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Re: ATM OT/ turning balls on a lathe
--- Reed Alan Spaulding <shellac@together.net> wrote:
>
> Reed Alan Spaulding wrote:
>
> Sam,
>
> Let me start by apologizing for not thinking about
> all the people who
> would read thin who do not have the experience in
> the shop that I do.
> SAFTEY IS NOT TO BE TAKEN FOR GRANTED.
> Another method is to use a vacuum cleaner to hold
one side of your sphere this will only work if your
head stock shaft is hollow..
There are many other systems of vacuum chucking and
I'm no expert.Regards Paul
> I agree that attemting to chuck a ball in a
> conventional 3 or 4 jaw
> chuck WILL result in bodily harm. The tailstock
> must be brought to
> bear
> in this case.
>
> Use your imagination here for a moment. Remember
> that you are not
> machining steel here but wood so the pressures will
> not be as great.
> Turning wood on a lathe allows you incredible
> freedom to grip the wood
> in many different ways. These ways are as varied
> as the people using
> them. Invent your own.
>
> First as noted earlier I would turn a cylinder, yes
> this takes a large
> piece of wood. The stock would have to be built up
> from narrower,
> thinner stock. Remember the Rule that you glue
> heartwood to heartwood
> and pith to pith but never heart to pith or pith to
> heart, meaning that
> the annunlar rings in the wood when viewed from the
> endgrain should
> always mirror each other like so(()) or ))((, but
> never (((( or )))).
> The glue up will be much more stable this way.
>
> Take the time to remove the corners on your bandsaw
> of table saw before
> mounting to the lathe, so you now have a octagon.
> Much closer to
> round.
>
> When you have your cylinder remove it from the
> lathe and mark a line
> down each side 180 degrees apart. On my lathe
> there is a series of
> holes in the driven pully and a pin that mates with
> them, so I would
> simply mark the lines while the cylinder is still
> between the centers
> using the tool rest as a straight edge.
>
> Now, mount the cylinder in the lathe, between
> centers using the newly
> scribed lines as the center points for the drive
> center and tailstock
> center. Yo will do a wee bit of damage to the
> surface here, unless you
> just want to trust pure friction here. In that
> case you COULD, but I
> do
> NOT recomend it, try to pinch the work between a
> small faceplate with a
> center pin and cup center mounted in the tailstock.
>
> Now CAREFULLY turn the cylinder in to a ball.
> Start the lathe on the
> slowest speed and go slowly. You should 'see' the
> ball when you look
> at
> the spinning cylinder.
>
> No mater how accurate you are, the wood will move,
> expand and contract
> very quickly. I advise you to get some finish on
> the ball very quickly
> after you are finish to slow down the moisture
> movement. The best way
> is to apply the finish while the work is still
> spinning in the lathe.
>
> Be careful and have fun.
>
> Sam Michael wrote:
> >
> > You will end up needing to turn the part 4 times
> using this method
> and you
> > will never line it up so that your ball wound be
> screwed up.
> >
> > In addition, he is talking about a 4" to 8" ball.
> This would require
> a
> > really big chuck. I have never seen an 8" chuck
> for a home lathe.
> >
> > In addition you are turning the FACE, meaning the
> tail stock is not
> engaged!
> > I wouldn't want to be around when an 8" piece of
> stock turning at
> 2000 rpm
> > gets lose and removes the nearest appendage.
> >
> > REALISTICALLY speaking, the stock MUST be secure
> both at the head and
> the
> > tail of the lathe for a part this size. ANYTHING
> else is extremely
> > dangerous on a part that is round.
> >
> > I also looked at turning the part on the sherline
> lathe. That makes
> a half
> > circle. Again, your ROUND material would have to
> be turned around
> and
> > chucked up. This simply isn't possible.
> >
> > Sam.
> >
> > ----- Original Message -----
> > From: Reed Alan Spaulding <shellac@together.net>
> > To: <atm@shore.net>
> > Sent: Monday, December 06, 1999 4:18 PM
> > Subject: Re: ATM OT/ turning balls on a lathe
> >
> > >
> > > There was an article in Fine Woodworking a
> while back this is more
> or
> > > less the gist of the article.
> > >
> > > Try turning a cylinder to the correct diameter
> and then turning it
> ninty
> > > degrees in the lathe and clamping it on the
> sides rather than the
> ends,
> > > then turning it to a sphere. Tha sphere will
> be visible because of
> the
> > > geometry of the cylinder spinning in the lathe
> in an oblong
> direction.
>
>
> --
> Reed Spaulding
> Spauldings Furniture Restorations
> 194 Main Street
> Lancaster, NH 03584-1714
> shellac@together.net
>
>
>
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