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263370 "Joseph Sullivan" <joe@j...> 2017‑09‑23 Difficult project fluting
Galootish friends:

I am mentally toying with a project that will be third or fourth on the
list, hence maybe late winter if at all.  The overall concept is of a sort
of nouvelle Greek revival coffee table meant to look nothing like Georgian
or Victorian furniture; in other words more like and antiquity than like an
antique:

1) Top is made of two pieces of walnut crotch more or less 1.5 ft wide and
elongated (roughly half-elliptical each) which are butt-joined by means of
hidden butterfly joints on the underside and then cut to form a true ellipse
and highly polished;
2) This is supported by support four arms, two long and two short which in
turn arise out of the neck of;
3) An urn with an elliptical horizontal cross-section (echo the shape of the
top);
4) The urn is fluted; 
5) Four curving  legs come out of the bottom of the urn at a flattened angle
and terminate in delicate claw feet.

Honestly, this is a very big challenge as I have never before done most of
what I propose to do. However, the flatwork including the top,  legs, and
supports are not too worrisome.  My cradles are far more complicated.  What
worries me is the construction of the urn and then the fluting of it.

Initial thought for construction is to start with a set of hollow
cross-sectional templates like we used to do for the hulls of wooden ship
models.  A rough shape would be built up of pieces of walnut glued up to
look something like an old-fashioned contour model of a mountain or a hill.
That would be rasped and chiseled to close to fair, and then finished with
spoke shaves.  PROBLEM  what about the foot and the neck?  They would
ideally be turned, but how does one turn an elliptical shape?

 Anyway, once the thing is faired and smoothed and is true to the templates
it would be time to flute.  I really don't know where to start.  The flutes
would run from the foot to the neck, so they would have to get wider and
narrower as they rose and fell.  I guess one would carefully mark off the
tops and bottoms of the lines where they hit the neck and foot an let the
swell take care of itself.  But how does one cut straight, true lines across
something like that?

Advice from anyone with ideas about how to attack any of the technical
issues in this project is urgent requested and most welcome.  Anyone who
thinks what I have already proposed should be done differently is doubly
welcome.

Joe



Joseph Sullivan
263372 Ed Minch <ruby1638@a...> 2017‑09‑23 Re: Difficult project fluting
Joe

> Initial thought for construction is to start with a set of hollow
> cross-sectional templates like we used to do for the hulls of wooden ship
> models.  A rough shape would be built up of pieces of walnut glued up to
> look something like an old-fashioned contour model of a mountain or a hill.
> That would be rasped and chiseled to close to fair, and then finished with
> spoke shaves.  PROBLEM  what about the foot and the neck?  They would
> ideally be turned, but how does one turn an elliptical shape?

That would work and would not take too long.  Perhaps turning it round first,
then knocking off the high sides to bring them into shape with the templates
> 
> Anyway, once the thing is faired and smoothed and is true to the templates
> it would be time to flute.  I really don't know where to start.  The flutes
> would run from the foot to the neck, so they would have to get wider and
> narrower as they rose and fell.  I guess one would carefully mark off the
> tops and bottoms of the lines where they hit the neck and foot an let the
> swell take care of itself.  But how does one cut straight, true lines across
> something like that?

I have thought of this a bit for a project in mind.  I might mount it in a lathe
and devise a way to hold it so that the flute I am working on in along the top -
for me, it would be the right height for that sort of work.  I know you can buy,
and therefore make, a disc that mounts on the piece that has some sort of
register holes in it for making everthing even - 20 flutes, 30 flutes, whatever
you decide on on

Good luck, andtake pictures

Ed
263373 Claudio DeLorenzi <claudio@d...> 2017‑09‑23 Re: Difficult project fluting
Hi Joe:
My old lathe has registration holes on the drive pulley for this purpose.
As Ed mentioned, you could also make a disc with registration holes that
are temporarily fixed to the work to accomplish the same thing if your
lathe doesn't have this feature built in.
    A purpose made rest can then be  clamped to the lathe bed then allows
for making flutes parallel to the long axis, as Ed mentions.  Rig a support
at center height from the lathe bed, and use that to mark/cut the flutes,
ensuring that the marks/cuts remain in the radial plane, parallel with the
lathe bed (at center height).  Working from the top is more difficult on
non-cylindrical objects.  You basically need to make a tool rest at center
height (center height minus ½ the width of the marking/cutting tool you are
using.  You can make it out of plywood that is cut to the profile you want
so that you have support right up to the surface of the work.  The time I
saw it done, the turner used a small trim router used on its side held in a
box, sliding it sideways on the table support, the depth of cut being
tricky if there are bumps to contend with.  You might be able to find a
video on that tube site.
    As for elliptical turning, it's not that complicated, but for large
objects you really need a very heavy, stable lathe and sandbags etc for
dampening the vibration. Even with small turnings (oval tool handles, for
example) there can be quite a bit of vibration to deal with.
Cheers from Waterloo
Claudio
snip

PROBLEM  what about the foot and the neck?  They would

> ideally be turned, but how does one turn an elliptical shape?
>
> That would work and would not take too long.  Perhaps turning it round
> first, then knocking off the high sides to bring them into shape with the
> templates

snip

>
> >
> > Anyway, once the thing is faired and smoothed and is true to the
> templates
> > it would be time to flute.  I really don't know where to start.  The
> flutes
> > would run from the foot to the neck, so they would have to get wider and
> > narrower as they rose and fell.  I guess one would carefully mark off the
> > tops and bottoms of the lines where they hit the neck and foot an let the
> > swell take care of itself.  But how does one cut straight, true lines
> across
> > something like that?
> Snip
> I have thought of this a bit for a project in mind.  I might mount it in a
> lathe and devise a way to hold it so that the flute I am working on in
> along the top - for me, it would be the right height for that sort of
> work.  I know you can buy, and therefore make, a disc that mounts on the
> piece that has some sort of register holes in it for making everthing even
> - 20 flutes, 30 flutes, whatever you decide on
>
Snip
263374 Erik Levin 2017‑09‑23 Re: Difficult project fluting
I've now thought about this for a bit and will throw in my $0.02....


>1) Top is made of two pieces of walnut crotch more or less 1.5 ft wide and
>elongated (roughly half-elliptical each) which are butt-joined by means of
>hidden butterfly joints on the underside and then cut to form a true ellipse
>and highly polished;
>2) This is supported by support four arms, two long and two short which in
>turn arise out of the neck of;
>3) An urn with an elliptical horizontal cross-section (echo the shape of the
>top);
>4) The urn is fluted; 
>5) Four curving  legs come out of the bottom of the urn at a flattened angle
>and terminate in delicate claw feet.

Elliptical turning isn't a big deal, but is best done with specialized
equipment: either an "elliptical chuck" or a rose lathe type setup with an
elliptical template. You could also, as you said,  use templates and fair it out
by hand. Might be the easiest way, as I would figure (pun intended) that there
will be a fair (pun intended) bit of match-by-eye-- make it look right, rather
than a mathematically perfect piece.

To lay out the fluting, I'd use a tape -- blank, not graduated, to get a
circumference at one end, divide the circ. into uniform measures (it is usually
an iterative process), and mark the piece. Do the same at the other end with
alignment as dead on as you can. Join the marks using a thin, flexible
straightedge to follow the contour. Then the fun begins.
Laying out the fluting equal by angle on a piece with elliptical cross section
(such that the flutes are axial, which it sound like you are doing) will look
wrong, as the widths will vary around a given circumference. It is surprising
how visible it is, and how weird it looks.

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263377 "Joseph Sullivan" <joe@j...> 2017‑09‑24 Re: Difficult project fluting
SNIP

Eric said:

 

If you google elliptical turning, you will find things like https://www
.youtube.com/watch?v=LX12OFJHQlg">https://www.youtube.com/watch?v=LX12OFJHQlg (David Springett) and ht
tps://www.youtube.com/watch?v=w5I2Yph57FI (American Woodworker) that show
the elliptical chuck. You can make your own, but it is a but of a specialty
item. If not turning a lot with it for income, you really need to want it.

 

From what I have seen in the wild, better and worse, the width of flutes looks
best when, as you say, follows the general profile, being wider when the section
is wider. The other thing is that flutes look horrible if they are not uniform,
within reason, at each section. For an elliptical section, equal angle will make
the flutes visibly narrower at the minor axis, and wider at the major. Unless
you are going for the modern (mid century modern), op-art, unsettling look, you
want roughly equal width at each section, so the layout should be done around
the circumference.

 

 

For layout, if you mount the elliptical part in the lathe, premark where you
want the flutes at one section (points around the circumference), you can use
the carriage to guide your markout. Use the flat top of the compound to guide,
and space up a mechanical pencil to put the lead on center line. Manually move
the carriage and trace, like scribing in a  countertop or baseboard to a wall or
uneven floor, respectively.

 

Or, as I mentioned, mark around t both ends and use a flexible straightedge. A
third set of marks in the middle will help. I have never done this for fluting,
but have done it for single details, like removing a quarter section to fit a
corner.

END SNIP

 

 

 

Eric, very interesting.  I had not thought of layout at the center.  I think
I’ll make up a couple of dummies (just cut so they have even curve and swell of
no particular shape in front, flat back) and practice both layout and cutting.

 

J 

 

 

Joseph Sullivan

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