>  >ssalb@l... writes:
>  ><< So this raises the obvious question:  What is "sprung"?
>
>To throw in my two-bits on this perennial topic, among the reasons I've
>heard for spring --all of them reasonable-- are:

Allow me to through my two-bits in, too.

>1] Economy
>(Since quarter-sawn wood --with its radial grain-- is prefered for a wooden
>plane, spring gives you a wider sole for the same width of the expensive
>wood.)

A mute question in the case of hornbeam sine the tress don't
generally get that big. Especially for a whooper like a panel raiser,
also called badger plane. Not a single one of my several historic
planes pay the least heed to the lay of the grain.  Not the horbeam
and not the pear, least of all the live oak.  Someone mentioned a
boxwood plane a day or two ago;  I would be curious where the plane
was from and how big it really was. Boxwood doesn't get very big. I
have made a couple of small planes of box and fine it totally
unsatifactory inspite of my love of the wood. Sexy it looks - a
breaks it does easily, not to mention warp.

>2] Consistency of the mouth
>(The throat on a wooden plane gets wider away from the sole.  As a result
>at the bottom of a "deep" groove in the sole the mouth will be wider than
>it would be at a "shallower" point in the sole.  The spring is choosen to
>give the narrowest "average" width of the mouth.)

This is untrue.  It depends solely on the geometry of the box (is
that the right term; in German Kasten). MY Drautz/Heilbronn badger ,
late 196th.c is not spring and is heavily skewed and the mouth is
parallel and reasonbly narrow.  This is one of the historic planes I
use routinely, not for panels, but for keyboards which have a wide
cross-gain rebate at the front for the coverings (generally of box).

>3] Restricted by the shape.
>(Some complex profiles would be hard, if not impossible, to cut if the
>plane were held vertically.)

True - and untrue. I don't own a single historic molding plane with a
side fench that is held at an angle, and they are very uncommon. Up
to a certain size of course. Very large ogees etc were planed "flat",
sprung if you wish. Large stuff , as on organ cases was assembled and
not planed at all in one piece. Many victorian moldings , epecially
English planes were sprung, but as you say, because of the shape, not
because of the mouth. The problem is the different in height that
makes a convoluted shaving. For this reason the mouth must be big,
not for geometrical reasons, and this "tortured" shaving is very hard
to shove. The larger the height difference, the harder. This is the
main reason for a sprung plane. On the other hand, this convolution
keeps the wood from tearing as readily as it might otherwise.
Complicated renaissance and baroque profiles were almost always made
with a scratch stock, making each part separately.

>4] Ease of use #1
>(Easier to hold a plane of this type against the wood by pressing down at
>an angle.)

and
>5] Ease of use #2
>(Easier to hold the fence against the edge of the work, given the possible
>weird shape of the sole.)

True and untrue again. It depends entirely on what you are planing.
Bear in mund that the bench vise and the German bench dog system are
a mid nineteenth c.invention. Before that, the bench had a dog at the
far end to plane against, a few holes for holdfasts in the top, and
maybe a vise against one of the legs. There was also usually a hook
on the far end front edge to accept panels on end on the floor.  Now
if your work piece is resting on the surface against the dog, it is
easier to press down against the bench vertically than  sprung, at an
angle to the bench surface.  there are always ways to work around the
piece sliding to the side (save nailing it to the bench) so both
types, sprung and unsprung, could be used. Since  the straight
variety can more often be used "out of the tool box" it was  probaby
more generally used.

>In short, I don't think there's "a" answer.  Also, the reason probably
>changes for different types of planes and different sole-profiles.
>
>N

I entirely agree.  The width and shape of the mouth are entirely the
result of the geometrical layout of the plane. As good as Krenovian
(pseudo Japanese) planes can be for simple designs, you cannot
extrapolate from them about how classic wooden planes were designed
and made.

regards,

b

William Jurgenson
http://www.zabernet.de/bill/index.html