My appologies for posting the subject for a second time but I am still searching for a relatively simple approach to this problem. I need to turn fairly regular high (100+) volumes of 40mm dia spheres in soft woods for use in a variety of toys that I make. They don't have to be "perfect" but they need to look "OK". I curently just turn them using a spindle gauge. Single piece blank to diameter then mark length. Plunge at length each end then half bead left then right. If I am on song then they are great ... but I am seldom on song. I have seen plans for several complicated devices to make and attach to the lathe but never attempted to make them. Surely this problem has been solved in the past. I would be grateful for any simple solutions ( on topic). eg would a set of LH & RH curved (20mm radius) scrapers work? If so how would the tool be sharpened and re-sharpened? regards, G
I use a piece of black iron pipe slightly smaller than the sphere about 12" long. put the end of the pipe on your grinder and form a burr.
After you rough out the sphere with a gouge, place the pipe on the tool rest and swivel back and forth with LIGHT pressure until you have a perfect sphere. Very little sanding required to ginish off.
What toys do you make? I make and sell a number of toys.
You can make a swinging cutter for balls that works quite well. It is described in David Springett's book, "Woodturning Wizardary." You can also purchase a metal version from Craft Supplies Ltd. in the UK, it is called a sphere turning rig.
Basically, all you need to do is make an "L" shaped piece out of a good hard wood. Put the long side of the "L" on the lathe bed with a hole through it and some means of locating the hole on the center line of the lathe (i.e., directly below the headstock center). On the one that I made several years ago, I used two bearings one below the lathe bed and one above it so that a bolt passed through the hole in the "L" would pass through the bearings and would swing freely and smoothly. When this is done, locate a spot that is directly on center on the upright leg of the "L". Drill a hole to accept one of your round cutting tools that has the cutting edge at centerline of the tool (this is so that the cutting edge is on center line of the axis of rotation). Now drill and tap a hole from the side or top that will intercept the hole for the tool. Insert the tool in the hole, insert a short bolt that matches the threads in the "L" and use it to secure the setting of the tool. You can now get nearly perfect spheres, by adjusting the fixture so that the point of swing is directly below the center of the ball that you want to turn. Adjust the tool so that it just cuts on its furthers swing to either right or left. Swing to the other side and cut, then move the cutter in a bit and repeat this overation until you cut across the top and the sphere is to proper diameter.
Another way is to clamp the wood in a chuck and locate the center of rotation
1/2 of the diameter from the end of the wood. You have to cut up hill on half of the cut, but it makes a perfect sphere of the diameter that you want.
You might find it less expensive to purchase already turned spheres, however. I personally like to turn my own. Good luck with your project.
I use the same method that Doug describes but I use a shorter length of pipe. Then I turn a handle with a tenon on the end. The tenon goes in the piece of pipe and stops at half the diameter of the pipe. The tenon is being used as a stop so the sphere can't go in the pipe more than half way to eliminate catches. You can make a whole bunch in a row if you hold your piece in a chuck. I turn a bunch in a row with light tailstock pressure to keep things on track then remove the tailstock and finish them with the homemade sphere scraper. Some people make there sphere scrapers with a hole saw. Just grind the teeth off and add a handle. You can make a whole bunch of spheres in short order.
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