Guys,
Here's what I got from my machining guru friend:
Greetings Ren,
Cutting a taper of 18" with a diameter of only 1/10th" to 1/4" in aluminum is extremely challanging for the home shop.
In industry tapers are "ground" on "centerless" grinders where the work piece is only supported during the "grind" by rollers and the "grinding" wheels at the location of the "grind".
http://www.youtube.com/watch?v=EP-hUXrC6KA
http://progrind.com/PRECISION_CENTERLESS_GRINDING_S.html
The key factor of industrial taper machining is "grinding".
A tool post "grinder" if used properly with multiple passes will exert far less force on the work piece than any cutter.
"Die grinders" acceptable for tool post use start at about $20:
http://www.harborfreight.com/catalogsearch/result?q=die+grinder
Some guys are inclined to use Dremel type tools, however, Dremel type tools lack the "rigidity" and horsepower of a "die grinder" for precision grinding.
The die grinder must be "rigidly" attached to the tool post, the compound or the crossfeed table:
http://www.home-machine-shop.com/projects/Tool-Post-Grinder/
As evidenced from your experience, supporting a long small diameter work piece between the lathe chuck and the tail stock or the steady rest is unlikely to be successful due to a lack of "rigidity".
The only way that I know of (after only 1 cup of coffee) to maintain "rigidity" for a long small diameter work piece "in the home shop" is to perform the "grinding" within 1 to 2 inches from the lathe chuck.
This involves a very painstaking process of only "grinding" 1 to 2 inches of the taper at a time and then advancing more of the work piece out of the lathe chuck for "grinding" the next 1 to 2 inches of taper.
Matching the 1 to 2 inch grinds for a smooth continuous taper can be very challenging and assisted by a magnifier or microscope mounted above the grinding location and approaching the grind with very light passes.
As the ground tapered portion of the work piece significantly protrudes several inches from the lathe chuck, the work piece should be loosely supported to prevent whipping.
Ned
So, I'll find another way to resolve this dilemma....
Ren
Received on Tue Jul 03 2012 - 08:34:38 CEST