The information from the manufacture for drilling the
blank to provide room for the hardware and peppercorns is in the left drawing
below. Since my finished pepper grinder
height is taller than the one shown in the drawing some revisions need to be
made. Also, two of the bits required,
the 1 1/16” and 1 3/16” diameter are sizes that I don’t have. The right shows what will be drilled to
accommodate what I do have along with the finished diameter understanding that
some additional other work will be required to get to the required 1 1/16” and
1 3/16” diameters shown.
Setting the blank up to drill requires the lathe’s drive
center to be removed and a 4-jaw chuck put on.
The bottom of the pepper grinder blank gets set in the chuck and lightly
snugged down. To make sure the top is
centered the tail stock is brought up and the live center’s point is set in the
same point as when the blank was held between centers. This assures the center line of the blank is
in the same position as it was initially turned round. With that done a 1 ½” Fostner bit is put in
the drill chuck and a 1/8” deep hole is drilled. Here all the above has been done.
Drilling the center hole is next. While it will eventually go all the way through for now
it gets drilled just short of coming through.
That’s so I can use the center mark on that end to align the blank when
it gets flipped end for end. The red
arrow points to a light pencil line on the bit to mark the depth of the
hole. I start with a ¾” diameter bit to
hog out most of the material as shown here.
Next a 1 1/8” hole gets drilled about 1” deep. The reason for that will get explained
later. Here the bit is just getting
going.
With the drilling done at the top the blank gets reversed
putting the undrilled part at the bottom.
There are three different diameters for the bottom. First, is the 1 ½” diameter hole that gets
drilled deeper than the original plans since the pepper grinder is taller than
the one shown in the supplied plans.
Second is one 1/8” deep and 1 3/16” in diameter. Since the closest bit I have to that size is
1 1/8” a parting tool is used to cut it the 1/32” wider on the side for a total
1/16” wider. Last is the 1 1/16” hole
the grinding mechanism fits in and the closest bit I have is 1”. Because this hole is deeper into the body of
the blank and smaller it can’t be enlarged using the parting tool. After trying several methods that didn’t
work, I settled on using the die grinder with a carbide burr. This is a pneumatic power tool that runs at
about 20,000 RPM’s and just glides through wood.
If I tried to using it under power with the burr to
remove 1/32” of material from the side of the hole (1/16” total diameter) it
would be like trying to do surgery with a chain saw. What did work was to hold the tool in place
turn the lathe on low speed and just hold the burr against the side of the
hole, like a file.
This process worked fine as the material removal could be
easily controlled. Once the correct size
was attained a little sanding is done to smooth the surface and I was
finished. Here is the end view of the
blank all drilled out. Now it would have
been a lot easier to make with the right sized bits and if I was going to make
several of these I would but I didn’t feel like buying the bits for a one-off
use.
With all the drilling done the grinding hardware gets
installed for a test fit. Everything fit
and the crank worked great. Next is to
chuck the blank up and turn the profile so it matches the existing salt and
pepper shakers.
Up to now the blank has been held in the chuck using jaws
that grab the outside of it. Now to turn
the exterior of the piece to its final shape the chuck needs to grip from the
inside. To do this requires changing the
jaws from what’s on the chuck body to a different set. Below on the left is the setup that has been
used so far. It’s minimum gripping size
from the inside is 2 3/8” way too big to use.
The middle is the blank as it is now and on the right is after the jaws
have been changed out. The minimum
inside gripping size is 1 1/16” which is 1/16” smaller than the 1 1/8” hole
drilled in the top of the blank. As the
bottom has a 1 ½” diameter hole it could be used but I will be using the top 1
1/8” hole because the walls are thicker and will provide more strength when the
chuck is expanded to hold the blank in place.
What I really don’t want to happen is to apply too much outward pressure
and split the blank apart.
In the top photo the blank is mounted in the lathe ready
to turn. The bottom photo shows the
outer edges and the center turned down to just over their final diameter. The white lines are for guidance while the
arc is being turned to give the piece a narrow waist so it feels better in
hand.
The tapering is not straight but a gradual curve or
hourglass shape to the waist. This is
done by working from both sides toward the center to make sure there is good
symmetry between the top and bottom.
Once satisfied with the hourglass shape the piece is
sanded up through 400 grit. It’s not
done as I do have a little more turning to do.
Right now, the top and bottom are flat and square to the now gracefully
curved sides. Once I break the bottom
edge it will be done but the transition from the top to the side is too
abrupt. What’s needed is for the top to have
a slight curve transitioning to a gently rounded corner that blends in with the
sides.
Next Up – Final Turning, Finishing & Assembly
No comments:
Post a Comment