The fixed steady
Though the fixed steady is a very simple device there are situations where its use essential. This is especially the case when a long workpiece cannot be supported at the far end using a center.
Examples of where a fixed steady might be useful are:
Workpiece on the end of a long bar
A number of workpieces are to be made on the end of a long round bar that is too big to fit into the spindle of the lathe. If these are parted off then though they might be supported by the tailstock for most of the time, when parting off there always come a point where there is not enough metal left to provide enough rigidity for the tailstock to support the main part of the bar. The solution is to support just to the left of where it will be parted off by using a fixed steady.
In this case the steady can be set accurately enough by fitting the bar in the chuck. The steady is mounted next to the chuck and the jaws set to hold the bar. Using this setting the steady is moved along the bed of the lathe to just left of where the workpiece will be parted off. If necessary the far end of the workpiece can still be supported by using the tailstock.
Long workpiece with a hole in the end
Another example it where, due to the nature of the finished workpiece, there is nothing for the tailstock to hold. This occurs when machining a female taper on the end of a long workpiece. This would happen where the workpiece was a spindle with a female taper in it.
A spindle like this could be made by putting a center in either end of the workpiece. The outside of this is turned to the required dimension(s).
When making a spindle like this it is essential that the steady is set up so the axis of the workpiece is coaxial with that of the lathes spindle.
Setting a fixed steady accurately
The solution is to make a bar with a center in either end. This is turned so its sides are parallel. A disk is made to fit this bar accurately but so the disk can be fixed anywhere along the bar’s length.The outside of the disk is turned to be the same as that of the workpiece. If the workpiece has several different diameters then the steady will need to fit the workpiece near the right hand end.
If the bar with the disk is held between the centers then the it can be used to set the diameter of the arms on the fixed steady at any point along its length. This can be done by using a dti against the disk for each arm on the steady in turn till all of the steadies are tight against the workpiece. This is far easy to do if the arms of the steady are fitted with ball bearings