Relieving Attachment for making TAPS

Charles Lamont said:

Eureka attachment, info from various sources:

http://www.youtube.com/watch?v=Wg0V36H6HsU

Model Engineer ran a two part article by D.H. Chaddock and Ivan Law starting in the February 6, 1987 issue. pages 138-139 and finishing in the March 6, 1987 issue, pages 280-281

The Eureka tool is described in:
Gears And Gearcutting by Ivan Law
No 17 in the Workshop Practice Series
ISBN 0-85242-911-8

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MCRIPPPer said:

it seems like you would need another gear set to drive an eccentric or something, as well as the lead screw gears in order to cut a tap.



what if you had a profiled cam that was mounted on the spindle that somehow was linked to the cross slide.

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Hopefuldave said:

Holbrook supplied a comprehensive kit for their toolroom lathes:
An 8:1 spindle speed reducer that sat on the ways ahead of the spindle and engaged with it, with a matching spindle nose and indexing assembly;
A cross-slide mounted relieving slide with an internal cam to advance and retract the tool;
A secondary gearbox driven from the reducer to drive the cam-operated slide via an universal-jointed splined shaft.

By varying The ratio between the spindle and cam you could get different numbers of flutes, whole-number ratios gave straight flutes, fractional gave spiral flutes. As the slide operated independently of the cross-slide and topslide, it could be used in conjunction with the taper attachment or even the profile copy attachment, and the leadscrew was available for "threading", it made almost any tap, milling cutter or hob possible!

There are some good pics of the relieving kit in the Model C brochure, which is on the Yahoo Holbrook group...

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