Photo 1 shows a circular cutout in the early stages of being made. As a high degree
of precision was not required I centralised the rotary table below the mill spindle
with a centre in the spindle and a centre drilled plug in the rotary table’s bore.
The workpiece being centre drilled for the centre of the cutout to be made was then
centralised again using the centre in the machines spindle.
Of course, the first time you use the method you should check the result using a
dial test indicator just in case the bore in the tables centre is not concentric
with the tables bearings.
Often, the centre of the cut being taken is outside the perimeter of the workpiece.
The fence in Photo 2 has been centre drilled at the appropriate position so that
with the workpiece against the fence and lined up with the end the curved slot will
be correctly placed, Photo 3
Mounting items onto the rotary table can often be a problem due to their small size
and the need to position the part central. Photo 4 shows the ends of a small link
being rounded and is mounted on a device I designed. This can provide a range of
central securing screw sizes and locating bush diameters. This should be evident
from the items it is securing Photos 5, 6 and 7. LINK
Sometimes a workpiece will benefit from being located off the table’s centre by some
means but large enough to be secured by more conventional means than those used
in the previous photographs, Photo 8. The locating device is seen in Photo 9. This
can locate in larger diameters by the addition of a bush made to the required size.
The top of the locating pillar is also centre drilled to enable it to be used for
centralising the rotary table under the machine spindle.
The part being made in photograph 8 then needed the portion between the two ends
to be machined barrel shape. This is being done in Photo 10 with Photo 11 showing
the clamp plate which both locates the part and secures it..
Photo 12 shows a toolmakers style vice mounted onto a rotary table, a style that
I cannot recommend more highly for this application. It should be obvious from the
photograph that the method of securing the it to the table gives plenty of freedom
as to where it is mounted. Typically, it could be mounted overhanging the side of
the table permitting machining to take place at a larger diameters. Other styles
of vice with their fixed securing lugs would have very little freedom over where
on the table it could be fitted. My firm preference for the toolmakers vice also
extends to a lathe’s vertical slide and any small milling machine. LINK
Photo 13 shows a three jaw chuck mounted onto a rotary table using a backing plate.
However, it is helpful sometimes to take the chuck directfrom the lathe and fit it
to the table using a screwed adaptor on the table matching that in the chuck.
This works well, typically for placing concentric holes on a PCD (pitch circle diameter)
but must not be used where machining is taking place on the outer face of the workpiece.
This is because the action of the cutter on the workpiece will be.
attempting to unscrew the chuck from the adaptor. Something that can happen with
Photo 14 should be obvious as it is an easy way of achieving an adjustable angle
plate if one is not available.
Do look at my pages on using a rotary table.