[Pnuemagger]

So I'm interested in building an aedes from a merlin extrusion in the near future... and while reading about other people's attempts around here bolt wear & breakage seem to be a common hurdle. I think I may have a solution but some input from everyone should prove helpful. I don't really want to attempt to make an aedes unless I know I can get everything to work. If not I'll just have to build an Evil M or something.

I took a little time and modelled up my variant of the aedes with the different bolt system. Basically, it ditches the spring/delrin and goes with more of a freestyle/spoolie style bolt. The bolt return air is supplied directly into the HP dump chamber in the tube below. As the MQ (or other PCP) is opening the air in the bottom tube is in a state of transition so air in front of the bolt should be allowed to get pushed back into the dump chamber easily... a decreasing force.

I feel the design is a marriage of the Aedes/MQ valve sytem and the freestyle bolt system. To do this, the back of the top tube also needs bored out, the valve hole needs drilled a bit further back, and a second small hole needs drilled for the bolt return air path. Please note, this model has no internals or sleve in the bottom tube (yet) and the green dots represent Bumpers & Orings.

Click for Fullsize:

[Lurker27]

Why not just use the air that normally vents to atmosphere to move the bolt - same trick the mini drivetrain uses. Then, you make the HP vent from the valve neutral or rear biased with respect to the bolt. Easy peezy.

The breakage is a natural problem with bolt speed - the mini has a variable flow system for that reason. I prefer the level 10 style I use in my own mini bolt, of course. The soft face helps as well.

basically, you'll end up with a "power tube" running through the bolt. You'll lose some speed, but not that much. You might need a sort of trick latching valve to get it to all work nicely together, but the original aedes was tolerance sensitve as well. You can incorporate a sort of reverse check valve with a spring loaded ball that seats and seats under heavy/rapid flow, but stays open under small flows (bolt return) - that way you need not worry about some of the aedes' inherent bolt return issues.

[Pnuemagger]

I'm not sure an MQ or similarly small PCP has the vent volume to actually get the bolt moving. The Mini's poppet is much larger with more movement and more volume behind it. From what I gather, an MQs venting is pretty insubstantial when it comes to wasted air/inefficiency. So I don't really see the motivation to complicate a design to ge tthe bolt moving when the primary airflow already does that.

What "inherent bolt return" issues are you talking about?

[y0da900]

I'm assuming he is referring to the air spring effect you have a good chance of seeing if the bolt is sealed at all points. That's part of the reason that I don't use an o-ring around the outer back end of the bolt when I build an Aedes drive train. If the air that is inside the upper tube between the bolt and the powertube is not able to escape, the pressure will climb as the bolt retracts, and it may not retract fully as a result or you can get some positional bouncing. You can avoid this as well by not using an o-ring on the bolt guide tip and relying on super close clearances between the pieces.

I really like the concept though. I've done pneumatic "FASOR"s with the same general air spring concept in an Etek and in my inline poppet valve prototype.

[Pnuemagger]

Lurker: I like the idea of a 2-stage type bolt so I did some minor modification (seen below) to the locatoin of the rear bumper which should open up the flow more and allow for another bolt oring that gives me 2-stage travel. With the static pressure in front of the bolt, the forward force should be below 20 lbf until the bolt travels about .2" where the air charge can reach the whole rear bolt face. It probably wont be "level-10 soft" but at least it shouldn't obliterate paintballs... lol. Thanks for the inspiration.

Yoda, I'm not sure the "air spring effect" will haunt this design because I'm guessing a few hundres PSI pushing back on the bolt will overcome the effect better than a spring return. And if it does become an issue, I can always remove the rear oring on the bolt guide so trapped air can leak out the rear. Thanks for the explanation.

I just ran some mass properties on the bolt and if it's aluminum it should weight about 9-10 grams. Heck, it's just a little sleeve of aluminum. If it's made of delrin about half that amount. I might beef up the rear shoulder on the bolt and try to make it delrin so I can ditch the bumpers... lighter bolt and fewer orings.

Two stage modification:

[pbjosh]

I would extend the oring that is mounted on the shaft that initally seals on the bolt into the bolt more.

This will give you a staged push, light pressure at first, say .25" of travel? So the ball can be indexed in the system a bit more, allowing the bolt to maybe even stop on a ball if it is half way in?


I think the problem in general is the action of the bolt. If you made it closed bolt, then activated the mQ, you would be set, and none of this would be an issue.

I believe the problem in the Adeas is the bolt action and back pressure with the mQ and timing. If mQ has different back pressure the bleed action works differently, causing the spool to be inconsistant.

[Pnuemagger]

no point in trying to pinch a ball... there's just to much area and the ball would get crushed. The first stage is approximately 20 lbs of force. And creating less area on the rear becomes difficult due to bolt wall thicknesses and limited oring size selection. At best I could prably reduce the first stage by about .030 radially by going to a metric oring.

An antichop bolt like an AGD level 10 has something like less then 7 lbs of force.

[y0da900]

I wouldn't have worried about it in some things due to the pressure pushing the bolt back, but I have had it happen in a bolt that I designed for an Ion that put things back to the drawing board. Removing the o-ring there is definitely a good way to eliminate the problem should it happen though. It looks like you have, relatively, a decent amount of volume back there as well which will help mitigate the effects.

2-stage bolt motion with an Aedes is much simpler with the traditional spring version because you don't need the bolt sail for the o-ring. What you may be able to do, however, is extend the length of the bolt system a little bit, and put the o-ring in front of the bore step. You could go down at least one size o-ring then, possibly enough to make staging the bolt motion worth it again.

I actually used the rear bumper o-ring as the first stage sealing o-ring on one I did recently. Nice low surface area and the ability to minimally bleed pressure should it pinch.

[bobfromaccounting]

Damn yoda, those parts are really clean. Nice work, all around

[Spitlebug]

I am not sure I am wild on this concept, I'd have to think about it a little more but I think a lot of the problems people have been running into is that they are using delrin, which is not an ideal material for this application. Also, it is possible to drill an air passage through the body, much like a standard valve and use a much smaller surface area to create an air spring.

[y0da900]

I've had issues with the bolt stop using aluminum as well, but adding an 1/8" thick o-ring as a bumper seems to have helped with that.

[Pnuemagger]

Keep in mind existing systems that use springs like the atuomag (similar blow forward spring return bolt). Those use a 70 or 90 durometer urethane bumper that's about 1/16 thick but nearly 1/4" wide. Alot of cushioning power.

[Spitlebug]

Yeah, I am thinking 0.4" thick 7075-T6 aluminum face and a grade 8 steel shoulder bolt and a straight up belleville washer - non serrated. The face being milled to allow three ports in a semi circular fashion - equispaced with about 0.09" material between ports. The housing would allow for some air to expand around it an a conical spring, wide face towards the bolt. The housing would include a stop for the bolt travel and could be made of 7075-T6 as well. The spring can have a relatively low spring rate so as not the put more stress on the bolt section. Increasing spring would increase ROF.

[Pnuemagger]

If you can swing it... titanium is TOUGH and should take impacts extremely well.
Great fatiuge and toughness. Better than any 2000 or 7000 series aluminum.

It's also a ***** to machine well and even worse to tap.

[PurpleDirt]

Why not use Nylatron? They use it as a replacement for steel in machinery sometimes, I'm no genius, but I've taken a 500lb hydraulic press to a 1/4" thick walled, hollow, 1.5"x4" stick of Nylatron, Delrin, and POM. NYlatron owned them all... Eventually it snapped, but after a much longer time than the other two materials. Didn't try aluminum, but I crushed an HE bolt with a normal hammer once, soo...

[new ion?]

soo, I know I don't know as much as many of you, but one thing that Colin was seeing was poor consistency, possibly due to back pressure on the valve. I worry this system does not solve that issue.

[paintballer50505]

what would be the problem with just using a mini's bolt and spring. Have the actual air released to fire the ball cycle the mini bolt. Set the bolt up so the air for the mg released behind it to push it forward. Then machine the shaft so when the bolt closes the breech, the air will be able to escape through the bolt and fire the ball. Would be simplest I'd think. Which is pretty much you idea but you would only need to make one part and use parts that are already proven that they dont wear out and break.

[new ion?]

that is not much different functionally from the standard bolt.