So I made my own on/off today (pics)

[Pneumagger]

Just used c360 brass, some unknown grade of stainless, and 7075 aluminum on a lathe. I'm still witing on the top orings and the aluminum top needs a chromic acid coating for protection. In the pic you can see it next to a classic on/off and a ULT. You can also see one of my pins next to a standard .750 RTP pin. Notice how the head is fatter and the post is thinner. The thinner post should make the pull lighter than a standard RTP on/off but the fatter head is where the real magic happens. This should make it ultra reactive. If the numbers work out, it should have about 3.5x more rectivity than a standard RT on/off. That means the feel of "2000psi reactivity" at only 800psi input. No grinding down pins or chipping bolts... just a lighter pull and more reactivity. :cool:

I'll be testing it in an xvalve and minimag valve around wednesday. I'm waiting for the top orings to arrive from mcmaster carr. It's going to use a quad ring but since it's bigger than standard I din't have a larger quad-ring on hand. I only have a CF frame (single trigger) minimag to test it in with a 800psi preset inline maxflo tank. If I can get RT full auto with that setup that'll be impressive. Sucess or failure... testing vids will be posted.

http://i53.photobucket.com/albums/g45/jrm33/2011-05-29205016.jpg

http://i53.photobucket.com/albums/g45/jrm33/2011-05-29205111.jpg

[WarHamster]

Will you be offering these for sale if they work out how you hope?

[Zone Drifter]

If these work out better for reactivity, I would LOVE to put one in my classic RT... that is if they'll fit.

[Pneumagger]

Will you be offering these for sale if they work out how you hope?

Only if I can outsource the pins to a centerless grinding shop. Machining stainless is not enjoyable... putting a mirror finish on a .062 diameter one inch long pin just plain sucks. Basically you gotta use a sharp tool and VERY VERY slow feedrate. The only reason I machined them myself was that the grinding shops I asked for quotes from failed to respond after 10+ days of waiting and I'm impatient.

It took 6 attempts to make the 2 pins in that pic... and one of them is still no good (too short).

If I have to hand-make for people there'd be no market because I'd be charging $70+ each.

[Pneumagger]

If these work out better for reactivity, I would LOVE to put one in my classic RT... that is if they'll fit.
It absolutely requires an on/off hole compatible with double orings. Like air valves and xvalves. Similar to the ULT requirements. If the valve can fit a ULT, it should be able to fit this.

I think some Retro and some RT valves only had a single on/off top.

[y0da900]

Have you considered trying to do pins from 303 or one of the other "free machining" stainless steels? Might make them significantly simpler to turn as usual and not have to have them ground. Some of the free machining tool steels that don't have exotic heat treating requirements might also be a doable alternative, like W1.

Nice work, I'm interested to see how it turns out.

[OPBN]

I only have a CF frame (single trigger) minimag to test it in with a 800psi preset inline maxflo tank.

I'm down in the Lima area. If you are looking for test fodder, I may be willing to send you an intelliframed, xvalved mag for some testing. Of course....

[Pneumagger]

Have you considered trying to do pins from 303 or one of the other "free machining" stainless steels? Might make them significantly simpler to turn as usual and not have to have them ground. Some of the free machining tool steels that don't have exotic heat treating requirements might also be a doable alternative, like W1.

Nice work, I'm interested to see how it turns out.

This is all prototype. doing one off pins with whatever material I have for now is fine.
Although, I think I wouldn't want to use 303/304/316 again.
I'm pretty sure 7075-T6 aluminum is stronger and harder than those common stainless and machines like a dream.

I found a centerless grinding place in cleveland that does all sorts of stuff. If these are actually ever produced the pins will be centerless ground 17-4PH or 6AL-4V Titanium. As soon as this is tested, assuming no major changes, I'll get quotes on the parts if people are interested. I would think I could have small runs (about 25-50 kits) made for less than $50.

OPBN, wanna meet up in masfield? There's gotta be some fields

[OPBN]

OPBN, wanna meet up in masfield? There's gotta be some fields
I've played at a place in Mansfield a year or so ago. My brother and I play a few times a year up at Battlefront in Hubbard. Typically, June and July are terrible for me to get free. I'll hit you up in August some time.

[spece108]

The top hat resembles a Reactor design while the bottom looks like a modified old fashion Max-flow piston. Love the new dimensions on the pin. How fun

[behemoth]

I've played at a place in Mansfield a year or so ago. My brother and I play a few times a year up at Battlefront in Hubbard. Typically, June and July are terrible for me to get free. I'll hit you up in August some time.

We need to have an AO Ohio get together at Battlefront one of these days.

Joe, me, you, timbo, etc.

[OPBN]

We need to have an AO Ohio get together at Battlefront one of these days.

Joe, me, you, timbo, etc.
Blitzkrieg on August 20th or any of the later games would be good for me.

[kcombs9]

very cool

I thought the ULT had such a light pull cause of the smaller head not pin dia, less surface area on the head = less pressure pushing it = lighter pull + less reactivity.

But I could be wrong

Looking forward to some test vids.

[hill160881]

This may make for a heavier trigger pull. The top of the on off pin has a larger surface area and thus may require more finger pressure to fully push it to the top position. it will undoubtedly be more reactive though. It may be a worthwhile trade off.

I look forward to seeing the test results. As I cant really visualize how this will affect the weight of the pull.

Very cool

[KC]

I think some Retro and some RT valves only had a single on/off top.

Correct.

[Pneumagger]

very cool

I thought the ULT had such a light pull cause of the smaller head not pin dia, less surface area on the head = less pressure pushing it = lighter pull + less reactivity.

But I could be wrong

Looking forward to some test vids.

In the open state, pressure completely surrounds the head (the pressure has filled the dump chamber too) so the head diameter is not relevent to the free travel trigger pull weight. All of the forces balance out except for the pin diameter going to the sear. Until the dump chamber empties, the head diameter plays no role in weight of pull.

This is why putting a RT on/off in classic mag greatly reduces the trigger pull and the same reason the centerflag on/offs had small diameter pins (less force for the solenoid to pill). Likewise, the ULT's rediculously skinny center post is what gives it that low pull force. I think uses something like a -001 oring. :wow:

In the past, all AGD and aftermarket on/offs created the inbalance or change of force by reducing the pull weight (pin diameter) or increasing the on/off top pressure (RT). This would become the first on/off to INCREASE the top diameter to amplify the RT effect.

My assumption as to why this hasn't been done before is either:
a) Field liability involving, more or less, full auto behaving automags
b) The excessive return force will buckle/bend the pin shaft
c) The excessive return force will somehow damage the sear.

Since Vetter pumping 3000 psi to mags (and others routinely putting 1200-1500 into them) my guess is that option b or c are unlikely. Now would I want to feed this on/off 1200+ psi?... probably not. But 800-1000 psi should not subject the pin or sear to forces previously unheard of.

I'm sure Tom/AGD has tinkered with the idea of super reactive on/offs.
Maybe he can shed some light on the subject.

[behemoth]

This may make for a heavier trigger pull. The top of the on off pin has a larger surface area and thus may require more finger pressure to fully push it to the top position. it will undoubtedly be more reactive though. It may be a worthwhile trade off.

I look forward to seeing the test results. As I cant really visualize how this will affect the weight of the pull.

Very cool

Welcome back.

[teufelhunden]

Welcome back.


hahahahahahaha +1 to you sir

[Ando]

Welcome back.
OGRE... http://images1.wikia.nocookie.net/__cb20070523030047/finalfantasy/images/5/50/OgreChief-ff1-gba.gif

[leloup]

If this works, and price points stay at $50 or less, put me down for one. Very neat ideas. How many other markers can people re-engineer the parts to change operational aspects. Very few, and they are all greats.

[Spider-TW]

As long as we are waiting around for a test, what size o-ring will that be on top?

Another reason it may not have been done before;

The force on the pin pushes the sear up on the bolt lip. To look at the sear, you would think that it was designed to let the lip ride down it. If you just let the sear go and immediately release the trigger, you might be able to catch the bolt coming back and stick it with the extra force.

[Pneumagger]

Don't worry... if it's too reactive I already have an auxillary design that should only give about 1.9X RTP reactivity.
Since it's a bit more difficult to make and the reactivity is lower I deided not to try it first.

I don't think sear wear would be an issue or all the people running 1200+ psi to get more reactivity would see greater wear too.

[Spider-TW]

I doubt it will do any real harm, I was just thinking it could bind. It's an interesting thought that 1200 psi is only a 50% increase in the RT pin force over 800 psi.

I see your numbers there. So, you're looking at about 14+ lbs on a discharged classic? Maybe 20-30+ lbs on an RT? That RT might get uncomfortable, but in a good way.

Do you still have a video camera? I found a copy of the old video "How to build a pneumag" the other day. :)

[hill160881]

^^^^Edit:Very funny, same lines of thought at the same time^^^^


If my thinking is right it will be very reactive. Im not doing any real math here but if you increase from 800 psi to 1000 psi then that is an increase of 25% not 350% lol.

My thinking may be wrong but increasing the PSI(pounds per square inch) is the same as increasing the surface area(square incheses) that it acts on right? It may just be I am missing something as I have not had my tea yet this morning..

[Spider-TW]

^^^^Edit:Very funny, same lines of thought at the same time^^^^


If my thinking is right it will be very reactive. Im not doing any real math here but if you increase from 800 psi to 1000 psi then that is an increase of 25% not 350% lol.

My thinking may be wrong but increasing the PSI(pounds per square inch) is the same as increasing the surface area(square incheses) that it acts on right? It may just be I am missing something as I have not had my tea yet this morning..

True, but the FAT HEAD on/off has a higher differential at any pressure and the idea is to get that force up without the higher input pressure.

That's my vote. FAT HEAD on/off, or FH for short. :)

[Pneumagger]

Increasing the pressure with any on off should increse the return force linearly, while incresing the pin head diameter causes a return force increase at a rate proportional to the square of the radial increase. That squared radius term is of primary concern here.

F=PA ... force = pressure X pi X radius^2

Example: Doubling the pressure should ideally double the return force. But doubling the diameter will cause a four-fold increase in return force. There are 4 important variables for an RT mag... 3 variable for a Classic mag. Pin diameter, head diameter, input pressure, and operating pressure.

Lets say operating pressure is about 400psi (although this may vary depending on velocity, temperature, gas used, or valve type). For now input pressure will be 900psi and an RTP pin diameters are about .071 & .120 inches. However, Fat Head diameters are roughly .062 and .183 (I havn't decided on final dimensions/forces yet). We'll have to compare the opposing forces to generate the ideal pull:return ratios... excluding oring & sear friction of course. I'd guess there is about 0.5-1 pound of opposing oring and sear friction in either direction for realistic estimates of return force ratios.

These are all just ideal calculations and estimates for now.

RTP @ 900psi:
(900psi*.120^2/4*pi) = 10.1# return force
(400psi*.031^2/4*pi) = 1.5# pull force
ideal Pull:Return Ratio @ 850psi... 1:6.7
est. realistic ratio @ 900psi... 1:3.6

Fat Head @ 900psi:
(900psi*.183^2/4*pi) = 23.7# return force
(400psi*.062^2/4*pi) = 1.5# pull force
ideal Pull:Return Ratio @ 900psi... 1:19.75
est. realistic ratio @ 900psi... 1:10.3

RTP @ 2100psi:
(2100psi*.120^2/4*pi) = 23.7# return force
(400psi*.071^2/4*pi) = 1.5# pull force
ideal Pull:Return Ratio @ 1600psi... 1:15.8
est. realistic ratio @ 900psi... 1:9.1

Classic (Stock on off):
(400psi*.120^2/4*pi) = 4.5# return force
(400psi*.120^2/4*pi) = 4.5# pull force
ideal Classic Pull:Return Ratio... 1:1
est. realistic ratio... 1:0.7

Classic (with Fat Head):
(400psi*.183^2/4*pi) = 10.5# return force
(400psi*.062^2/4*pi) = 1.2# pull force
ideal FH Classic Pull:Return Ratio... 1:8.8
est. realistic ratio @ 900psi... 1:4.3

Summary: For an RTP on/off to appraoch reactivity ratios of the prototype FH the input would need to be around 2000+psi. I may end up dialing the FH reactivity back a bit... but I'll know more after testing.

Also interesting is the fact that the severely stepped pin should give a CLASSIC VALVE similar force ratios like an RT valve. These are just offhand calculations so i'll believe this when I see it. I'm skeptical but I'll go ahead and test it too. Plus, with only 400psi topside on/off pressure flow will be limited and shootdown would be severe if the trigger were attempted to be bouced.

[hill160881]

I love it. :clap:

My reverse mag may as well :ninja:

[Tropical Life]

This may make for a heavier trigger pull. The top of the on off pin has a larger surface area and thus may require more finger pressure to fully push it to the top position. it will undoubtedly be more reactive though. It may be a worthwhile trade off.

I look forward to seeing the test results. As I cant really visualize how this will affect the weight of the pull.

Very cool

Good to see you back! :shooting:

[behemoth]

Good to see you back! :shooting:
Real talk. It was a shame to lose such an asset to the community.

[mobsterboy]

Quit yer yapping and get to testing!
:D

[AT&T]

So will this possibly increase the rate of fire, or does it make the sweet spot larger(easier to find)?

[Pneumagger]

Automags are semi... ROF is determined by how fast you can pull or bounce the trigger.
It increases the return force so bouncing becomes easy.

Testing update: Marginal success. I got some air and paint but can't find my halo for testing. I'll keep looking and if I can't find it I'll use an evoIII egg.

Dry firing: I'm testing two new on/off types. I got the one pictured to work pretty good in an Xvalve. I can get a single trigger CF frame to bounce like mad using only a preset 850psi. Probably 15-20 bps... and pulling single shots is hard uness you really pull hard. I did not test the Classic Valve yet.

There was occasional leakage with the trigger fully depressed. Im not sure if it's due to the type of quad ring I'm using or not... so I'll try to pick up some round top orings. Perhaps the pin is too short... perhaps I need a wider diameter head... I'll have to investigate this further as well (I'll machine two longer pins during my lunch break today). Also, the trigger pull seemed short and snappy. I'm going to cut away the side of a rail and secion it so I can see if I'm getting full sear travel.

I'll probably try more testing saturday. I have two more alternate designs but it'll day to make each one. At this point, it is still not ready to sell to people.

[AT&T]

I am aware that mags are semi.. I was referring to how fast the trigger would bounce. I am more than happy with the rate at which my trigger bounces, I just have a hard time finding the sweet spot while under fire. :rolleyes: I would be very interested in anything that would make the sweet spot larger.

[the mag guy]

A god amongst mortals! This is totally sick! You know before I took a leave of absense from here you and I were building pneumags and I was pm-ing for advice. I come back and you're a freakin mag surgeon now whipping out all sorts of custom mag parts and valves. Keep up the great work, pretty soon I'll be emptying my wallet at you...
:cheers: