Pneumatic Cylinder Disassembly & Lubrication Findings
I have a number of old & new pneumatic cylinders that I wanted to improve in regards to smoothness and overall performance.
The standard lubrication seems to work OK but I found that smoothness & performance can be improved by selecting a suitable replacement lube.
Note that no physical modification was done to the cylinders apart from substituting the lube used.
Tests were to be done with and without a working model to see what effect the various lubes had. Model I had readily available was the Custom Bricks - Grubber kitted out with my 42054. - See vid below (not my video)
First step was to disassemble a number of cylinders so that I could I try a couple of different lubricants to see what effect they would have Vs the stock lubricant LEGO use.
To de-grease the cylinders thoroughly and without causing any damage to the plastic or rubber and silicon components I chose to use an electronic component cleaning solvent.
These are generally safe for use on the majority of plastics, rubber and silicon parts as the solvent needs to be safe for many electronic components which also use these materials.
Once de-greased, the cylinders were ready for the replacement lube.
A small snapshot of some of the cylinders which I was testing.
Closeup of 19475c01
Closeups of 2793c01
Closeups of 47224c01
Closeups of 19467c01
Initial test was with 80 weight silicon oil - I had high hopes for this as the oil is very 'slippery' and I thought it would act as an excellent lube for the cylinders.
What I did not count on was that it actually caused 'stiction' issues whenever piston movement stopped and restarted which caused very jerky operation.
Not only that - overall pressure/performance was also reduced possibly due to small amounts of blow-by leakage around the seals.
So the silicon oil was actually quite a disappointment and I would not recommend it as an internal lube for these cylinders.
What I found the silicon oil good for is using at as lubricant for pneumatic pumps as these operate at moderate rpm's where the oil seems to work better than grease.
Check out this persons video which does a reasonable job in showing you how to disassemble them.
NOTE: NEVER drill out and modify the holes in your cylinders as shown in the video as this will destroy their overall performance for normal applications in our models. Enlarging the holes is only useful when using them for air powered engines as you need a very fast acting piston.
The small cylinders are easy - It is the larger ones which are a little harder to open but still reasonably easy to do.
I only use some basic jewellers type screwdrivers for the job - 2x 3mm flat blades and one smaller bladed driver (this one is simply used as a spacer to temporarily hold one side open.
**Note that my photos below show the cylinder top already removed, but you get the idea.
First step is to pry the black top in one of its lower corners with one of the larger flat blade drivers.
Once you catch the corner of the top you can work the driver in and move it around to where the yellow nipple is - sounds easy but you will find that the screwdriver will want to push itself out due to the force of the black top pushing down on it.
Next I insert the small screwdriver into the gap and this is used as this screwdriver will stay in place whereas the larger one will not stay in place while we open and work on the other side.
Now move over to the opposite side and insert one of the larger drivers and once this driver is positioned where the nipple is, try and hold it in place and then at the same time insert the other large driver back in where the smaller driver is holding the other side open.
Once both large drivers are in position - carefully move them outwards so that you flex the black top over the nipples - try and do this on both sides at the same time and you will find that the top will slide off.
It is much easier to accomplish if you have 3 hands...
Once apart - they do go back together very easily which is a bonus.