Some Thoughts on the Mule

[souptree]

Oops! I spilled my photons!

Well, I wanted to give this light some time before I posted, and I wanted to say something more substantial, and hopefully useful to Don than just acknowledging receipt. I also wanted to try to give some comments that I haven't seen posted so far in the assorted Mule threads. The maestro has asked for feedback, and I would like to provide a little.

First of all, this is the best light ever. Best. Light. Ever. It has totally changed my thinking about what a flashlight can and should be. I don't remember who it was, but someone in one of the threads said he thought the only reason reflectors became the standard was the lack of sufficiently bright light sources historically. A brilliant insight! Another poster said it was like having the moon in your hand. Completely true. This light is a total revelation.

That being said, a couple minor comments/criticisms/suggestions:

- I think this head would be better served by a C pack than a PD pack. Not only is it a teensy bit too small to squeeze the PD comfortably, but the purpose a light of this type would serve seems better served by a clicky to me. I guess this is just a personal preference, but for me it would be easier to use, and more useful all rolled into one. I tend to use a momentary for spotting something a distance away, but for local area lighting use, I tend to turn the light on, set it down (or hold it with my mouth), do something, then turn the light off.

- I am a little fearful about the exposed o-ring outside the light. If I were to put the light in my pocket with keys, would I be at risk of slicing the o-ring? For that matter, the cuts in the Ti itself look fairly sharp. Is it possible that pressure could cause the o-ring to be cut by the slot itself? And (this is a newbie question) if the o-ring WERE to be severed/compromised, what would be the impact on the light? At what point does water resistance become an issue? How much attention do I need to give to maintenance of that o-ring? For that matter, even on the other lights with the o-ring holding the lens in, such as the S27 there is still exposed rubber on the outisde of the light. Forgive me if this subject has already been beat to death.

- The bevels on the 8 head grooves are a little sharp for my poor fingers. Actually a bit more than a little. I would prefer an additional facet on each side of the little bites taken out of the side of the head. This is a real functionality issue for me, as in the wilderness, my fingers get completely thrashed from constantly pulling on boot laces, straps, webbing, and the like. Anything that increases finger abrasion becomes a real problem after a week outside. I have come back from 30 mile hikes with my feet ready to keep going and my fingers nearly bleeding. I am thinking one possible solution to this for me, for now, is to cut down an F04 and install it around the head somehow. Interestingly, this doesn't bother me even a little bit on the PD-S, even though the cut is the same on the grooves. (Well, OK, maybe a teensy bit -- but probably 20% as much). I guess the added length of the head, combined with the area that the grooves don't extend to make a real difference in my comfort handling them one handed.

- There are too many green trits floating around in my darkness, and I'm not sure which is which. It sure would be helpful if different lights could be distinguished by trit color in the dark. Maybe different colors could just be added to the mix and then randomly distributed (i.e., not take requests). People could then luck out, trade, or settle for what they got. This seems like a possible compromise to avoid adding complexity to your distribution arrangement. I do realize things are complex enough without needing to bother with who wants green and who wants blue.

- I wish all lights had replaceable bezels. It is nice to know that I can spiff them up easily if they get dropped or beat up over time by simply unscrewing what's usually the most thrashed part of the light and buying a new bezel, as opposed to having a cosmetically damaged but otherwise perfect head I can't do much to improve the state of. This also relates to the o-ring discussion above. The screw in bezel eliminates the exposed rubber.

- I would be interested in a discussion of the merits of using the Cree vs. a Seoul in the Mule. Has this occurred elsewhere and I just missed it? The reason I bring it up, is all the Seouls I have are pretty close to my U60XRGT tint-wise, but the Cree is way green to my eyes, so I'm wondering if maybe an emitter swap is a reasonable mod to consider. I know you don't want to get into tint discussions, so you'll note I am intentionally not going that direction.

Last but not least, this head is dying to be attached to a headlamp. If it was a two-headed headlamp with a Mule head and an S27 head side by side, with a detached battery pack that ran down to a jacket pocket, it might just make me cry.

Thanks very much for creating this light. I think it has really generated a lot of interesting thoughts, and for me this is the light I have been waiting years for. I want the Mule's photon distribution on every light in my house. I have a feeling in another LED generation or two, there will be virtually no reason to use a reflectored light unless you really need throw for some specific purpose, which, of course, there are many.

Sorry for the long and rambling post. I hope I didn't beat too many dead mules! :nana:

 

[McGizmo]

Souptree,
Thanks for the thoughtful and extensive post! I would like to make some comments in response and hopefully answer some of the questions posed.

The Clickie pak allows one momentary or constant on of preselected level from the rear. The piston allows for momentary activation of both levels from the rear. Constant on of both levels is available as a twisty function with both paks; by design with the PD and in the case of latched on with the clickie pak. It may well be the case that the C pak would serve the majority of users better than the PD with the mulehead. This is ultimately a subjective call, IMHO. I donot consider the Mule a tactical light even though I would guess many engaged in tactical situations could gain benefit from a light like the Mule. I personally find my self going back to the PD over a clickie but this is my preference and not because of some true for all cases advantage the PD may have over the clickie. :shrug:

Now for O-rings. Even in lights that don't have visibly exposed O-rings there is still exposure of O-rings to the elements and environment. Proper choice of O-ring material should minimize environmental impact and durability of the O-ring. In most cases, they should be considered as a normal wear item. In the lights I now use an O-ring for window retention on, the O-ring can provide secondary seal but it is not the primary seal or depended on as a seal. You can effectively retain the window with just a few disconnected segments of the retaining O-ring. Take a razor blade to the exposed sections in the ports of the Mule and see what happens. You will need to push the majority of the segments out of the groove to allow the window to escape captivity. Again, its seal is underneath it.

Atthough it is not a big deal, any portion of a flashlight aside from its optic that is inthe path of it photons is in the path of its photons. I have found I can effectively reduce this photon shaddowing by going away from a threaded bezel/ window retaining ring. With the Ti, I am not worried about dings to the extent that they go beyond cosmetic considerations and become functional problems. At this point, if I really wanted to design in a replaceable "bumper" I would stick with the present window retention scheme and have a molded part that extended forward of the present O-ring groove and fold over the front lip of the head. I would be concerned that this could make it easier to knock the retainer out of position though.

As to the sharp edges of the Mule head, they are what they are. After building this first wave and working the threads in a bit on each unit, I was painfully aware of how effective the grip of these heads are!! On consideration of this though, I have no plans to change this design. The short head does not provide a lot of surface area and what is available to grab needs to provide sufficient grip. You can alleviate much of the pain and suffering when twisting the head if you let your fingers go in front of the head and pull the head towards the pack while you twist. Yes your fingers block the beam during this process but presumably this is not during a tactical or critical moment. I have no doubt that a different design could serve many in a better or preferred fashion. I would not be surprised if there is a better approach in design than the one I have settled on. I have not identified it at present and I am satisfied with the solution I have come up with. I don't mean seem to come off on the defensive here and I hope that isn't perceived as the case.

On the H3 vials, it's funny you bring this up because I am looking at potentially having a partial wave of the next lights due to lack of green H3 vials. I have a number of red and blue that I could use while I wait on more green but these are not as bright and to offer a choice in color would add a dimension of additional limitations in addition to options and be an opportunity for trouble and mistakes to enter. :green: I have considered just building out with what I have and posting them as x with green, y with blue and z with red H3 and available while supply lasts. :shrug:

Seoul or Luxeon VS the Cree XR-E in a bald headed floodlight. IMHO, the XR-E with its narrower beam distribution pattern has advantage here. As it turns out, I just received some sample material from Wayne Y. that is called MC-PET reflective sheet. Newbie turned Wayne on to this new, cool material. I formed a shallow cup of this (crude but effective I believe) and just moments ago tested a mule with and without this reflective material in my integrating sphere. A shot of the test light with the MC-PET face:

This mule is driven with a DB500 and I measured 80 lumens without the MC-PET face and 92 lumens with it. So the mule saw a 15% gain of light out the front end when coupled with a highly reflective material that better releases the off axis output than the stock "empty chamber" forward of the LED. Now I am confident that if you used a Seoul or Luxeon in the mule head this difference would be measureably greater than the case here with the Cree. In fact, it seems the Mule with the Cree is as efficient and probably more so, in out of the head delivery of photons as a typical light is when coupled witha secondary optic. A Seoul or Luxeon based bald headed flood light would also be very useful but I don't think as efficient as a Cree based one. In terms of particular tint, this is a function of the LED itself and not the model or make of the LED. There are warm and cold LED's from all of the manufacturers. :shrug:

My laptop battery is about dead now so I will quit my rambling here.

Again thank you for the comprehensive post and all of your comments!

 

[Kiessling]

Good post !

The Cree was chosen because it's beam angle is narrower than the lambertian Seoul that would have been too wide. The Cree is perfect for this application making a second optical element (reflector) unnecessary.

A Mule headlamp ... would be perfect. Small, CR123 driven ... with the ideal beam distribution. I agree.

bernie

 

[Kiessling]

Typed too slow again ... even DOn was faster than I was :nana:


This reflective stuff ... interesting. Very interesting. Wouldn't it be great for all those lights with optics ... to collect the stray photons and re-inject them in the beam?

bk

 

[easilyled]

I would like to add that I agree with Souptree regarding having a bezel
retaining ring in the Ti lights's design. (Not just the Mule, but the whole Ti range)

Whilst I understand Don's argument about "strangling" photons by blocking part
of the emerging beam, this can be limited by having a shallow, bezeled
retaining ring.

I think the advantages of being able to access the window & reflector cleanly
and renewing or changing the style of the bezel ring outweigh the
disadvantages of beam strangulation from a user's point of view.

Just to reiterate if the bezel ring only protrudes from the bezel lip by
a small amount and its chamfered so that it tapers outwards, I don't think
much strangulation will occur anyway.

:shrug:

 

[McGizmo]

Bernie,
This MC-PET sheet is really cool stuff but its surface is not specular. Angle of incidence does not equal angle of reflection. I guess anywhere from 97% and up of the photons that hit this surface will bounc off of it but they will bounce in a a number of directions (diffuse).

This stuff is the surface that a bead blasted reflector dreams of being. (It's too bad that DougS and Newbie weren't present to discuss this material.) In days gone by, we have had discussions of various white paints VS non smooth metal surfaces in terms of an efficient lambertian relection. This stuff could probably compete with the pricey material now used in integrating spheres and in fact might lend itself for some viable DIY integrating chambers. If you like flood, this material is very exciting. If you were to replace an existing reflector with a similar shaped reflector of this material, I would guess you would end up with a very nice and artifact free flood. You would also see a gain in flux out of the front end.

Souptree, by virtue of some of his comments here has "seen the light" as it relates to flood and the MC-PET is a material which can allow us to get flood from LED's and lights that aren't otherwise as optimal for such, or designed specifically for it, like the Mule was. That measured gain in output for the Mule that I mentioned above appears to be a gain in distribution seen in off axis and perhaps even an improvement in artifact reduction. The Mule can do fine without the MC-PET but it is measurably if not so obviously improved with the addition of the MC-PET. If the original McFlood had the photon bounce you can get from this MC-PET, I am not sure how much time and energy I would have devoted to some of the later reflectors I got involved with! I can't tell you how much time I have spent trying to come up with an orange peeled surface that would mimic what this stuff can do!

The MC-PET is worthy of its own thread and I am sorry for taking this thread as far off tangent as its inclusion has. I believe it does address some of the comments and questions in the original post but perhaps we should get back to topic here.

 

[McGizmo]

Easilyled,
The photon shadow is not that big of a deal and especially in a light that's primary focus is that of a collimated beam. In terms of access to the window, I won't agree that a threaded bezel makes access easier because I have seen and experienced many cases contrary to that. For any of you whose only experience with an O-ring window retainer has been a HD45 well what can I say. The HD45 is a PITA.

With sapphire windows which can take some rough knocks, the O-ring retainer is friendlier but not necessarily of great significance. In the case of a glass window with great A/R coating though, I venture to say that a nose drop on a bezel that has a hard contact with the glass is more likely to chip or damage the window than a similar drop when the window is sandwiched between O-rings. :shrug:

From a design and building point of view, an O-ring retainer has more lattitude in a tolerance stack than does a threaded bezel. I really prefer the elegance of the simplicity with no threaded bezel. Granted one is not given the options of changing the style of something that is not present in the first place. :duck:

 

[AndyTiedye]

I'd like a red or blue trit even better than a green one, actually.

 

[PoliceScannerMan]

Don, is there a chance you could maybe send me a precut sheet of the PET for my mule? bullred(at)cox.net if ya can!

EDIT: Sevaeral minutes later.

If outdoors, I doubt the Mule could be your only light. You would need a light that can throw some lumens out there. For me, like Codey says, the mule and a27LT-S make a perfect combo. A combo that could tackle 99% of all situations.

 

[Nebula]

Don and Souptee, very informative posts.

Don, I do hope that you make another run soon. Oh, and I am not picky - green, red or blue trit will be fine with me.

Cheers

Kirk

 

[griff]

Guys, To sum it all up. I still think the mule peforms like a moonbeam in my hand ,and I wouldn't change a thing!! THANKS DON

 

[souptree]

Sorry for the delay, I didn't have adequate time over the weekend to respond. Thank you for taking the time to post such an extensive response.

First of all, I do NOT take your responses as defensive or dismissive. I didn't expect you to redesign the head in response to my comments! But I do think sometimes people are afraid to give constructive criticism on the fear that it might be perceived as an attack. Maybe one or more of the suggestions will gnaw relentlessly at the back of your mind, and come back in a future design. Maybe they are just something to think about. Probably in all cases, you have given the subject more thought than I ever will by a multiple factor. Either way, it makes for an interesting discussion, and I am honored to have you consider my ideas, no matter what you eventually decide to do with them.

- As far as tritiums go, it seems like the fashionable trend in CPF-land is to seek out the brightest capsules available. I must say though, that in true darkness, I find the green tritiums too bright, and sometimes MUCH too bright! I have some reds that are far less bright, such that in the city they're basically useless, but in the dark, they're plenty bright enough to help me find a light. Indeed, I find some of the really bright trit/glow powders distractingly bright on a moonless night, especially bouncing around on a lanyard while I hike. So for what it's worth, there are some of us out here who in some circumstances will benefit functionality-wise from dimmer trits. Plus, I already color code my lanyards, which aids GREATLY in grabbing the right item the first time. Matching the lanyard to the trit is just the natural extension of the madness for when it's too dark to see the lanyards.

I am glad you mentioned that you were considering delaying or reducing the size of the coming wave due to the supply of green trits. I strongly urge you NOT to do this! Believe me, the alternates will not be a compromise! My guess is they'll become quite coveted, especially if the trend returns to green only in the future. I favor the solution that adds the least stress to you, which is probably to not give buyers a choice. Multiple colors would be a great thing to make available, but not a great thing for you to expend much time on, IMO. It's perfectly reasonable for you to offer the buyer a color preference that is not guaranteed to be filled, or even no preference at all. Hopefully that would preclude any problem of screwed up orders, or worse, it contributing to you feeling burnout.

- Regarding the screw-in bezel vs. machined-into-head bezel, I do hear you on the parts tolerance issue and the added energy absorbtion the o-ring provides in the event of a drop. I hear your decision to not go this route loud and clear, and I don't intend to keep bugging you about it, but I did wonder in response to your answer how feasible it would be to combine the impact resistance of the o-ring buffering the window with a screw-in bezel, i.e. the stack would be head -> o-ring -> window -> o-ring -> bezel. Presumably one bezel option could be something along the lines of an HDS or a SF G2 where it screws in but does not extend forward of the head. All of that being said, all of my lights are users, and I certainly do not intend to shy away from using these lights just because the head might get scraped up. These are truly fantastic lights, and trying to keep them pristine is not a goal of mine. I will now stop beating the dead mule.

On the point of o-rings being a normal wear item, I figured this extended to o-rings between body and tailcap and between body and head. In a design like the mule, I can clearly see this would also extend to the window-retaining o-ring. But what about o-rings inside the head? For instance, it would be close to impossible to replace the o-rings inside a SureFire turbohead, and might void the warranty to try. What is a conscientious maintainer to do? Should I consider it necessary to remove the Mule/S27/PD-S window and replace the inner o-ring as part of standard maintenance? If so, how often should this become a concern?

Take a razor blade to the exposed sections in the ports of the Mule and see what happens.

Ummmmm.... NO! :nana:

As for the inset faceplates, it might be helpful to someone to provide an exact measurement that one should be cut to. Outer diameter, hole diameter and thickness info. Hopefully at that point, someone with the means to do so will start making them available to the Mulees. I still think a Ti with a contrasting surface treatment would go nicely with the all Ti theme. That reflective material certainly does sound intriguing though! I'm with PSM -- any way to make some of those available to the team? I'm a little afraid to crack one of these beautiful heads open, but perhaps someone here will convince me. I do like the way it looks stock too, so maybe they won't. The joy of possibilities....

Again, I thank you very much for your thoughtful reply and everything else you do.

I will say this though -- I never thought buying a flashlight could create so much stress! A certain person, who shall remain nameless, said to me "You do realize while you're sitting here hitting reload like an idiot, he's in the ocean?" :sigh:

 

[easilyled]

Souptree, you compose your thoughts in a highly articulate, intelligent
manner (of which I'm jealous).

I have thought the same things about bezel retaining rings and tritiums
yet cannot express them as eloquently as you.

 

[McGizmo]

..........but I did wonder in response to your answer how feasible it would be to combine the impact resistance of the o-ring buffering the window with a screw-in bezel, i.e. the stack would be head -> o-ring -> window -> o-ring -> bezel. Presumably one bezel option could be something along the lines of an HDS or a SF G2 where it screws in but does not extend forward of the head.........

There are any number of possiblities here and not one an obviously superior solution. It does help to consider the "Z" requirement for the various stacks and the impact this has on the amount of shadow produced by material forward of the optic. The other thing to consider is the thickness of the various components and what this means in terms of crumple forces and head on impacts. I ended up going with full section thickness of a ring forward of the head as I felt this provided a better bumper. I had a few of the Alephs get damaged by nose drops where the bexel ring and head were jointly deformed and this made removal more problematic. If you sandwich the window between two O-rings or seals that have some give then clamp them with a threaded ring you have added more Z to the stack and you also need to insure that the threaded ring doesn't back out. I am not convinced that the compression against the seals is enough to insure that the ring stays fixed. You also need drive features on the ring if it is internal and these likely reduce its strength locally as well as may require it be taller than otherwise.

Regardless, I prefer a full thickness at the front end and this equates to a ring that extends past the lip of the head if a ring is used. The 27LT didn't need a ring extending past the head because its wall thickness was massive in itself. Most designs however favor a minimum OD on the head which was not the case with the 27LT.

I am approaching a dead horse or dead mule as it were so I will now cease in my rambles.....

 

[souptree]

Don, your rambles are very much appreciated, dead or otherwise! I hope mine haven't offended or annoyed in any way!

easilyled, those are very kind words! Many thanks!! :wow: