VERITAS Mk.II, Руководство пользователя

Страница: 62 / 70

56
Veritas
®
Mk.II Power Sharpening System
It is also conceivable that you would want the wings on
a parting tool swept back slightly. This would be the
case if you were making stop cuts with the tool, cuts
that butted some other feature.
As a fi nal consideration, regardless of how you sweep
the wings, you will fi nd that reducing the bevel angle as
you come up the wing will increase the maneuverability
of the tool. The rationale is exactly the same as that given
in the shaping of gouges. A reduced bevel angle reduces
lateral wedging. In fact, there is no reason that the tool
could not have some inside bevel, as recommended for
gouges, to strengthen the upper wings.
The inhibiting factor in all of this shaping is that parting
tools are so hard to sharpen well that you may want to stop
when you have a keen edge and a workable shape, even if
it is not ideal. You would not be alone if you did.
Sharpening Parting Tools
V-tools should be sharpened very carefully, and for this
reason I would use a fairly fi ne belt (no coarser than 120x)
on a belt sander. I would also hold the tool so that the
wing edge is almost parallel to the direction of travel of
the belt, as shown in the top right photo on the previous
page. This orientation makes it easiest to ensure an even
grind along the entire edge. If you accidentally grind past
the line of light at the heel, you must square up the wings
and start over again. Otherwise, you will have a fi ber trap
at the heel that will constantly frustrate you in use.
A parting tool cannot be sharpened adequately on the
face of a grinding wheel – it’s much too fi nicky a job. If
you don’t have a belt sander or a horizontal wet wheel, I
would recommend clamping the tool at a suitable angle
and using a bench stone or slipstone to shape the edge
(see the middle photo on the previous page). For honing,
use a micro-fi nishing abrasive belt, a leather belt with
chromium-oxide compound or custom-made wooden
forms charged with chromium-oxide compound. As
with gouges, a parting tool will shape its own hone
(bottom photo on the previous page).
Inshaves
Inshaves have a variety of uses, from dressing the inside
of barrel staves to forming chair seats. Most inshaves
sold in North America today come from a German
manufacturer of drawknives. The stock blade is bent
into shape, hardened, tempered and then ground only
on the outside of the tool. This is probably the best
example of the curious belief still held by some that a
tool can be sharpened by working on only one of the
two surfaces that make an edge.
An inshave is not an easy tool to use, and it must be very
well sharpened to be effective. A new inshave of the type
mentioned above needs a fair amount of work on the
inside. This is best done with a sanding drum, as shown in
the photo below. Whenever you are using a sanding drum
for sharpening, use the largest-diameter drum that will fi t
in the curves of the tool. The smaller the drum, the more
scalloped the edge you will create. Use a confi dent sweep of
the drum on the tool (if it is being held in a fl ex shaft) or of
the tool on the drum (if it is drill press mounted). Hesitation
or indecision will leave you with a nasty little groove in
one spot on the edge. When the lion’s share of the work
seems to be done, you can switch to using a gouge cone
or a sandpaper-covered wooden form to fi nish grinding the
inside. Then use micro-fi nishing abrasives or chromium-
oxide compound on a wooden form for fi nal honing.
The outside bevel is very easily done on a belt sander
or manually. For most uses, the outside bevel should be
slightly rounded so that the tool can cut in a gentle arc,
as is necessary when making chair seats, for example.
Sharpen the inside of an inshave with a sanding drum.
(Photo by Susan Kahn)
Sharpen the outside bevel of an inshave in the slack of the
belt on a belt sander. (Photo by Susan Kahn)