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Capstan – examples
The sequence given here makes one nut per cycle. However it should soon be obvious that time can be saved because it is possible to drill the hole for several nuts in one go. Similarly it would be possible to tap more of the feedstock in one go than was needed for just one nut. This is covered at the end of this page.
Set to length/center drill
Drilling and tapping can be done at once for more than one nut
Part off with a cutter shaped on both sides. Every parting operation not only cuts the left side of the part being parted off but also cuts the right side of the next part. Usually, when parting, Both of these are flat. But, in this case, the shape required is a flat surface with a chamfer on both sides. This can be done with a specially ground parting blade. In this case, to get the right shape on the part it is essential that the depth of cut is exactly right. This would be easily done by means of a stop.
Saving time by drilling and tapping for more than one nut
Care is needed to ensure that any error in drilling the holes do not accumulate. For example, a group of cycles might start:
drill for ten nuts
second tap one for ten nuts
plug tap for ten nuts
then the following cycle is repeated for ten nuts
feed to stop
it might be necessary to face the end of the feedstock here