optimum viscosity for potentiometer grease? - Page 1
Forum section: electronics / general

author: coppercone2
author_rank: Super Contributor
timestamp: February 10, 2023, 04:19:51 pm
content: So I was repairing a HP instrument that had a slightly different kind of potentiometer in it.Most HP instruments I have have a potentiometer where when you take it apart, the wiper is running on top of the coil near the lid of the potentiometer, like running your hand on top of the combing side of a comb. I feel like there is higher pressure and the contact maybe is better at wiping, but that its maybe a bit stressful on the parts(1), this is just a single leaf that pushes into the wire from the top.This one had a potentiometer that has the wiper running on the wide side of the coil, like running your fingers across the side of a comb.These feel more structurally sound/stable (2). They run smoother. The contact is two leafs that run in different directions (like two parabolic trajectories offset on the Z axis)I use Deoxit grease (from the tooth paste squeezer) on basically all my potentiometers, and I noticed the following:After full cleaning of the pot (ultrasonic + flush/brush with alcohol), and applying the grease, for case1) I feel a vibration when I turn the pot, and hear a very slight 'zip' noise. Feels like you are plucking on a spring or something. No electrical problems but the sensation is a bit weird.2) It feels wonderfully smooth. I don't really wanna change anything here, very satisfied with the result from 260 grease.Now they both work fine, but it made me wonder if the normal Deoxit Grease (L260D) is the best substance to use on Type I potentiometers.Do you think a thicker grease, or some kind of loaded grease, would improve the feel of these 'knife edge' potentiometers?I bought Superlube Silicone w/ PTFE particles and also Deoxit Faderlube (optimized for carbon and plastic pots) to try out soon. But there are very very many grease options, even from just Caig. I wanted to try more, but I wonder if there are guidelines someone can think of to narrow down the search? I think the type II potentiometers are better quality, but face it, you would be lucky to be able to get replacements, even if you were willing to try to look for them. I even thought maybe to try just silicone dielectric grease on the knife edge pots, its horribly tacky and structural... I assume superlube might be very similar, I have not received it yet.My plan was also to put the various greases in a syringe and try to extrude a column of it, to see which one is the most stable. This is mostly for my harrison power supplies, which I love, but they all have the knife edge nested potentiometers that zip/ring/sing/vibrate with the 260 grease. Very slight, I don't plan on doing any replacements, but when I run into these pots in the future I wanna be able to deal with them better if possible. The noise they make makes me think of something like a VERY tiny hack saw, like if you listen to a lego man use a hack saw from across the house. And I mean mechanical noise when they are powered off.

author: Gyro
author_rank: Super Contributor
timestamp: February 11, 2023, 11:57:47 am
content: Lower value wirewound pots always feel more 'zippy' than higher value ones because they have fewer turns of larger diameter wire - you feel the wiper crossing adjacent turns.

author: coppercone2
author_rank: Super Contributor
timestamp: February 11, 2023, 01:27:46 pm
content: but do you think there is a solution involving sufficiently thick grease?Because before they were serviced, it felt smoother. But it was like total garbage inside and had poor electrical characteristics. (like it was fossilized), I think the ancient grease filled the gaps or whatever, but the control was very erratic.I need to take a look @ the ohms value, I thought it was similar between the two different kinds of potentiometers I have seen

author: Gyro
author_rank: Super Contributor
timestamp: February 11, 2023, 01:31:23 pm
content: I think you would need something like Kilopoise damping grease in the shaft bush itself rather than anything further on the winding. Anything that fills the valleys between adjacent turns would likely lead to intermittent contact (again).

author: coppercone2
author_rank: Super Contributor
timestamp: February 11, 2023, 01:56:29 pm
content: Hmm, I have high vacuum grease. Is that the same stuff, or is the kilopoise grease even thicker? Amusing that its just named by how viscous it is. I want it if its thicker, but I don't want to buy the same thing in a jar.

author: coppercone2
author_rank: Super Contributor
timestamp: February 11, 2023, 02:07:12 pm
content: absolutely fascinating

author: Gyro
author_rank: Super Contributor
timestamp: February 11, 2023, 02:08:01 pm
content: Kilopoise has strange viscosity properties, the faster you turn the shaft, the stiffer it becomes. I don't know of anything else like it - maybe there are alternative brands but it doesn't sound like vacuum grease.Edit:Quote from: coppercone2 on February 11, 2023, 02:07:12 pmYes.

author: coppercone2
author_rank: Super Contributor
timestamp: February 11, 2023, 02:18:12 pm
content: I am kinda starting to think that I should just put up with it, I don't want to have to use two different kinds of grease, that is gonna make some kinda fucking mess in the future and contaminate things. That high vacuum grease severely pissed me off when I used it for different things. Pretty sure it was worse the silicone electric grease which I don't like too much anyway. If it was purely mechanical with big parts I would not care, but the idea that it might do something to that crimped shut potentiometer is annoying as hell. I feel like this is a bomb that will go off some time in the future.

author: coppercone2
author_rank: Super Contributor
timestamp: February 11, 2023, 02:23:17 pm
content: also this video makes it seem like the whole industry is well.. greasyperceived value, luxury feel, etc.Amusing though because cheap objects that are uh... fortified.. with that kind of technology are eventually gonna 'deflate' and soil the surrounding area The hydraulics lost power and its limp now.

author: coppercone2
author_rank: Super Contributor
timestamp: February 11, 2023, 04:11:54 pm
content: actually... if you have some, would you be willing to see what happens if it gets into a potentiometer directly?How does that grease age also?Kinda hard to get the specific product. If it really is unique I am willing to get some. I suppose its worth one experiment. Just some of the potentiometers I have are SUCH a total PITA to get at, that I would be going nuclear if it went bad in the future because of such a silly luxury.I spent like 50$ a pop for some unique potentiometers for a repair or two recently, and a few extras, because damn like less stress about getting screwed by some damn electromechanical crap. I still have yet to varnish that relay coil I wound, the replacement I got is just a hair too big, and the one I wound needs to be varnished and then I need to file the teflon a little bit because its just a tiny bit too tall. Repair has been delayed for like.. a month nowsome of this equipment repair is literary 20 miles of bad road, like holy shit. I got like 4 open chassis under the table all delayed be trivialities. I need to make a tiny screw pem for a flat panel (gonna use epoxy putty to stick a seatable insert that I file down on the back of a plastic panel and reinforce it with some flowable epoxy (because its disintegrating), deal with the relay, get some odd power resistors and remake some brass turn clasp thing that goes on the inside of a keithley HV power supply (they use these brass plates that are attached to screws that you rotate to press the chassis top into the chassis, so it means alot of weird bending, finding the right type of brass or bronze or whatever the hell it is... like it has to be proper because they use that for the electrical safety guarantee (but I do measure low impedance with the panel just sitting in place), probobly will put some alodine on the seam also to make sure that its a safe contact and test it with higher power).

author: Gyro
author_rank: Super Contributor
timestamp: February 11, 2023, 07:17:28 pm
content: Sorry, I don't have any, it costs a fortune. The only place I have come across it first hand is on the damped lowering / cueing device on turntable arms. My guess would be that if it got under the wiper, the viscosity would be so high that it would lift it off the winding when you move it. In these damped mechanical devices, I doubt there is any metal - metal contact going on!I would be tempted to leave well alone, the feeling of the movement over the wirewound turns is a good reminder of the pot resolution.

author: DimitriP
author_rank: Super Contributor
timestamp: February 11, 2023, 09:09:33 pm
content: Once a pot is "rinsed" of all its grease, getting that old smooth feeling back is not easy unless you can remove the shaft.But if you manage to add even a small amount of grease in the shaft it takes a way that "looseness".My favorite is Nyogel 767A. It's thick, sticky, expensive and it works. 28185 cSt @ 40C !!!

author: coppercone2
author_rank: Super Contributor
timestamp: February 11, 2023, 11:13:15 pm
content: yeah I take them apart and put lubricant in there with a stick, I think its just that certain wire dimensions might require a thicker lubricant. I got the faderlube today so I can try that and the superlube out next time (soon, I want to fix up all the calibration pots in this meter).

author: coppercone2
author_rank: Super Contributor
timestamp: February 16, 2023, 01:26:50 pm
content: I made uh, small samples up for all my different greases and oils for a 'mini grease lab' and holy crap that's alot of samples. From air compressor oil to arctic silver MX6 (new compound). I got luer lock syringes with 1ml of each grease in them that were labeled with clear heat shrink over labels.Might actually make me use marine grease if I don't have to fish it out of a 1/2 liter tube each time I need it.... Those sizes are just not suitable for electronics, let alone vacuum tubes even.

author: Overspeed
author_rank: Frequent Contributor
timestamp: February 16, 2023, 03:14:50 pm
content: HelloTake in consideration that some grease are not ''lubricant '' some are just high viscosity fluid for damping as shock absorber , other have just thermal purpose , a real lubricant have a specific formula linked to the purpose .1) Shall be safe on copper as a lot of lubricant tarnish the copper and high alloy copper2) viscosity at the planned temperature of use and yes or no the system will be used with a wide range of temperature3) the load but in most case electronic component have light contact load or light load on bearings) the aging performance as the lubricant shall keep its original performance a long period of time4) water / humidity performance as the grease shall be water / humidity proof and dont absorb water with timeRegardsOS

author: coppercone2
author_rank: Super Contributor
timestamp: February 18, 2023, 12:47:13 am
content: while not related to potentiometers, who knew this happens to bearingshttps://www.maintenance.org/fileSendAction/fcType/0/fcOid/425349565432807082/filePointer/460686892551345448/fodoid/460686892551345444/Technical%20Document%202019%20Updated.pdf

author: helius
author_rank: Super Contributor
timestamp: February 18, 2023, 06:03:36 am
content: I think you don't want too high viscosity between the track and wiper because the wiper won't be able to displace it to make a good contact. Something very thin like Super Contact Cleaner PPE will lubricate the track enough to prevent wear and tear but still be displaceable.I got a case of something called "Head, Disk, and Tuner Cleaner" that seems to do a pretty good job on potentiometers.I would also feel safe using No-Ox-Id A-Special on metal-to-metal pots. Not sure about on carbon tracks.

author: Overspeed
author_rank: Frequent Contributor
timestamp: February 18, 2023, 10:37:22 am
content: Helloan interesting article on copper corrosion protection additivehttps://www.copper.org/publications/pub_list/pdf/a1349.pdfRegardsOS

author: coppercone2
author_rank: Super Contributor
timestamp: February 21, 2023, 10:21:15 pm
content: Well I have 4 pots I cleaned with ultrasonic, 2 carbon and 2 ww. I put fader lube on the carbon ones (both same value) (and a drop of precision lubricant on the shaft, since its non removable). One of them feels tight but very smooth, the other one is looser and a bit scratchy. I guess it depends on the potentiometer, even for identical parts, but for the one that is less worn or whatever, IMO it is a very good feel, super smooth, I feel that during adjustment it will be very easy to set that one, the other one might be replaced if it proves to be problematic, but I would still say its good, just not amazing. I will leave them alone unless there is a problem for alignment.For the WW I put deoxit 260, and the values are 50k and 5k. These both came apart fully and I grease the shaft and the shaft holder with the 260 grease. The 50K one feels very nice, with a microscopic amount of scratching.The 5k one however feels atrocious. The contacts looked nice, and the wire was cleaned, but it almost feels jumpy when it runs. I am not sure if its because of the thicker wire, but it has the contact configuration which I thought would be favorable (middle of the line not a knife edge rider). This one I might take apart and try again with super lube instead of deoxit to see if it makes a difference. It's greased nicely but it feels like its gonna cut through the wire or something. CIS brand, and I thought this one would be the best out of all of them, because its the highest quality. I feel like I had 5k WW pots that ran alot better.

author: coppercone2
author_rank: Super Contributor
timestamp: February 21, 2023, 11:51:52 pm
content: Well I put super lube in there ( did not clean out the 260 grease), not optimal, but it does improve it a little bit.So if you have a really shitty pot, perhaps low value WW, the superlube with teflon particles seemed to have helped a little. It appears to be stable electrically.The 260DL grease on this pot feels like you are hitting obstructions, like sanding something that has a bur or obstructions on it with rough sand paper, like jagged. Like its jumping or something. The sensation when you try to sand something that was rough cut.The superlube w/ptfe feels like you are running coarse sand paper over a smooth surface, non jagged, but not pleasant. . like you are done sanding a jagged cut plate but bumpyI mean this is compared to the smoothness of a nice carbon flat pot, its not really that bad, the 260 is acceptable I guess, especially for a internal adjustment pot, probobly for a parameter that is not too sensitive... but go for superlube if you run into this. Not sure what effect mixing the greases had, but I don't want to heat up the ultrasonic just to experiment on a internal pot that may only be adjusted once.