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Harold Hall

Workshop Projects

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Having a liking for screwed shank cutters, this was the route I chose. Two approaches were possible, one to remove the spindle from the assembly and make another specifically for the task, or alternatively, to make an adapter to enable larger collets to be fitted. The second method, as per my original design but with an adapter, would still enable the smaller collets to be used and also the drill chuck. As a result I choose the route of using an adapter. On balance, I feel that even if the reader does not have the spindle already available this may still be the preferable approach, as having the facility of a drill chuck will be a useful option in some cases.

 

Column Assembly AS1

This is a simple arrangement based on four columns of precision ground mild steel though only two need the precision of ground bar. The bars are mounted between two steel plates and the arrangement as drawn suits a flat bed lathe, for other forms some changes will no doubt be required. The blocks that slide up and down the bars are made of cast iron on the basis that dissimilar metals move more easily one on another.

 

I was tempted to take the easy route with regard to the leadscrew and use a standard metric thread. However, the only available thread that would give a tidy calibration would be M6 having a pitch of 1 mm. This though was considered too fine requiring too many turns to move the head up and down. An M10 thread with a pitch of 1.5 mm would be a slight improvement but the idea of working with one and a half millimetre per turn did not appeal. Because of this, I opted for the more usual format of using a square thread even though this meant more work to complete the project.

 

Whilst I work almost exclusively in metric dimensions my machines are imperial. This gives me no problems until I am required to cut a thread on the lathe and here, as invariably I am making both the internal and external threads, I work to metric diameters but use an imperial pitch. Because of this I made my leadscrew 10 mm diameter, as per the drawing, but with a pitch of 0.1". This would calibrate nicely and be in keeping with the calibrations on the lathe on which it was to be used. Also, it would move the head up and down reasonably quickly. Whilst the drawings I have included, quote a pitch of 2 mm you may also like to adopt my approach.