Simple Oscillating Steam Engine - Pivot Nut

The pivot nut was turned from a piece of brass bar although a commercial nut could be used if preferred.

Click for larger drawing









First some brass bar was mounted in the chuck and the shoulder to push against the spring was turned.









To set up the lathe for knurling the knurler was clamped in the tool post and set square to the bar.

The type of knurler used was of the clamp veriety. This had the advantage of applying a high knuling force without producing a high load on the lathe bearings.

To achieve maximum benefit the knurler was opened just slightly smaller than the diameter of the bar.









The lathe was used in a slow spindle speed and the knuler wound in to start the knurl. Then the tool was wound along the work piece to even out the knurling.









Next the nut was centre drilled, drilled and tapped.

Centre drilling



For tapping - the tap was held in the tail stock chuck, but the tail stock was not locked to the lathe bed. The chuck was turned by hand with light pressure applied to the tail stock to cut the thread. The chuck was reversed regularly to clear the thread.

Finally the nut was parted from the bar stock.

As with all parting the tool was kept as short as possible to minimise vibrations, the lathe was used on its slowest spindle speed.

Part way through the tool was retracted and a file used to add a chamfer to the nut. The other edges were also tidied with the file before the nut was parted off completely.