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Posted: Thu Dec 13, 2012 7:20 pm
by stickthrower
Terry, Thanks again for the write up. I can't wait to make a few pens.
Nathan
Posted: Thu Dec 13, 2012 7:44 pm
by heathicus
What's the significance of the 60 degree dead center? Why is a center like that required? Why not 55 degrees, or 65 degrees? What is your shop made center made from and how durable is it?
Posted: Thu Dec 13, 2012 9:05 pm
by reible
In the last few posts I see "dead" center, should that be drive center? We are talking about the one that is turning the stock right?
Ed
Posted: Thu Dec 13, 2012 10:25 pm
by fjimp
reible wrote:In the last few posts I see "dead" center, should that be drive center? We are talking about the one that is turning the stock right?
Ed
Good Question Ed, each time I read this thread I wonder if we are actually referring to a 60 degree "
Live" center. Which would be used to keep wood from burning at the opposite end of the motorized lathe drive. Like this one]
http://www.pennstateind.com/store/LCENTLT2.html[/url]
Jim
Posted: Thu Dec 13, 2012 10:36 pm
by heathicus
Dead, live, drive... why 60 degrees?
Posted: Thu Dec 13, 2012 10:45 pm
by pennview
For turning pen blanks between centers, you would use a "dead" center in the headstock and a "live" center in the tailstock in a traditional lathe. Since you can't use a morse taper dead center in the headstock on the Shopsmith, you must improvise and and make something with a point on it that fits the Shopsmith spindle to drive the pen blank.
I've never turned a pen between centers, but one way to accomplish this would be to mount the 1/2" router chuck and add a piece of dowel on which you turn a taper to fit inside the pen blank. I'd also fashion some wood to cover the live center in the tailstock, adding a taper to it as well to fit inside the pen blank. Use something like wood or Corian so that the lathe tool edges don't get damaged when you turn the blank.
The 60 degree angle of the tailstock live and dead centers comes from metalworking where that angle matches the angle of center drills used to drill the end of metal stock destined for turning between centers on a metal lathe. Also, the divot on the end of the mandrel used for pen turning is 60 degrees, while the typical woodworking live center has a much more acute angle than that so using a woodworking live center with the mandrel results in a mismatch that can result in sloppy, out of round pen parts.
These centers don't necessarily have to be 60 degrees. They just have to fit inside the pen bank.