I have been ruminating on this for a while so I'll throw it out there for analytical discussion. There is a lot of effort to upgrade the GTA E-Bolt board to allow higher rates of fire than the 13 bps stock setting.

There are some who claim that the stock single acting ram cannot go any faster anyway. There are several places on the web showing how to modify the ram to make it double acting along with the installation of a 4 way solenoid to power the ram in forward and aft movements. The mods are supposed to be necessary to obtain the ROF available with a replacement card like the DM4/5/C.

I have another idea. Everyone knows that certain mods to the sear of a stock 98C can produce rates of fire in excess of 25 bps. This tells me that the blow-back pushes the hammer back quickly enough to the cocked position to allow for this very high ROF. My idea is to harness that blow back gas in either of two ways to provide for the high-speed return of the ram.

First idea was to modify the hammer end on the ram shaft to incorporate an "O" ring just like the stock bolt. The solenoid controlled ram drives forward to strike the poppet valve pin in the back of the power valve. When the poppet valve opens gas flows out and makes two right angle turns to go forward to get to the paintball. But, some of the gas leaks around the valve pin and exerts pressure on the hammer to blow it back to the cocked  position. This works well with the stock bolt, so with the lesser weight of the ram head it should throw it back to the "cocked" position at a higher rate of speed than it can the stock bolt...allowing for very quick cycle rates and the chance to see if my new Cheetah board can make my Halo actually give me 35 bps.

The other method would be to either modify the ram to be a two way or obtain one of the BSI two way rams. On the side of many/most power tubes is the port that supplies gas to operate the Cyclone Hopper. I would take that connection and install a tube to connect that gas pressure to the front of the ram. Thus as soon as the marker fires gas would be flowing to push the ram back to the "home" or "cocked" position.

Should be as-fast-as-fast-can-be. Tell me my flaws in the thought process?

Monk wrote: Might want to add a buffer somewhere on or in the ram as to not tear it up. And modding the RT fitting to the ram I think would only give you about 18-22 cps. Even then, you may not even get a complete cycle.

Now think about this, first off, I could leave the return spring in the modified stock ram so that the gas return pulse would be assisting the spring. The spring by itself can cycle the ram fast enough for at least 13 bps. Also realize that the air pressure supplied to the ram from the solenoid is less than 100 psi. The blow-back gas coming from the hopper port is going to be at least 200 psi and higher in most markers.

I do agree that a buffer "O" ring is likely needed and would install one on the ram shaft between the head and the body of the ram.

Monk wrote: Yeah, but the RT uses blowback and it can only cycle fast enough for 18-22 cps. I retract my may not cycle statement, I confused myself. lol.

Eighteen to twenty two would be all that I need. I am not looking to fire full, or RT or even burst. I have never fired my marker at any setting other than semi-auto. But, when I was getting a lot of play time in and practicing walking the trigger, I could occasionally get well ahead of the 13 bps of the GTA board.

Once I get the new board installed I will make these mods to the ram just to see of what the marker is fully capable.

I would suspect that the speed limitation of the Cyclone is related to the mass of the parts being moved. Also, the pneumatic cylinder operating the Cyclone suffers the same limitations as the standard E-Bolt ram...its return rate/speed is controlled by a spring.

The gas pressure supplied out of that port has to be more that the blow back pressure leaking past the valve pin.  And again, blow back can cycle a standard marker in excess of 20 bps. Seems only logical that using the pressure more directly would cycle the ram equally quick or even faster.

Yer on the right track Bruce !

I dont have any experience with the e-bolts , but I can confirm some of your thinking about the physics of making the marker cycle faster .

The 98C (mechanical) can cycle up close to 40+ CPS , there has been debate whether the BPS rate is that fast or not , but it should be close to it anyway , with that as a somewhat debatable "Outer Limit " of what its capable of ,,,

Less reciprocating mass equals faster cycle times , so your gas assisted bolt is a very real option , I went with  these guys for a lighter faster rear bolt , but a bolt made from A2 tool steel in a bobbin/spool configuration would yield the same result ; http://www.darkhorizoncorp.com/index.asp - http://www.darkhorizoncorp.com/index.asp

Also , if you are going with a 98 casting , as you've seen the castings are far from perfect as far as mating surfaces . The casting's mating surfaces can be surface ground (or done with a long Norton Dual grit Stone ) to bring them into an almost perfect mating surface , this translates into more CO2 gas being contained within the recievers to do what it was intended to do , namely propell the paintball forward , and blow the rear bolt back into the cocked position . The benefit of doing this is obvious as gas efficiency number one , but also with higher gas efficeincy , you get higher pressures blowing the rear bolt backward , read faster cycle time .

I left the Mainspring in place , but to achieve a bit faster cycle time coupled with the lighter rear bolt , a heavier spring can be used (I thought seriously about the Maddman spring kit ), at the cost of more wear and tear on your rear bolt and sear .

I have found that with the above mentioned mods to a mechanical 98C (with the exception of the Maddman spring kit) , I was outshooting every hopper I put on my 98 except a Halo . I am guessing I ocassionally hit in excess of 15 BPS , because I have not chopped a ball since I put the Halo on the "Widowmaker" (98C , Highly modded) ,, Thats Purely mechanical !!

Oh,, There's one other small detail I have done , and this is only because I felt it would help with keeping the reciever castings from flexing under the pressure of firing and venting gasses where I didnt want gas to go,, I mounted the Red-dot sight directly to the top rail of the casting . There are only two screws along the top of the castings of the recievers and about 7 inches inbetween them . I mounted the BSA sight dead smack in the middle of that to hold the castings tightly together , again , the less gas escaping means more gas doing what I want it to .

Bruce , you must remember compressed CO2 is an elastic material , the more tightly it is confined , the more pressure it will build , and using that to its fullest is what tinkering is about ! (I suggest NOT tinkering with Tippmann's engineering as far as the CVX valve itself is concerned , my experience says they got it perfect) , porting it wont help , but if you want to try,,, I'll send you one , lol

    You will only be able to set your dwell at a maximum number of miliseconds before the CVX valve trys to destroy your solenoid valve and/or cylinder. If your dwell is set too high the spool in the solenoid will be in the energized position, your cylinder will be extending because of it and when it reaches its full extended stroke the CVX valve will open and try to re-cock the marker. The greater pressure contained in the CVX valve being near primary pressure multiplied by the greater surface area being the face of the hammer will easily overcome the force that the energized solenoid valve is exerting via the hunderd psi or so multiplied by the 5/16 or so piston in the cylinder and the cylinder will retract whether the solenoid valve is energized or not. The one hundred psi or so contained in the blind end of the cylinder will increase and may even increase to a level that will blow out the seals in the solenoid valve. With this going on the cylinder is retracting to a point where the air trapped between the CVX valve and hammer face finds a way out and dissapates into the atmoshere. If the solenoid valve is STILL energized the cylinder will extend and hit the pin of the CVX valve for a second time. Causing the cycle to start over. 

There is a way to protect the cylinder and solenoid. If a check valve is added to the output side of the solenoid valve and a quick exhaust valve is added between the check valve and the blind end of the cylinder any unwanted back pressure in the blind end of the cylinder should be halted by the check valve, thus protecting the solenoid vavle, and the air should vent through the quick release valve, protecting the ram. However you still will only be able to energize the solenoid valve a certain length of time before its effects become null and void because of the CVX's blow back gases acting on the hammer. This will become a problem if velocity is below what you like because changing the dwell is the primary way to increase the velocity in an E-bolted Tippmann.

     Consider engineering a way to adjust the flow past the valve pin. I would completely seal off the valve pin blow back area and drill a hole next to it that passes through the valve bulkhead. Then I would drill and tap a hole at a 90 degree angle to the hole that I just made in the bulkhead. Then I would throw in a set screw and have a fully adjustable orfice to regulate blow back flow. (like how Tippmann adjusts velocity in the powertube) 

     Also consider adjusting the flow rate going into and coming out of the rod end of the cylinder. Flow rate coming out of the rod end should be as fast as can be so that the cylinder can extend quickly. It would make sense to regulate the flow rate going into the rod end of the cylinder because the rod end could be used as a dampener so that the hammer can be slowed down if it is retracting too fast which could also cause damage. Someone already suggested using bumpers. My suggestion is more of an air brake.

There is actually a lot to consider when dealing with an single acting inertia assisted return cylinder. Maybe thats why Tippmann stuck with springs  

I believe that Tippmann stuck with springs in the E-Bolt because it was less expensive.

Let me go into my operation method. I learned early on that it was easy to get the dwell just a little too long which interfered with ball feed. With just a slightly longer dwell it was possible to trigger a forward cycle of the ram before it was fully retracted from the previous cycle. At best this was preventing the bolt from coming back far enough to allow the next ball to drop into the receiver so no ball was fired.

At worst the bolt would move just far enough rearward for the ball to start to drop, but the next cycle triggered and the ball was chopped half way through the feed port. I worked and worked to shorten the dwell to the optimum level. Once there I have not touched it since. All of my velocity adjustment is now done with the secondary regulator (Palmer Stabilizer). Velocity can also be adjusted with the LP regulator that supplies pressure to the ram, but is limited to a maximum of 100 psi. (the solenoid valve starts to leak when pressure gets much above 100 psi)

With my dwell set as short as it is I thing I will not have a problem. There is another piece of information. The ram has no seal on the front end, so pressure pushing the ram piston rearward is not going to run up against a pneumatic lock. If the piston can't be pushed rearward the gas will likely vent around the unsealed shaft at the front of the ram.

Another thing is that since the solenoid leaks at pressures above 100 psi if the blow back gas were timed such that it impinged against the piston while the solenoid  was still energized I think there would just be leak down.

Monk wrote: Wouldnt a QEV solve all the problems?

It seems that it might solve any venting problem.

karll wrote: What board are you going to put on your ebolt? Are you running the GTA ebolt kit right now?

As I mentioned in another subject line, I have just been given a brand new TAG DM4/5/c board. (along with a Cheetah board for my Halo B) That will be the heart of my E-Bolt, but it is going to be a few weeks before I have a chance to put it all together. Right now I am looking for the correct connectors to use to attach my wires.

karll wrote: Found some info on this Bruce. A guy on Tippmann Owners said he tried this and it didn't work. Not a lot of info in that thread, but figured I would let you know. http://www.tippmannowners.com/showthread.php?t=5185 - Thread.

OK, the likely reason there wasn't enough gas coming out to blow the hammer back is because the LPK valve pin fits MUCH closer to the rear bulkhead hole than does the standard valve pin. 

As you said there wasn't much detail there. I can't imagine that with a good fitting "O" ring mod to the ram's hammer head that there would not be enough force generated to push it back all the way to your elbow. Particularly when the head , rod and piston's total weight is about half that of the stock hammer (the hammer head on the end of the ramrod is smaller diameter than that of the stock hammer. It would require making a replacement that is larger in diameter to make an "O" ring fit. I will make an aluminum hammer with a steel striking button where it impacts the valve pin. A few calculations indicate that this aluminum hammer will be no heavier than the original solid steel one that comes on the pneumatic ram, requiring no more pressure to operate.)

Monk wrote: I also think the guy might have had the problem because (I think) he wasnt using QEVs.

I don't disagree with that. 

Bruce A. Frank wrote: Right now I am looking for the correct connectors to use to attach my wires.

Bruce, i used the plugs out of an old R/C truck i built years ago, you may want to check http://www.towerhobbies.com/index.html - http://www.towerhobbies.com/index.html  that's where i used to get all of my R/C goodies. the setup i use is a 2 conductor setup and has a very small plug i use as a disconnect for when i remove the drop wich houses the battery.

good luck with the project, i don't see why it wouldn't work.

karll wrote: I am talking to other people on Tippmannowners.com about this and getting flamed for it. I think I understand why a QEV would help, but can some one elighten me fully. It would allow gas to escape from the ram which in turn would let it return faster/easier. right?

It allows the gas behind the ram to vent more quickly when the ram starts to move the other way.

Why are they flaming you? What do they find offensive? 

Jeez. I don't think I'm gonna hang around there anymore...

That "super mod" is worse than Enos!