Hi,
I need (well, would like) one elliptical leg for the end of an
elliptical table. The other end will be attached to a wall, so it only
has one leg.
I have several ideas how to make one, layering lots of pieces of
bandsawn wood (or plywood) and then shaving and sanding until I'm blue
in the face.
Is there a simpler solution? The leg doesn't have to be tapered, just a
piece of wood with a elleptical profile, about 6 x 10 centimetre (2 1/2
x 4 inch) inches thick.
Or should I order it from somewhere where they have a spindler moulder
and the required profile(s)? Or a CNC cutter. I only need one, and don't
want it to cost me an arm as well.
--
mare
Is a thumbnail router bit profile a 1/4-ellipse? If so (or, even if
not), this would get the OP even closer to the final desired
cross-section shape before having to sand/scrape/plane/spokeshave/etc.
Just a thought,
Chris
Steven and Gail Peterson wrote:
> You also can get a good start with a router with a 1" round over.
Draw the
> ellipse on each end for reference. Round over all 4 side corners. I
would
> then use my planer to reduce the place(s) that have the largest
difference
> from the reference ellipse. Keep going until the shape is getting
close.
> Finish by sanding.
>
On Wed, 20 Apr 2005 13:06:55 -0400,
mare*Remove*All*0f*This*I*Hate*Spammers*@mac.invalid.com (mare) wrote:
>Hi,
>
>I need (well, would like) one elliptical leg for the end of an
>elliptical table. The other end will be attached to a wall, so it only
>has one leg.
>
>I have several ideas how to make one, layering lots of pieces of
>bandsawn wood (or plywood) and then shaving and sanding until I'm blue
>in the face.
>
>Is there a simpler solution? The leg doesn't have to be tapered, just a
>piece of wood with a elleptical profile, about 6 x 10 centimetre (2 1/2
>x 4 inch) inches thick.
>
>Or should I order it from somewhere where they have a spindler moulder
>and the required profile(s)? Or a CNC cutter. I only need one, and don't
>want it to cost me an arm as well.
This is a perfect opportunity for a snipe hunt.
Draw the ellipse of your dreams up and cut it out on the bandsaur or
with whatever you have that will make the cut.
Having created a pattern - take that sucker out and look for a really
perfect piece of wood that fits it.
By that I mean that the wood is interesting and that the natural lines
fit your pattern.
Old timey boat guys do this when looking for white oak knees for their
projects> I hope that your project isn't white oak, because the boat
guys are pretty thorough.
I happen to agree with the rough-cut and plane folks. Here's my
contribution: Use the old fashioned moulding planes known as hollows
and rounds. The sole and iron of the plane are rounded to cut convex
and concave shapes. They come in sets with different radii, but you
will probably have the most luck finding them at a flea market. You
will probably need at least two hollows (with a concave sole...for
cutting convex curves) with radii that approximate the major and minor
radii.
In article <[email protected]>,
Roger <[email protected]> wrote:
>Ralph wrote:
>> Turn The leg on two offset centers at 180 degrees with the center point
>> equal distant from the center.
>>
>
>
>I guess I'm missing something. How does this form an ellipse? Aren't
>the ends going to be circular rather than elliptical in section? Unless
>the lathe moves the center while rotating as is possible with some
>ornamental lathes the section can't be elliptical.
>
>Roger
Consider a circular cylinder.
Consider what you get if you slice that cylinder at an angle.
Now, construct a cylinder perpendicular to that angled cross-section slice.
You have, obviously, and elliptical cylinder.
It should be "obvious to the casual observer" that you can take an angled
slice of _that_ cylinder in a manner that will yield a circular cross-
section. That cross-section is perpendicular to the minor axis, and at
an angle to the major axis such that the 'diagonal' is the same length
as the major axis. Mathematical "proof" gets a little messy, but is
fairly straightforward -- take the equation of an ellipse, parameterized
as a function of the major and minor axis lengths, set the two lengths
equal, and "reduce".
"A quantitative answer is left as an exercise for the student." *GRIN*
I believe the problem can be solved throught the use of a spindle drum.
construct a drum to proper specifications of the leg, length. place recesses
in each end plate to hold the stock then add a second end plate. Mount the
number of legs you wish to turn in the drum attaching with a screw through
each end. The drum should contain spacers between each of the mounting
points. you turn you turn down to the spacer prior to mounting the legs. You
can use stock of any size as long as the recess is properly constructed. I
am being simplistic in my description but I am sure there are people out
there who could help..
To turn an ellipse turn the stock to the desired thickness and shape. then
remount each leg by tuning it over once. 180 degrees. the circumference of
the drum will dictate the curve. Old europe spindle turners used this
technique often and keep a variety of drums and sample patterns on hand.
Dave Hinz <[email protected]> wrote:
> On Wed, 20 Apr 2005 13:06:55 -0400, mare
> <mare*Remove*All*0f*This*I*Hate*Spammers*@mac.invalid.com> wrote:
>
> > Or should I order it from somewhere where they have a spindler moulder
> > and the required profile(s)? Or a CNC cutter. I only need one, and don't
> > want it to cost me an arm as well.
>
> You can get close with a lathe. I think I saw Roy do it a few years
> back. Think of the profile as two circles with different centers.
> Lay the circles and centers out on the end of the stock, and turn it
> once with each of the two centers. Gets you close to an ellipse - if
> mathematical precision is vital, nevermind.
It is, sorry. In a true ellips, there are no circle sections. The angle
changes gradually. I want a leg the has (more or less) the same profile
as the table.
> I seem to recall that Roy had some fun with the very unbalanced work
> in the lathe - speed is probably not your friend in this case.
It doesn't sound very safe to me.
--
mare
C & S <[email protected]> wrote:
> You poor guy.
Indeed I am. I could be a girl though.
> You have gotten at least 7 *completely different answers to this problem:
>
> 1. Table saw rip then plane
> 2. eccentric turning
> 3. Pure neander (draw knife/spoke shave)
> 4. Router template
> 5. Router bit (actually quite diffrent than 4)
> 6. Skelletin with skin
> 7. "Find the right tree"
>
> Sorry, but since all of these are reasonable ('cept maybe the tree one) I
> find that amusing.
Well, it's better than no answer at all.
> Let us know what you choose.
I'm probably going to try number 4, but might also talk to a aquintance
who is a professional turner, to see if he can do me a favour on his
bosses expensive lathes.
Thanks for all the answers, my head is still spinning. It's almost
elleptical now.
--
mare
Dan Bollinger <[email protected]> wrote:
> > I need (well, would like) one elliptical leg for the end of an
> > elliptical table. The other end will be attached to a wall, so it only
> > has one leg.
>
> There are no simple solutions to turning an ellipse, or an oval for that
> matter. You might get some ideas from these websites. Dan
>
>
> My oval turning lathe nearing completion
> http://www.claycritters.com/lathe/
Impressive video. Would such a Volmer type lathe be also of use with a
longer piece of wood? Say 75 cm (30")? Or would you need a similar
contraption on the other end, linked/synced to the one closer to the
lathe?
--
mare
Ken Grunke <[email protected]> wrote:
>WillR wrote:
>> mare wrote:
>>
>>> Hi,
>>>
>>> I need (well, would like) one elliptical leg for the end of an
>>> elliptical table. The other end will be attached to a wall, so it only
>>> has one leg.
>>>
>>> I have several ideas how to make one, layering lots of pieces of
>>> bandsawn wood (or plywood) and then shaving and sanding until I'm blue
>>> in the face.
>>>
>>> Is there a simpler solution? The leg doesn't have to be tapered, just a
>>> piece of wood with a elleptical profile, about 6 x 10 centimetre (2 1/2
>>> x 4 inch) inches thick.
>>>
>>> Or should I order it from somewhere where they have a spindler moulder
>>> and the required profile(s)? Or a CNC cutter. I only need one, and don't
>>> want it to cost me an arm as well.
>>>
>>
>> This wood be better in r.c.woodturning. I just crossposted.
>>
>> Most look here -- but might miss it.
>>
>> Some do some pretty fancy stuff.
>>
>> There are some specialty sites on this type of ornamental turning. DAGS
>> on it. (ornamental turning that is)
>>
>>
>
>How about a router carriage, the length of the spindle, with an
>adjustable edge guide. The blank is held between centers in a lathe-like
>setup (or a lathe itself, if possible) with an elliptical template
>attached to one end. Use an end-cutting bit in the router, whose depth
>and positon is set to the template. It would be necessary to lock the
>blank in position, while making the cut the full length--then move the
>spindle a few degrees each time, adjusting the depth and lateral
>position of the router so it cuts tangent with the curve. Round the
>facets off with a sander.
I was thinking of exactly the same process, with different tools: a
bandsaw to cut the rough facets, and a plane to bring to final shape (
and a flexible card scraper if the tiny flats still left by the plane
are undesirable).
Same idea--just whatever tools you have available and are most
comfortable or prefer to work with.
--
Alex -- Replace "nospam" with "mail" to reply by email. Checked infrequently.
On Wed, 20 Apr 2005 13:06:55 -0400, mare <mare*Remove*All*0f*This*I*Hate*Spammers*@mac.invalid.com> wrote:
> Or should I order it from somewhere where they have a spindler moulder
> and the required profile(s)? Or a CNC cutter. I only need one, and don't
> want it to cost me an arm as well.
You can get close with a lathe. I think I saw Roy do it a few years
back. Think of the profile as two circles with different centers.
Lay the circles and centers out on the end of the stock, and turn it
once with each of the two centers. Gets you close to an ellipse - if
mathematical precision is vital, nevermind.
I seem to recall that Roy had some fun with the very unbalanced work
in the lathe - speed is probably not your friend in this case.
On Thu, 21 Apr 2005 17:41:01 -0000, Robert Bonomi <[email protected]> wrote:
> Consider a circular cylinder.
> Consider what you get if you slice that cylinder at an angle.
> Now, construct a cylinder perpendicular to that angled cross-section slice.
> You have, obviously, and elliptical cylinder.
Right, ... so far, so good.
> It should be "obvious to the casual observer" that you can take an angled
> slice of _that_ cylinder in a manner that will yield a circular cross-
> section. That cross-section is perpendicular to the minor axis, and at
> an angle to the major axis such that the 'diagonal' is the same length
> as the major axis.
You just broke my brain.
> Mathematical "proof" gets a little messy, but is
> fairly straightforward -- take the equation of an ellipse, parameterized
> as a function of the major and minor axis lengths, set the two lengths
> equal, and "reduce".
Or, he could just make a template, turn it close-enough, and fine tune
it to fit.
> "A quantitative answer is left as an exercise for the student." *GRIN*
Hm. Sometimes, "close enough" is, well, close enough.
>
> It is, sorry. In a true ellips, there are no circle sections. The angle
> changes gradually. I want a leg the has (more or less) the same profile
> as the table.
>
>> I seem to recall that Roy had some fun with the very unbalanced work
>> in the lathe - speed is probably not your friend in this case.
>
> It doesn't sound very safe to me.
>
> --
> mare
Offset turning is not all that hard if you chuck it properly. For a true
ellipse, the turning on the lathe will get you very close with 4 offset
setups. Finish with a spokeshave and card scrapers.
Dave
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WillR wrote:
> mare wrote:
>
>> Hi,
>>
>> I need (well, would like) one elliptical leg for the end of an
>> elliptical table. The other end will be attached to a wall, so it only
>> has one leg.
>>
>> I have several ideas how to make one, layering lots of pieces of
>> bandsawn wood (or plywood) and then shaving and sanding until I'm blue
>> in the face.
>>
>> Is there a simpler solution? The leg doesn't have to be tapered, just a
>> piece of wood with a elleptical profile, about 6 x 10 centimetre (2 1/2
>> x 4 inch) inches thick.
>>
>> Or should I order it from somewhere where they have a spindler moulder
>> and the required profile(s)? Or a CNC cutter. I only need one, and don't
>> want it to cost me an arm as well.
>>
>
> This wood be better in r.c.woodturning. I just crossposted.
>
> Most look here -- but might miss it.
>
> Some do some pretty fancy stuff.
>
> There are some specialty sites on this type of ornamental turning. DAGS
> on it. (ornamental turning that is)
>
>
How about a router carriage, the length of the spindle, with an
adjustable edge guide. The blank is held between centers in a lathe-like
setup (or a lathe itself, if possible) with an elliptical template
attached to one end. Use an end-cutting bit in the router, whose depth
and positon is set to the template. It would be necessary to lock the
blank in position, while making the cut the full length--then move the
spindle a few degrees each time, adjusting the depth and lateral
position of the router so it cuts tangent with the curve. Round the
facets off with a sander.
Ken Grunke
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Ken Grunke wrote:
> WillR wrote:
>
>> mare wrote:
>>
>>> Hi,
>>>
>>> I need (well, would like) one elliptical leg for the end of an
>>> elliptical table. The other end will be attached to a wall, so it only
>>> has one leg.
>>>
>>> I have several ideas how to make one, layering lots of pieces of
>>> bandsawn wood (or plywood) and then shaving and sanding until I'm blue
>>> in the face.
>>>
>>> Is there a simpler solution? The leg doesn't have to be tapered, just a
>>> piece of wood with a elleptical profile, about 6 x 10 centimetre (2 1/2
>>> x 4 inch) inches thick.
>>>
>>> Or should I order it from somewhere where they have a spindler moulder
>>> and the required profile(s)? Or a CNC cutter. I only need one, and don't
>>> want it to cost me an arm as well.
>>>
>>
>> This wood be better in r.c.woodturning. I just crossposted.
>>
>> Most look here -- but might miss it.
>>
>> Some do some pretty fancy stuff.
>>
>> There are some specialty sites on this type of ornamental turning.
>> DAGS on it. (ornamental turning that is)
>>
>>
>
> How about a router carriage, the length of the spindle, with an
> adjustable edge guide. The blank is held between centers in a lathe-like
> setup (or a lathe itself, if possible) with an elliptical template
> attached to one end. Use an end-cutting bit in the router, whose depth
> and positon is set to the template. It would be necessary to lock the
> blank in position, while making the cut the full length--then move the
> spindle a few degrees each time, adjusting the depth and lateral
> position of the router so it cuts tangent with the curve. Round the
> facets off with a sander.
>
> Ken Grunke
>
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Ken:
Forgot about that idea. It's in the Router Magic book -- or sumpin like
it. If the guy is interested in the idea I can dig out at least one plan.
--
Will
Occasional Techno-geek
> If I were to do this, and I didn't want to hand carve it, I would likely
do
> it on a CNC vertical mill. "Didn't suggest that as few people have that at
> their disposal.
Speaking of ovals. My oval turning lathe is nearing completion. I've been
working on it for over three years. And no, it won't do oval spindles! Dan
http://www.claycritters.com/lathe/
Ralph wrote:
> Turn The leg on two offset centers at 180 degrees with the center point
> equal distant from the center.
>
I guess I'm missing something. How does this form an ellipse? Aren't
the ends going to be circular rather than elliptical in section? Unless
the lathe moves the center while rotating as is possible with some
ornamental lathes the section can't be elliptical.
Roger
It's not elliptical, really, and in any case needs some handwork at the
end to blend it, but you certainly could get "close" with 3-center
turning, the same way many "oval" things are turned on regular lathes.
You tun on center to the profile you want the "fat part" (long axis of
the oval/ellipse) to be.
You go offcenter and turn one side down to (or as close as you want it
to) the centerline. You turn the other side to match. You're a lot
closer to where you want to be when you pull out the inevitable
spokeshave, and the evitable or not rasps, files, and sandpaper.
Try some test pieces - there's a bit of a trick seeing/feeling when
you've gotten the sides where you want them.
A lot more accessible to most mere mortals than anything that will cut a
true ellipse leg shape.
Or the really easy (but slow) way - turn the leg round out of green
wood, and wait for it to dry. Differential shrinkage will get you quite
a ways along with this approach.
> Piece of wood+drawknife+spokeshave=eliptical leg.
At some point carving it by hand is the cheaper way to go. Of course its a
little difficult to make a bead or cove using only a drawknife, but your
point is well taken nonetheless.
Besides carving...
a person could also fabricate this from gluing up multiple sections of split
turnings...
or use a copy lathe like they do for oval axe and hammer handles...
or program a CNC lathe...
or turn a hollow tube and steam bend into an oval by squishing it in the
middle...
all sorts of ways! Dan
Piece of wood+drawknife+spokeshave=eliptical leg.
"Dan Bollinger" <[email protected]> wrote in message
news:YZAae.15046$NU4.12798@attbi_s22...
> > I need (well, would like) one elliptical leg for the end of an
> > elliptical table. The other end will be attached to a wall, so it only
> > has one leg.
>
> There are no simple solutions to turning an ellipse, or an oval for that
> matter. You might get some ideas from these websites. Dan
>
>
> My oval turning lathe nearing completion
> http://www.claycritters.com/lathe/
>
> The Elliptical Turning Association
> http://www.elliptical-turning-association.co.uk/
>
> THE SOCIETY OF ORNAMENTAL TURNERS (U.K.)
> http://www.the-sot.com/
>
> ORNAMENTAL TURNERS INTERNATIONAL (AMERICA)
> http://www.turners.org/
>
> THE OLD SCHWAMB MILL
> http://www.oldschwambmill.org/
>
> More Woodturning has had oval turning articles
> http://www.fholder.com/Woodturning/woodturn.htm
>
>
Does it need to be solid? I'd think in terms of cutting a number of
elliptical disks of plywood, wrapping them with bending plywood to make
an elliptical tube, and then veneering the outside in a vaccuum bag to
yield your leg.
OTOH, for an elliptical section this small I'd probably do it by hand
rather than worrying about a machine setup. Lay up a big enough blank,
knock the corners off on the table saw and then use a hand plane or
spokeshave to refine the shape (great excuse to buy the really sweet
spokeshave from L-N. Make a cutout of the profile in a piece of plywood
to check the shape as you go.
I've seen lathes for elliptical facework--mechanical contraptions that
slide the headstock back and forth to keep the cutting position
constant, but never lathe to turn an elliptical spindle. See
<http://www.elliptical-turning-association.co.uk/index.htm> for examples.
Roger
mare wrote:
> Hi,
>
> I need (well, would like) one elliptical leg for the end of an
> elliptical table. The other end will be attached to a wall, so it only
> has one leg.
>
> I have several ideas how to make one, layering lots of pieces of
> bandsawn wood (or plywood) and then shaving and sanding until I'm blue
> in the face.
>
> Is there a simpler solution? The leg doesn't have to be tapered, just a
> piece of wood with a elleptical profile, about 6 x 10 centimetre (2 1/2
> x 4 inch) inches thick.
>
> Or should I order it from somewhere where they have a spindler moulder
> and the required profile(s)? Or a CNC cutter. I only need one, and don't
> want it to cost me an arm as well.
>
You also can get a good start with a router with a 1" round over. Draw the
ellipse on each end for reference. Round over all 4 side corners. I would
then use my planer to reduce the place(s) that have the largest difference
from the reference ellipse. Keep going until the shape is getting close.
Finish by sanding.
We once renovated a kitchen, and put in a pair of cabinets that were rounded
instead of having square corners. I had to make the curved quarter-round
molding. Started with oak planks, cut the curves close to shape. Make many
trips up and down the stairs for test fits. Once the curve fit, turning
into quarter round wasn't too difficult.
Good luck
Steve
> Impressive video. Would such a Volmer type lathe be also of use with a
> longer piece of wood? Say 75 cm (30")? Or would you need a similar
> contraption on the other end, linked/synced to the one closer to the
> lathe?
thanks! Yes, you'd need something on the other end for spindle turning
unless you were OK with it gradually turning from an oval to a circle by
using a standard dead center.
> I believe the problem can be solved throught the use of a spindle drum.
> construct a drum to proper specifications of the leg, length. place
recesses
> in each end plate to hold the stock then add a second end plate. Mount
the
> number of legs you wish to turn in the drum attaching with a screw through
> each end. The drum should contain spacers between each of the mounting
> points. you turn you turn down to the spacer prior to mounting the legs.
You
> can use stock of any size as long as the recess is properly constructed.
I
> am being simplistic in my description but I am sure there are people out
> there who could help..
>
> To turn an ellipse turn the stock to the desired thickness and shape. then
> remount each leg by tuning it over once. 180 degrees. the circumference of
> the drum will dictate the curve. Old europe spindle turners used this
> technique often and keep a variety of drums and sample patterns on hand.
>
That's a elegant solution, especially if you need more than one spindle.
You didn't say, but it should be noted, that the two end plates are firmly
attached to each other by a central shaft. It will make a bobbin shape. This
insures that the end plates travel in unison. The bobbin shaped drum is
turned between the centers. Actually, I'd use a face plate attached to the
drive side plate. Dan
> I need (well, would like) one elliptical leg for the end of an
> elliptical table. The other end will be attached to a wall, so it only
> has one leg.
There are no simple solutions to turning an ellipse, or an oval for that
matter. You might get some ideas from these websites. Dan
My oval turning lathe nearing completion
http://www.claycritters.com/lathe/
The Elliptical Turning Association
http://www.elliptical-turning-association.co.uk/
THE SOCIETY OF ORNAMENTAL TURNERS (U.K.)
http://www.the-sot.com/
ORNAMENTAL TURNERS INTERNATIONAL (AMERICA)
http://www.turners.org/
THE OLD SCHWAMB MILL
http://www.oldschwambmill.org/
More Woodturning has had oval turning articles
http://www.fholder.com/Woodturning/woodturn.htm
On 21 Apr 2005 17:53:14 GMT, Dave Hinz <[email protected]> wrote:
>> It should be "obvious to the casual observer" that you can take an angled
>> slice of _that_ cylinder in a manner that will yield a circular cross-
>> section. That cross-section is perpendicular to the minor axis, and at
>> an angle to the major axis such that the 'diagonal' is the same length
>> as the major axis.
>
>You just broke my brain.
He just makes it sound tough. Shine a flashlight straight down and it
lights up a circle. On an angle it's an ellipse; has to do with trig
if anyone insists. It still doesn't solve the probelm. Beside most
layout is based on some hefty math, but the layout is to make it all
easier. That's what got perspective geometry into the game, making
tough to impossible jobs relatively simple. An ellipse can be drawn
using two concentric circles and lines form the center ...etc..
But this doesn't in any way make "turning" a rectangle into an ellipse
over a length of material any easier. There might be some giant
industrial shaper around that would do it. The ellipse is symmetric
...the same in four sections... so only one section needs to be dealt
with at a time, then times four. Baring an industrial machine, I'd go
for approximate cuts on an oversize piece using the table saw, then
hand plane then sand as was suggested earlier.
>
> I have several ideas how to make one, layering lots of pieces of
> bandsawn wood (or plywood) and then shaving and sanding until I'm blue
> in the face.
>
> Is there a simpler solution? The leg doesn't have to be tapered, just a
> piece of wood with a elleptical profile, about 6 x 10 centimetre (2 1/2
> x 4 inch) inches thick.
Here's what I would do:
Laminate solid stock to yeild a 4x2.5 block
Draw your elipse on the end of your block
Rip 4 facets do that you have something that looks like a squashed octagon
(stop sign). A 12-sided figure (6 rips) would be even better. Each rip
should be tangent to the drawing of the elipe on the end of the block.
Double the number facets with a hand plane flattening each "corner" ( I
think I would reach for my #5, but any bench plane would do).
Now you sould have something approaching a eliptical cross section. One more
pass on each of the "corners" with a hand plane and you should be able to
start in with abasives.
-Steve
Drawknife to rough it out. Spoke shave to refine. Plane at the end to make
sure you don't have any bumps. Should take about a half an hour.
-j
"mare" <mare*Remove*All*0f*This*I*Hate*Spammers*@mac.invalid.com> wrote in
message
news:1gvbing.o712vc14x2mtcN%mare*Remove*All*0f*This*I*Hate*Spammers*@mac.invalid.com...
> Hi,
>
> I need (well, would like) one elliptical leg for the end of an
> elliptical table. The other end will be attached to a wall, so it only
> has one leg.
>
> I have several ideas how to make one, layering lots of pieces of
> bandsawn wood (or plywood) and then shaving and sanding until I'm blue
> in the face.
>
> Is there a simpler solution? The leg doesn't have to be tapered, just a
> piece of wood with a elleptical profile, about 6 x 10 centimetre (2 1/2
> x 4 inch) inches thick.
>
> Or should I order it from somewhere where they have a spindler moulder
> and the required profile(s)? Or a CNC cutter. I only need one, and don't
> want it to cost me an arm as well.
>
> --
> mare
You poor guy.
You have gotten at least 7 *completely different answers to this problem:
1. Table saw rip then plane
2. eccentric turning
3. Pure neander (draw knife/spoke shave)
4. Router template
5. Router bit (actually quite diffrent than 4)
6. Skelletin with skin
7. "Find the right tree"
Sorry, but since all of these are reasonable ('cept maybe the tree one) I
find that amusing.
Let us know what you choose.
-Steve
Sorry if I missed one.
"Roger" <[email protected]> wrote in message
news:[email protected]...
> Ralph wrote:
> > Turn The leg on two offset centers at 180 degrees with the center point
> > equal distant from the center.
> >
>
>
> I guess I'm missing something. How does this form an ellipse? Aren't
> the ends going to be circular rather than elliptical in section? Unless
> the lathe moves the center while rotating as is possible with some
> ornamental lathes the section can't be elliptical.
>
> Roger
No, this won't form an ellipse, but with proper layout it can form a
reasonable approximation. I did a quick sketch in AutoCad to see what could
be done. Start with a cylinder 4" in diameter and offset it ~1.3" at both
ends and turn .75" of material from the highest spot. Have extra length and
do NOT turn all the way to the ends , because the offsets are outside the
finished ellipse. Now offset if again 1.3" from the original center but in
the opposite direction as the first offset. Again turn .75" material from
the highest spot. This will leave 4 lines the length of the "ellipse" where
the original cylinder and the two offset turnings intersect. These lines
are about 0.035" proud of the true ellipse and should be easier to hand sand
to blend the curves. This is still not a true ellipse, as you go from the
major diameter to the minor diameter the piece is a bit shy, with the
maximum deviation being about 0.05". This might be good enough for his
purposes.
Hope this helps
Martin
On Wed, 20 Apr 2005 14:36:27 -0700, the inscrutable "J"
<[email protected]> spake:
>Drawknife to rough it out. Spoke shave to refine. Plane at the end to make
>sure you don't have any bumps. Should take about a half an hour.
Seconded!
>"mare" <mare*Remove*All*0f*This*I*Hate*Spammers*@mac.invalid.com> wrote in
>message
>news:1gvbing.o712vc14x2mtcN%mare*Remove*All*0f*This*I*Hate*Spammers*@mac.invalid.com...
>> Hi,
>>
>> I need (well, would like) one elliptical leg for the end of an
>> elliptical table. The other end will be attached to a wall, so it only
>> has one leg.
>>
>> I have several ideas how to make one, layering lots of pieces of
>> bandsawn wood (or plywood) and then shaving and sanding until I'm blue
>> in the face.
>>
>> Is there a simpler solution? The leg doesn't have to be tapered, just a
>> piece of wood with a elleptical profile, about 6 x 10 centimetre (2 1/2
>> x 4 inch) inches thick.
>>
>> Or should I order it from somewhere where they have a spindler moulder
>> and the required profile(s)? Or a CNC cutter. I only need one, and don't
>> want it to cost me an arm as well.
>>
>> --
>> mare
>
=========================================================
Save the Whales + http://www.diversify.com
Collect the whole set! + Website design and graphics
=========================================================
"Martin Rost" <rostmartin @ hot mail . com> wrote:
>I did a quick sketch in AutoCad to see what could
>be done.
Interesting idea. Seeing your note spurred me to do the same thing
with another approach. Starting with a 2-1/2" x 4" rectangular blank,
and with the table saw blade or band saw table set at 30 degrees, cut
an elongated hexagon with sides tangent to the ellipse. The resulting
points to plane off vary from slightly under 1/8" to slightly under
1/32" proud of the ellipse, with the worst ones being on the flat
side. Cut four 15-degree bevels with the stock vertical before moving
to the 30-degree bevel, and there is really very little planing to do.
As someone else said, lots of good approaches to this one.
--
Alex -- Replace "nospam" with "mail" to reply by email. Checked infrequently.
mare wrote:
> Dave Hinz <[email protected]> wrote:
>
>
>>On Wed, 20 Apr 2005 13:06:55 -0400, mare
>><mare*Remove*All*0f*This*I*Hate*Spammers*@mac.invalid.com> wrote:
>>
>>
>>>Or should I order it from somewhere where they have a spindler moulder
>>>and the required profile(s)? Or a CNC cutter. I only need one, and don't
>>>want it to cost me an arm as well.
>>
>>
>>You can get close with a lathe. I think I saw Roy do it a few years
>>back. Think of the profile as two circles with different centers.
>>Lay the circles and centers out on the end of the stock, and turn it
>>once with each of the two centers. Gets you close to an ellipse - if
>>mathematical precision is vital, nevermind.
>
>
> It is, sorry. In a true ellips, there are no circle sections. The angle
> changes gradually. I want a leg the has (more or less) the same profile
> as the table.
>
>
>>I seem to recall that Roy had some fun with the very unbalanced work
>>in the lathe - speed is probably not your friend in this case.
>
>
> It doesn't sound very safe to me.
>
It is safe -- find the ornamental turners that I mentioned. There were
some links in the rec.crafts.woodturning forum that I mention -- about a
month ago? Interesting stuff.
I actually bought a 4 jaw independent chuck with this in mind...
And have some fun.
--
Will
Occasional Techno-geek
[email protected] (Robert Bonomi) wrote:
>In article <[email protected]>,
>Roger <[email protected]> wrote:
>>Ralph wrote:
>>> Turn The leg on two offset centers at 180 degrees with the center point
>>> equal distant from the center.
>>>
>>
>>
>>I guess I'm missing something. How does this form an ellipse? Aren't
>>the ends going to be circular rather than elliptical in section? Unless
>>the lathe moves the center while rotating as is possible with some
>>ornamental lathes the section can't be elliptical.
>>
>>Roger
>
>Consider a circular cylinder.
>
>Consider what you get if you slice that cylinder at an angle.
>
>Now, construct a cylinder perpendicular to that angled cross-section slice.
>
>You have, obviously, and elliptical cylinder.
>
>It should be "obvious to the casual observer" that you can take an angled
>slice of _that_ cylinder in a manner that will yield a circular cross-
>section. That cross-section is perpendicular to the minor axis, and at
>an angle to the major axis such that the 'diagonal' is the same length
>as the major axis. Mathematical "proof" gets a little messy, but is
>fairly straightforward -- take the equation of an ellipse, parameterized
>as a function of the major and minor axis lengths, set the two lengths
>equal, and "reduce".
>
>"A quantitative answer is left as an exercise for the student." *GRIN*
>
True, but irrelevant to what I understood to be suggested. I think the
offset idea was to turn two circular arcs of relatively large
diameter, which combine to form an elongated curved pointy-ended shape
that then can be further worked with planes, scrapers, sanders, etc.,
to approximate an ellipse. As I understood it, both ends of the leg
were going to be offset in the same direction, thus the concern for
caution with inherent imbalance.
I think what you are talking about can be used to cut a circle in a
single slanted plane, which will be useful as a gauge cut for the
ellipse. But the ends of the leg will have to be offset pretty darned
far from the lathe center if the leg is of any length.
--
Alex -- Replace "nospam" with "mail" to reply by email. Checked infrequently.
On Wed, 20 Apr 2005 20:18:51 -0400, Roger
<[email protected]> wrote:
>Ralph wrote:
>> Turn The leg on two offset centers at 180 degrees with the center point
>> equal distant from the center.
>>
>
>
>I guess I'm missing something. How does this form an ellipse? Aren't
>the ends going to be circular rather than elliptical in section? Unless
>the lathe moves the center while rotating as is possible with some
>ornamental lathes the section can't be elliptical.
I think he means that an ellipse has two "centers", or focal points.
However, it won't work, as you suggest, since the ellipse is nowhere
"circular", and no matter where the center, the cut will be circular
to that center. I think no matter his choice of methods, each has its
problems. The closest solution might be the one suggested to cut on
the TS or bandsaw to rough shape then plane/sand to taste. The
difficulty would be stabilising the already cut part while cutting the
rest, but a wood channel and well-placed clamps should do it.
mare wrote:
> Hi,
>=20
> I need (well, would like) one elliptical leg for the end of an
> elliptical table. The other end will be attached to a wall, so it only
> has one leg.
>=20
> I have several ideas how to make one, layering lots of pieces of
> bandsawn wood (or plywood) and then shaving and sanding until I'm blue
> in the face.
>=20
> Is there a simpler solution? The leg doesn't have to be tapered, just a=
> piece of wood with a elleptical profile, about 6 x 10 centimetre (2 1/2=
> x 4 inch) inches thick.
>=20
> Or should I order it from somewhere where they have a spindler moulder
> and the required profile(s)? Or a CNC cutter. I only need one, and don'=
t
> want it to cost me an arm as well.
>=20
This wood be better in r.c.woodturning. I just crossposted.
Most look here -- but might miss it.
Some do some pretty fancy stuff.
There are some specialty sites on this type of ornamental turning. DAGS=20
on it. (ornamental turning that is)
--=20
Will R.
Jewel Boxes and Wood Art
http://woodwork.pmccl.com
The power of accurate observation is commonly called cynicism by those=20
who have not got it.=94 George Bernard Shaw
If I were to do this, and I didn't want to hand carve it, I would likely do
it on a CNC vertical mill. "Didn't suggest that as few people have that at
their disposal.
"Dan Bollinger" <[email protected]> wrote in message
news:OgPae.16136$r53.10548@attbi_s21...
> > Piece of wood+drawknife+spokeshave=eliptical leg.
>
> At some point carving it by hand is the cheaper way to go. Of course its
a
> little difficult to make a bead or cove using only a drawknife, but your
> point is well taken nonetheless.
>
> Besides carving...
>
> a person could also fabricate this from gluing up multiple sections of
split
> turnings...
>
> or use a copy lathe like they do for oval axe and hammer handles...
>
> or program a CNC lathe...
>
> or turn a hollow tube and steam bend into an oval by squishing it in the
> middle...
>
> all sorts of ways! Dan
>
>
>