sphere on spindle, help

Re: sphere on spindle, help

Richard Allen

>Get a washer with a 3/4" hole in it. Flatten one side so as to "sharpen" the edges of the hole. With the lathe running gently rub the hole adainst the "ball" and keep it moveing. The edge won't last very long but the shape will help you get a ball.

You can also use a short 3/4" pipe, "sharpen" the end. Rub that sharp end against the ballas it spinns on the lathe.

These methouds are easy to tell you about but seeing it done makes the whole process a LOT easier.

Good luck

Re: sphere on spindle, help *LINK*

Fred L. - North Carolina

>I built a jig to turn balls on the end of a spindle. Mine is made of aluminum, and was originally for my metal lathe. It will turn balls to about 1".

Since I don't have a pic, please look at Jean Michel's page in the link below, under Chinese balls. I can be made easily from wood. The jig looks like a letter "L", and can be cut from sturdy 3/4" wood. There is a 1/4" hole in the horizontal part of the L, about 1-1/4" from the VERTICAL part. This sits on the base and allows rotation of the jig. The cutter goes through a 5/16" hole in the vertical member of the L, and points to the axis. (where it rotates). The bit is held by a 1/4" thumbscrew. If you use wood, you can drill and tap the hole, and reinforce it with CA, or use a tee nut, etc. It is best to angle the hole for the bit slightly donw.

The cutter I use is a 1/4" HSS metal cutting bit, ground like a scraper. A piece of drill rod coulg be substituted, or any steel that is hard enough. I ground mine like a rounded, pointed scraper, so it will be able to get close to the stem. The diameter of the ball is adjustable. The more the bit sticks out of the jig, the smaller the ball.

The jig is built so the bit is approximately at spindle center height. The bit points down at a small angle, just like I would do with a scraper.

For a l" ball, I would rought it out a bit, and use the jig for the final cut. Just cut the ball a bit oversized with your regular tools, and then use the jig to get the proper spherical shape.

The jig is positioned so the bit touches the end of the wood at the center. Then the jig is rotated to cut around the ball to the stem.

That is actually how I put a ball at the end of a Bic pen !!!!

This is by far the best way I found to do ball finials.

Hope this helps, I wish I had a pic.

FredL

Fred


http://www.jeanmichel.org/woodturnjigs.htm

Re: sphere on spindle, help -email

Fred L. - North Carolina

>

Re: sphere on spindle, help

Phil Joines Krum, Tx

>You can use a hole saw the same way. Grind the teeth off and add a handle. The metal remaining after removing the teeth is still hard and will hold a good edge.

Make a template to hold against the piece to check the shape as you go.

Perfect spheres

Bob Hackett

>Take a holesaw that has an inside diameter of the sphere you want and grind all the teeth off leaving a flat and square surface(I chuck the drive mandrel in a jacobs chuck and use the lathe to spin it while grinding).Hone the edge inside and out.You now can use a bolt and nut to make a mandrel to hold this "sphere scraper".Put the mandrel in a handle and whenever you need a sphere of a different size just modify a new holesaw and go to work.

If you can`t find a holesaw in the exact size where the scraper pops over the ball when it reaches tolerance then just use a smaller tool and check for size as you approach final size.The spheres are guaranteed to be spherical using this scraper as long as you keep the entire edge in contact with the ball and keep the entire edge moving and cutting.

Mainely,Bob

Re: sphere on spindle, help

John Lucas

>Bill

I only tried the sharpened pipe thing once and it didn't work very well for me. Perhaps I didn't sharpen it correctly. I cut a square bead using the parting tool to get the dimensions of my ball. Then I knock the corners of at 45 degrees. This leaves an 8 sided ball. Then I take these corners off leaving the ball almost round. Then I use the skew as a scraper (please don't tell Nick Cook). By taking light cuts I can get a nearly perfect ball.

Re: sphere on spindle - CHEAT !

Fred L. - North Carolina

>I think all the methods mentioned in the prior posts will work, if they are used after the ball has been roughed out to an approximate shape. Even with my jig, I can only cut the last 1/16 or so. I use a cardboard pattern to get the approximation.

Crafts places like Hobby Lobby sell ready made wood balls, and some even have a hole to attach them . . . I think 1" balls are two for a buck !

Don't tell anybody and I won't either ..

Fred

Re: sphere on spindle, help

Al Kapocius, Metro Greendale

>Saw one technique in a Brit magazine. Turn a cylinder to desired sphere diameter. Make a gage or template, say out of hardboard or plywood and burn it in against the workpiece to get an exact contour. Use the gage to refine the rest of the sphere.

Al Kapocius

thanks to all sphere suggestions

Bill Tindall, E. TN

>the technique posted by John Lucas works very well. It is the same technique the hand tool folks would use to make a quarter round on a table edge with a plane or shave. I got out my drafting equipment and studied why it works. turns out that a circle will just inscribe inside an octagon of the same size as the square that inscribes the circle(sphere), etc for the remaining equal sided polygons. Anyway, it worked great.