping experience with a mechanical mod.
Acquire a multi-meter
A multimeter is a very useful device when using mechanical mods and they can be purchased from any electronics store for under $10. With a multimeter, you'll be able to monitor battery voltage and resistance of your clearomizers and atomizers and detect shorts on the mechanical mod body.
Something to note with cheaper multi-meters is the resistance reading (Ohms) may be somewhat inaccurate due to the multi-meter itself having resistance. The way to test for this is to touch the multimeter probes together and note the reading. That reading needs to be subtracted from any measurement.
Battery type and quality
Don't skimp on batteries - it's not worth saving a few dollars at the risk of your safety. Old batteries and those with a damaged outer casing or any other noticeable defect should not be used.
Also choose the right type of battery. Unprotected standard lithium-ion (ICR - lithium cobalt oxide) batteries should not be used in mechanical mods as these have a greater risk of overheating. A good quality protected ICR chemistry battery is a better choice and some would argue that IMR (lithium manganese oxide) battery chemistry is safer again due to it being less volatile.
All battery chargers are not created equal and charger quality is crucial. A poor quality charger can over-charge a battery, making it unstable and greatly increasing the change of an overheating, venting or explosion scenario while in use.
A fully charged IMR battery should be somewhere between 4.15 and 4.20 volts. Much above that (4.25V) and its life will be shortened and instability becomes a concern. Above 4.5v is a recipe for disaster.
Battery low voltage
Unlike an electronic personal vaporizer that has low voltage cut-offs; a mechanical mod will run down the battery until it is absolutely flat, which is very bad for lithium based batteries - this is where having a multimeter is very important. Even without a multi-meter, a low battery voltage will be noticeable due to a substantial decrease in vapor production. For the best experience, recharging at 3.6V is advised or as soon as you notice vapor production drops off.
Battery polarity
Ensure you insert the batteries the right way.
Battery stacking
This is another potential point of catastrophic failure and we advise against battery stacking. Use a single battery only.
Remove batteries
When not in use, it's a good idea to remove the battery - this not only helps protect against accidents, but will also prolong the life of the mechanical mod's spring.
Resistance testing
Atomizers and clearomizers should be checked when new and regularly during use to ensure a short situation has not occurred or that resistance isn't too low. For safety reasons, we recommend using atomizers and clearomizers that have a resistance no less than 1.8 Ohms - take into account the multi-meter's own resistance (if any) as described above.
To test the resistance of a clearomizer or atomizer, touch the positive probe to the center post where it emerges from the device and the negative probe to the metallic outer ring beside the post.
The mechanical mod itself should also be tested for shorting. This is achieved by removing the end cap and battery, then touching the positive probe to the positive pin of the mod and the negative probe to the body. Any reading other than the default on the multimeter indicates a problem and the mod should not be used.
Vent holes
A mechanical mod should have vent holes in the device to allow the escape of gases in an overheating event. Without venting holes, a mechanical mod is basically a hand-grenade in a battery venting situation.
Firing button lock
Most good quality mechanical mods will have a switch locking devices, which is usually engaged by spinning a small knurled wheel in an anti-clockwise direction.
All of the above appears to be a lot to have to observe when using a mechanical mod, but it all becomes automatic with time. An experienced vaper isn't one who can ignore these guidelines - if anything they pay special attention to them, knowing the potential consequences of faulty equipment.
Consider adding a fuse
Devices such as the Vape Safe have been developed for mechanical mods that are designed to trip if a short occurs; reducing the risk of thermal runaway and battery venting.
