Some months back I posed a question for the group regarding how to make a long thin tapering rod. The taper being from 0.25" (6.35mm) to 0.080" (2mm) over about 6" (150mm). From kicking various ideas around I came up with the solution shown in the dropbox. It works very well. Many thanks for all the help.
Clever!
What keeps the end of the rod from just lifting up at the tip, from the cutting forces? - GWE
David
Clever. I've been thinking about making long tapered reamers for making woodwind bores, but I hadn't come up with a setup I liked. Your setup is a considerable improvement over anything I'd thought of. Gonna have to remember that one.
Jim
David, maybe I just need new glasses but I couldn't quite figure out how that turning setup worked. Any chance you could describe how it works? - GWE
The rod rest in a semi circular bottomed groove in the brass bar which is about .150" deep horizontally, the bar radius being .125" so a little above and below forward of the vertical centre line. The groove depth vetically is about .252", a little clearance for lube. Because the bar is only .25" diameter it is flexible and the brass guide forces it forward towards the front of the lathe at the tailstock end so producing the required taper. The brass guide supports all the rod length from close to where it leaves the chuck. The tool grind is basically a threading tool so the resulting cutting forces should keep the rod in the groove in addition to the force due to it being bent once it leave the chuck. The taper is small so the bending is within the elastic limit of the material. The cutting is done towards the chuck so the initial cut on the current items is 0.085" reducing to 0 nearer the chuck. Luckily the rod is happy to transmit the cutting torque and the EN24T (4340) machines very nicely.
I h> David, maybe I just need new glasses but I couldn't quite figure out how
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