I've just been given one of these. I have no idea how it's supposed to
work! It has a brass barrel with an unscrewable top and ditto point end,
both ends contain springs. The point partially retracts into the barrel but
doesn't lock Can someone please tell me how to use it?
The best-made auto centre-punches were produced by Eclipse and Moore&Wright.
It may be a Taiwan cheapo. Has it definitely got an internal compression
spring and a clicking centre-pointed "anvil"?
There should be two knurled, threaded parts that you fine-rotate to set up
to get it to operate percussively after down pressure. Try it out on a
How it is supposed to work is:
You carefully align the point where you want the mark.
Push down gradually against the spring. The point will move in and lift
an equivalent of a little hammer inside. The hammer is pushed up
compressing a spring. The more you push down, the harder it gets, as the
spring is compressed.
However, there is a release mechanism inside, set to release the hammer
when the spring pressure is great enough. Normally that tripping point
can be set by rotating the knurled bit at the top, from practically
nothing (tiny dent) to a heck of a lot (big dent - maybe even a hole).
However, at that extreme you have to be really pushing down really
The hammer comes down and hits, well, basically the other end of the
point, much as if you had hit it with a hammer. BANG.
When you lift the tool from the work, the springs reset everything back
ready to do it again. The point never locks in the "pushed-in" position.
Now, if you have it set really high - you may not be pushing down hard
enough to get it to trip. Indeed, with some, I am not physically strong
enough to push down that hard.
The answer is to play with the knurled top and try it at one extreme and
the other and places in between.
Typically, you try it with a scrap piece of the material you want to
mark, adjusting it and trying it until the punch mark is the depth you
want. It should then punch mark after mark, all to near enough the same
Personally, I prefer a real hammer and a real centre punch..
Thank you all for your assistance, with your help I've finally figured it
out! It does take quite a bit of pressure to make it work but now I know
the principle I can experiment til I get it right.
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