turning a perfect sphere.

[vyvsdad]

Hello all,
I wander if anyone can help. Is there a specific technique, tool, jig that is used for turning perfect spheres. I'm looking at about 50mm diameter initially, but the father in law wants some new croquet balls, so potentially quite large, depending on technique.

Many thanks,

Dan

[Bryan Milham]

Dan,

there are 4 ways I know of. So I'm assuming you've discounted the first just turn it with your tools, so the other 3...

1. Get hold of a holesaw a little smaller than the diameter of the sphere you want to turn and grind the teeth off and a then a cutting edge all around the saw - make and fit it to a handle. Turn your sphere to just a little bigger than you want and then holding the holesaw cutter against the rotating wood and moving it around gently it will round off the edges and finish it nicely for you, some sanding will be required.

2. There is a guy on e-bay who makes and sells sphere urning tood/jigs for woodlathes.
http://www.ebay.co.uk/itm/WOODTURNING-LATHE-100mm-BALL-TURNING-TOOL-/290840802467?pt=UK_Crafts_Other_Crafts_EH&hash=item43b77674a3 - you can also make a simple version of this for yourself.

3. Lastly there is a set of callipers for turning spherers called Soren Burger Sphere Callipers - no idea where to buy them in the UK or how much, but here is a video of them in use, very clever. https://www.youtube.com/watch?v=R4s5LziiS08 - at the end it also shows the holesaw method as he cleans up with it.

[John D Smith]

Dan I think this is the perfect answer it will only cost you a few Quid I made one and it cost me £2 for the piece of tool steel all the rest of the materials I had lying around.(my wife says I never throw anything away).If you can get hold of a copy of "Woodturning" issue 217 September 2010 there is an article by Gabor Lacko page 32 with pictures and plans I think you could google this and find it somewhere but I am sure another member of this forum will come up with a link to the issues web site of the magazine if all else fails send me a PM with your address and I will photocopy mine and send it to you. Regards John 

[malcy]

I have the device alluded to in the link in the reply by dr4g0nfly. It works very well and is simple to use and set up. I made 62mm box balls with it. I believe you will need a different size device( Ithink he makes both) for balls about 100mm though. Malcolm.

[John D Smith]

Hi Dan any feed back on your attempts to turn a Sphere Regards John

[Eric Harvey]

I was given a tip at my woodturning club the other month,they said if you use a cone drive and a cone on the revolving tailstock with a bright light to see the shadows when its revolving,then turn a section,move it around  then return it and so on untill you have a perfect sphere,going by some of the balls turned ,it certainly works,no doubt with practice and patientsanyone could get the same results,regards,

Eric.

[Bryan Milham]

Poking around I came across these instructions for making your own ball turning jig,

http://www.bobchapman.co.uk/_6__ball_jig.pdf

[vyvsdad]

Thanks for all of the tips guys.
I've not yet tried layout as I'm away from my lathe and am just planning some projects.
For the smaller 50mm balls, as I'll need quite a few, I think I'll just buy them, but when I come to do the croquet balls I think a home made ball turning jig is going to be the order of the day.
I'll keep you all posted.

Thanks to all,

Dan

[Haggy]

Dan, an easy quick method to turn a sphere is to cast a shadow onto your lathe bed with a lamp (see pic).
If you have a circle drawn on a piece of flat material that rests on your bed you can shadow turn.
You can focus the shadow by moving the lamp back and forth on the work piece -this is a quick, simple way to get good results.  The kids I teach love this,  is easy to set up and change the OD of the sphere.
Worth a try!
   Haggy

[Haggy]

Sorry, meant you to see this pic- if I have not made things clear please get back.