Turning a Sphere

[pigoo3]

I have been wood turning for a number of years...and recently I thought up a project that required the turning of a sphere.

I admit that I really didn't do much research...thought that I would just jump in & turn a sphere.

I turned it yesterday...and it took me almost all afternoon!

It was/is about 5.5 inches in diameter (about 14cm). I of course used a profile pattern/template to maintain the spherical shape.

My question is...There is no way turning a sphere should take all afternoon.

What special tools should I have to turn a sphere on a lathe to make it easier next time?

Thanks,

- Nick

[Skew ChiDAMN!!]

It was/is about 5.5 inches in diameter (about 14cm). I of course used a profile pattern/template to maintain the spherical shape.

My question is...There is no way turning a sphere should take all afternoon.

What special tools should I have to turn a sphere on a lathe to make it easier next time?

Pick an answer:With practice & knowhow: none. Not even a template. Good lighting, ordinary gouges and good technique will, as usual, do the best job. A perfect ball almost every time. Turn a cubical blank round, then rotate it 90° between the centres, using small "cup chucks" tailored to take cylinder sides (they have a 'v' cut into 'em instead of a cup) and turn it down to the shadow-line. Replace the cup chucks with proper cup chucks, (ones which'll hold a ball) so the bits that were covered by the other cup chucks can also be turned to the shadow line. Change the ball's orientation between centres several times, just to check that it's true. Hard to put into words, easy to do. :rolleyes:

An easier way for smaller spheres, but one that leaves a small stub tenon, is to use a good quality steel pipe sharpened as a scraper. The internal diameter of the pipe should be slightly smaller than the diameter of the planned sphere (eg. 2" pipe to make a 2.5" ball) else the ball may jam badly if it fits inside the pipe. It's a noisy, brute force approach but it works surprisingly well.

The 3rd way is to use a sphere-making jig. This will also leave a small stub tenon but is probably the easiest for a beginner. Unfortunately it will not teach you any skills that will let you turn a ball without the jig. ie. the jig turns the ball, not you. If the jig breaks, you're stuffed. (You might be able to tell that I really don't like these jigs? :o)

You're right... none of the above should take an afternoon if you know what you're doing. I'd say about 30 mins at a guess. On the other hand, if you don't know what you're doing, then an afternoon is nothing. You can't say it's wasted... because I'll bet you've learned enough in that arvo to be able to turn the next ball in a fraction of the time. ;)

[rsser]

And see 'Round ball instructions' at http://www.woodturners.org/tech_tips/frame_1.htm

[pigoo3]

Skew,

Thanks for the detailed answer/instructions...makes a lot of sense.

Ern,

Thanks a ton for the sphere link. The pictures definitely help explain the procedure.

- Nick

[Skew ChiDAMN!!]

Hmmm... I've never seen that method before Ern. Thanks for the link, it's always nice to see alternative methods.

But I think I'll stick to my cup chuck technique, as I'm familiar with it and it doesn't leave a stub to turn away. ;)

[hughie]

(http://www.woodturners.org/tech_tips/frame_1.htm)http://www.woodturners.org/tech_tips/frame_1.htm
(http://www.woodturners.org/tech_tips/frame_1.htm)


Good link Ern, I shall have a good look through it.

Cheers

[TTIT]

And see 'Round ball instructions' at http://www.woodturners.org/tech_tips/frame_1.htmHadn't seen that method either. Thanks Ern. Will come in handy - - one day!

[OGYT]

Saw a webpage somewhere that a man turned a cylinder, then drew a center line around it, then divided the halves, then the quarters, and used a parting tool to turn the quarter and eighths lines down to the proper mathematically dreamed up depth, then turned it down to a sphere, leaving nubs on each end.
Then chucked it between two cupped out scraps and turned off the nubs.

[Skew ChiDAMN!!]

Saw a webpage somewhere that a man turned a cylinder, then drew a center line around it, then divided the halves, then the quarters, and used a parting tool to turn the quarter and eighths lines down to the proper mathematically dreamed up depth, then turned it down to a sphere, leaving nubs on each end. Then chucked it between two cupped out scraps and turned off the nubs.

I guess it just goes to show that no matter how simple a job is, there's always someone who'll work out a way to complicate it! :D

[La truciolara]

An entire afternoon for the first ball? That is not surprising at all. You’ll see, after the first dozen it will go faster.
Otherwise you have to use a gig, but you loose all the fun of turning<O:p</O:p

[Schtoo]

I coulda thrown a couple at you, provided my arm was good and you don't mind them in pine. :rolleyes:

I put spheres on the top of some bed posts once, in said pine. Major pain to get them right, but I did manage to get them close enough that you can't see if they are off or not.

And doing them like that, without being able to move them about is not easy at all let me tell you. Even less so in softwoods.


And I still don't own an actual lathe. :D

[pigoo3]

Yes...a whole afternoon for my first ball...but believe me...my procedure was wayyy primative!!! It would be similar to emptying a swimming pool with a drinking glass. ;)

Now that I know the proper procedure (or a couple of procedures)...once I am setup to start turning...if it took me more than 30-60 minutes, I would be very surprized!

- Nick

[rsser]

Hadn't seen that method either. Thanks Ern. Will come in handy - - one day!

Pleasure.

There's all these enduring tips and links that IMHO would go well on a Wiki.

Like, how many times do we want to respond to 'what lathe should I buy?' ?? (groan; like posts about what oil or what tyres on motorbike forums).

(eg. Hughie's encyclopeadic knowledge of turning and turning links MUST be recorded before he runs off with his young secretary, or worse .... :eek: And we could post extended tool or technique tutorials.)

I've suggested to the management that a Wiki might be a useful complement to the forum. Should we run a poll?

[La truciolara]

You can even do some amazing things with a ball sur as an awl ;)
http://www.la-truciolara.com/forum/Chouette.jpg

[powderpost]

Had a contract once, for 300 spheres, 1 3/4" diameter. They were for the corner posts of square "colonial" wooden plant pot holders. The bloke that made the planter boxes didn't hav a lathe. Used Skews first method. Can't say I am real keen on turning spheres now though... :eek: :D
Jim

[RETIRED]

Had a contract once, for 300 spheres, 1 3/4" diameter. They were for the corner posts of square "colonial" wooden plant pot holders. The bloke that made the planter boxes didn't hav a lathe. Used Skews first method. Can't say I am real keen on turning spheres now though... :eek: :D
JimI can relate to that!;) :D

[mick61]

G`Day exuse my ignorance but what does a bedan tool or negative rake scraper look like? Merry xmas

[rsser]

Bedan is in cross section like a square scraper but the left and right walls are relieved to allow clearance for the cutting edge. Good for peel cuts as well as scraping.

[Skew ChiDAMN!!]

Bedan is in cross section like a square scraper but the left and right walls are relieved to allow clearance for the cutting edge. Good for peel cuts as well as scraping.

Good description. I sharpen my 5mm sq scraper as a bedan, adding a 1" bevel down each side at the start and touching it up occasionally as the edge shortens.

This is the only time I break the cardinal rule of "DON'T use the side of the wheel for sharpening" :o ... 'cos to get one of the sides the handle hits the other wheel (this is on a bench-grinder) if done normally. Still not a recommended practice, but. :rolleyes:

[hughie]

This is the only time I break the cardinal rule of "DON'T use the side of the wheel for sharpening" :o ... 'cos to get one of the sides the handle hits the other wheel (this is on a bench-grinder) if done normally. Still not a recommended practice, but. :rolleyes:
[/QUOTE]

Not a uncommon practice in engineering. There are wheels available for use on both side and front. Such wheels are normaly recessed at the hub on the side to be used, often called 'cup' wheels

http://www.georgiagrindingwheel.com/wheelsizesgrind.htm

I have often thought of getting one for the bench grinder. Some mods maybe required as they are normally a bit thicker than standard wheels.