Yesterday, I talked about my SPIKY, a very versatile
tool for forming concave surfaces. As with anything else,
however, there are rules.
You just cannot apply SPIKY anywhere you like on the
initial flat surface, underneath which a concave is to be
formed.
Take a look at the following illustration.
A refers to it. You must start down in the middle, in an area
in red. This is because Spiky is a rotating sphere and is
trying constantly to ride over the rim area outside the
dotted area in green. This is detrimental, if that happens,
as it leaves a fairly deep scurr in its wake. It becomes awfully
messy to mend these scurrs.
In the worst case the recess into the concave must be reduced,
renderig some of the spoons utterly useless.
What you must do is to dig a trench in the red area, as deep as
the concave recess, or very nearly. That will provide you with
the hold you need with the rotating Spiky.
Effectively, you go for a territorial expansion, towards the rims
by pressing the Spiky on the walls of the concave as it is
gradually widened.
Watch out for Spiky's ride-over tendency!
And, you do that initially between the two dotted
lines in red. Areas outside these red lines must be
treated with extreme care, later on in the territorial
expansion.
Incidentally, B and C refer, respectively, to straight
stem and bent stem spoons.
I now refer to another illustration below. This is because
operating with Spiky is not an event-free uniform digging for
concave surfaces.
There are two spots on the way to an eventual concave.
These spots are illustrated as per below.
Once again, areas in red designate those two spots.
When these areas are ground by Spiky, you must press
Spiky onto the concave surface towards outside the
spoon. Other two corners are easy to negotiate, but,
at these two places in red hold ing of Spiky becomes
difficult and unstable. You need to do it yourself,
if you want to be asbosuletely sure about the reason.
B and C refer to the scurrs left over by Spiky and the
flappers. They are illustrated as per below. A is the Spiky
and B is the flappers.
Strictly speaking they are normally refered to as flap
foils, but, I call them simply flappers. Flapper wings are
abrasive enough and do not leave deep scurrs.
Anyway, in the first illustration, B is showing you the deep
scurrs left by Spiky, which are parallel to the grain of
the wood.
C is the scurrs left by the flappers, perpendicular to the
grain and thin and shallow, easy enough for paper sanding
to obliterate them, later in the operation.
I think this is good enough for the day, but before I go,
I will show you today's output and test pieces I used.
Sorry, no test pieces, just a chopstick container.
As you can see disk magnets are in place and chopsticks
are placed in the trench anti-paralell simply because
the trenches are shallow, in order to make the whole thing compact.
I may talk about this topic later. OK, I go now!
tool for forming concave surfaces. As with anything else,
however, there are rules.
You just cannot apply SPIKY anywhere you like on the
initial flat surface, underneath which a concave is to be
formed.
Take a look at the following illustration.
A refers to it. You must start down in the middle, in an area
in red. This is because Spiky is a rotating sphere and is
trying constantly to ride over the rim area outside the
dotted area in green. This is detrimental, if that happens,
as it leaves a fairly deep scurr in its wake. It becomes awfully
messy to mend these scurrs.
In the worst case the recess into the concave must be reduced,
renderig some of the spoons utterly useless.
What you must do is to dig a trench in the red area, as deep as
the concave recess, or very nearly. That will provide you with
the hold you need with the rotating Spiky.
Effectively, you go for a territorial expansion, towards the rims
by pressing the Spiky on the walls of the concave as it is
gradually widened.
Watch out for Spiky's ride-over tendency!
And, you do that initially between the two dotted
lines in red. Areas outside these red lines must be
treated with extreme care, later on in the territorial
expansion.
Incidentally, B and C refer, respectively, to straight
stem and bent stem spoons.
I now refer to another illustration below. This is because
operating with Spiky is not an event-free uniform digging for
concave surfaces.
There are two spots on the way to an eventual concave.
These spots are illustrated as per below.
Once again, areas in red designate those two spots.
When these areas are ground by Spiky, you must press
Spiky onto the concave surface towards outside the
spoon. Other two corners are easy to negotiate, but,
at these two places in red hold ing of Spiky becomes
difficult and unstable. You need to do it yourself,
if you want to be asbosuletely sure about the reason.
B and C refer to the scurrs left over by Spiky and the
flappers. They are illustrated as per below. A is the Spiky
and B is the flappers.
Strictly speaking they are normally refered to as flap
foils, but, I call them simply flappers. Flapper wings are
abrasive enough and do not leave deep scurrs.
Anyway, in the first illustration, B is showing you the deep
scurrs left by Spiky, which are parallel to the grain of
the wood.
C is the scurrs left by the flappers, perpendicular to the
grain and thin and shallow, easy enough for paper sanding
to obliterate them, later in the operation.
I think this is good enough for the day, but before I go,
I will show you today's output and test pieces I used.
Sorry, no test pieces, just a chopstick container.
As you can see disk magnets are in place and chopsticks
are placed in the trench anti-paralell simply because
the trenches are shallow, in order to make the whole thing compact.
I may talk about this topic later. OK, I go now!
