Struggling with spheres ...

[TobyB]

Asked to make a set of skittles ...

Making some balls turns out to be difficult ...

I'm using a jig ... the Laymar Crafts pages advice (amongst others) seemed helpful ...

Having started on the between-centres setup, all seems well ... but finishing not going well ...

Made a wooden cup to fit onto a revolving centre for the tailstock support, and have similarly made (a couple of) cups in scrap wood held in the chuck for a drive ... following pictures in various "how too" guides.

Struggling to hold/drive the potential sphere to actually make a ball. Even with very light cuts the thing stalls and/or spins, loads of unpleasant rattling(?) noise ... tried cranking up the tailstock compression to a point where it feels like I'm overloading the bearings but still problems ... tried wet paper, wax and inner-tube cut-offs as friction surfaces ... tried multiple reshapings of the drive cup either for just a rim support or for a matching-curve ... and I've generated scorch marks on a cup and the ball ... but still haven't trimmed it spherical ... and doing these things looses the centre-set of the jig ...

This feels like my experience with jam-chucks ... books say you get a good hold and it's easy to centre the bowl with a couple of taps ... not in my hands!

Anyone have any ideas about what I'm doing wrong? Tricks & tips?

Cheers

Toby

 

[jpt]

HI

I have not turned spheres but on similar things I use router matting between the object and the holding piece.

If you havent got router mat you can get similar in cheap shops for a lot less money.

john

 

[miles_hot]

in his book about stuff which all starts with spheres David Springett talks of having chucks with little squares of sand paper is to help grip... The book woodworking wizardry is fantastic and contains some detailed instructions...

HTH

Miles

 

[Paul.J]

Here are some YouTube videos that might help.
But Our own Richard Findley made a set of balls not so long ago,so perhaps it might be worth asking him how he made them :?:

 

[stevebuk]

i believe Richard uses a pipe to get round balls, he puts a burr on the inside of the pipe and presses it against the wood, i saw him demonstrate at our club a few weeks ago.

 

[toysandboats]

There's a 4 page article on this in the current British Woodworking - page 49, Issue 12 - by Jason Breach,
In essence he turns the balls between centres till there is just a spigot at each end.
He then refits the ball using two "dished" wooden holders, he suggests lime or ash. One fits over the revolving centre and the other fits to the headstock.
The ball is held between these and the two spigots are turned off.

He makes it look easy but he has been turning for 25 years!

David

 

[Richard Findley]

Hi guys,

As Steve said I do sometimes use a bit of pipe/tube but this only works for small balls less than about 35mm (I've found!!) I would imagine if Toby is making balls for skittles they'll need to be somewhat larger.

These balls were 90mm diameter so probably more like what you're after. I used the method outlined above and in the BW article:

Turn between centres to a template until you are correct but for a couple of spigots, I then cut the spigots down to a minimum size and re-mounted the ball between wooden cups to turn off the spigots.

Sounds to me like you're on the right lines, you need the right combination of padding and pressure to get it right. Use a softer wood for the cups than for the ball to help minimise damage to the balls. And don't worry about damaging your bearings, it really is unlikely that you'll cause any harm from tightening your tailstock onto them. Turning huge out of balence bowls on the otherhand......

Hope this helps. Let us know how you get on or if you need any further help,

Cheers,

Richard

 

[TobyB]

I have done the almost-complete balls and cut much of the spigots off, and had done the wooden cups mentioned for each ... and not tried router mat but thought the thin rubber of inner tube would be much the same. As Richard said - these are bigger than the 35 mm max he suggests ... 95 mm or so. I'd compressed so hard the lathe sounded strange and enough that I crushed the lips of some scrap spalted beech I'd used for the first cup - second and third ones were ash (different diameters and depths) - now got a tulipwood scrap. Sandpaper sounds interesting idea to try. I will persevere ...

 

[Bodrighy]

Make sure that your tools a really sharp Toby otherwise they will cause drag. Also try rolling the spindle gouge around the ball to cut as opposed to cutting into it. Don't know if that makes sense but it's like doing a giant bead. Less chance of a catch and less drag.

Pete

 

[Richard Findley]

Hi Toby,

The other thing to add to Pete's comment is that when working on the spigots, they are end grain so to achieve the best finish you need to work "up hill" if that makes sense, rather than down hill as you were when doing the majority of the ball.

Richard

 

[TobyB]

I have some ideas now to face going back to a disheartening struggle ... I'll see what transpires ... though it may not be for a few days because of other comittments ... so any other good ideas MOST WELCOME!