Guys, I am about to build a reciprocating wood lathe for cutting out
multiple bowls from a half log section. The bowls will be up to 24" od.

The reason for the reciprocating action is that I remembered the old bodgers
in the 17th century made multiple bowls by using a curved tool with a hook
on the end. These were made on a pole lathe, with a recip action. What is
important about that is that when the shaving was cut, it went thru the hook
and gravity helped it out of the kerf. If a shaving stuck, it only lodged
ontop of the tool shank for a couple of revolutions maximum, then when the
pole pulled the spindle backward, the shaving impacted the bottom of the
tool shank, resulting in expulsion from the kerf. In essence, it was a
self-cleaning system.

In our modern systems, the tool is a scraper, so the shavings pile up on top
of the tool shank. Once you get more than a small handful of shavings
packed in there, you cannot advance the tool, or withdraw it. So you turn
off the lathe, rotate the wood backwards enough to withdraw the tool a ways,
then turn on the lathe and run the tool backwards and forwards several times
to clear the shavings. Then you cut some more.

A reciprocating lathe (powered by an electric motor, not my right leg) would
function the same way, and would be very interesting to watch in addition!!

The method of inducing the reciprocating motion I have come up with is a
sun/planet gearbox, something like the old Ford Model T transmission. I am
sure such devices are used in quite a few applications, but I just don't
know of any. Can you guys put me onto a source? I really don't want to
build one unless there is no other choice.

Thanks in advance,
James Johnson

You just need any old reduction system, gearbox or a set of sheaves to get
the speed you want and a nice plate on the end of the reduction with an
eccenctric pin to make the back and forth motion on the lathe will do fine -
sort of like a steam engine being driven by the flywheel.
While the treadle lathe in any of it's various forms is nice, they really
weren't that good for turning except to show for what the oldtimers back
then really had to put up with.
FWIW, the Woodwright Shop (PBS) does have a tape on doing a treadle lathe
and springpole lathes have also been shown in other episodes.
--
Why do penguins walk so far to get to their nesting grounds?

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"JRJohnson" wrote in message
...
Guys, I am about to build a reciprocating wood lathe for cutting out
multiple bowls from a half log section. The bowls will be up to 24" od.

The reason for the reciprocating action is that I remembered the old
bodgers
in the 17th century made multiple bowls by using a curved tool with a hook
on the end. These were made on a pole lathe, with a recip action. What
is
important about that is that when the shaving was cut, it went thru the
hook
and gravity helped it out of the kerf. If a shaving stuck, it only lodged
ontop of the tool shank for a couple of revolutions maximum, then when the
pole pulled the spindle backward, the shaving impacted the bottom of the
tool shank, resulting in expulsion from the kerf. In essence, it was a
self-cleaning system.

In our modern systems, the tool is a scraper, so the shavings pile up on
top
of the tool shank. Once you get more than a small handful of shavings
packed in there, you cannot advance the tool, or withdraw it. So you turn
off the lathe, rotate the wood backwards enough to withdraw the tool a
ways,
then turn on the lathe and run the tool backwards and forwards several
times
to clear the shavings. Then you cut some more.

A reciprocating lathe (powered by an electric motor, not my right leg)
would
function the same way, and would be very interesting to watch in
addition!!

The method of inducing the reciprocating motion I have come up with is a
sun/planet gearbox, something like the old Ford Model T transmission. I
am
sure such devices are used in quite a few applications, but I just don't
know of any. Can you guys put me onto a source? I really don't want to
build one unless there is no other choice.

Thanks in advance,
James Johnson

"Bob May" wrote in message
...
You just need any old reduction system, gearbox or a set of sheaves to get
the speed you want and a nice plate on the end of the reduction with an
eccenctric pin to make the back and forth motion on the lathe will do
fine -
sort of like a steam engine being driven by the flywheel.
While the treadle lathe in any of it's various forms is nice, they really
weren't that good for turning except to show for what the oldtimers back
then really had to put up with.
FWIW, the Woodwright Shop (PBS) does have a tape on doing a treadle lathe
and springpole lathes have also been shown in other episodes.
--
Why do penguins walk so far to get to their nesting grounds?


Bob, I think it is a little more complicated than that. The system you are
describing would not impart 3 revolutions forward, and then 3 backward.
Rather, the spindle would simply oscillate back and forth. If I had a
cutter on each side of the blank, that might work. But with only one
cutter, and the wood not making a full revolution, it really wouldn't work.

Incidentally, I have not changed my plans. I will use a hydraulic pump and
a hydraulic motor, with the control valve actuated by a DC gearmotor. The
DC will give me a variable (within limits) speed, plus by changing the
parameters of the mechanical linkage to the control valve, I can fine tune
the amount of revs it makes before reversing.

I like the Woodwright Shop, but as I have built 3 very heavy duty lathes in
the past (plus several lighter duty lathes), I will not try to re-invent the
pole lathe. But I do want to see if the recip action will actually work as
well as I imagine.

Thanks for the reply.
James Johnson
Founding member of the American Association of Woodturners.

I guess I'm not understanding the problem. Why couldn't an added
compressed air nozzle keep the shavings from building up?


JRJohnson wrote:
[...]
In our modern systems, the tool is a scraper, so the shavings pile up on top
of the tool shank. Once you get more than a small handful of shavings
packed in there, you cannot advance the tool, or withdraw it. So you turn
off the lathe, rotate the wood backwards enough to withdraw the tool a ways,
then turn on the lathe and run the tool backwards and forwards several times
to clear the shavings. Then you cut some more.
[...]

Would some sort of washing machine motor transmission assembly work? There
might be one doing the actions you're seeking.
Karl

"JRJohnson" wrote in message
...
Guys, I am about to build a reciprocating wood lathe for cutting out
multiple bowls from a half log section. The bowls will be up to 24" od.

The reason for the reciprocating action is that I remembered the old
bodgers
in the 17th century made multiple bowls by using a curved tool with a hook
on the end. These were made on a pole lathe, with a recip action. What
is
important about that is that when the shaving was cut, it went thru the
hook
and gravity helped it out of the kerf. If a shaving stuck, it only lodged
ontop of the tool shank for a couple of revolutions maximum, then when the
pole pulled the spindle backward, the shaving impacted the bottom of the
tool shank, resulting in expulsion from the kerf. In essence, it was a
self-cleaning system.

In our modern systems, the tool is a scraper, so the shavings pile up on
top
of the tool shank. Once you get more than a small handful of shavings
packed in there, you cannot advance the tool, or withdraw it. So you turn
off the lathe, rotate the wood backwards enough to withdraw the tool a
ways,
then turn on the lathe and run the tool backwards and forwards several
times
to clear the shavings. Then you cut some more.

A reciprocating lathe (powered by an electric motor, not my right leg)
would
function the same way, and would be very interesting to watch in
addition!!

The method of inducing the reciprocating motion I have come up with is a
sun/planet gearbox, something like the old Ford Model T transmission. I
am
sure such devices are used in quite a few applications, but I just don't
know of any. Can you guys put me onto a source? I really don't want to
build one unless there is no other choice.

Thanks in advance,
James Johnson