Pin length vs RT effect trend

[cockerpunk]

i have about 5 different on off pins, and im wondering exactly the connection between pin length and RT effect. is there a hard and fast rule?

[Looper]

I have very good luck with the .712 emag pin and a quad o-ring.

[maniacmechanic]

I have very good luck with the .712 emag pin and a quad o-ring.

nO nO that will only work in E mags

[cockerpunk]

I have very good luck with the .712 emag pin and a quad o-ring.

i want to know the trend, not just "use this"

shorter = more RT? thats what i seem to be reading.

[Coralis]

Yes typically shorter on/off pin lengths enhance the RT effect.

[secretweaponevan]

i want to know the trend, not just "use this"

shorter = more RT? thats what i seem to be reading.

Gordon, make sure you accurately caliper the pin's heads to eliminate the excess drag from too tight of an o-ring fit.

[cockerpunk]

Gordon, make sure you accurately caliper the pin's heads to eliminate the excess drag from too tight of an o-ring fit.

i gotta mic, so im good on the measuring front. i just need to know the trends so i can select the right pins for the feel i want.

[dark blade]

shorter = more RT due to the fact that the pin has less exposed when in the "open" position, and has less distance to travel to become open when "closed"

basically, the amount of material blocking the internal o-rings lessens (depth wise) so it takes a shorter amount of time to release it and open it.

hope that makes sense

[secretweaponevan]

i gotta mic, so im good on the measuring front. i just need to know the trends so i can select the right pins for the feel i want.

"They" say that shorter pins make it "seem" more reactive. I am thinking it has something to do with the trigger/sear geometry, since a shorter pin in no way affects the surface area nor the pressure acting upon it.

[Spider-TW]

"They" say that shorter pins make it "seem" more reactive. I am thinking it has something to do with the trigger/sear geometry, since a shorter pin in no way affects the surface area nor the pressure acting upon it.

Like dark blade said, it's also less travel through the o-ring, which is less lost RT effect. The amount of available RT effect work is the same at any given charge rate, shorter pins just mean less of it is used in the over travel of the on/off pin and engagement of the sear as you noted. The RT effect is transient and dissipates quickly. Pin and sear travel require force and time.

With a high flow / high pressure regulator like an old max-flo, you get plenty to kick for a 0.750 pin. With a wimpy reg, you would be lucky to tell the difference against a classic valve at any shorter pin length.

[secretweaponevan]

Like dark blade said, it's also less travel through the o-ring, which is less lost RT effect. The amount of available RT effect work is the same at any given charge rate, shorter pins just mean less of it is used in the over travel of the on/off pin and engagement of the sear as you noted. The RT effect is transient and dissipates quickly. Pin and sear travel require force and time.

With a high flow / high pressure regulator like an old max-flo, you get plenty to kick for a 0.750 pin. With a wimpy reg, you would be lucky to tell the difference against a classic valve at any shorter pin length.

I am having a hard time understanding this.

I can only understand that the RT effect is based upon input pressure against the surface area of the head of the pin against differential pressure acting beneath it (atmospheric or thereabouts) after the dump chamber vents.

I don't see how the distance that the pin travels would decrease the force being enacted upon it (unless of course that the input pressure was of a fixed volume and therefor the lowering of the on/off pin would be decreasing the pressure by increasing the volume of the pressure vessel (tank reg to hose to on/off pin top) but then even still the increase in volume and resulting drop in pressure would be so miniscule as not to matter (1%??)).

Can you think of another way to describe it so that Sailor Jerry and I can understand it?

[Spider-TW]

Yeah, sorry. I'm in a refinery more than 10 hours a day lately. (7 days a week)

Two things about the RT effect;

1) it's an extra puff of pressure that results from the heat of charging the regulator and it goes away about as fast as it occurs. time of use is short. less length of travel by the sear means less time used.

2) think 'work' energy instead of force. You get a little pulse of energy if you slam fill the reg. The RT effect is a very quick variation of pressure that you are trying to use.

Lets say you get enough energy for .025 inches of travel against the sear train (from the sear pin to the top of the on/off pin through the o-ring) and your finger. The more friction you have, the more work is required for each 0.001 inches. You can't do a whole lot about the friction, but most of it is in the on/off and the sear pin. The force has to be greater than your finger pull after you add up the friction as well. This movement takes a little time too, of which there isn't much according to the RT charts for velocity tuning.

If you can't get the sear to catch after 0.025 inches, you get nothing. If you shorten your pin a little, you may get the total effort to be less than the amount of RT effect you are getting, letting it push your finger back and the marker recharge again, hopefully with your finger still pressing the same.

I don't know...does that read any better?

[secretweaponevan]

Yeah, sorry. I'm in a refinery more than 10 hours a day lately. (7 days a week)

Two things about the RT effect;

1) it's an extra puff of pressure that results from the heat of charging the regulator and it goes away about as fast as it occurs. time of use is short. less length of travel by the sear means less time used.

2) think 'work' energy instead of force. You get a little pulse of energy if you slam fill the reg. The RT effect is a very quick variation of pressure that you are trying to use.

Lets say you get enough energy for .025 inches of travel against the sear train (from the sear pin to the top of the on/off pin through the o-ring) and your finger. The more friction you have, the more work is required for each 0.001 inches. You can't do a whole lot about the friction, but most of it is in the on/off and the sear pin. The force has to be greater than your finger pull after you add up the friction as well. This movement takes a little time too, of which there isn't much according to the RT charts for velocity tuning.

If you can't get the sear to catch after 0.025 inches, you get nothing. If you shorten your pin a little, you may get the total effort to be less than the amount of RT effect you are getting, letting it push your finger back and the marker recharge again, hopefully with your finger still pressing the same.

I don't know...does that read any better?

I TOTALLY forgot about the temperature side of pv=nrt. Watching the .wmv from zdspb doesn't have a temperature reading. lol.

Thanks for bringing up temperature. It helped, but leaves me wondering, what causes the increase in temperature? If it is because of the system pressurizing, that occurs after the on/off pin RT's. Doesn't it?
Could it be because as the system vents (a shot), the powertube cools causing even more of a pressure disparity between the top of the on/off pin (input pressure) to the bottom (even less than atmospheric due to cooling)?

This makes sense to my booze-addled mind.

BTW, really enjoying this "conversation". :)

[Ando]

It's the rush of air. Next time you fill your tank, pull your cover off and you'll feel it heat up a little.

[secretweaponevan]

It's the rush of air. Next time you fill your tank, pull your cover off and you'll feel it heat up a little.

Air doesn't rush while the on/off is in the off position and therefor when the RT effect would be felt.

Edit: The rush of air OUT would lower the pressure (think venting CO2 tank), decrease the pressure of the powertube/dumpchamber/on off bottom area, therefor increasing the pressure differential between the on/off pin top above the o-ring and the on/off pin top below the o-ring.

Sailor Jerry and Spider-TW helped me figure this out.

I'm just looking for confirmation that I have the correct answer.