Silicone Grease or Lithium Grease ?

Rectangular · December 21, 2009, 05:10:27 PM

I recently acquired some old tube gear, and it uses a lot of 8-gang pots, rotary switches, and vernier dials. all of the controls are pretty seized up, you can feel a lot of friction when changing any of the settings.

I've cleaned all of the contacts with Contact Cleaner... but there are a lot of surfaces that still require a persistent lubricant; a grease of some kind, that won't affect conductivity, won't corrode metal, and is safe for rubber washers.

looking into older posts, a lot of Wah-buildings have suggested using Lithium Grease. I've also been told that Silicone grease would be a good choice. has anybody used one or both of these, and would you be able to give me some pros/cons about either ? I'd imagine R.G. probably encountered a lot of this kind of Tube equipment back in the day, but I can't expect him to chime in on every one of my posts

after dumping 30 bucks on Deoxit spray, only to discover it was basically just another contact cleaner, I realized it was best to get some advice before I go out and splurge more money away.

puretube · December 21, 2009, 05:17:54 PM

There`s a difference between the electrical contact parts,
and the mechanical friction parts...

Rectangular · December 21, 2009, 05:35:41 PM

hey puretube. I don't require the grease to conduct, if that's what you mean.

I have this unique control assembly... its not quite a potentiometer, or a rotary switch. its a series of wipers gliding over a PCB, so that you can "glide" between different capacitors, in order to change the frequency. does that make sense ? anyway, I need a grease that will lubricate the wipers going over the copper-plated boards.

puretube · December 21, 2009, 05:41:58 PM

"Tuner"-spray!

[edit]: Kontakt-Chemie 600

(has been working for me since over 20 years, over 2GHz, >2MOhm...

)

p.s.: don`t lose the "straw" that comes with it!

ubersam · December 21, 2009, 05:45:10 PM

i use lithium grease on the rack and pinion parts of a wah but not on the contacts of pots/faders. your're contact cleaner might not have lubricants so you might want to use something else, like the Caig Labs DeoxIt stuff

PRR · December 21, 2009, 05:55:07 PM

Silicone and Lithium greases were not used on electronic knobs in 1950, and are probably not "right" today.

First: the knobs worked OK when new. They used medium oil or thin grease for feel and long life. If they are VERY stiff now (I had an H-P knob which I could not turn with Channel-Locks), then the old oil has attracted dust and then oxidized into a rock. Sometimes you must start with a thin solvent, work the old crud out. Plain old Zippo fuel would be very traditional. Put a half-drop in the crack between shaft and bushing, let sit an hour, another half-drop, let sit overnight. It took 50 years to get gunked-up, be patient un-gunking.

Rubber: most oils eat genuine rubber. But rubber rots even without oil. What you have is probably one of the neoprene-like "rubbers". But even so, gear designers usually did not put "rubber" near where you might put oil. In general you use the LEAST possible oil around electronics. It just makes trouble. That's why they make syringe-like needle-oilers, so you can get teensy amounts right in the friction zone, without getting oil on contacts or parts or bumpers.

Shaft-bushings may have been greased in assembly for a smooth "feel", but switch/pot shafts can't be properly greased once together. Yes, you can use "spray grease" to work a little grease in, but you get a lot of grease everywhere else, and you can't get the smooth feel with a grease which is 90% solvent so it will spray.

I'd think that "sewing machine oil" would be most like what the old guys would have used.

If it must be stable for decades, today I think I would use a 5-20 engine oil. Compared to classic oils, the oxidation resistance is MUCH better.

Please do not use WD-40. It's good stuff, but it stinks, it gets ALL over, and in a few months it dries-up and you have to spritz it again.

> wipers gliding over a PCB

Ah. That was a dumb idea 40 years ago, and has not improved with age.

As puretube says, tuner-cleaner is made for similar problems, and probably the best you can do. However I don't think KONTAKT CHEMIE leaves any lubrication behind. There was another stuff which left blue foam residue. It is a Bad Idea for many problems, and I have had to soak a lot of it away. But wipers on bare PCB might benefit.

Can you find "carbon paper"? Gently work it under the contact and turn a little. A very small (invisible) trace of carbon might take the "dry edge" off the contact.

Be sure your stiffness IS in the contacts, not the shaft/bushing or the detent. If the bushing or detent is packed with dust/gunk, lubing the contacts won't change a thing.

Rectangular · December 21, 2009, 05:55:56 PM

yeah I'm aware of the deoxit stuff. the red syrupy stuff, right ? the problem is that I'd have to order it from the States or somewhere else. I'm looking for a locally available grease (ideally)

I thought when I was buying the deoxit spray, that I would be getting a spray-form of the same red lubricant, but it was contact cleaner, which is not what I needed. so I'm hesitant to buy from them immediately, they've got so many products its ridiculous.

are you two saying that lithium and silicone grease will interfere with the electrical contacts if I used them for lubricating my wiper/pcb assembly ?

what would you recommend for lubricating the pot/rotary switch shafts (where there are no electrical contacts involved)

Rectangular · December 21, 2009, 06:07:35 PM

hey PRR, thanks for the long response

I have a couple of hp function generators that will require a lot of de-gunking (the grease has solidified after 50 years), but I've worked on those before, so they're not of any concern to me.

the real meat of my problem is that wiper/pcb assembly. you're right, its a weird idea, but I respect it as a kind of weird engineering anachronism.

the friction is occuring in two places: where the leaf-spring style contacts scrape along the copper pads on the PCB, you can feel a bit of "skating" as they do this.

Im trying to think of how to explain the other one... basically, there is a rubber washer in between the wiper "arm" that is connected to the main shaft or axle, and the pcb (with the copper pads on it).

so it goes : |arm| |washer| |PCB| , and then repeat that 8 times.

those rubber washers seem to be in good condition, but they're really squeaky as I turn, and I need some way to lubricate them

puretube · December 21, 2009, 06:28:51 PM

ahem: "condom-safe" lubricant...

Rectangular · December 21, 2009, 06:38:29 PM

puretube: my understanding is that those are all water-based. lets not get off topic here, please.

Paul Marossy · December 21, 2009, 07:30:22 PM

Quote from: PRR on December 21, 2009, 05:55:07 PM
I'd think that "sewing machine oil" would be most like what the old guys would have used.

If it must be stable for decades, today I think I would use a 5-20 engine oil. Compared to classic oils, the oxidation resistance is MUCH better.

Please do not use WD-40. It's good stuff, but it stinks, it gets ALL over, and in a few months it dries-up and you have to spritz it again.

Maybe. But that oil is kind of runny, just like the 3-in-1 type oil is.

I agree, WD-40 sucks for that sort of stuff. It's very hard not to get it all over everything. And I'm not sure it is good for the internals of a pot, either.

I vote for a tiny bit if lithium grease on the mechanical contacts. Just enough to get the job done.

Rectangular · December 21, 2009, 07:44:17 PM

thanks paul

ok, that's one vote for lithium, on the mechanical contacts. I'm assuming mostly the shaft/bushing contacts. is that strictly metal-to-metal ? I still have the rubber washers to deal with as well, and I'm not sure if lithium will damage that.

Paul Marossy · December 21, 2009, 07:56:04 PM

I wouldn't use lithium grease on rubber. I don't think there is anything in terms of grease or oil that is safe to use on rubber as a lubricant. I wonder if graphite might be OK to use?

The rubber parts might be dry and hard, and simply in need of replacement. Hard to say without actually seeing anything.

Rectangular · December 21, 2009, 08:12:01 PM

as I said, the rubber washers are actually in good shape, and don't need replacing. it just need a bit of renewing/lubrication.

maybe I should look into that rubber renew stuff. also silicone grease is recommended for rubber, or at least thats what the wikipedia article states. I was hoping one of you was familiar with it.

arawn · December 21, 2009, 10:05:53 PM

silicone or dielectric grease should work for you wityh the bushings, you might even try just the tiniest bit of dielectric grease on the pcb tyraces (it is conductive and also safe for use on rubber sparkplug boots). Either should be available at your local auto parts store.

Skruffyhound · December 22, 2009, 09:19:02 AM

Hi, I've never used it in connection with pedals but silicone oil, a liquid, works wonders for rubber. I had to change my car windshield a while back and couldn't find a replacement flange, I cleaned the old one with silicone oil and it became flexible, shiny, cracks disappeared, basically like new. Surprisingly good

Paul Marossy · December 22, 2009, 11:19:01 AM

Quote from: Skruffyhound on December 22, 2009, 09:19:02 AM
Hi, I've never used it in connection with pedals but silicone oil, a liquid, works wonders for rubber. I had to change my car windshield a while back and couldn't find a replacement flange, I cleaned the old one with silicone oil and it became flexible, shiny, cracks disappeared, basically like new. Surprisingly good

Yeah, but for how long? Are you sure that it won't eat the rubber eventually?

oldschoolanalog · December 22, 2009, 12:07:03 PM

Something like this?
http://www.stabilant.com.au/stabilant_22_-_application_not.html

Thanks to Mark Hammer for pointing this stuff out.

Skruffyhound · December 22, 2009, 04:10:40 PM

QuoteYeah, but for how long? Are you sure that it won't eat the rubber eventually?

I'm also a member on a very active Volkswagen forum, I work on my car because I can't afford a mechanic, but these guys are professionals with years of experience, they recommended it. 3 years on its still looking great. We are talking old volkswagens her, mine is from '86, and thats a relatively young one, so old skanky rubber is the norm.

Rectangular · December 22, 2009, 04:28:00 PM

that Stabilant stuff seems pretty interesting, albeit somewhat exotic. I'm not sure if I want something that is sometimes electrically conductive on my wiper/pcb assembly. I read their description of how it worked, and they mentioned quantum tunneling at one point, so I don't know if its all BS or not. did Mark Hammer say if he actually used this stuff ? he's in ottawa, and they have a distributor there...so maybe he did.

as for the silicone grease, yeah, I've read that it is safe for rubber, and if your vintage volkwagon forum hasn't denounced it, that's a pretty good sign.

wiki:
"Silicone grease is commonly used for lubricating and preserving rubber parts, such as O-rings. Additionally, silicone grease does not swell or soften the rubber, which can be a problem with hydrocarbon based greases. It functions well as a corrosion-inhibitor and lubricant for purposes that require a thicker lubricant, such as the operating mechanism of the M1 Garand rifle."

I'll have to see if it can be bought at Walmart or Canadian Tire.

I'm still interested in anyone else's suggestions.

so far I'm thinking deoxit or stabilant for the wiper/pcb part, and silicone grease for all of the mechanical (

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Silicone Grease or Lithium Grease ?