"T i m" wrote in message
...
Hi all,

In the spirit of d-i-y I've taken the non return valve out of my Bambi
75/150 compressor and found out why it is leaking.

The actual valve is small rubber 'bullet' (10mm diameter x 10mm long)
that has a fairly light coil compression spring clipped over a
shoulder at the back and this 'bullet' is pushed against a conical
seat, initially by the spring than then the stored air pressure (~120
psi).

From close inspection it looks like something has been trapped in the
valve and formed a slight ridge in the rubber bullet face, stopping it
sealing properly.

So, on the grounds I've little to lose (I'm probably in for a new
valve anyway[1]), if I could gently hold said bullet in the lathe,
what sort of tool (hand or machine) would be most likely to get me
re-surface this without ripping it up do you think please?

The rubber is about the consistency of a pencil rubber.

An alternative solution could be a 10mm diameter rubber ball and I
could always turn a small nylon cup to carry the spring etc.

All the best ..

T i m

[1] My local Bambi dealer doesn't carry a spare valve so I've got a
bit of time to play. Also it seems a shame to throw away a perfectly
good, nicely machined and chromed brass fitting for the sake of a 10p
rubber valve. :-(


If you haven't already tried the suggestions - the fiddly part with rubber
being finding a piece as hard/soft/solvent proof etc. as the original; if
you can find a piece of the right stuff, I find an old set of lab
technician's cork borers often comes in useful for making washers/bungs and
the like - you might find that your original can actually be *revived*.

We used to sell 'blanket reviver' for rubber printing blankets. This was
basically a mixture of white spirit and a solvent like dry cleaning fluid or
paint thinners. This swells the rubber and takes off the glaze. The right
mix can make rubber double or treble in size or more with soaking. In your
case you only need to soak it long enough to take out the ridge. Note that
while the rubber is swollen full of solvent it will be weak so let it dry to
a 'no smell of solvent' state before you put it back.

Academic as you've probably finished by now...

S