I've been thinking of compiling an unofficial Arc6 FAQ guide for quite a while, so here goes...
Add your own tips, corrections and FAQ's below and i'll merge them in.
Updated on 08/11/28
Arc6 FAQ & Tips
* My Arc6 is stepping down from Level 7 to approximately one fifth of the initial output in just a few minutes. What is going on and are my batteries dead?
Arc6 has two step-downs - a thermal step-down and a battery step-down. Thermal step-down occurs when the body of the flashlight heats up to about 50 deg. C, to protect the emitter, and always goes down to Level 3. Battery step-down occurs when the battery is nearing depletion and steps down a single level at a time, until it reaches the lowest level.
* My Arc6 isn't working properly on Level 7. It flickers and dies or drops to a lower level immediately. I'm using AW brand protected RCR123A batteries...
AW batteries seem to have a pretty conservative over-current protection, that cuts them off almost immediately after activating Level 7. Level 7 draws huge currents and should be used with primaries and unprotected batteries that are known to be able to sustain high discharge currents (up to 4-5A).
* Even disregarding the thermal step-down, my Arc6 doesn't seem to last very long on a single charge at Levels 7 and 6. It seems pretty inefficient. Why is that?
Levels 7 and 6 are inefficient by design. They are there for short bursts, not continuous use. Drivers can't really be made efficient at both, extremely high output levels and extremely low output levels. Arc6 is designed to be an EDC, so there really isn't much sense in making them highly efficient at the expense of having inefficient medium and low levels. On top of that, Levels 6 and 7 overdrive the LED emitter which, in itself, reduces the overall efficiency (don't worry, though, the emitter is safe thanks to thermal protection).
To sum things up, Levels 6 and 7 waste a lot of energy (into heat). If you use them often, the overall amount of lumens per hour will be much lower than if you use lower levels only. Use them sparingly.
* Should i replace the battery as soon as the Arc6 steps down a level?
If you're using a rechargable battery - by all means, YES! If you want to prolong its life, that is. Lithium-ion batteries don't "like" being discharged too low too often. Topping them up rather than recharging them in complete cycles is much healthier for them.
* I've just switched my Arc6 on and it did a little "tint-shuffle" - the tint of the light shifted for a split-second, then returned to normal. What gives?
It's a side effect of Arc6's MCU adjusting to a discharge curve of a new battery or a sudden change in voltage (change of temperature, possibly?). Its nothing to be particularly worried about.
* I've been using the Arc6 at higher output levels for a while when it suddenly started shifting to yellow or green, then stepped down to a lower level. Is my emitter fried?
No, everything is just fine. The Arc6 has a "tint-control" feature that does it's best to keep the tint as uniform as possible throughout the various output levels by combining constant current (DC) and PWM regulation. When the battery voltage starts going down (i.e. the battery is nearing depletion), it starts losing the tint control (which is good, because it conserves power) and the tint starts shifting back to its "natural" state for a given level (which is usually yellow for the lower output currents).
* My piston is VERY stiff. What can i do to make it easier to activate? (you there, stop snickering!)
A number of things. You can replace the stock grease with some Krytox 50/50 blend from the Sandwich Shoppe or make a similar grease/oil blend yourself. You can degrease the part where the bottom of the piston touches the bottom of the battery sleeve, to prevent it from "sticking" to it. You can lube the piston with a less viscous oil only. You can use a thin screwdriver to bend the kilroy loop flatter, so the distance between Stage 1 and Stage 2 is shorter.
Finally, you can find a replacement spring, make one yourself from a suitable piece of wire or mod an existing one. Cutting and stretching the stock spring allegedly helps too. Heating and cooling it isn't recommended because it usually ends up with the spring breaking.
You can switch to using the guarded sleeve as well if you don't mind the extra size. It gives a better grip and makes keeping the piston depressed easier.
* What should i use to lube my Arc6?
Non-viscous oil works well on the piston. A mix of grease and oil, such as the Krytox 50/50 blend, works well on the threads (as it has a nice balance of resistance and smoothness, just right for the twisty action). Silicone oil sprays don't work that well, because they flow off the piston and/or threads quickly. Same goes for various graphite sprays, nano-lubes etc. Also, note that certain silicone greases and oils can make the silicone o-rings in the Arc6 swell!
* Where can i get replacement o-rings that fit the Arc6?
They are the same as the ones used in Don McLeish's (McGizmo's) Piston Drive lights. The Sandwich Shoppe has them every now and then. Search for "Silicon 16 O-ring for PD".
* What material is the piston made of?
The orginal PD was brass with nickle plate, the Arc6 uses 6061 Al with hard nickle plate. Same surface hardness (essential for smooth rotation against kilroy), about 1/3 the weight.
* What should i use to mount a tritium vial locator on my Arc6's piston?
Option 1 - Devcon two-ton clear epoxy. Option 2 - rear-view mirror glue. Option 3 - Norland Optical Adhesive NOA61. Norland is clearest and deals with UV best (in fact, it hardens when subjected to UV light). Devcon yellows with age and UV exposure. There's not much known about the rear-view mirror glue, but someone suggested it as a viable option in one of the CPF threads once.
There's also a fourth, fallback option - using a glue rated for metal, glass and plastic. You'll have to take care to do things in two stages (putting a layer of glue, seating the vial on the layer, then adding a bit more glue on top) to keep the layer on top of the vial as thin as possible, so as not to attenuate the vial's output too much, though.
* I've heard there could be some problems with the "plus nipple" (the little ball of solder) collapsing under certain conditions. Is it something i should be worrying about? Also, there are some wear marks on the kilroy loop from the piston edge.
Unlike some other implementations, the plus nipple on the Arc6 isn't hollow, but a solid ball of solder, so there is no danger of it collapsing if the battery is subjected to mechanical shocks. Regarding the kilroy, there have been quite a few Piston Drive lights in the field for several years now and it's been unheard of any of them wearing through a kilroy. In the highly unlikely event of it actually happening, the light will be repaired under warranty (according to Peter).
* I've removed the bezel and the sapphire window to clean my reflector/emitter dome and now i don't know how to put it back. How do i find the correct orientation of the window?
Both sides of the window are coated with an AR layer, so it doesn't matter. Put it back whichever side you want.
* Are the clip screws on the Arc6 guarded sleeve made of titanium?
A thread about the McLux spare screws and Ti clip reports that the McGizmo screws are titanium but the screws sold by the Sandwich Shoppe when you buy a spare clip are stainless steel. The Arc6 screws seem to have a flatter head than the McGizmo screws and would seem to be consistent with the ones sold by the Shoppe. Also, they are colder to the touch than the clip itself (titanium is a worse heat conductor than stainless steel) and don't look (colorwise) like titanium. To sum it up, they're quite probably stainless steel.
* Switching from Stage 1 to Stage 2 seems extremely unreliable on my Arc6. It flickers and/or doesn't work at all at times. What's going on?
Try cleaning the upper piston edge, the kilroy loop and the contact ring in the head from any residue, oil or grease. Also, check if your kilroy's got bent too flat - if it gets so flat that it's almost level with the contact ring, there will be no or almost no distance between the Stage 1 and Stage 2, causing flickering or making the Stage 2 inaccessible.
* What is Stage 3?
Stage 3 is a virtual stage, meaning it doesn't correspond to any "real" position of the head or distance the piston travels when you push it. You activate it by pressing or twisting all the way to Stage 2 from off, without stopping at Stage 1. Sort of like slamming on the brakes. It's disabled by default and you have to enter the configuration menu to set it up (refer to the Arc6 manual for instructions on how to do that).
* What is Soylent Green?
Soylent Green is people!
* I can't seem to get to the configuration menu, no matter what i do. What am i doing wrong?
Firstly, make sure you've twisted the head to Stage 1 then started pressing the piston to Stage 2 ten times. Secondly, make sure all the contacts are clean. Thirdly, press in an even manner, about twice a second. Finally, bear in mind that if you fail to enter the menu within 10 seconds of switching the light on (twisting the head to Stage 1), the menu will be disabled until you swithc it off and start all over again (that's a safety feature implemented to prevent accidental menu entry).
* I've just unpacked my shiny new Arc6's and the battery sleeve and/or head have uneven anodizing / splotches / stains. What kind of shoddy craftsmanship is this?!
Relax, breathe, don't worry. It's not an artifact of the anodization itself, but an oily residue of some sort on its surface. It's been reported by quite a few users. It will go away on its own after a few days - probably even faster if you keep playing with your new shiny toy over the course of the next few days
* The contact ring in my Arc6's head looks burnt. What's up with that? Will it impair its performance?
A few early Arc6 heads seem to have had contacts rings that look slightly "burnt" - i.e. slightly blackened or showing "rainbowy" artefacts. That's caused by the way the rings were soldered on (using a solder pot) and it has absolutely no effect on the lights performance. The ring is a switch contact only, i.e. it doesn't carry any current from the battery - all the current goes through the plus nipple and the kilroy loop.
* What's the little empty IC socket i can see on the PCB when i unscrew the Arc6's head? Did i lose a part?
It's an I2C socket used to connect the Arc6 to a computer for programming and calibration. According to Peter, there were plans once for an end-user-friendly interface board and software, which would enable the "braver" Arc6 users to change the output currents for each level and tweak or even disable thermal management parameters. So far, still no news on that front.
* Will there be cake?
No. The cake is a lie.
Add your own tips, corrections and FAQ's below and i'll merge them in.
Updated on 08/11/28
Arc6 FAQ & Tips
* My Arc6 is stepping down from Level 7 to approximately one fifth of the initial output in just a few minutes. What is going on and are my batteries dead?
Arc6 has two step-downs - a thermal step-down and a battery step-down. Thermal step-down occurs when the body of the flashlight heats up to about 50 deg. C, to protect the emitter, and always goes down to Level 3. Battery step-down occurs when the battery is nearing depletion and steps down a single level at a time, until it reaches the lowest level.
* My Arc6 isn't working properly on Level 7. It flickers and dies or drops to a lower level immediately. I'm using AW brand protected RCR123A batteries...
AW batteries seem to have a pretty conservative over-current protection, that cuts them off almost immediately after activating Level 7. Level 7 draws huge currents and should be used with primaries and unprotected batteries that are known to be able to sustain high discharge currents (up to 4-5A).
* Even disregarding the thermal step-down, my Arc6 doesn't seem to last very long on a single charge at Levels 7 and 6. It seems pretty inefficient. Why is that?
Levels 7 and 6 are inefficient by design. They are there for short bursts, not continuous use. Drivers can't really be made efficient at both, extremely high output levels and extremely low output levels. Arc6 is designed to be an EDC, so there really isn't much sense in making them highly efficient at the expense of having inefficient medium and low levels. On top of that, Levels 6 and 7 overdrive the LED emitter which, in itself, reduces the overall efficiency (don't worry, though, the emitter is safe thanks to thermal protection).
To sum things up, Levels 6 and 7 waste a lot of energy (into heat). If you use them often, the overall amount of lumens per hour will be much lower than if you use lower levels only. Use them sparingly.
* Should i replace the battery as soon as the Arc6 steps down a level?
If you're using a rechargable battery - by all means, YES! If you want to prolong its life, that is. Lithium-ion batteries don't "like" being discharged too low too often. Topping them up rather than recharging them in complete cycles is much healthier for them.
* I've just switched my Arc6 on and it did a little "tint-shuffle" - the tint of the light shifted for a split-second, then returned to normal. What gives?
It's a side effect of Arc6's MCU adjusting to a discharge curve of a new battery or a sudden change in voltage (change of temperature, possibly?). Its nothing to be particularly worried about.
* I've been using the Arc6 at higher output levels for a while when it suddenly started shifting to yellow or green, then stepped down to a lower level. Is my emitter fried?
No, everything is just fine. The Arc6 has a "tint-control" feature that does it's best to keep the tint as uniform as possible throughout the various output levels by combining constant current (DC) and PWM regulation. When the battery voltage starts going down (i.e. the battery is nearing depletion), it starts losing the tint control (which is good, because it conserves power) and the tint starts shifting back to its "natural" state for a given level (which is usually yellow for the lower output currents).
* My piston is VERY stiff. What can i do to make it easier to activate? (you there, stop snickering!)
A number of things. You can replace the stock grease with some Krytox 50/50 blend from the Sandwich Shoppe or make a similar grease/oil blend yourself. You can degrease the part where the bottom of the piston touches the bottom of the battery sleeve, to prevent it from "sticking" to it. You can lube the piston with a less viscous oil only. You can use a thin screwdriver to bend the kilroy loop flatter, so the distance between Stage 1 and Stage 2 is shorter.
Finally, you can find a replacement spring, make one yourself from a suitable piece of wire or mod an existing one. Cutting and stretching the stock spring allegedly helps too. Heating and cooling it isn't recommended because it usually ends up with the spring breaking.
You can switch to using the guarded sleeve as well if you don't mind the extra size. It gives a better grip and makes keeping the piston depressed easier.
* What should i use to lube my Arc6?
Non-viscous oil works well on the piston. A mix of grease and oil, such as the Krytox 50/50 blend, works well on the threads (as it has a nice balance of resistance and smoothness, just right for the twisty action). Silicone oil sprays don't work that well, because they flow off the piston and/or threads quickly. Same goes for various graphite sprays, nano-lubes etc. Also, note that certain silicone greases and oils can make the silicone o-rings in the Arc6 swell!
* Where can i get replacement o-rings that fit the Arc6?
They are the same as the ones used in Don McLeish's (McGizmo's) Piston Drive lights. The Sandwich Shoppe has them every now and then. Search for "Silicon 16 O-ring for PD".
* What material is the piston made of?
The orginal PD was brass with nickle plate, the Arc6 uses 6061 Al with hard nickle plate. Same surface hardness (essential for smooth rotation against kilroy), about 1/3 the weight.
* What should i use to mount a tritium vial locator on my Arc6's piston?
Option 1 - Devcon two-ton clear epoxy. Option 2 - rear-view mirror glue. Option 3 - Norland Optical Adhesive NOA61. Norland is clearest and deals with UV best (in fact, it hardens when subjected to UV light). Devcon yellows with age and UV exposure. There's not much known about the rear-view mirror glue, but someone suggested it as a viable option in one of the CPF threads once.
There's also a fourth, fallback option - using a glue rated for metal, glass and plastic. You'll have to take care to do things in two stages (putting a layer of glue, seating the vial on the layer, then adding a bit more glue on top) to keep the layer on top of the vial as thin as possible, so as not to attenuate the vial's output too much, though.
* I've heard there could be some problems with the "plus nipple" (the little ball of solder) collapsing under certain conditions. Is it something i should be worrying about? Also, there are some wear marks on the kilroy loop from the piston edge.
Unlike some other implementations, the plus nipple on the Arc6 isn't hollow, but a solid ball of solder, so there is no danger of it collapsing if the battery is subjected to mechanical shocks. Regarding the kilroy, there have been quite a few Piston Drive lights in the field for several years now and it's been unheard of any of them wearing through a kilroy. In the highly unlikely event of it actually happening, the light will be repaired under warranty (according to Peter).
* I've removed the bezel and the sapphire window to clean my reflector/emitter dome and now i don't know how to put it back. How do i find the correct orientation of the window?
Both sides of the window are coated with an AR layer, so it doesn't matter. Put it back whichever side you want.
* Are the clip screws on the Arc6 guarded sleeve made of titanium?
A thread about the McLux spare screws and Ti clip reports that the McGizmo screws are titanium but the screws sold by the Sandwich Shoppe when you buy a spare clip are stainless steel. The Arc6 screws seem to have a flatter head than the McGizmo screws and would seem to be consistent with the ones sold by the Shoppe. Also, they are colder to the touch than the clip itself (titanium is a worse heat conductor than stainless steel) and don't look (colorwise) like titanium. To sum it up, they're quite probably stainless steel.
* Switching from Stage 1 to Stage 2 seems extremely unreliable on my Arc6. It flickers and/or doesn't work at all at times. What's going on?
Try cleaning the upper piston edge, the kilroy loop and the contact ring in the head from any residue, oil or grease. Also, check if your kilroy's got bent too flat - if it gets so flat that it's almost level with the contact ring, there will be no or almost no distance between the Stage 1 and Stage 2, causing flickering or making the Stage 2 inaccessible.
* What is Stage 3?
Stage 3 is a virtual stage, meaning it doesn't correspond to any "real" position of the head or distance the piston travels when you push it. You activate it by pressing or twisting all the way to Stage 2 from off, without stopping at Stage 1. Sort of like slamming on the brakes. It's disabled by default and you have to enter the configuration menu to set it up (refer to the Arc6 manual for instructions on how to do that).
* What is Soylent Green?
Soylent Green is people!
* I can't seem to get to the configuration menu, no matter what i do. What am i doing wrong?
Firstly, make sure you've twisted the head to Stage 1 then started pressing the piston to Stage 2 ten times. Secondly, make sure all the contacts are clean. Thirdly, press in an even manner, about twice a second. Finally, bear in mind that if you fail to enter the menu within 10 seconds of switching the light on (twisting the head to Stage 1), the menu will be disabled until you swithc it off and start all over again (that's a safety feature implemented to prevent accidental menu entry).
* I've just unpacked my shiny new Arc6's and the battery sleeve and/or head have uneven anodizing / splotches / stains. What kind of shoddy craftsmanship is this?!
Relax, breathe, don't worry. It's not an artifact of the anodization itself, but an oily residue of some sort on its surface. It's been reported by quite a few users. It will go away on its own after a few days - probably even faster if you keep playing with your new shiny toy over the course of the next few days
* The contact ring in my Arc6's head looks burnt. What's up with that? Will it impair its performance?
A few early Arc6 heads seem to have had contacts rings that look slightly "burnt" - i.e. slightly blackened or showing "rainbowy" artefacts. That's caused by the way the rings were soldered on (using a solder pot) and it has absolutely no effect on the lights performance. The ring is a switch contact only, i.e. it doesn't carry any current from the battery - all the current goes through the plus nipple and the kilroy loop.
* What's the little empty IC socket i can see on the PCB when i unscrew the Arc6's head? Did i lose a part?
It's an I2C socket used to connect the Arc6 to a computer for programming and calibration. According to Peter, there were plans once for an end-user-friendly interface board and software, which would enable the "braver" Arc6 users to change the output currents for each level and tweak or even disable thermal management parameters. So far, still no news on that front.
* Will there be cake?
No. The cake is a lie.
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