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Using the Tailstock


Long and/or slender billets need to be supported by the tailstock. Unless the tailstock is positioned with great care, the lathe carriage will collide with it and push it out of place. The care must begin when designing the part and how it is to be machined. The tool paths and tool change position must be planned thoughtfully. Keep in mind the following:

1 The right hand end of the billet must be faced off and centre drilled before the tailstock can be used. If the billet will pass through the headstock spindle, use appropriate good practice to face off and centre drill with the lathe under manual control from the PC keyboard. Otherwise, prepare the billet on another lathe with a headstock spindle which can accommodate it.

2 Use a live (running) centre in the tailstock rather than a dead (non-rotating) centre.

3 If the left hand end of the billet is held by a chuck, it is possible that the centre drilled right hand end will not be perfectly in line with the tailstock centre. Therefore, the left hand end should be supported by a centre and driven by a carrier and catch plate.

4 When machining at the right hand end of the billet, there is a risk of the tool tip hitting some part of the tailstock centre. Find out the smallest diameter which can be machined safely. For the right hand tool that diameter is about 8mm. There is very little room between the end of the billet and the tailstock centre's body. Plan carefully.

5 There is a risk that the quick change tool post or the lathe carriage will hit the tailstock body or its two clamping handles. Set the handles so that, when locked, they cannot be fouled: see Fig 1.

6 If more than one tool is required to machine the part, there must be room for the carriage to move to the right, without hitting the tailstock centre body. Note the gap in Fig 1. Plan the tool movement path carefully.

7 The tool change position could be at Z = +5 and X = +50: Fig 1. These values take account of the diameter of the body of the tailstock centre and the differing projections of tools from their holders.

8 To satisfy all these requirements, it is likely that the tailstock barrel will need to be wound forward quite a lot from the body of the tailstock. Try to keep this distance to a minimum.

Note the important details shown in Figs 1 and 2.

         

AlphaCAM and the Tailstock Centre
Billet Length