by Admhawk » Wed Jun 22, 2016 1:22 pm
Poul, there are many ways to approach this, but explaining can be challenging.
One way would be to hunt through craft stores, toy stores, sports stores for a ball of some sort that is the correct size. Material isn't a big issue, as long as it can be cut and painted.
Next comes measuring and eyeballing. Mark a centreline. Turn 90 degrees and Mark another centreline. This should help keep things symetrical. To get a good centreline, push three pins into the ball in a small triangle equidistant apart. Balance it on a flat surface and slowly spin it with a pencil marking the half way point. To find the halfway distance place the ball between two perpendicular objects, like blocks of wood and measure the distance between. Half that distance is the height the pencil needs to be held at. You can cut wood and glue or tape it on to keep the pencil steady.
Where the two lines cross on one side, use that as your bottom. It doesn't matter which one you pick. Remove the three pins. From the top crossing, use a compass to mark a line part way down the side at the level of the bottom of the cut out.
Now Mark another centreline.
On each side, at the point where this new centreline crosses one of the vertical centrelines, use the compass to Mark rings where the cutout sides will be.
Now you should have the cutouts marked. You can darken the areas if it helps you, but it isn't req'd.
At this point, you either cut the areas out with a saw or knife, or cut the whole top piece off, then cut the two side pieces off that top and then glue it back on. If the ball is hollow, you will need to put some plastic walls in the cutout. If the ball is hollow, and you cut the whole top off, a thin piece of plastic covering the hole will give a good platform the glue the top back on to and fill the area the saw blade took away.
You can use tape or plastic for the ridge that goes around the outside.
Clear as mud!!
Good luck!!
Poul, there are many ways to approach this, but explaining can be challenging.
One way would be to hunt through craft stores, toy stores, sports stores for a ball of some sort that is the correct size. Material isn't a big issue, as long as it can be cut and painted.
Next comes measuring and eyeballing. Mark a centreline. Turn 90 degrees and Mark another centreline. This should help keep things symetrical. To get a good centreline, push three pins into the ball in a small triangle equidistant apart. Balance it on a flat surface and slowly spin it with a pencil marking the half way point. To find the halfway distance place the ball between two perpendicular objects, like blocks of wood and measure the distance between. Half that distance is the height the pencil needs to be held at. You can cut wood and glue or tape it on to keep the pencil steady.
Where the two lines cross on one side, use that as your bottom. It doesn't matter which one you pick. Remove the three pins. From the top crossing, use a compass to mark a line part way down the side at the level of the bottom of the cut out.
Now Mark another centreline.
On each side, at the point where this new centreline crosses one of the vertical centrelines, use the compass to Mark rings where the cutout sides will be.
Now you should have the cutouts marked. You can darken the areas if it helps you, but it isn't req'd.
At this point, you either cut the areas out with a saw or knife, or cut the whole top piece off, then cut the two side pieces off that top and then glue it back on. If the ball is hollow, you will need to put some plastic walls in the cutout. If the ball is hollow, and you cut the whole top off, a thin piece of plastic covering the hole will give a good platform the glue the top back on to and fill the area the saw blade took away.
You can use tape or plastic for the ridge that goes around the outside.
Clear as mud!!
Good luck!!