ULT & Trigger pull

[adlar]

I'm curious what the actual return force of the ULT is. I'm also curious what the pull length needs to be to fire the marker. IE at what point in the trigger pull will the marker fire, how far do the sear rod, and on/off pin need to travel in order to function properly? I know from reading the forums that the force needed to pull the trigger is about 15oz, but not sure what range the return force is due to decreased reactivity from the ULT. I've done a search, and I usually come up with information on why not to shorten the trigger rod, of course, I do not want to do anything with the trigger rod. I'm more curious about the specs for getting a proper 'noid to use with the ULT. I have a number of different 'noid apps I'm considering so just using the same one as a hyperframe or Emag does not necessarily fit the bill. Thanks in advance to anyone who contributes information.

[i_baked_cookies]

the return force on the ult is significantly weaker than the return force of a stock on/off. however, the trigger pull length is, if not the same, very, very close to that of a stock on/off. the 15oz. is measured at the point where the trigger rod meets the trigger, not at the bottom of the trigger itself (im assuming your doing this on an intelliframe). its alot lighter, yet less reactive than the stock on/off.

[adlar]

Thanks, for the reply. I'm really wondering if anyone has accurate measurements on these things, or if AGD has posted the actual tech data somewhere. I've been unable to search it or find it so far. I'm guessing I'm going to have to take some test measurements to get an appropriate length, but I'm thinking AGD or one of the other members has more precise data than I can measure on my own less than steady hands, lol.

[warbeak2099]

Hey, I'd like to know the same thing. How long is the ULT trigger pull? AGD states the weight, 15oz, but not the pull length. Probably because it's not made to shorten the pull, but I'd still like to know. Oh, and about the ULT lessening the reactivity... does it completely eliminate it or is there still a little reactivity left?

[adlar]

It is still somewhat reactive. I have mine set up with 4 shims, plus 2 in the level 10 with red spring and I get decent reactivety at about 800 psi or so. If I hold my finger on the middle bump on the two finger style trigger I can even get some bounce, but you are in for a few chuffs if you let it bounce. Bounce isn't normally an issue for me during play as you really have to be trying to get it to do this at lower pressures. Turn it up and it will go out of control. I found with one less shim the pull got lighter, but it was easier to chuff during rapid fire, so four was perfect for me. I might turn back the pressure just a bit to take out the little bounce I'm getting though. I have an adjustable, so I can tweak to extremes.

[the electrician]

the only real way to figure it out is take force measurements on your particular gun. if you can't figure out how to do it, you could just calculate it out. figure up the surface area of the top of the pin, and the bottom the pin. this will give you a force factor and just plug in the operating psi of your gun.

i came up with 500 psi for the operating pressure of my gun. this is using a level 10. it's lower with a standard bolt. the ULT pin has a .072" dia top and a .0325" dia bottom. these force factors are .004 for the top, and .000829.

so at 500 psi the air pushes the pin down with 2 lbs of force. and the pin can be pushed if you can over come .41 lbs of force.

now you need to take into consideration the force of the bolt pushing on the sear, minus the spring, and if it's lvl 10 or standard makes a difference. not sure how to do that, except using force calculations from operating pressure of a ram. I've built an e-mag using a small ram style actuator and a micro 3-way solenoid valve to control it. I've found out alot about the different force needed in the automag since I built it. basically with a lvl10 and a RT on/off, I can operate my ram at 50 psi minimum. it's 3/8 bore, so it creates 5.5 lbs of force . 1 lb of that is return spring, 2 lbs of that is on/off pin, so tha leaves 2.5 lbs of force to pull the sear off the bolt, when using a level 10.

the other thing i noticed is minmum stroke required can be measured by measureing the travel of the sear from fully forward, and catching the bolt as much as it can...to the point at which it is far enough down to be level with the inside of the body tube. this ensures enough movement to avoid excessive bolt and sear wear. if measured at the on/off pin, this movement should be about .130" of travel of the on/off pin I believe.

so your solenoid plunger stroke will be a bit more I belive, depending on where you put it. it's a catch 22 when comes to leverage and solenoids, shorter stroke, closer to the pivot point might be benificial, or it might not, depending on the solenoid used. where it's high power area is.

either way, you will need a minimum of 2.91 lbs of force at whatever stroke your going to end up with, and that's not including return spring force and the fact that if you want speed, you'll want to almost double the force at the given stroke t get it.that's a big solenoid, and perhaps a big battery/capacitor. that's why I went pneumatic.

one thing you'll notice if/when you get it running. you want to keep your solenoid energize time to a minimum. probably 30 msec. too much shorter and you'll start chewing up the bolt. too much longer and you're taking away from recharge time.

you'll also notice a definite corelation between energize time, how much you shim the ULT and the resetiing abilities of the level 10 bolt. at a specific energize time, if you shim the ULT too much, it will not let the lvl10 reset properly after pinching a ball. not something you want to find out in the middle of a game. basically the sear comes up and puts pressure on the bolt before it has had a chance to reset, then if the ult is shimmed too much, with the sear in this half up position it will start letting air into the dump chamber and cause the bolt to ge stuck, and blow air down the barrel.

well that's what I've figured out so far.

[adlar]

Thanks Electrician. That is very informative, and exactly the kind of input I'm looking for. I guess I'll really have to play around with the formulas and 'noid position in order to find the best fit. I've already ordered a board to program, have a trigger frame I want to experiment on, but I'm still undecided on how to actuate the sear. I'd like to use a 9V as power, but I can put together just about any battery I need. This is more for the fun of making something than anything. Just getting it to work will be a huge milestone for me. I'd like to keep it simple, and not have to deal with an lpr, ram, and 3way. Maybe once I learn more I'll get more adventurous.

[the electrician]

well I finally found the parts I was looking for.

have you seen this in the workshop forum?
http://www.automags.org/forums/showthread.php?t=125891

this set-up is very efficient with current consumption and air usage.

if you go with a direct solenoid actuated sear, you'll want a capacitor big enough to fire the gun a few times by itself. that is how I make my electro-cockers, but they don't need to come up with much force at all.