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