The use for faceplate dogs is either to secure, position, or both, a workpiece that
requires to be mounted onto the faceplate for machining. For more detail regarding
their use see my pages on using the faceplate.
Photograph 1 shows a bearing block being bored to take a spindle. The flat piece
of steel on the faceplate (fence) enables a second block to be added and then bored
at the same height.
The four faceplate dogs are the only method of securing the part but they also serve
to adjust the block's position so that the hole bored is central across the width.
The situation in Photograph 2 is quite different. The largish piece of cast iron
is secured to the faceplate using two screws from the rear of the faceplate into
tapped holes into the workpiece. However, whilst making it concentric with the lathes
spindle was not critical, it needed to be close.
Having placed it onto the faceplate and added the screws it was next to impossible
to move such a heavy item into the position required. With the screws only lightly
tightened to enable adjustments to its position to be made with a soft hammer, the
screws would loose their grip and the part fall to the lower end of the faceplate’s
slots . If then the fixing screws were tightened further then the part would not
move, even with a quite heavy hit with the hammer.
This problem was overcome by adding the faceplate dogs which enabled slight adjustments
to be made until the part was sufficiently accurately placed. when the fixing screw
on the rear were fully tightened.
The faceplate dogs could have then been removed as the screws were more than adequate
for the task. However, I chose to leave them in place.
I should add that faceplate dogs should not be used with parts that project appreciably
from the plates surface. As a guide, no more that the narrowest dimension of the
part’s footprint. Say for a part with a footprint of 80mm x 40mm, then no more than
40mm. This becomes more important for parts that create an intermittent cut.
Manufacture is easy so I have given no explanation of a possible method.
Whilst the drawing gives dimensions for those seen in the photograph, smaller and
or larger sizes may also be considered worthwhile.