Tips for Square Edge Bowls archive

Friday 7 December 2012

Philip Greenwood looks at various techniques you can apply for turning square edge bowls

Gallery

People often ask me how I turn a bowl that has square edges – did I cut off the four sides after turning a bowl? The answer is no, you can turn a square edge bowl. You must always respect any item on the lathe, but with a non-round item this is even more important. You must always keep your fingers at your side of the toolrest. One point to check is that there are no faults in the piece of timber, split marks especially, or it could split while it's turning. It is always a good point to stop the lathe as you progress and check that no faults have appeared. If this is to be your first square bowl then start small, something in the region of 100mm square, and progress to larger sized pieces.

Marking out

When turning a square or rectangular bowl the piece of timber needs to be cut at 90° as near as possible at the corners; this will help you to achieve an even edge and make sure the bowl is not offcentre. Mark the centre as accurately as possible and drill with the correct drill for the screw chuck. If you have a larger piece, bring up the revolving centre to give additional support or use a faceplate for large bowls

Set the lathe speed

This is where there is a lot of misunderstanding, as most will want to turn at a very low speed when it is far better to turn the speed right up, but this will depend on the lathe and your ability. When cutting near the edge, your tool will only be in contact with the bowl for a short time. Most of the time it will have no bevel support, as you are only cutting on four points, at 500rpm, and your tool will be in contact 33 times per second, or at 2,000rpm, 133 times per second giving you more support

Marks placed on the toolrest

A pencil mark or a piece of masking tape on your toolrest will help you know where the edges are. Place the toolrest close to the bottom of the bowl, line up a corner with the top of the toolrest then place your mark there at the bowl corner. Revolve by hand to check each corner and adjust the mark as necessary. When you start the lathe your mark will show you when your gouge will come into contact with the corners

Sharp tools

Sharp tools are essential to achieve a clean cut. With this type of item think ahead and leave most of the middle in until you have finished the outer part to a sandable finish to cut down vibration if turning to a thin thickness. Do not even think of sanding near the edges with the lathe running or you will have sore fingers


Woodworkers Institute

Tagged In:

Philip Greenwood , workshop know-how