Methods of Work Essay
There are many ways of turning bowls.
Over the years I’ve made numerous tools to help me in my
turning. Here are
some of the details. Perhaps
they will be of some interest if not use to you.
I’ve been working on a homemade lathe since 1972, first as a
secondary part of my woodworking, now as the sole focus of my
woodworking. My lathe
has evolved over the years with various improvements and additions
until I finally replaced the last original part in 1997.
I now have a 2 HP variable speed three phase AC motor driving
a 1 3/4” dia. shaft in heavy duty spherical roller pillow block
bearings. A home-cast
concrete block serves as a riser from the 4" x 8" oak wooden ways to
the 2" of plate steel that the bearings bolt to.
The tool rest posts are 1 1/2" inserted into a 4" diameter
column welded onto two 1" x 2" bars that make up the banjo.
Parts of an ancient square head planer are bolted to the
headstock and the tail of the lathe to provide a 36" wide base at
the floor. The bed length is
only 32", to allow easy access to the insides of bowls (I do not use
a tailstock). All this mass
greatly minimizing vibration and gives me a very stable platform to
work from. I can swing
25” diameter maximum, but usually stick to 22” and smaller.
That's more than enough weight to deal with.
Photos of my lathe and other tools mentions here may be seen
on the My Lathe page.
Bowl blanks are trimmed and cut octagonal in the lathe room with an
electric chainsaw. After
using up 3 or 4 Craftsman saws that always leaked bar oil, I bought
the Makita UC4000 that is very satisfactory, though the clutch tends
to slip too easily I think.
Faceplates are mostly 4” diameter made up from ½” plate steel welded
to a 1”x 8 tpi nut, with two concentric rings of six ¼" dia holes.
I usually use 1”x #12 pan head sheet metal screws in the
inner ring of 6 screws, then 1-¼” x #12 in the outer ring, all
angled 15-20 deg. towards the center toenail fashion.
On bowls over 120 pounds I may switch to #14 screws.
For the biggest globes I switch to a 5” Dia. faceplate
threaded 1 ½”x8 tpi, and 1-½”#14 screws.
I do the bulk of my turning
with a deep bowl gouge ½” in diameter.
I like the Glaser, but am very satisfied with the Packard ASP
2060 (3/8” nominal, ½” actual) Deep Flute Bowl Gouge.
I use a long fingernail grind.
The Side Grind Bowl Gouge they sell has a wider flute which
is great for final cuts but is less rigid and tends to chatter under
heavy stock removal or over long extensions.
These powered metal tools hold an edge way better than the
old HSS, and we won't talk about the carbon steel gouges of the 70's
and before.
I have made extensions for my gouges to get more use out of the
flute. I take ¾" cold
rolled steel about 7-8" long, drill a hole ½" diameter hole 1 ½"
deep into one end, and superglue the ½" gouge into this.
The other end goes into an old 5/8" gouge handle.
For 5/8" diameter gouges I
use 7/8" stock. All
handles are covered with 4 to 6 mm black textured neoprene using 3M
90 spray adhesive. This
neoprene cushions the hand and allows you to use a much lighter
grip, all ergonomically good for less arm fatigue.
Source:
http://www.foamorder.com/neoprene.html?gclid=CO7o8obIyZQCFQQrFQodsnb5kw
My parting tool is made from a 1/8” thick planer blade, with the
cutting bevel painstakingly ground away, 1-1/8” wide by 12” long to
begin with, This thing
is nice and bulky, holds an edge pretty well, but there are times a
parting tool 1/16” thick is needed to slip between the bottom and
the screws. An old heavy
duty hacksaw blade works well for this, with just the cutting tip
hardened with Mapp gas and water quenching.
I sharpen freehand on 80 or 100 grit wheels.
I now prefer the Norton 3X
wheels over the white wheels.
The Oneway balancers sure can make a difference on a grinder,
for no matter what brand wheel I have tried, many are out of balance
even when trued up. I
sharpen at the slow speed until the wheel gets to a smaller
diameter. A light
touch and a smooth rotation of the wrist is the ticket.
I have used a scraper for bottom cuts on open bowls made from a
planer blade 8” long x ¾” wide welded to 3/8” x ¾” mild steel stock,
fitted with wood handle.
I seldom used this now, preferring a light shearing to scraping cut
with the gouge across the bottom.
Thickness calipers are made from 3/16” cherry or maple for the
smaller ones, ¼” plywood for the big ones.
The newest one has a 9” throat, with a 3 ¾” wide inside the
curves, lightly spring-loaded and with the reading gauge about 7”
from the pivot point. I
aim for about 3/16+” thickness which will sand and dry down to about
1/8+" thick .
Big calipers have 13” throat, small ones 6”.
Extra large custom shapes reach around globes.
Depth gauges vary.
The medium one is made from 3/16” maple, 5/8” wide for the main
shaft, and 8” long lower bar, 18” long upper bar.
All are assembled with superglue for a snug slide.
A seamstress’s gauge helps set the depth.
I aim for 3/8” thick for the bottom, which translates to
closer to 3/16” with the undercut.
Better too thick than too thin, or the bottom of the bowl
will wrinkle and be fragile.
My cutoff saw made from ¼” bandsaw blade 18” long, set in an
old-fashioned bow saw with 8” throat, tensioned with tie wire.
One blade has lasted 25 years or more.
The sanders are made from the Makita GV5000 sander/polisher.
A hard rubber disc may be 2" in diameter is attached to the
drive stub, with a ½” disk of dense foam glued to that, and then a 3
¾" disc of a softer foam glued to that, all with 3M 90 adhesive. I
use the DuraFlex D44 from FoamOrder.com.
Thin but tough leather is glued to that, smooth side up, to
attach the sandpaper to.
The leather is primed with 3M Feathering Disc Adhesive.
One priming will last months if you keep the dust off.
I used to use standard A weight sandpaper and could get 5
discs from a single sheet of sandpaper, using the feathering disc
adhesive to glue it on by smearing a thin coat of feathering disc
adhesive on the whole sheet before cutting out the discs.
But they tended to spin off when they got hot. I now now use
3M gold PSA disks from 80 to 500 grit, which stay on great.
It’s better to start with 80 grit if possible, to avoid
unwanted scratches showing up later .
The Econ-Abrasives 5” PSA Disc Gold 60 grit works OK too, and
seems to quickly become more like an 80 grit with use.
A standard wall dimmer switch wired to a duplex outlet, placed in a
square steel box, makes the speed control.
I sand a bit over half speed.
Since I usually spend more time sanding than turning a
standard open bowl, I’m always on the lookout for better ways, and
am open to suggestions.
These sanders are so useful that I became paranoid that the Makita
GV5000 would be discontinued, and bought a third one last year.
It works well to keep different grits on each, especially
toward the end of a sanding.
After 500 grit on the Makita I go to a
Grex random orbital sander to which I have some blue foam attached
by hook and loop, again with leather for the upper surface.
I put 500 grit on this, and find it does an excellent job of taking
out swirl marks.
After stationary sanding to finest grit I go to ScotchBrite.
On a round bowl this is easy with the bowl spinning, but on a
natural edge bowl you have to rub some parts by hand. Then I
tried sticking some to a hook and loop disc and found it a great
improvement. The soft foam 3" dia disc sold by The
Sanding Glove mounted on a high speed Sioux 45 deg. angle head drill
makes a fine final polisher for any kind of bowl. I start with
3M grey-green fine #7448, then go to the gold very fine #7745, and
end up with the white ultra fine #7445 than buffs. This
sequence almost polishes the bowl at the end, and can be effectively
used to buff out blemishes and scratches later on. It seems to
blend the Behlen's Salad Bowl Finish right over the offending area.
For more aggressive buffing at the start use the maroon 7447, but it
leaves visible scratches.
For
flattening the bottom of a dried bowl I use a homemade rig which is
an 8 ½” dia. disk of plywood glued to a pulley locked to the end of
a shaft set on pillow block bearings.
A cheap motor runs it at 1750 rpm.
The whole thing is mounted to piece of ¾” plywood with
blocking such that I can easily affix it to the end of my workbench
with the disk spinning horizontally at table level.
. I glue120 grit
garnet paper on top.
Sitting on a low stool, I can lower the bowls down and
flatten the bottoms. The
sanding marks are removed with 320 grit on the foam-backed sander.
I use Behlen’s Salad Bowl Finish on all open salad bowls.
I use Waterlox on all globes, vases, and other art bowls that
won't be used for salads.
Usually 2 coats is enough, except on light porous woods that
I have to build up coats on.
I used to use worn cloth, but now find the Scott paper rags
to be acceptably smooth and texture-free, and certainly more
consistent.
After the first coat is on, the bowl is set aside to dry, first in
the back room, and then out in the attached greenhouse spring to
fall or a board suspended above the wood stove during winter.
Drying raises the grain some, so it is necessary to sand a
second time. This is
hard to do without leaving marks, and was hard on my arms with the
Makita disk sanders.
What I use now is a small modified random orbital sander, a DeWalt
DW423, with the disk cut down to 3 ¾” dia.
I sanded the grit off a velcro sanding disk, glued on foam,
and then the thin leather, to make a soft padded random orbital
sander that with 600 grit paper will remove the fuzz with no visible
marks. It is wonderfully
easy on the elbows.
The Colwood
Cub woodburner with a fine tip sanded round like a pencil allows me
to carefully sign in cursive.
It is essential to set the right heat, just barely hot
enough.
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