Civil Engineering Reference
In-Depth Information
Fig. 5.6. The edge finder is used to find the edges of work.
Using a centre finder
The centre finder looks like an edge finder with a point. No one ever explained
to me how to use this type of edge finder so I have figured it out for myself.
Some edge finders are double ended, with a point on one end and a cylinder
on the other. I use the centre finder in three different ways. Firstly, you can
use it to find the intersection of a pair of scribed lines; secondly, you can use
it to find the centre of a slot that is too narrow to get a standard edge finder in
by using the centre finder halfway down the point; and finally you can use it to
find the centre of a hole in the work.
To set zero using an edge finder, you need to know half the diameter of the
end of the edge finder or wobbler. When you bring the edge finder up to the
edge of the work and it rolls away, the edge finder is exactly half the diameter
of the end away from the edge. Say the edge finder has a 6mm end diameter.
This means you have to raise the edge finder above the work and move the
edge finder 3mm closer to the edge. This will put the centreline of the edge
finder exactly over the centre of the edge of the job.
