you need
  • Protective goggles (optional).
  • Depending on the method:
  • glass cutter, pliers, rope and sucker;
  • tubular drill, drill and an abrasive;
  • Diamond fabric and thick cardboard (or plywood);
  • scissors and a bowl of water.
Guide
1
One of the easiest options - take an ordinary glass cutter and make adaptation to otcherknut perfect circle.To do this, you need to attach the suction cup to the presumed middle of the finished product, then tied a rope to it, then measure out the desired length of rope (it should be equal to the radius of the circle of the future) and to attach to it a glass cutter.Then draw a circle they limited the length of the rope, and from the outer boundary of the circle glass cutter procherknite "rays" to the edges of the glass preform.
Then carefully break off ticks extra pieces of glass - for this and needs "rays" to do everything gradually and carefully.
2
If you need a range of relatively small diameter (less than 30 cm - is the limit for this method), you can use the drill tube.It consists of a metal tube with a holder for a drill at one end.The edges of the drill is absolutely smooth as glass cutting is carried out solely by the abrasive (usually aluminum oxide) mixed with water.So, take a drill with a tubular drill, abrasive mix with water, put on the glass at the edges of the circle and the alleged start drilling.Take your time and make sure that under the drill was always abrasive with water, otherwise the glass to overheat and break.Thus, the drill through the workpiece, and you get a smooth glass circle.
3
If you have no glass cutter and drill pipe, you can use the diamond saw.It is a smooth metal strip, one side of which there is a diamond plating, instead of teeth.To start, you need the template on which you will cut out the circle.It can be cut out of cardboard or plywood - most importantly, that the stencil does not razmok water.Ready circle is best to stick to the glass blank, so it does not move out.Now you can start to cut.Remember that the workpiece must be constantly moistened with water, otherwise the glass will crumble, and eventually crack.You can water it occasionally or lowered into the water tank, but it is easier and safer to cut the glass in the bath or in the sink under a continuous stream of cold water.The process is very long, so you need patience and accuracy.
4
There is a very interesting way of handling thin glass (2-3mm) using ordinary scissors.It can be used in the event that you do not have the proper tools, and make a circle of glass needed urgently.For example, to replace a broken piece of glass in the lantern.So take a stencil and apply the contour of the future range on the glass water-resistant marker.Then dip the glass into the water and begin to cut it.Do not try to cut from the marks - the essence of this method is that the glass should be cut at the edges, biting off small pieces.Gradually, the shape of the workpiece will be closer to the right.Unfortunately, this method has a drawback - circle turns out not quite flat, but in an emergency it is not important.