Photograph 8 shows a similar situation where a number of large washers were being
made, making it necessary to part off at a large diameter of 38mm. Most lathe users
will know that parting off is one of the more problematic tasks and can only be undertaken
easily close to the chuck and with a rear mounted tool. However, the method described
above works well showing that the fixed steady is not limited to just light duty
tasks. If the task has been running for a few minutes though you will need to reset
the steady's arms as even with the smallest clearance chatter will occur. In this
case, for smaller diameters, just drop the top arm to take up the clearance, for
larger diameters adjust all three.
The advantage of both the above examples being that there are no short pieces left
that may never find a use, particularly worthwhile where large diameters, such as
38mm, are involved. If you do not have a motorised hack saw or band saw then the
method can avoid the laborious task of cutting a piece off manually.
I realise that the above only describes a limited range of tasks but feel that the
examples given cover the essential requirements.
Using the travelling steady is quite different from using the fixed steady in that
the fixed steady is used for supporting mostly ridged workpieces that project too
far from the chuck holding it, the problem being in the grip of the chuck rather
than the flexibility of the workpiece. The travelling steady though is for machining
parts that are too fragile to withstand the forces being placed onto it.
There are two ways of using a travelling steady, in one the arms are supporting the
diameter in front of that being turned and the other supporting the diameter being
turned. In the first method the arms lead the cutter whilst in the second method
they trail the cutter, both having their advantages and disadvantages.
Method 1. Considering first the method where the arms are supporting the diameter
in front of the cutter, Sk.3.A. The main advantage of this is that at the start of
a cut the arms will already be supporting the material and so the start is problem
free. How then is the steady set for this method. Having mounted the steady onto
the saddle the cutter is set just behind the trailing face of the arms, say 4mm,
using the top slide and the slide locked in this position. With a short piece of
the material projecting from the chuck and the arms well clear, machine a short length
to the diameter eventually required and lock the cross slide. Following this the
steady's arms can be moved in to contact the larger diameter and secured. This setting
stage can be done using the material to be used for the finished part, alternatively,
a small scrap portion of the same diameter.