If making a slot or a step in a workpiece on the milling machine or lathe then a
digital or vernier calliper is the first choice for accurately determining its measurement,
for the viewer who possesses one maybe a depth micrometer. Unfortunately though,
within the confines of the machine there is often insufficient room to gain access
unless the workpiece and or the tooling is moved away in which case register between
cutter and part may be lost. To overcome the problem the little device in this project
enables a replica of the distance to be taken which can then be measured remotely
as shown in Photograph 1.
The device has a measuring spindle that passes through a hole in a sprung loaded
plunger and with this depressed the spindle can drop into the slot or down the side
of a step and then held in that position when the plunger is released. With that
done the measurement can be established.
Being a simple device manufacture is not that difficult but a few things are worth
First cut a short length of 10mm diameter, 20mm long, and face both ends for use
as a gauge. Having cut the base to size, but without the tapers, mount in the lathe
and bore to size using the piece of 10mm diameter as a gauge, making it a close sliding
fit, Photograph 2. The base of the bore is thinner than would normally be expected
so as to make the maximum space available for the spring to be fitted. Because of
this, it will be a good idea to use a saddle stop, else you may bore right through
and it will be a case of start again. Next, produce the tapers on the milling machine.
Place the length of 10mm, previously use as a gauge, fully into the bore in the base
and drill through both for the spindle. Remove from the Base and with it back in
the lathe face the inner end until there is just a very thin web between the end
and the hole just drilled, the purpose is again to provide maximum space for the
spring. Reverse in the chuck and face the end to length making it slightly concave
for comfort in use.
Photograph 2 shows that I am using my Four jaw chuck alternative for holding the
base for boring. If the viewer is not conversant with this, click on the above for
details. I am using it in a two jaw form and with the supports for thin pieces added
to the jaws. I found this easier than using a normal four jaw or a conventional faceplate.