The height being quite critical there is a temptation to make up the packing with
a number of pieces and whilst just OK on the machine table this is taboo on the faceplate
in terms of safety and practicality. Try holding a pack of packing pieces, the workpiece,
the clamp and a spanner, maybe two, to tighten the assembly, it's just not on. The
process is difficult enough without making it even more so.
Another consideration regarding the packing is that it should itself be secured,
that is, not relying on the clamp to hold it in place. The reason for this should
be obvious as should the clamp become loose whilst the lathe is running the packing
will be thrown with what could be devastating results, particularly if the lathe
is running at high speed. Such a situation is not unknown especially where the machining
This leads me to introduce a clamping system that I have designed and is detailed
in my projects section. Of all the things that I have developed this one must be
at the top of the list for making a very difficult situation relatively problem free.
The main feature is that as the packing is threaded and is first secured by the clamp
screw. This can then be used with a nut to clamp the workpiece using a clamp bar.
Secondary packing pieces are made with clearance holes so that the height of the
packing can be adjusted. Do view the above link for more detail
The main benefits of the system are compactness, secure packing and ease of use,
the latter point due to the clamp screw being made secure before needing to clamp
the actual workpiece. They can be seen in a number of the photographs throughout
these pages, also see Sk. 1.
Whilst using the simple bar clamp is probably the first choice and the one most often
used, there are other methods, simplest of these are the small faceplate dogs. Again
see the projects section for details of these. They are ideal for squat workpieces
and have the advantage of being easily able to make small changes to the workpiece
position. Photograph 5 showed an excellent example of their use.
However, I do use the term squat with good reason, as a part that projects appreciably
from the dogs could easily be pulled from them with the machining processes, especially