A Leaning Tower of Ti, C-Pack Safety Style

Rather than continue OT in another thread, I decided to make a new thread.

Here are my previous posts from Poll/Discussion. Which do you prefer, the C-pack or the PD???:


And


After using some retention ring ChannelLock pliers to insure that the switch is fully seated inside the C-pack, I installed the silicone o-ring, then fully seated the switch boot inside that o-ring, and finally seated the EPDM o-ring over the boot. After waiting a few minutes to let things "settle", here's how it looks:



The light is tilted every so slightly towards the camera, and it's a bad picture, but it should be obvious that the boot extends slightly out of my C-pack. I wonder if the EPDM o-ring's ID is slightly smaller than average, exerting a slightly larger "squeeze" on the boot in my particualr light? Or maybe the boot is slightly larger somehow, or maybe it's a combination of tolerances. I don't have it figured out yet, but the frustrated engineer in me sees it as a challenge to be solved!

After attaching my McLuxIII Ti PD's head to speed up the heating process (good idea Kiessling!) and letting it run on high for 20 minutes using a primary cell, it now looks like this:



After another 10 minutes, it seems to have stabilized (no further protrusion):



(The rubber pull cap doesn't serve a purpose, except to keep me from shining my light around the office and bugging co-workers! It's a really slow day and I'm waiting for some code to compile, so I'd be twiddling my thumbs anyway.)

When I removed the head, the boot immediately recovered about half of the way back to where it was in the first picture. How much of that recovery was due to the heated, and thus expanded, air and how much was due to gas from the cell (don't you just love the smell from Lithium primaries) is anyone's guess, but I think this helps to prove a couple of things. First, the C-pack's use of o-rings is a good design - with slighter higher internal pressure (as opposed to greater outside pressure when submerged), it still maintains a good seal. Even letting a new primary cell run all the way down, the protrusion doesn't increase any more that is shown in the second picture. Second, if a cell was to vent, the o-rings and switch boot will prevent a violent body rupture, just as Don intended. Bravo, McGizmo! :rock:

After waiting 40 minutes for things to cool down completely, the boot still protrudes more than the first picture shows, but not by much. A few firm presses around the edge of the boot returns it to the same position as shown in the first picture. Obviously, the internal pressure is pushing the button out slightly. IMO, this is a fair trade for the increased safety in the event of a cell venting.

I still have a preference for the C-pack and I certainly don't see this as a defect in the XR19-C. If anything, I simply was on the losing end of the tolerance stack of my individual parts. I've got spare o-rings, boots, and switches that I may try. I did a quick eyeball check with the parts from my XR19-C and the spares I have, but I didn't see any differences. But then, I do wear contacts and didn't have my reading glasses handy.

Contrary to what the length of this post might imply, this really is just a minor thing to me. I use tailstanding a fair bit inside the house, but it's almost always for short periods, and even on a long run, it doesn't fall over, though it does come close.

I thought about not even posting this. We sometimes seek perfection where none was promised, and I think that can be unfair to the builder, especially when the light comes so close to reaching perfection. If builders attempted to build perfect lights, we'd never have any lights. And McGizmo goes out of his way to fully explain his well thought out designs. Don, I don't need no stinking explanation, nor solutuion, :nana: so I hope you don't feel like you have to make a big post about this. No matter how much you explain things, everyone won't understand and everyone won't be happy. I'm neither!

Besides, no one else has mentioned having this problem, so hopefully it's just mine.

Still, if tailstanding is important to someone and they are otherwise unable to decide between the PD and the C-pack, this might be something to consider.

I'll do some part swapping to see if I can spot the culprit.

In the meantime, I hope I don't get cut off for such a long post on a truly minor thing... :duck:

This is way more protrusion than I imagined from your initial post yesterday. :thinking:
I will let mine run down a battery again to make sure mine doesn't do this, but so far I only had wobble problems when I took apart the rear end and didn't re-assamble it correctly :green:

Interesting that it didn't vent, I wouldn't have thought the seal would be this strong.

bernie

Codeman said:

I thought about not even posting this. We sometimes seek perfection where none was promised, and I think that can be unfair to the builder, especially when the light comes so close to reaching perfection. If builders attempted to build perfect lights, we'd never have any lights. And McGizmo goes out of his way to fully explain his well thought out designs. Don, I don't need no stinking explanation, nor solutuion, :nana: so I hope you don't feel like you have to make a big post about this. No matter how much you explain things, everyone won't understand and everyone won't be happy. I'm neither!

Besides, no one else has mentioned having this problem, so hopefully it's just mine.

Click to expand...

Codeman - I think we all know how awesome Don's lights are, so pointing out one thing that might not be perfect about them is totally fine, IMHO... it certainly wouldn't discourage me from buying one!

My tail sticks out as well - just a bit - although I haven't done the same test as you, so I don't know if it stays as it is, or expands, when the light stays on for a while. Maybe tonight!

Thanks for the photos and writeup!

john

the solution could be plain and simple: just press the button slightly when you screw the head on! it will create a bit of a vacuum and keep the rubber just enought in.
As far as I could see, its only mm difference.

It could become more noticeable when the rubber cap grows older. From other clickies (like on older HDS EDC's) the rubber "grew bigger" as it got use more, and the wobble would get, well, wobblier

BTW this is CPF at it's best, not just bashing on modders/makers/manuf. but doing some sturdy research into the matter
A superb analysing of a situation Codeman!!

Very interesting... Like brnie said, I didnt think it was that drastic! Maybe I should run a cell down to see if mine does that. The longest run my XR-19 has been on is maybe 20 minutes, BUT, I didnt try to tails stand it. So i guess mine could do it.

Cool thread Codey and thanks for sharing!

BTW: If you come to the compound while I'm gone, say hi to bennie for me.... (Bennie is my dog, who protects my lights while I'm gone...)

Codeman,

I believe all of the C-paks have this aspect of boot extending past guard. I thought it was mentioned at one point but probably not. In cad renderings, at least mine, there is no simulation of what happens when parts are mated that have some interference in real life. In the drawings, the parts will happily occupy the sames space and not move as displaced. I noticed this after the first assembly of first article parts and using the light but after confirming that I couldn't get the light to come on by pushing the light down firm on its tail, I decided to let the production run as was. The internal pressure when it exceeds external pressure can displace the boot outward to this condition. The rubber boot and EPDM retaining O-ring are not rigid parts and predicting how they will move as forces on them vary is certainly beyond this guy. I confirmed that I couldn't blow into the pak hard enough to get the balloon to pop and figured that was sufficient for normal conditions. I could have rigged up a test and applied pressure to see at what piont the bubble did burst but I doubt that such a test would provide any useful information nor should one assume that all assemblies would behave in identical manners. This was also about the same time that it was becomming clear to me that the likelihood of an event with a single CR123 of reasonable quality was slim to the point of non issue.

I had more concern that some would feel the latching on of the switch was already a bit of a challenge and having the guard come back further to insure no boot extension past it would require more penetration into the guard than as it stands now.

I am glad you brought this up because it may be an issue for some and at least something to consider. I didn't and don't plan to change the geometry to compensate for this but I also failed to mention it.

PoliceScannerMan said:

BTW: If you come to the compound while I'm gone, say hi to bennie for me.... (Bennie is my dog, who protects my lights while I'm gone...)

Click to expand...

Here's a recent shot of Bennie watching over PSM's lights... scaaaary! Ten seconds later, the person who took this picture was killed by the poisonous drool that Bennie emits when licking them to death.



Ok - I have to find something to do that does not include Photoshop.

john

I added a remark and the link to this thread to the FAQ.

BTW ... after another long burn with the ti-PD head on the C-pack mine now wobbles ever so slightly. I would never have noticed it if you hadn't pointed me in that direction. In no way it is as "serious" as yours though.

Dito on how good the "issue" is handled. Like it should be on a place where friends gather.

Alec ... good idea there !!!

bernie

McGizmo, you probably did mention it, but I'm a year older and more forgetful of things. Either way, no harm, no foul. Though, I wish someone had taken a picture of your blow-into-the-c-pack-pressure test! That could go along with that other pictue of you that was recently re-posted around here somewhere. A helmet was involved, I think!

Seriously, I agree with your reasoning. I'd rather have a little protrusion than a more difficult to press switch.

On the plus side, my parrot seems to enjoy the leaning Ti as it's beam circles on the ceiling overhead. :lolsign:

Thanks for the suggestion, AlexGold!

Gas mask/hazmat suit with toxic drool barrier added to equipment list, jch79. Thanks! I already had a 12 oz rib eye on the list! :nana:

Don, do you mean to say that future iteration of Mcree lights clicky version will have the same "boot sticking out" issue? If so, whats the point of the tail guard then? I liked the original PD because it can firmly stand on its tail, and not become a leaning tower like my now-sold L1P.
I have been eyeing the new clicky version of the Mcree (granted, no money to get one), and frankly, this expanding boot is a minus point for the light.

Interesting thread

From your pictures it seems your boot sticks out a lot more than mine Codeman. By eye it looks like mine is protruding maybe 1/4 of a millimeter, not enough to cause a wobble. I'll let it run on high for a while and see if there is any change.

Edit: After about 15 minutes on high the boot sticks out a little bit more, maybe 0.5 mm. I can get it to wobble -slightly- if I give it a little push, but it seems to stand perfectly straight if left alone.

shiftd,
I consider the primary function of a tail guard is to guard against accidental activation of the light. Many don't like it because it makes access to the switch more difficult. If you could push the tail of the light down on a table or other surface and have the light activate, then I would feel the guard has failed in its guard duty. Since the clickie pak adds length to the light, I targeted a minimum guard depth but did not anticipate the fact the boot could and would balloon to the extent that it does. If and when all of the clickie paks now in process are gone and if I decide to do more. I will consider this issue but I won't say for certain whether I will increase the depth or not. :shrug:

Would this sort of thing also occur with altitude, such as when flying?

I've seen products that are fully sealed, where the keypad buttons actually expand to several times their size (imagine LARGE jawbreakers) with altitude.

Sometimes sealed items at altitude will slowly return to normal as they slowly leak. Is the button hard enough to press that when you go down in altitude it wouldn't self activate?

If it is, in the future, Gore makes some very nice low-cost membrane materials that will allow an item to breathe, yet be submerged without leaking. The other thing, is they help prevent the accumulation of gases.

Some will take the blast of a water jet, and even allow 30 minute submersion to 1 meter depth.
http://www.gore.com/MungoBlobs/957/966/membrane_vents_QPE.pdf

Mechanical impact resistant, 1.5 meter water depth for 30 minutes, salt spray resistant, and more:
http://www.gore.com/MungoBlobs/636/496/membrane_vents_HPM.pdf

This one has the benefits above, and does an even better job of filtering particles down to less than 1/4th the wavelength of blue light (99.999% efficient against 0.1μm particles):
http://www.gore.com/MungoBlobs/882/693/membrane_vents_HPC.pdf

I had the idea the construction of the boot was to prevent for fatal battery problems, as well be easily serviceable in the field (no tools, not very sensitive for scratching of sand etc.) and it is still very resistant to water! I've read 6 bar/180feet depth could be possilbe and perhaps even more! so 1 meter would be a real bummer for me as I like just the fact that this light is so strongly build.
Membrames, by definition, are the weakpoint here and will prob fail first. Besides failing, I'm wondering how much dirth would end up in front of the membrane. Most membranes are very critical about salts btw. Salt cristals can interfere with the function of those membranes and let them leak tiny amounts of fluid.
It is perhaps possible to build a membrane in a light, but IMHO not without high costs and severe dificulties to overcome!

If internal pressure were a real problem and concern the boot itself could be designed as a purge valve. When it looked like these lights needed some design consideration for pressure relief (the height of the "events" discussions), I also had a plan for the window to lift up away from the seal in the head and channeling for blow by if internal pressure got too high.

All of these lights with good seals will experience some effect from barometric pressure changes. The simple act of changing the battery and screwing the flashlight back together will typically add some positive pressure to the chamber. With twisties that are left close to on engagement, you can find that the light may come on. The PD is a barometer itself!

I always knew Don's lights were good value and well featured but he is the first with a built in storm warning system! and completely free of charge!

FWIW my boot doesn't protrude at all! I turned it on high and stood it on it's tail for 10 minutes. No wobbling whatsoever and afterwards (while still on high) I was able to touch the end of the tail guard with a straight-edge and see some space between it and the boot.

thanks for the answer, Don.

Wow, that was a lot of ifs.

I sure hope you have a plan to do a run of the clicky pack in HA Nat/BK just like the original PD. I really like the original PD and I believe the clicky will make the whole experience a lot more enjoyable than it already is(it is already, but the stiff PD makes momentary high a bit hard to hold for >10s).

Please do consider to make necessary revision for the clicky/tail guard. I am sure the additional functionality never hurts

chellyc said:

FWIW my boot doesn't protrude at all! I turned it on high and stood it on it's tail for 10 minutes. No wobbling whatsoever and afterwards (while still on high) I was able to touch the end of the tail guard with a straight-edge and see some space between it and the boot.

Click to expand...

You have a highly coveted C-pack then! I'll remember that if you ever
put it on B/S/T

hi, still waiting for mine to land , but could this be due to weak rubber,just a thought,me i would change the boot, just to see if there were any changes.failing that send all these lights to me for inspection,im sure at least one will land.
john