Trigger Contact Grease

[Ian_Gere]

So, does anybody use this kind of stuff?

 

ASG ELECTRICAL SWITCH GREASE

From the blurb:

"AIRSOFT ELECTRIC SWITCH GREASE

 

For high conductivity and prevention of arcing

Helps your battery and helps your Motor if the main AEG switch has a good contact."

 

Sounds promising, eh? But then I started to wonder whether any grease, even one which, as this appears to, contains microscopic metal particles, can have a lower electrical resistance than copper contacts.

 

For those who aren't familiar with the issues involved, the trouble with bare metal contacts is that, at the microscopic level, even a new one which appears very smooth is in fact more like a miniature mountainous terrain, full of peaks, valleys, crags, and cliffs of micro-crystaline topography. When you bring two such surfaces together there are obviously gaps, where the peaks and troughs do not line up, which being full of air do not conduct electricity except by arcing.

 

Oxidised Copper 3000 x magnification Scanning Electron Microscope

 

In sensitive circuitry such micro-arcing generates noise, or interference, which is why good audio or video equipment uses gold surfaces, because the micro-crystaline structure of gold produces round shapes in its surface topography, which fit together better than that of other metals. For our purposes the effects of noise are negligible, however the more the ratio of air to copper between our trigger contacts, the higher the electrical resistance.

 

Micro-arcing and increased resistance cause us a few problems: less power available to the motor and more heat generated; the power taking longer to ramp up from zero to as high as it gets, making trigger response slower; oxidation and pitting of the contacts as these micro-arcs literally burn the surfaces away, making the problem a viscous circle. Something which reduces these problems would be good therefore, and obviously anything which fills in the air gaps must prevent micro-arcing, but that doesn't mean however that it genuinely leads to "high conductivity". In fact, because it is a barrier between two pieces of copper conductor, it may actually increase the resistance of the switch considerably.

 

Another thing it should do is improve the ramp up time, as a greater surface area of each switch conductor makes contact the moment the trigger is pulled than without the conductive grease. The question remains though, just how conductive is it? A better question however is, can you get trigger switches with precision engineered polished surfaces, or better yet, solid 3 carat gold contacts?

 

Something that I am convinced of, after thinking it through, is that this stuff must improve the trigger response by, possibly several tens of, milliseconds on a gun with a MOSFET, because the resistance of the switch in that case is not the issue, purely the speed at which the trigger voltage rises from zero to that necessary for the transistor to allow the full power to flow to the motor.

 

Does anyone have experience of this, or any other brand, of electrical contact grease? Opinions also welcome, as ever

[sp00n]

kinda looks like copper slip, a copper based anti seizing compound. what i don't understand, is if it is copper slip how a oil based grease can be conductive, oil being an insulator, that's if it is oil based .....

 

gold is good for solid contacts but for a switch, it wears out. in industrial switching they tend to use silver but that may be a cost thing or a longevity thing.

 

to be honest the tiny amount of voltage/current required to switch a mosfet, i don't think you would see any real benefit ... i may be wrong though, and i would be interested in finding out either way.

[Gecko]

Can't contribute anything useful, but just to thanks Ian that was a interesting post to read.

[NickM]

Spitballing here but could it be a silicone based grease? Metal particles plus playing on silicon being a semiconductor? No idea if that would even work....

[Ian_Gere]

kinda looks like copper slip, a copper based anti seizing compound. what i don't understand, is if it is copper slip how a oil based grease can be conductive, oil being an insulator, that's if it is oil based .....

Exactly what I thought. As it goes, I've bought some copper slip to use on the outside of gearbox bearings and between the shims / between shims and bearings to seal oil inside the bearings.

gold is good for solid contacts but for a switch, it wears out. in industrial switching they tend to use silver but that may be a cost thing or a longevity thing.

Hadn't thought of that, but I wonder if 3 carat gold might be hard enough to last alright. Gold doesn't oxidise readily so it's difficult to see where it could go, eh? If both contacts are the same gold, the surfaces ought to simply polish each other smoother over time. It's not like we're using voltages sufficient to produce macro-arcs that would vaporise the gold. I dunno though... it just struck me as something which I wouldn't be surprised to find being made by the likes of Systema.

to be honest the tiny amount of voltage/current required to switch a mosfet, i don't think you would see any real benefit ... i may be wrong though, and i would be interested in finding out either way.

Well, about 14ms is the threshold for us to notice any improvement so, although I don't know either, I think it's not impossible. I imagine that the MOSFET's required trigger voltage is the most important variable in this case. Although, now I come to think about it, you might be right for a different reason: the transistor must be designed so that transitory high voltage spikes do not open the gate for the full power, otherwise it could be set off by static, so there may well be a built in minimum response time that we can't improve on.

 

@Nick: yeah, I imagine so. I just don't know what form of silicone is in oils/greases and whether it does conduct well enough to be thought of as a semiconductor. I mean graphite is carbon which conducts very well, but plastic is polymerised hyrdrocarbon that usually doesn't...

 

Oh yeah, and thanks Gecko

[sp00n]

think of a CPU in your computer, it has billions of transistors, and they are pretty darn quick and there usually insulated against static. In a gun, they should be in an enclosed system (no electrical connections are exposed) and decently insulated. I may be wrong though.

 

As for the gold on contacts, in an industrial contractor the contact surfaces can literally be burned away by arching and back emf. This can even happen in low power 24v dc systems. I have replaced numerous burned out relays with thyristors (solid state relays).

[Mike1971]

Sp00n, you should have kept all those old relays if they had gold contacts, but on saying that who we work for are too cheep to buy gold contact relays LOL