When making cuts on floor tiles using the angle grinder and diamond blade, this is where the tricky part comes into practice. Not only is it a hand held tool which is more difficult to control for doing straight lines, but you also have to gradually cut the tile from the reverse underside. When marking your tile for cutting, you actually have to mirror the measurements to obtain the correct dimensions for topside laying, and this can be a somewhat confusing aspect at the best of times.
Once happy with your desired markings, you then follow your lines with lightly scored cuts, going over the same spot maybe around 4 to 5 times to as far as the glaze only, and never straight through in one go. If you attempt this, you'll probably just end up breaking the floor tile in no time, so the trick to cutting with the angle grinder is with gentle sweeping strokes, and never all the way.
4 1 2 Grinder
For ease of control to suit your own preferences, you can either hold the main body of the angle grinder with one hand, and with the other hold the optional grip handle which sticks out from either the left or the right. This method will give you a more precise and rigid control over cutting which is ideal for straight lines.
For rounded lines however, then with both hands on the main body you can achieve a more free-flowing action ideal for circular sweeps. The guard which protects your hands from the blade can also be rotated to suit your choice of cutting angle, but whatever you do, never remove it from the grinder. It is there for a purpose if it's your own personal protection that you value most.
If you have a circular pattern to remove from a tile, do this in stages like with the wet tile saw in making a 'comb teeth' pattern following your main line of cut. Once you have a series of 1/4" to 1/2" inch wide 'teeth' along your line cut from the reverse side but not entirely all the way through to the glaze, you can then easily nip these off with either your tile nippers or standard pliers, and clean up the sharp edges as you go. As always though, safety first, so never forget to wear your eye protection even when nibbling tiles. Those shards can snap off like bullets.
As an ideal method of practice to get the hang of these techniques before actually applying them to your job, it is always wise to get a little experience in first to establish your comfort zone. Using off-cuts or broken floor tiles beyond salvage, first get some training in on how to cut tiles using the angle grinder. You can never be too careful when trying out something new, and the last thing you want is unnecessary wastage and higher expense to the budget of your floor tiling project.