Failure analysis/proposed solutions, Arc4 switch
The post is not to criticize Arc, but to try and figure out exact failure mode of Arc4 (rev1 & rev2) and why battery length is ending up so critical. I'm assuming, that no way Arc would knowingly send out a product that will give problems, so Arc has not figured a solution to the problems yet and/or we have not seen the fix yet. Ok Ok … I assume too much ha ha ha. /ubbthreads/images/graemlins/grin.gif
Flame suit on… /ubbthreads/images/graemlins/evilgrin07.gif in the spirit of cpf, I'm only trying to contribute.
The gold disc is the heart of Arc4's power linkage, just as the front micro-switch is the real switch. The gold disc measures .0125 X. 7630in. Only 12.5 thousands thick, but expected to deform .080in on rev2 to make contact with battery. Then add .050 micro-switch travel, this means the gold disc must deform .125in+ to do it's job.
Further it must maintain contact with the battery at all times up to 1.25amp load. The cone spring must deform gold disc .080 to maintain contact. Because spring is at the end of designed travel, marginal contact may result in contact not supporting the full 1.25 amp load at level 1. I wonder if this could be causing some of rev2's to flicker on level one, but not at other levels.
On rev2, the gold disc's travel is 10X it's own thickness, almost to the point of rupture. On rev1 the travel required to make battery contact with gold disc is aprox. .067in+ .035 still a large distance as compared to thickness of structure.
So when rev2's tube ended up being .017 longer. It made a marginal contact situation into a very hard to operate Arc4. The solution of inserting a longer/stronger cone spring to maintain battery contact doesn't solve the base issue of Arc4's battery length tolerance problem.
Proposed solutions:
1. A spacer inserted below gold disc reducing travel necessary for gold disc to make contact. Currently the easiest way to accomplish this is applying a blob of solder to the center of gold disc. You would need to apply just enough solder to raise disc off end of battery tube with your brand of battery in place.
2. A gold spring/spacer be engineered that can be soldered to the center of gold disc. This would get rid of battery length, contact issues and hard to operate switch issues.
3. With the above described spacer/spring in place. A simple rubber disc can be used directly on top of gold disc, instead of the domed cap/spring assembly. This would result in a protected switch with a light tactile feel and way less prone to accidental activation. ((tailcap mod V1.2) )
4. A shorter battery tube, then spacer would not be necessary. Gold spring described above would solve battery length tolerance problems.
5. Extending the plunger length along with a longer cone spring would solve hard switch problem and battery length issues. But would gold disc survive the distortion?
The best solution is probably a combination of the above. I anxiously wait to see which solution Arc uses. /ubbthreads/images/graemlins/icon3.gif
Thanks,
CY
The post is not to criticize Arc, but to try and figure out exact failure mode of Arc4 (rev1 & rev2) and why battery length is ending up so critical. I'm assuming, that no way Arc would knowingly send out a product that will give problems, so Arc has not figured a solution to the problems yet and/or we have not seen the fix yet. Ok Ok … I assume too much ha ha ha. /ubbthreads/images/graemlins/grin.gif
Flame suit on… /ubbthreads/images/graemlins/evilgrin07.gif in the spirit of cpf, I'm only trying to contribute.
The gold disc is the heart of Arc4's power linkage, just as the front micro-switch is the real switch. The gold disc measures .0125 X. 7630in. Only 12.5 thousands thick, but expected to deform .080in on rev2 to make contact with battery. Then add .050 micro-switch travel, this means the gold disc must deform .125in+ to do it's job.
Further it must maintain contact with the battery at all times up to 1.25amp load. The cone spring must deform gold disc .080 to maintain contact. Because spring is at the end of designed travel, marginal contact may result in contact not supporting the full 1.25 amp load at level 1. I wonder if this could be causing some of rev2's to flicker on level one, but not at other levels.
On rev2, the gold disc's travel is 10X it's own thickness, almost to the point of rupture. On rev1 the travel required to make battery contact with gold disc is aprox. .067in+ .035 still a large distance as compared to thickness of structure.
So when rev2's tube ended up being .017 longer. It made a marginal contact situation into a very hard to operate Arc4. The solution of inserting a longer/stronger cone spring to maintain battery contact doesn't solve the base issue of Arc4's battery length tolerance problem.
Proposed solutions:
1. A spacer inserted below gold disc reducing travel necessary for gold disc to make contact. Currently the easiest way to accomplish this is applying a blob of solder to the center of gold disc. You would need to apply just enough solder to raise disc off end of battery tube with your brand of battery in place.
2. A gold spring/spacer be engineered that can be soldered to the center of gold disc. This would get rid of battery length, contact issues and hard to operate switch issues.
3. With the above described spacer/spring in place. A simple rubber disc can be used directly on top of gold disc, instead of the domed cap/spring assembly. This would result in a protected switch with a light tactile feel and way less prone to accidental activation. ((tailcap mod V1.2) )
4. A shorter battery tube, then spacer would not be necessary. Gold spring described above would solve battery length tolerance problems.
5. Extending the plunger length along with a longer cone spring would solve hard switch problem and battery length issues. But would gold disc survive the distortion?
The best solution is probably a combination of the above. I anxiously wait to see which solution Arc uses. /ubbthreads/images/graemlins/icon3.gif
Thanks,
CY
