Jay's Portable Bowl Lathe
I love my Jet
1642 lathe but it's in the basement, and unless
it’s raining or
snowing I really prefer to spend my time outside. I’ve
dreamed of being
able to turn bowls outdoors in the garden, to enjoy the nice weather
and to
create bushels of wood shavings right where they will be used on the
garden
paths rather than spraying shavings all over my basement shop. But my
Jet lathe
weighs about 500 pounds and it’s just not practical to move
it anywhere.
So I designed and built this portable lathe that is easy to move
around, yet still
has the capacity to handle big bowl blanks up to 16” in
diameter.
Design
Firstly I wanted it to be portable,
with no piece weighing over 50
pounds so I can easily
carry it out to where I want to work. The lathe body and the base ended
up
weighing almost exactly 50 pounds each, with the motor weighing about
35 pounds
and the legs around 20. It also had to be quick to set up and take
down, and I
can set it up in under 10 minutes including the time to carry each
piece out to
where I’m going to work.
I designed the lathe primarily for turning bowls so it has a short bed, just long enough to handle good-sized bowl blanks and to let me use a tailstock for holding bowls against a jamb chuck for turning the bottom. It could also handle spindles up to about 10” long but I didn’t make it for spindle work. There are plenty of commercially-available mini lathes that work fine for spindles and are easy to transport, but you won’t find many 16” bowl lathes that you can easily carry around.
I considered making it bigger, perhaps to handle blanks up to 20” in diameter, but I decided to make it with the same geometry as my 16” Jet lathe so that I can use the same tool rest and tailstock and avoid the expense and time of making them. Having a 16” capacity lets me make finished bowls up to about 14” diameter which is a good practical size, and it would have been difficult to make it heavy enough to swing bigger pieces of wood yet still easily portable.
I made the spindle threads the same
as on my Jet lathe so I
can use the same faceplate and chuck. I decided to go with a solid
spindle
rather than trying to bore a Morse taper, which made the spindle
construction
much simpler. That means I can’t use a drive center in the
spindle but I
don’t need one for bowl making anyway (although I could
easily make a
thread-on drive center if I ever decide I need one). I also
can’t use a
vacuum chuck unless I bore a hole through the spindle but at this point
I don’t
have any plans to do that since I don’t have a vacuum chuck.
Most of the
time I make green-turned bowls for which I don’t even need
the tailstock,
just a faceplate and a scroll chuck. When turning outdoors, the fewer
accessories I need the better.
In order to make a lathe stable while swinging a big out-of-balance piece of wood one wants it to be heavy, but of course that’s not good for portability. Therefore I made the base of the lathe a platform that I can stand on, to use my own body weight to help stabilize the lathe. At the moment that adds about 155 pounds to the base, but as I get older the lathe will probably get more stable. :-) I made the bed the same height (above the platform) as my Jet lathe so that my posture is the same when I’m standing at either lathe.
To keep the drive simple I went with
a three-step pulley
(2-3-4”) on the motor and an 8.5” sheave on the
spindle. With a
1725 RPM motor this gives me three speeds of about 400, 600 and 800 RPM
which I
find is a good range for bowl making. I start turning the blank at 400
RPM to
get it reasonably balanced, do most of my turning at 600, and sand at
800. The
1 HP motor has plenty of power because unlike my variable-speed Jet
lathe, the
motor runs at full speed all the time. I mounted the motor down on the
base to
help stabilize the lathe, and I used a link belt to minimize vibration
and to
make it easy to get exactly the length I needed. It’s also
long enough
that I can shift it to any of the 3 steps on the motor pulley without
much
misalignment, and because the motor is on a hinged platform I can
change speeds
in about 30 seconds. I didn’t enclose the belt so it is a
potential
hazard, but I figure it’s less hazardous than the big piece
of wood turning
right in front of me. The most dangerous part of any tool is, of
course, the
operator.
Since this is meant to be used outdoors I bought a 25-foot, 12-gauge extension cord to use as the power cord. By wiring this to an outlet box on the motor base, I also have two outlets to provide power for a sharpener and if necessary, a fan to blow away dust while sanding. I’ve been using it with an additional 85-foot, 12-gauge extension cord and it seems to work fine. I haven’t yet measured the voltage at the motor while it’s under load but it doesn’t seem to be getting unduly hot so I expect that the voltage drop is minimal.
Construction
Click here for lots of detailed photos showing the
construction
sequence.