lightlover
Flashlight Enthusiast
Conversion of a SureFire M2 to run 3x CR123A
- The 3-Cell LL-Wobbly BlankF*re™ M2 Conversion (Reversible) - It's EXTRA Bright! -
I've searched CPF, but haven't found any references to running a 3-cell M2. This conversion depends on gaining every possible millimetre of internal length: my M2 works, perhaps others will not.
There are plentiful discussions about using P60 LED drop-ins in the SF M2. Many concern the issue of heatsinks for the LED, and the possibly insulating property of the Shock-Absorption System's foam.
I love the anti-shock feature of the M2 – it is elegant, simple, and effective.
(By look and touch, the foam in two ~10yr old M2's I have appears to be in perfect condition still – a high spec after dealing with much heat and time).
So, yes, it's terrific for incands, but not relevant to any LED I can think of.
I realised that without it, quite a lot of room was made available . . . .
Deep Thoughts about what I might make of that followed, as naturally as bears go into the woods.
The shock-absorbing system can be removed / replaced very easily, once the Lens Retaining Ring is removed. (Soften the threadlocker by boiling your head in a thick cloth bag, and just let it cool slowly. Even Borosilicate glass can be broken by cooling too fast – I know this to be true . . . . ).
Reading back, I seem to have made this seem really complicated, so I've numbered the points P1, P2 etc.
To Convert a M2 Into a Wobbly, These Are The Main Steps:
P 1. Remove the components of the shock-absorbing system.
P 2. Take the Locating Collar and wrap it once around with a short length of copper tape. (Wire could probably be used, but I've got a reel of the tape).
P 3. Take the Nitrolon Lens Retaining Ring, and fit the Locating Collar inside it, with the narrower diameter facing outwards. (Same orientation as it was).
P 4. Wrap the copper tape around that too, so that when replaced, the Locating Collar is electrically linked to the body. (The tape is thin enough that you'll still be able to screw the Retaining Ring into place, and then the copper tape connection ensures the circuit to the body is completed).
P 5. The Locating Collar will protrude a couple of millimetres past the end of the bezel, the flange holding and centering the P60 Module, recessing it a little back, so acting as a bumper, FWIW.
P 6. All that allows about 10mm extra space internally.
P 7. DOWNSIDE: the module isn't safely behind a lens - it protrudes beyond the end of the bezel by about 2mm. The module's lens could be chipped / scratched, if it falls. (It is still behind the flange though).
P 8. And the end of the module is now much too far away to make contact with the usual complement of 2 batteries.
So, just go on to make that Tragedy even more Comedy:
P 9. Screw the completed head back onto the body as per usual: but ONLY to the point where the head just safely covers the body front O-ring.
P 10. DOWNSIDE: the head is left SLIGHTLY WOBBLY – but not enough to make it loose and insecure, or break the circuit path.
P 11. The head is actually held aligned and quite tight by the ~2.5 turns of thread it can make, and reinforced by the pressure of the O-ring.
P 12. If you want to make the O-ring fit tighter, then it's possible to wrap a few turns of plastic thread, (for instance, monofilament fishing line) in the O-ring groove. That takes up enough space to make the difference.
P 13. Tested by 1hr immersion in water, the greased-up O-ring still seals the join.
P 14. A thicker O-ring may give extra bracing, but I haven't tested that yet.
P 15. The light is sealed by the original O-ring, but to protect it I add another O-ring to the outside as a dust and debris seal.
P 16. With the head+body put together in that position, you gain another ~8mm space.
P 17. The CR123a's that I'm using measure ~35mm from +ve to –ve contact points (the wrapping adds another 0.3mm, but that doesn't come into play).
P 18. Removing the shock-absorbing system and screwing on the M2 head on only just enough to, combines to ~18mm, a little over half a battery.
P 19. Screw the tailcap on just enough to cover both the O-rings, and complete the circuit path.
P 20. The external length of the M2 is now increased by only ~7%, from ~143mm to ~151mm, so 5.6" to 5.95".
P 21. Conversion and ~Measurement errors included! (Say an extra ~10mm / 0.4").
Now, the generous allowances of the M2 design allow a third CR123a to be fitted in, even though it is only designed for two.
P 22. I've tested it using a Sportac 2 level P60 drop-in, and that fits neatly into the new forward position of the Locating Collar.
P 23. DOWNSIDE: Of course, the result of the two rings at the lens end holding in and centering the P60 module isn't a waterproof seal – that problem still has to be dealt with.
P 24. For now I'm thinking of applying a clear silicone, as that is heat-resistant, seals and sticks, while still being easily removable.
P 25. As far as I can make out, the Sportac Module itself is sealed at the front, so at the least, it's weather-protected.
P 26. DOWNSIDE: the third battery is only part supported by the battery tube, held in place by spring pressure. It would benefit from a washer to position it, or best of all, a machined heatsink shaped to fit the tapered space. Someday …
P 27. It's important to be make sure that the third battery meets properly with the Sportac's contact disc, as that disc is surrounded by the usual raised plastic wall to hold the battery button in place. If it is a little bit out, the third battery button contact won't seat correctly, won't make contact.
P 28. It's probably best to fit the head to the body, then precisely fit the first battery into place. The 2nd and 3rd batteries will be guided to follow the tube.
But, I've managed to successfully use 3 batteries in a working M2!
I'm currently running a 6V Sportac drop-in on 2x CR123a's and 1x spacer, and so far, it's been reliable and predictable.
P 29. DOWNSIDE: The standard SF twisty tailcap works, but for some reason, the momentary press-ability seems to be lost. That may be because the quite strong SF switch spring is compressed beyond its usual limits. Turning on and off is by rotating the tailcap only 180 degrees, which also seems enough range to solidly lock-out.
P 30. Obviously, improvements to the LL-Wobbly system are needed: I haven't yet dared to cut down the Sportac's contact spring for another ~3.5mm space. That would involve permanently removing the Sportac's contact disc, and so make their 18650 adaptor unusable, at least without some fooling around (as far as I can see).
P 31. Another way of increasing the available length of the battery tube would be to cut-down the spring of the tailcap switch. Haven't dared do that yet either …
P 32. I think a McClicky with the spring shortened and end filed smooth will be my next step – that should give more room.
P 33. Is the McClicky switch's travel (if any) contained within its body?
P 34. If so, cutting the spring down to one turn should give the most space in practical terms. I seem to remember McGizmo mentioning that he sometimes has cut the spring down for some applications.
P 35. And an Oveready-type metal Lens Retention Ring would probably give a more secure hold, even if it was fitted partly undone – that way, I'd gain an extra ~1mm or so, maybe try to fit a lens in.
P 36. I think that with a metal Lens Retention Ring fitted, I'd use a soft threadlocker or soft glue for added security, with an O-ring filling the slight gap left by screwing it on only part-way.
P 37. But, currently, Oveready only have the S/Steel smooth available in the black finish, while my M2 is an uncoated, plain Aluminium finish. (At the moment, the clear S/Steel is not available un-crenellated, and I just don't like pronounced crenellations much, however practical they are.
As I long-ago removed the HA3 from my M2, and after all the polishing-up I've done, I really don't want to have a contrasting colour.
P 38. If I get the slight taper at the bezel end of the body bored straight and parallel, it should be relatively simple to get a cylindrical heatsink made up – not sure yet about the dimensions though. Just enough to reach the end of the battery, or to where? Past the button?
P 39. Thankfully, there is no P 39.
QUESTIONS:
Q 01) If it can use 3x CR123a's, could I use 2x 17670's?
Q 02) Could I use other battery combinations? What would I get out of other combinations?
Q 03) While experimenting and developing the Wobbly, due to the pressures they were put under, two fresh CR123a's I with now have slightly dished -ve ends. Seem to work OK, but should I retire them?
Q 04) A Boring Question (Yawn): If bored out to 18.90mm as precisionworks.com do, and I'd very much like to do, the wall thickness rermaining would only be 0.80mm at the O-ring channel. Wouldn't that be too, too thin? – I'd always be thinking about the fragility of it if dropped.
Q 05) Is it actually mechanically possible to bore the tube out without damaging the body at that thinness?
Q 06) Anyone using an M2 with that kind of wall thickness?
Q 07) Anyone using a Sportac P60 with the spring cut down to just one coil? For what particular reason?
Q 08) Running the M2 without the shock-absorbing system and only 2 batteries could be done, but to what purpose?
lightlover / BlankF*re™
"I'm sorry that this post is so long; I did not have the confidence to compose a shorter post" (Paraphrasing Blaise Pascal)
- The 3-Cell LL-Wobbly BlankF*re™ M2 Conversion (Reversible) - It's EXTRA Bright! -
I've searched CPF, but haven't found any references to running a 3-cell M2. This conversion depends on gaining every possible millimetre of internal length: my M2 works, perhaps others will not.
There are plentiful discussions about using P60 LED drop-ins in the SF M2. Many concern the issue of heatsinks for the LED, and the possibly insulating property of the Shock-Absorption System's foam.
I love the anti-shock feature of the M2 – it is elegant, simple, and effective.
(By look and touch, the foam in two ~10yr old M2's I have appears to be in perfect condition still – a high spec after dealing with much heat and time).
So, yes, it's terrific for incands, but not relevant to any LED I can think of.
I realised that without it, quite a lot of room was made available . . . .
Deep Thoughts about what I might make of that followed, as naturally as bears go into the woods.
The shock-absorbing system can be removed / replaced very easily, once the Lens Retaining Ring is removed. (Soften the threadlocker by boiling your head in a thick cloth bag, and just let it cool slowly. Even Borosilicate glass can be broken by cooling too fast – I know this to be true . . . . ).
Reading back, I seem to have made this seem really complicated, so I've numbered the points P1, P2 etc.
To Convert a M2 Into a Wobbly, These Are The Main Steps:
P 1. Remove the components of the shock-absorbing system.
P 2. Take the Locating Collar and wrap it once around with a short length of copper tape. (Wire could probably be used, but I've got a reel of the tape).
P 3. Take the Nitrolon Lens Retaining Ring, and fit the Locating Collar inside it, with the narrower diameter facing outwards. (Same orientation as it was).
P 4. Wrap the copper tape around that too, so that when replaced, the Locating Collar is electrically linked to the body. (The tape is thin enough that you'll still be able to screw the Retaining Ring into place, and then the copper tape connection ensures the circuit to the body is completed).
P 5. The Locating Collar will protrude a couple of millimetres past the end of the bezel, the flange holding and centering the P60 Module, recessing it a little back, so acting as a bumper, FWIW.
P 6. All that allows about 10mm extra space internally.
P 7. DOWNSIDE: the module isn't safely behind a lens - it protrudes beyond the end of the bezel by about 2mm. The module's lens could be chipped / scratched, if it falls. (It is still behind the flange though).
P 8. And the end of the module is now much too far away to make contact with the usual complement of 2 batteries.
So, just go on to make that Tragedy even more Comedy:
P 9. Screw the completed head back onto the body as per usual: but ONLY to the point where the head just safely covers the body front O-ring.
P 10. DOWNSIDE: the head is left SLIGHTLY WOBBLY – but not enough to make it loose and insecure, or break the circuit path.
P 11. The head is actually held aligned and quite tight by the ~2.5 turns of thread it can make, and reinforced by the pressure of the O-ring.
P 12. If you want to make the O-ring fit tighter, then it's possible to wrap a few turns of plastic thread, (for instance, monofilament fishing line) in the O-ring groove. That takes up enough space to make the difference.
P 13. Tested by 1hr immersion in water, the greased-up O-ring still seals the join.
P 14. A thicker O-ring may give extra bracing, but I haven't tested that yet.
P 15. The light is sealed by the original O-ring, but to protect it I add another O-ring to the outside as a dust and debris seal.
P 16. With the head+body put together in that position, you gain another ~8mm space.
P 17. The CR123a's that I'm using measure ~35mm from +ve to –ve contact points (the wrapping adds another 0.3mm, but that doesn't come into play).
P 18. Removing the shock-absorbing system and screwing on the M2 head on only just enough to, combines to ~18mm, a little over half a battery.
P 19. Screw the tailcap on just enough to cover both the O-rings, and complete the circuit path.
P 20. The external length of the M2 is now increased by only ~7%, from ~143mm to ~151mm, so 5.6" to 5.95".
P 21. Conversion and ~Measurement errors included! (Say an extra ~10mm / 0.4").
Now, the generous allowances of the M2 design allow a third CR123a to be fitted in, even though it is only designed for two.
P 22. I've tested it using a Sportac 2 level P60 drop-in, and that fits neatly into the new forward position of the Locating Collar.
P 23. DOWNSIDE: Of course, the result of the two rings at the lens end holding in and centering the P60 module isn't a waterproof seal – that problem still has to be dealt with.
P 24. For now I'm thinking of applying a clear silicone, as that is heat-resistant, seals and sticks, while still being easily removable.
P 25. As far as I can make out, the Sportac Module itself is sealed at the front, so at the least, it's weather-protected.
P 26. DOWNSIDE: the third battery is only part supported by the battery tube, held in place by spring pressure. It would benefit from a washer to position it, or best of all, a machined heatsink shaped to fit the tapered space. Someday …
P 27. It's important to be make sure that the third battery meets properly with the Sportac's contact disc, as that disc is surrounded by the usual raised plastic wall to hold the battery button in place. If it is a little bit out, the third battery button contact won't seat correctly, won't make contact.
P 28. It's probably best to fit the head to the body, then precisely fit the first battery into place. The 2nd and 3rd batteries will be guided to follow the tube.
But, I've managed to successfully use 3 batteries in a working M2!
I'm currently running a 6V Sportac drop-in on 2x CR123a's and 1x spacer, and so far, it's been reliable and predictable.
P 29. DOWNSIDE: The standard SF twisty tailcap works, but for some reason, the momentary press-ability seems to be lost. That may be because the quite strong SF switch spring is compressed beyond its usual limits. Turning on and off is by rotating the tailcap only 180 degrees, which also seems enough range to solidly lock-out.
P 30. Obviously, improvements to the LL-Wobbly system are needed: I haven't yet dared to cut down the Sportac's contact spring for another ~3.5mm space. That would involve permanently removing the Sportac's contact disc, and so make their 18650 adaptor unusable, at least without some fooling around (as far as I can see).
P 31. Another way of increasing the available length of the battery tube would be to cut-down the spring of the tailcap switch. Haven't dared do that yet either …
P 32. I think a McClicky with the spring shortened and end filed smooth will be my next step – that should give more room.
P 33. Is the McClicky switch's travel (if any) contained within its body?
P 34. If so, cutting the spring down to one turn should give the most space in practical terms. I seem to remember McGizmo mentioning that he sometimes has cut the spring down for some applications.
P 35. And an Oveready-type metal Lens Retention Ring would probably give a more secure hold, even if it was fitted partly undone – that way, I'd gain an extra ~1mm or so, maybe try to fit a lens in.
P 36. I think that with a metal Lens Retention Ring fitted, I'd use a soft threadlocker or soft glue for added security, with an O-ring filling the slight gap left by screwing it on only part-way.
P 37. But, currently, Oveready only have the S/Steel smooth available in the black finish, while my M2 is an uncoated, plain Aluminium finish. (At the moment, the clear S/Steel is not available un-crenellated, and I just don't like pronounced crenellations much, however practical they are.
As I long-ago removed the HA3 from my M2, and after all the polishing-up I've done, I really don't want to have a contrasting colour.
P 38. If I get the slight taper at the bezel end of the body bored straight and parallel, it should be relatively simple to get a cylindrical heatsink made up – not sure yet about the dimensions though. Just enough to reach the end of the battery, or to where? Past the button?
P 39. Thankfully, there is no P 39.
QUESTIONS:
Q 01) If it can use 3x CR123a's, could I use 2x 17670's?
Q 02) Could I use other battery combinations? What would I get out of other combinations?
Q 03) While experimenting and developing the Wobbly, due to the pressures they were put under, two fresh CR123a's I with now have slightly dished -ve ends. Seem to work OK, but should I retire them?
Q 04) A Boring Question (Yawn): If bored out to 18.90mm as precisionworks.com do, and I'd very much like to do, the wall thickness rermaining would only be 0.80mm at the O-ring channel. Wouldn't that be too, too thin? – I'd always be thinking about the fragility of it if dropped.
Q 05) Is it actually mechanically possible to bore the tube out without damaging the body at that thinness?
Q 06) Anyone using an M2 with that kind of wall thickness?
Q 07) Anyone using a Sportac P60 with the spring cut down to just one coil? For what particular reason?
Q 08) Running the M2 without the shock-absorbing system and only 2 batteries could be done, but to what purpose?
lightlover / BlankF*re™
"I'm sorry that this post is so long; I did not have the confidence to compose a shorter post" (Paraphrasing Blaise Pascal)
