Oiling the action - for geeks
Since the original article on Oiling
The Action was published I've had a few emails from repairers
and seen references on various web sites which claim that this method
of oiling the action is ineffective.
This has always surprised me, given that my standard 'lecture
to a lazy client' involves placing a drop of oil at each end of
a rattly key's barrel and then working the key as the oil wicks
in. It's an effective demonstration, as both the client and I can
hear the rattles fade away as the oil does its work.
But it's been suggested that the oil is only getting part-way into
the barrel (if at all) - so I put my 'myth-buster' hat on and set
up a small experiment.
I approached the project with an open mind - I was pretty sure that
the visible results would match my hands-on experience, but I was
more than prepared to accept being proved wrong. As it turns out,
I found out more than I bargained for...
dug out an old 'beater' sax, cut the key arms off the G# key and
replaced the barrel with a stiff acrylic tube. I then made and fitted
a rod screw, and just to make it a tough test I made sure the rod
screw was a very snug fit. I glued the key arms in place and fitted
a spring - with no spring cradle on the key I simply ran the spring
over the top of the link arm (which rests on the G# key cup arm).
To make it an even tougher test I laid the sax at the angle shown
in the photos rather than stand it upright - and finally, just to
make it interesting, I used some old gear oil (I figured the black
oil would show up better)...with around twice the viscosity I'd
So, we have a well-fitting pivot screw in a wear-free barrel, a
shallow angle and some very heavy oil. At this point I was wondering
whether I'd overcooked it, but what the hell - the experiment was
set to go and all that was needed was a couple of drops of oil.
The sequence runs left-to-right, top to bottom.
You can see the oil that's just been applied in the first shot (top
left) - and here's the really odd thing...I'd set a timer going,
and having applied the oil I turned away briefly to make a note
of the time - and when I turned back a few seconds later I saw what
you can see top right. In a matter of mere seconds the oil has wicked
about a third of the way in from each end. Even more interestingly,
the oil on the lower pillar has wicked upwards. This will be due
to capillary action - in effect the oil is being sucked into the
This kind of knackered my test a bit, I'd made plans to operate
the G# lever against the clock and take photos at specific intervals
so that I could present a posh-looking graph showing ingress of
oil against time - and while I was busy cursing and damning, the
oil met in the middle of the barrel (lower left).
I felt a bit left out now, so I gave the G# lever a few presses
- and about 10 seconds later I noted that the oil had completely
filled the barrel. The whole sequence of photos covers barely a
couple of minutes.
So what can be deduced from the test?
Well, the most obvious point is that popping a drop of oil at each
end of a key barrel is going to result in oil getting where it's
supposed to go - even when the odds are stacked against it. Personally
I'm quite surprised at the speed of the coverage (and, incidentally,
it's even faster if there's a bit of wear in the barrel - I tested
that too), as well as the ease with which such a heavy oil wicked
into the barrel.
Another interesting outcome is the clear importance of giving the
pillars a bit of a wipe-over with a tissue after oiling - even with
such a heavy oil you can just see (on the lower pillar) where it's
starting to make its way down the pillar.
A certain amount of oil seems to remain in a 'pool' around the ends
of the key barrel. Some of this eventually migrates away down the
pillar (which is why you need to re-oil the action from time to
time), but equally some of it gets sucked back into the barrel as
the key is operated.
For most readers with a slightly geeky predilection, this is all
you need to know - and at this point you should turn your computer
off and go do some practice (or have a beer or three).
For the advanced nerds, however, there's more...
With the oil inside a see-through barrel I was able to observe
how it moved about when the key was pressed. In both cases (with
the tight and loose barrels) it was plain to see that the flex of
the key barrel (and there will always be some) acts like a pump,
distributing oil around and along the barrel. What was most revealing
was that the pivot screw is not fully lubricated all of the time.
For example, as this particular key is pushed down the barrel flexes
and oil is pushed away from the upper rear surface of the pivot.
As the key is released the barrel relaxes and oil is sucked back
in to the void. The effect is just as noticeable on a worn barrel
- but rather surprisingly the amount of unlubricated surface area
is less, due to the less-effective pumping action as a result of
the wear in the barrel. There seems to be a 'break-point' though...a
small amount of free play seems to increase the pumping action,
but once it gets beyond a certain point it allows the oil to slosh
around more liberally. It's also the case that the harder you press
the keys, the stronger the pumping action - so heavy-handed players
should perhaps oil the action more frequently.
Furthermore, the areas affected by the tension of the spring when
the key is at rest (the point where the tip of the spring acts against
the barrel and the end of the key nearest the mounting point of
the spring) are more-or-less devoid of oil.
phenomenon was more evident with a thinner oil. Here I've mixed
some black oil with a bit of typically thin shop-bought key oil.
The pumping action was rather more rapid and widespread, and there
was far less evidence of the pooling effect at the end of the key
barrels. In short, the oil was simply being ejected from the key
As you can see on the left here, with the key at rest (top) there
is complete coverage of the pivot screw by the thin oil - but as
soon as the key is pressed, the oil is pushed away from the rear
of the key over almost the entire length of the barrel. This effect
is less widespread with a thicker oil.
This caused me to wonder whether grease would be a far better lubricant,
so I tried it - and it is...but not for long.
The same pumping action is in evidence - though rather than being
a fluid (ho ho) action it's more of an accumulative one. It seems
to be unequal too - there's clearly a stronger pushing force than
there is a suction one, which means that once the grease has been
pushed away from a particular area, it doesn't get sucked back.
In short, the pivot screw has to 'wait' until such time as the grease
is pushed into an adjacent space - at which point it might then
get pushed into the dry spot. And then the cycle repeats. It has
little or none of the 'recovery flow' patterns that oil has - whereby
it flows into dry spot when the key is at rest - and from a purely
observational perspective it's apparent that a greased pivot screw
has more dry spots than an oiled one.
One way around this problem is to use thicker, stickier grease -which
I tried - but the required stickiness is such that the action of
the key is severely affected, and the instrument never gets to the
sort of temperatures where a grease would become thin enough to
be an effective lubricant.
So what does this all mean?
My feeling is that it's very much a case of "Damned if you
do, damned if you don't".
It should at least be very clear that there's some sort of 'peristaltic'
action going on, and that stripping an action solely to oil
it is arguably a complete waste of time (unless you clean/degrease
it at the same time). You simply can't get more oil into a key barrel
once it's full, and what determines the distribution of the oil
is not how much you put on but how it's pushed around inside the
barrel by the pumping action of the key barrel. The two images above
demonstrate that clearly - the key was pre-oiled before assembly.
It's clear too that the thicker the lubricant, the more effective
it's going to be - but only up to a point. Once it gets too thick
it becomes rather less good at its job due to its poor 'recovery'
rate - and beyond that it will have a detrimental effect on the
speed of the action. It's also very evident that a thin lubricant
really isn't much use at all - and that the tighter and more precise
the action, the higher the peristaltic pressure will be (though
a smaller volume of oil will be shifted - but it will be shifted
further, and faster).
To be sure, the stiffness of the barrel plays a major part in the
mechanics - but the tubing used for the experiment was pretty stiff
stuff, and although I wouldn't expect the effects within a similarly-sized
brass key barrel to be as severe, I still wouldn't dismiss the accumulative
effects - and once you introduce the slightest amount of wear into
the equation the pump-effect ramps up, at least until such times
as the wear becomes so great as to negate it.
And so it's easy to conclude that if you want to avoid wear and
tear to the action - buy a worn-out horn and slap a load of light
grease on it.
Update January 2019:
Some time ago I made the mistake of putting synthetic gear oil
onto a rod screw that I'd earlier lubricated with silicone grease
(as detailed in a
Benchlife Blog entry). I noticed that the addition of the oil
made a noticeable difference to the speed with which the key operated.
This is exactly what you'd expect, given that the oil altered the
viscosity of the grease and produced a thinner lubricant.
This got me wondering whether the two lubricants were incompatible
in any way. If it turned out that they reacted with each other in
some fashion, it might mean that, say, the mixture would congeal
over time and eventually slow the action down - which would not
be good. So I set up a series of tests to see what was going on
- and the results surprised me.
grease is bog-standard high tack (HT) silicone grease and the oil
is 75W90 synthetic gear oil (as shown in the article on Oiling
The Action), and the first test was to mix the two lubricants
together to see what happens.
I stuck an adhesive tack bung on the bottom of a perspex tube, popped
a dollop of grease into the tube and then added a quantity of gear
oil - and gave it all a good stir.
The lubricants appeared to blend together to form a milky goo. At
first glance it looked like they'd properly blended, but on close
inspection I saw that the oil had broken down into minute bubbles.
What I'd made was an emulsion - one liquid suspended within another.
This is what emulsion paint is, and it's also what your salad dressing
is (a mixture of oil and vinegar).
have a tendency to separate over a period of time - hence the 'stir
well before use' warning on pot of emulsion paint and the 'shake
well before use' on a bottle of salad dressing - so I left the tube
standing, to see whether or not the lubes would separate and, if
so, how quickly.
It didn't take long. Separation was evident within the first hour,
with a clear film of oil forming on top of the mixture. Over the
next couple of days the oil rose to the top of the mix until the
film became a clearly visible band - but it took a good couple of
weeks before all the oil has risen to the top and a very clear boundary
between the oil and the grease could be seen.
I re-stirred the mixture and left it to stand again - and repeated
the test a number of times, and in each case the oil eventually
rose to the top.
It seems clear then that there's no reaction between the two lubricants
and even heating the mix made little difference (other than to speed
up the rate of separation), so it appears that they'll quite happily
co-exist with each other and won't combine without some sort of
And it's this property that raises an interesting question. My tests
with the transparent key barrel showed that there were pros and
cons depending on which lubricant was used - but could an emulsion
of oil and grease overcome the cons? Would it be the best of both
worlds, so to speak? Only one way to find out - and that's by putting
it to the test.
began by testing how the silicone grease performs on its own inside
a key barrel.
In order to give it the best chance I made sure I got as much grease
as possible into the barrel, but as expected it pretty much just
stays put. The pumping action of the barrel when the key is operated
will move the grease away from the areas where it's most needed,
and when the key is released the grease is reluctant to move back.
It can be quite hard to see what's going on, but fortunately there'll
always be a few air bubbles that will act as indicators. You can
just about see them in the centre of the barrel, and with each operation
of the key they'll move back and forth very slightly. You might
also be able to see a dark line running either side (parallel with
the spring) of the first key arm, which is the beginnings of an
area where the grease will be pushed away from over time (a wear
point, in other words).
Now I've dripped some gear oil (dyed red) onto one end of the key
barrel. I'm interested in seeing whether the pumping action will
still work - or whether the grease shuts the process down.
result is very encouraging. With only a few presses of the key you
can see that the oil and been drawn around a quarter of the way
into the barrel, and is just starting to make its way past the first
key arm. And it's travelling uphill.
It eventually got to the other end of the key, but it took rather
longer than it would had oil alone been used. Normally you'd apply
the oil at each end of the barrel...but I like to make these tests
This tells me that even when the barrel is initially filled with
grease, operating the key will create voids that oil can flow in
to. This means a greased key can be further lubricated with oil
without having to remove the key - which is a considerable plus-point
in maintenance terms. It also means that when you're assembling
a horn you can run a greased rod screw through a key barrel and
then apply oil to the rod just prior to fitting the key. In other
words there's no need to premix the oil and the grease.
the final test I premixed a batch of oil and grease to see whether
it acted any differently to the oil being applied separately.
As you might expect there's instant coverage along the entire length
of the barrel - and on operating the key it's immediately apparent
that some of the bubbles of oil that were held in suspension have
been forced together by the pumping action of the barrel and are
now flowing back and forth as the key is pressed down and released.
You can see a large bubble of oil in the centre of the barrel, but
what's especially interesting is that as the bubble moves there
appears to be a certain amount of reintegration at the boundary
edge - and I think it's fair to assume that rather more of this
is going on where the pressure is highest...which is directly beneath
the key arms.
Note that the dark line across the key arm has gone. In fact it's
still there, but now it's filled with the dyed oil - and the stiffness
of the grease surrounding this wear point seems to be regulating
the back-and-forth flow of the oil, making it less easy for the
oil to completely flow away. As such it acts rather like a sump
- maintaining a supply of oil in the area where it's most required.
This, it has to be said, is a very significant feature.
So what does it all mean? Well, It means lots of good things.
From the experiments carried out earlier in the article we know
that the drawbacks of using grease are that it doesn't readily flow
back into the areas where it was pushed away from, and that although
its more tenacious (it doesn't dribble away) than oil it comes at
the price of adding drag to the action. You can mitigate this to
a degree by using thinner grease but you'll still never achieve
the fluidity of oil.
Oil, on the other hand, has excellent flow characteristics but isn't
so good at 'hanging on in there' - and very readily flows away from
the areas it's most needed when the key is operated.
The solution has always been to select a grade of oil or grease
that provides the best compromise, which typically means a light
grease or a heavy oil. There are some systems where it's possible
to mix the lubricants, but you're still only altering the viscosity
of what's essentially a single product. In other words it's a 'monograde'
The properties of the silicone grease/synthetic oil mix are such
that it's a 'multigrade' solution. The oil will never fully combine
with the grease, but will happily integrate with it on a temporary
basis - and neither will they react with each other to form an undesirable
compound. It gives you all the staying power of grease and all of
the speed of oil. And it remains viable over a wide range of temperatures.
It also means being able to use a grease that's far stiffer than
you'd normally be able to get away with - and this has significant
benefits in terms of reducing the mechanical noise from the action.
In terms of application you have a couple of choices. You can premix
the lubricants and apply them as a normal grease. The ratio can
be variable, but a 50/50 mix is a good place to start.
Or you can mix on application. This is my preferred method as it
allows you to gauge and adjust the drag while you're fitting the
keys. I tend to grease the rod screw up along its length, insert
it into the key barrel and work it back and forth a little to ensure
the bore of the barrel is fully coated. I then remove the rod and
give it a quick wipe off with a bit of clean kitchen roll. I then
apply oil to the rod and reinsert it into the barrel.
This is typically on a barrel with very close tolerances. On a horn
where there's a bit of wear and tear I'll often skip wiping the
grease off the rod and simply add the oil.
The advantage of doing it this way is that you can tailor the mix
to suit the key. Thus you might favour more grease on heavily-sprung
keys (such as the palm keys) and more oil on the ones that need
to be more sprightly (such as the G# cup key or the octave mech).
If you get it wrong or simply want to tweak the feel of a key, just
pull the rod screw out, give it a wipe and add more oil/grease depending
on which way you want to go.
In addition to the bench tests I've been carrying out 'field tests'
with the multigrade method and so far I haven't come across any
drawbacks, and have a sneaky feeling that this might well be a perfect
solution for lubricating the keywork.