Civil Engineering Reference
In-Depth Information
Fig. 8.19. Then the back plate was double drilled to the size required. Double drilling
is where you drill an undersized hole and then follow through with a size drill.
Using chuck spiders
A chuck spider is machined to clear the chuck jaws so the component can
rest on it in the chuck. It is basically a disk with three slots machined in it to
take each of the chuck jaws. You will find spiders are of use a lot especially
when machining thin items.
Another method of supporting work in the chuck is to use three bits of round
bar under the work. If you turn grooves at each end of the bars you can clip a
single tension spring on both ends and use the spring to hold the bars on the
chuck jaws.
The collet attachment
The collet chuck is much better for small work than a three-jaw chuck as it
grips all around the work to support it. You set up the collet attachment on
the milling table in a similar way to the three-jaw chuck. You may have to fit
a backstop inside the collet chuck to stop the work pushing back in the collet.
The backstop can be as simple as a bit of tee shaped bar placed inside the
collet and resting on the machine's table or the bottom of the tee slot.
Youcaneitherclockthecolletchuckorclocktheworkdiameter.Inthiscase
I clocked the actual work diameter here on each individual component, as the
