LS20 - piston making 'clicking' noise?

[mcmc]

Hi all,

I have an LS20, and it's a wonderful light =) Even with the cooler DS Nichias, great beautiful flood on low, and the high, the more I use it, is surprisingly sufficient, even at 'only' 80 lumens. And very tight throw, surprising for such a small reflector (I guess the small emitter helps).

I had a question about the piston. I've cleaned the piston and etc. out pretty thoroughly, but when I press the piston to engage momentary, there's kind of a 'clicking' sound, as the o-ring and even part of the piston itself, I think, well, 'clicks' past some other part in the body. Depending on if I press directly down, or slightly with angled force, seems to change the nature of the click, sometimes it doesn't click at all.

I experimented by backing off the head twisty a ways, so the piston could travel further; a bit better, but sometimes on the piston return, it'll snag, and then 'pop' back as it gets past that obstruction.

Is this something normal and something that just needs the light to be broken in? Or should I put more lube? (it's got a minimal amount of whatever it came with, as I wiped some of it clean and spread the rest around, to abide by the 'less is more' camp of lubing).

Thanks guys!

 

[Kiessling]

Do not worry, it is normal. The piston has no "guidance" at the top and is loose in trhe body to ensure minimal resistance to movement.
This makes it possible though that there is lateral displacement, causing a clicking noise.

Just ignore it.

Or ... if it disturbs you, put some teflon tape around the upper part of the piston. IIRC.

bernie

 

[precisionworks]

Bernie -

My Ti PD-S clicks also, but the location is right below the trit. Pretty sure that mine is a spring coil compressing. Eager to see if that continues when the new low force spring is installed.

 

[Kiessling]

Ah ... now that you mention it ... maybe there was more to it than just the top of the piston shifting.

I thought we had that discussion but couldn't find it any more :thinking:

bernie

 

[McGizmo]

I can't see what is happening in there but I do believe that a fair amount of the clicking I have encountered has to do with the battery spring coils interfering with each other during compression.

 

[maxspeeds]

Could it be the top of the piston slipping on Kilroy's nose from lateral displacement? That's my best guess.

 

[mcmc]

Hm, interesting ideas, all! I could see it being any one of those =) At first I thought it might have to do with the piston hitting the holes tapped for the clip screws, but they shouldn't be slipping past one another, right?

 

[Oddjob]

Could it be the top of the piston slipping on Kilroy's nose from lateral displacement? That's my best guess.

This is exactly what was happening with my PD-S. As Bernie mentioned, I simply wrapped a bit of tape around the piston close to the opening and it keeps the piston centred and eliminated the clicking.

 

[mcmc]

Cool, I should have some teflon tape around here, I'll try it out!

Btw, slightly unrelated q - with the piston's o-ring traveling up and down, does it retain waterproofness even in use? Same with the twisty head?

 

[Oddjob]

Cool, I should have some teflon tape around here, I'll try it out!

Btw, slightly unrelated q - with the piston's o-ring traveling up and down, does it retain waterproofness even in use? Same with the twisty head?

Waterproofness is certainly better when the parts aren't moving. I have turned on my PD via twisting and piston while underwater with no sign of water entry. I only did it a couple of times so I do not know about constant or extended use underwater.

 

[darkzero]

I've also experienced the clicking. As mentioned already, filling the gap at the top of the piston does the trick. There was a xray picture of a PD-S posted somewhere that shows how the piston can sit at a slight angle.

 

[UnderTheWeepingMoon]

Wrapping a small amount of teflon plumbing tape around the top of the piston solved the clicking issue in my PD lights.

 

[jumpstat]

I do agree that the clicking is from the spring compressing and 'rubbing' against the coils....

 

[precisionworks]

with the piston's o-ring traveling up and down, does it retain waterproofness

O-rings are often used in sliding applications. As long as:

The outside of the O-ring is the proper compression fit to the inside of the bore, and

As long as that bore is very smooth, and

As long as the O-ring is correctly lubricated (so as not to tear or deform) ...

They will maintain a seal under pressure or vacuum.

 

[darkzero]

I do agree that the clicking is from the spring compressing and 'rubbing' against the coils....

Aside from spring noise, my PD-S also makes the clicking from the piston as reported here but not often. I have a new shorter spring in mine now, no more noise from the spring but still from the piston. Doesn't bother me though.

 

[mcmc]

O-rings are often used in sliding applications. As long as:

The outside of the O-ring is the proper compression fit to the inside of the bore, and

As long as that bore is very smooth, and

As long as the O-ring is correctly lubricated (so as not to tear or deform) ...

They will maintain a seal under pressure or vacuum.

Cool, thanks for the info!

I think the PD qualifies on all of the above, but the one in bold - the smoothness of bore - I am wondering if the fine machining marks are ok, or if they may hinder the waterproofness a bit?

 

[precisionworks]

I am wondering if the fine machining marks are ok, or if they may hinder the waterproofness a bit?

O-rings, by their nature, are somewhat compliant. They have a limited range of compression, depending on the material (Buna-N, Viton, Silicone, Urethane, etc.) Some are less likely to take a compression "set", where deformation becomes permanent, others have better memory. Others are more wear & abrasion resistant, some do better under vacuum & pressure.

In an absolute sense, smoother is generally better, although a micron level crosshatch plateau finish will retain enough lubricant to reduce friction. The way this is often done in industry is with a Sunnen Hone Machine (about $100k and up), or with an abrasive Flex-Hone (under $20).

http://www.brushresearch.com/product-line.php?line=1

A Flex-Honed bore will probably look & feel nicer, but I doubt the sealing function would be noticeably changed. As my Dad used to say, if it ain't broke, why fix it:D

 

[mcmc]

Very interesting info. You sure know your stuff =) I'm guessing based on your knowledge, and your cpf name - do you run a machine shop?

 

[precisionworks]

do you run a machine shop?

Before becoming plant manager at a small factory, I was a full time machinist at a coal mining repair shop. We often worked on the electrical enclosure boxes, which were O-ring sealed. The box would get mounted to the milling machine table where the sealing face would be milled perfectly flat, +/- .001. The lid was then milled flat, and the O-ring groove was recut to the necessary depth. After the box was finished & assembled, an inspector from MSHA would try to poke a .006" feeler gage between the box & the lid, so the fit had to be less than that. Can't remember that we ever failed that test:D

Now I do machine work & welding in the evenings & on weekends. My business name is (no surprise) Precision Works. Mostly smaller jobs, some contract work, lots of really odd stuff -- like bushings for the wing on a McLaren TransAm car.

Having that background gives me a real appreciation for Don's extraordinary design & execution:twothumbs

 

[js]

Another cause of the clicking noise can (may) be the spring buckling due to travel off axis (i.e. off to the side), pushing the end of the battery off as well, causing the whole battery to get tilted off axis. I found that wrapping tape around the battery to keep it on axis in the piston solved this for me--and it was rather annoying, both in feel and in sound. I haven't tried wrapping tape around the top of the piston, but that sounds like something to try also. In addition, using a softer / shorter spring, or cutting off the top loop of the stock spring (being careful to bend the sharp tip down slightly so it doesn't dig into the battery) are also things to try. Personally, I didn't like using a softer spring. I like the force the way it is. I just don't like the clicking or *sproinging* of shifting to happen. My LunaSol 20 hasn't done much of this at all--and only rarely when it did--but my Ti-PD-S wouldn't stop until I added the tape.

One last point, a lot of times if you slap the back end of the light into your palm to get the end of the battery inside the piston to shift a bit to one side or the other, you can often stop the spring from buckling (if this is what is causing the clicking). Try knocking the end of the battery into different places in the piston (four "cardinal" directions is plenty of positions to try). In my experience, this often eliminates the unpleasant action artifacts. (And is easier than wrapping your battery or piston in tape).