LunaSol 20 PD Modifications

I have just picked up a LunaSol 20 over in B-S-T. Like most CPFers I really love the dual lighting system setup. It's a terrific light! The only thing that was going to keep this light out of EDC rotation are the ergonomics of the PD. Then I ran across this thread: https://www.candlepowerforums.com/threads/209661
and realized that I'm not alone. I know that usually these postings are usually about swapping LEDs or drivers or other electrical gizmo so I hope that you find this an interesting departure.

A quick intro to me: I'm a mechanical process engineer and I also play with race cars. I spend a big part of my life optimizing processes and machinery. As such I can't turn that off in my private life. It's a curse and a blessing...:duh2:

I took the light to work and took some measurements of the force required to actuate the light and compared those forces to the L1 (my current ergonomic favorite). Here's what I found for actuation button force:

Light/Low Level Force (lbs)/Hi Level Force (lbs)
L1 / 1.7 / 3.0
LS20/ 3.7 / 5.2

The values above were recorded on the L1 with tail cap aligned with the machined dots and on the LS20 with the head screwed out to the extent that the light could not be actuated by pressing the head down.

As you can see the LS20 requires roughly twice the force to actuate than the L1.

I figured that I could live with the higher force level if I could press the button easier. The LS20 button is recessed within the tail cap providing a very stable tail stand platform. The L1 button protrudes about 3/8". In my preferred overhand grip I found the button very difficult to work comfortably and with a cigar grip only marginally better. I decided to make a button extension for the LS20. Initially I set the dimensions so that the button would extend 1/8" beyond the tail of the light. I attached the button to the light using a VHB PSA that I had in my garage. The PSA is probably expired so this installation is temporary in my view.

So far I've found this to be much more comfortable. I plan to put the light into dog walking duty for a while to see if I need to make another adjustment or if this will suffice.

Here is a digipic comparing the L1 to the extended LS20 tail button length:



The next two show the comparison of the two lights in my preferred grip:





With the extension I am getting to the button a little better, its just a matter of whether its better enough to satisfy me. I'm still a little concerned with the force level but only time will tell if that will be okay for me.

Regards,
HB

HB,
You can cut off the final "dead" circle from the battery spring and then if need be, stretch the spring taller. This will yield a lower activation force requirement, compared to "stock". On the PD, the spring is the battery contact spring and its force is required to return you to off. Consequently you can't necessarily get it as soft as you might like were the spring only providing the function of switching and not other duties in addition. :shrug:

When I was looking over the light it was apparent that the spring performed battery contact and on/off. I decided not to mess with the spring for now since I didn't want to compromise the electrical connection, which works just fine. I did notice that Lee Spring has some battery springs that are similar, however, with k values much lower than the one installed in the LS20. I may order a couple of samples up to see what they do. Of course, there is the oring fit/stiction to overcome as well.

I'll let you know what happens next.

Regards,
HB

HB,

If I may, I'd like to suggest that you give the stock light a chance. It takes a couple weeks, but certain little used muscles in your hands will develop and change your entire outlook on the whole recessed vs. protruding button issue.

Right from the get-go, I too suspected that I wouldn't like a recessed button nearly as much, as my previous experiences, and my prejudices in general about such matters, were against the whole notion of having to jam your thumb in at such an angle. So that was a concern for me about the LS20. But I also was excited about the tailstanding/candlemode ability. So I figured it was a wash and I'd so how I adapted to it.

There was actually a bit of soreness involved, but probably because I couldn't stop playing with the light for the first weeks I owned it! But by two weeks in, I found that I just LOVED the whole set up. Every little thing. And I wouldn't change a thing about it at this point. Not the force, not the throw distances, not the piston protrusion length.

Your mileage may vary, of course, but you might consider giving the stock setup a try! It's stock for a very good reason, in my opinion.

Not that you shouldn't mess with it, though. I'm cool with that. Just think that you want to mess with it AFTER you find out how it really will be for you after a short "break in" period (or build-in, muscle-wise).

js said:

HB,

Not that you shouldn't mess with it, though. I'm cool with that. Just think that you want to mess with it AFTER you find out how it really will be for you after a short "break in" period (or build-in, muscle-wise).

Click to expand...

+1

no comment

light man said:

Don's lights are very well thought out. Everything is designed around tradeoffs. The ability for a light to stand in candle mode far outweighs any seemingly insignificant notion that it's inferior to a protruding actuation design, and the recessed plunger further protects the light from potential damage. Further, if you don't have enough strength to push the plunger.....God help you :laughing:

With all of you're education, you must be aware of the 101 common sense law which states......if it ain't broke, don't fix it.

Click to expand...

My god man, I thought I invented "if ain't broke don't fix it."

Seriously, I don't value candle mode trail standing since it has no relevance in my life. I have lights in my home.

I am interested in the quality of the LS20 lighting and find it useful and unique. Enough so that I'll probably pickup a LS27 soon on B-S-T.

Everything in design is a trade-off. I am just doing a little more trading to tailor the light to my specific needs and wants. Giving the design constraints in the LS20 (effective waterproofing, robust electrical path, cost, multilevel switching with a PD... ) I think I've got a basic handle on why it is the way it is. My frame of reference for ergonomic comparison comes from other well designed lights (Novatac, Surefire, Ra, MJ, Lumini, Lightflux, Photon, Lumapower, Maglight, Fenix) as well a life lived paying attention.

Certainly, I can adapt to the light, however, I see no reason to do so when I can affect change.

To me what I am dialing in here is no different than swapping an LED or reaming out a L1 to run AW cells, or adding a pocket clip. No single design is perfect for everyone, especially not perfect for the enthusiast.

Hopefully we are all open to exploring all possibilities without artificial constraints. Let's see what happens next! :laughing:

Regards,
HB

The main reason I stopped using a Mr. Bulk Lion Heart or Lion Cub for EDC was the fact that if you drop either of them or even set one down to tail-stand a bit too hard, the spring pressure was not sufficient to force continued battery contact with the front contact and the light goes out. None of the lights I've used from Don has done this. I prefer clickies myself but the sheer drop-dead-stupid reliability of the PD design trumps most other considerations for me in my EDC light. They do get easier to turn as the threads wear in - especially with a little help from Mr. Dremel on the threads.

Just my opinion

Bill S.

HB,

My point was that if you try it as-is for a week or so, your preference might change. If it doesn't, then, nothing lost: affect the change in the design you desire. But if it does, then you don't have to change the light.

We all adapt when using a new tool. It happens when you learn to drive. It happens when you learn to type. It happens when you play the piano. And it doesn't make sense to mess with the action on your piano to make it easier to depress the keys during that critical time when your finger muscles are developing!

It's a fundamentally different hand grip than the L1. Don't get me wrong, I love the L1 and A2 and L2! I've waxed poetic about the LOTC on these lights in places. And I dislike it when a shroud is put around the LOTC so that you are forced to jam your thumb-tip in instead of using the pad of your thumb. No question. On those lights, I like the protruding button setup.

And I was worried about the recessed button on my LS20 when I first got it, but I figured it was a trade off and that I got candle mode and that I could always just activate it at the head of the light the majority of the time. And when I got the light, I found it bit difficult to activate, and even a bit painful on rare occasions. My suspicions were confirmed!

But then, I couldn't stop playing with the light, and started to really fall in love with it's utility and form factor and so many other things. And by and by, before two weeks was up, I found I could easily activate the light, and that I preferred the jam-your-thumb-tip set-up. I go back to my A2 from time to time, and while I still really like the LOTC and the UI and ergonomics of it, it is not nearly as AWESOME as my LS20 piston-drive UI.

Stock.

Unmodified.

So, my point (to reiterate) is just that if you mod it NOW, before you give it a chance, you might never know if you would have preferred it stock.

OK. More than enough said on my part! Hope I didn't belabor the issue too much!

no comment

First of all If you feel the need to Mod the light then Mod the hell out of it and share the process here with us.
Next I have to agree with the idea that your perception of the light may change with a week or two of use.

Personally I EDC a lunasol 20. Why? Because the overall package fits my needs just right.
Is it perfect? Nope. None of my lights are perfect. Does it matter? Not one bit.

OK the concept of changing the amount of force required to operate the light is a rather normal need.
Gun owners make this adjustment all the time. Why not flashlight owners?
I had a aleph that had what seemed like a stiff spring. I switched out the button cover with a next gen boot and the force required to operate that light became just about perfect.

Unfortunately this mod is not as simple on the Lunasol.
I would definitely get my hands on some of the springs used in the Lunasol and experiment. You may just happen upon a happy pressure zone...the perfect activation pressure needed.
So Go for it have fun. Oh and do get your hands on a lunasol 27 if you like the 20 you will likely like the 27 too I sure as heck do.
Yaesumofo

yaesumofo said:

First of all If you feel the need to Mod the light then Mod the hell out of it and share the process here with us.

Click to expand...

Right on! That's what I gonna do.

Later,
HB

i do have the need with tactile interfaces to search, tweak or modify them to my liking.

As many say flashlights are tools, but for me, tools need to feel more like an extension of your body and less than tools, to be more efficient tools.

coincidentially i also use the L1 as the standard and is definitely my preferred switch and UI, and its not only the activation force, its also about the travel and the fact that you can hold on to the mode you are using even if the force varies, in other words, the range for the modes is very good.

i have a KL1 head+E1Lbody+McE2S+McTC, which i like because its like a smaller, more versatile L1, the flood beam is beautiful (McR20s with a SSC P4 U bin), and i tweaked the switch to a point its really good, the force of activation is even a bit lower than the L1, the travel is a bit smaller, and the twist operation needs less twist, but the L1 still is champion on the range of force need for modes department, as perfect as force needed i have tweaked on the McE2S, it still changes mode with a much smaller variation in force (unintentional sometimes) than the L1, specially on high.

however the McE2S is a great switch, and you need to tweak it to be good, but its definitely worth it.

i made a thread about this light, it was Brizzler previous EDC, and he made a really good job, but as soon as i got my paws on it, i knew i had to fiddle with the switch.

https://www.candlepowerforums.com/threads/209988

on the second page i have some pics of what i tweaked and some parts i had to change.

what for me works better: softer boot, fill the gap between boot and button, and there definitely needs to use a cylindrical, not conical spring, its very important for the positive feedback, as the force needed stays a bit more linear

manoloco said:

i do have the need with tactile interfaces to search, tweak or modify them to my liking.

As many say flashlights are tools, but for me, tools need to feel more like an extension of your body and less than tools, to be more efficient tools.

Click to expand...

What he said...

I had noticed when I pressed the plunger I could feel the machined finish on the O.D. of the PD plunger scraping across the I.D. of the body. Once again this was really stepping on my buzz with respect to this light. This morning I polished the O.D. of the PD. I took .001" off a band .5" wide from the open end of the PD. This had an enormous affect on the tactile feel of operating the light and no effect on the actuation force level. The scrapping is completely gone. The PD is starting to feel like a precision mechanism now.

I now have the +1/4" tail. That is a tail cap that protrudes 1/4" beyond the rear of the light. I'll fit the cap up this evening to see how I like it. The +1/8" cap has been pretty okay. I'm anticipating that the +1/4" version will be the cats meow.

I've also ordered some alternative battery springs to reduce the actuation force levels. I should have those tomorrow for testing.

Just for fun while I was x-raying some experimental results this morning I threw the LS20 in the x-ray machine. I've attached that x-ray below.

Later,
HB

The x-ray is very cool. I like seeing things like that. :thumbsup:

Very neat Xray pic!

Mayo

HB, very nice!, and its great to see someone tweaking his tools to the millimeter

About the springs, my recomendation for battery springs is to try cylindrical shaped ones, not conical, conicals apart from being stiffer, offer more progressive resistance, cylindricals tend to need a force more inclined to being linear for activation (which i prefer).

Surefire uses this method for its L1/L2/A2 switch.

Heckboy, could you post a link to your source for these springs? Or does anyone else know of a source for original equipment springs?

Cool image HeckBoy!

If you are going to extend the button as far as you say, have you considered a means of securing it to the piston itself? If yes and depending on how and when it is secured, you might also want to consider having an interfering band on the button that provides a stop in advancing it forward. This could give you a lock out feature which might be useful with an exposed button.

I made one proto for Peter a few years ago that had a full diameter button as I recall. It had a male stud that screwed into a blind hole in the end of the piston. Super easy to activate in the manner of your preference and it would still tail stand. It also would lock out by backing out the head a bit (O-ring was still covered and providing a seal). The L1/L2/A2 tail switch is a great system and a key feature, IMHO, is the ability to lock out. When I originally designed the PD, minimum length was high in demand and lock out a preferred feature set at the time. The design did not and does not provide any lock out but the nature of force required as well as the guarded piston end has shown through experience of users not to need a lock out.

The piston/ sleeve resistance is annoying on some of the lights initially but I have found with my personal lights that this is a surface contact that will improve with wear. I have held back a few serious offenders on this issue for my own use and have been pleased with how well they come around in use.

I am of the same school as you and manoloco when it comes to taking something stock and then modifying it to beter suit my needs and desires. I got started in this "madness" years ago by taking brand new and perfectly functioning SureFire lights and chucking them up in my bench lathe.

If you can make a tweak or improvement by altering one of my lights to better suit your needs then by all means. If the tweak is an improvement on a global level then I need to pay attention to what you have done! Some improvements are nothing more than a change in the compromise set whereas others may just be an overall improvement in design or function. Some may be practical for the individual but not feasible necessarily for production. Optimizing the mate of a particular set of components is possibly one such example; depending on the time and effort required.

Scottiver said:

Heckboy, could you post a link to your source for these springs? Or does anyone else know of a source for original equipment springs?

Click to expand...

Here are couple of sources. The Century Spring website isn't as nicely organized as the Lee Spring. I haven't seen an exact match for the original spring, but, I'm not looking for one.

http://www.leespring.com/battSpring_intMount.asp

http://www.centuryspring.com/

Regards,
HB