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.
a person could also fabricate this from gluing up multiple sections of split
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
all sorts of ways! Dan
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.
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.
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.
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,
Steven and Gail Peterson wrote:
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.
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.
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.
Make yourself an elliptical router jig that would find around your
stock. The jig would just be two ellipses that were the size of the
target ellipse plus the router depth of cut. The bit would pass
between the two sides of the jig while the router base rode on the
outer diameter of the jig.
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.
On Wed, 20 Apr 2005 14:36:27 -0700, the inscrutable "J"
======================================================== Save the Whales + http://www.diversify.com
Collect the whole set! + Website design and graphics
On Wed, 20 Apr 2005 13:06:55 -0400,
mare*Remove*All*0f*This*I*Hate*Spammersemail@example.com (mare) wrote:
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.
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.
Sorry if I missed one.
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
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
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