I have been asked many times about the methods i use to frag my LPS.There are many tools that can be used to do this and the right tool for each coral makes the job much easier.
The tools i prefer to use are a large flat head screwdriver,heavy duty shears/snips,a dremel
w/carbide blade(diamond blade is much better though)and my personal favorite,a 4" angle grinder w/diamond blade.With each type of coral growth form(branching,encrusting,boulder,etc..)I use a different methodl.With branching corals such as Euphyllia spp.,Caulastrea spp.,SPS corals like Acropora spp.,I use 2 different approaches.Thin branched SPS corals can simply be snipped off with shears.Thick branched SPS require a dremel.With Euphyllia spp. they have a very porous skeleton.If the colony is small,you will most likely be able to use shears/snips to cut the branches apart.In a tightly packed colony,a dremel works nice allowing you to get into those hard to reach places.When cutting through the skeleton with the dremel,you only need to cut it about 1/2 way then you can break it apart easily due to the porous skeleton.Caulastrea spp. are also branching but have denser skeletons than Euphyllia.Sometimes shears/snips can work well on these corals but with the 4" grinder,you can hack up a colony alot faster and with greater precision.
Now for the boulder/brain type corals(Favia,Favites,Platygyra,etc..),this is where the 4" angle grinder really shines.Alot of people will cut through the tissue when fragging these types of corals.Although this works,you end up with alot of tissue damage.I prefer to turn the coral over and cut from the bottom.Don't cut all the way through the coral,rather cut just deep enough to leave approx 1" of skeleton/rock where the tissue is at on the opposite side.Then simply take a screwdriver and pry the halfs apart(Gently).Have a sharp razor blade nearby so you can cut the tissue that might be hanging on to the two halves.FYI,study the coral carefully before cutting and look for the idea place to make the cut.Often,there will be certain places you can cut without having to cut through the corallites(where the polyps emerge from)
With some of your smaller polyped LPS corals like Acanthastrea,precision cutting is often needed to make 2-3 polyp frags.This is where the dremel comes in hand as it will allow you to cut through the ceriod(joined together)corallites.
Whenever you are ready to start fragging corals it is impotant to have all your tools layed out,an old towel on the counter,and 2 sepertate containers(i use the square ones you store leftover food in) of tank water.Make sure your "frag station" is well lighted too.
Whatever corals you plan on fragging,especiaaly with Euphyllia spp.(FS,Hammer,torch),you want to try to get the polyps to recede before removing them from the tank.Then just place them on the towel and begin the cutting/clipping procedures outlined above.Immediately after the cutting,swish the frags vigourously in the one container to clean them,then remove them to the other(clean water)container.
Repeat the process until the colony/colonies have been fragged.The frags are now ready to be superglued/.epoxied to LR rubble(if needed to be).Then they can go back into the display.Upon re-introduction,I recommend turning the lights out for that day while the coral heals..If done right,you will see very little exposed skeleton/corallites on the coral and the tissue will rapidly overgrow this.If you have poor water quality,excessive algae growth in your tank,then you night want to this as well.Take a little superglue gel and seal the outer margins of tisue/skeleton.This will help keep algae from invading the exposed skeleton.In conclusion,the most important thing you can now do is feed your corals and try to maintain low nutrient water quality.That way,the algae growth is slowed and the coral can regrow over the tissue that you might of accidentally damaged.