Top Dead Centre Mod v. Action Army Hop Up Chamber

[Showe22]

Originally Posted by daishi

Its a bit more complicated then that.

You also might have to position the m-nub slight off center depending on your hop to get it to make straight contact depending on the tolerances of your hop-up unit.... all of which oyu can only figure out once you resembled it... so gluing and un-gluing...tons of fun.

Would you be able to give an example or explain it in another way?

I might have to position the m-nub off centre, off centre of what in particular? I'm not sure what you mean by the tolerance of my Hop Up unit.

Sorry, I'm new to doing this kind of work. I don't know anyone who can do it for me if I pay them

[Drakker]

You have to adjust the m-nub relative to the angle of the arm. Depending on how much hop you apply, the arm will be at an angle of a few degrees compared to the rubber when you look at it in the "direction" of the barrel.

Then, the hop-up arm can move sideways inside the chamber. If you are using a Tokyo Marui chamber and a DangerWerx arm, chances are you will have a perfect fit and will not need to do anything here, but if you have, say, a JG or Well chamber, the hop-up lever arm will wiggle inside the chamber. You will have to shim it to remove that side play, then determine if the arm once shimmed is at the center of the hop-up rubber. If it is, good, put the m-nub in the center, if it sits more on one side than the other, you will have to move your m-nub accordingly.

[ThunderCactus]

Not only does a TDC work well on a PDI chamber, it's my current working configuration lol
The dual arms are totally useless, and I think they're REALLY only there to correct any issues you might have in not being able to align the barrel properly due to the crap design. So I've just got one bolt pressing on both arms.

Not sure why anyone's worried about bottoming out an arm. It's an Rhop. It doesn't have to go down very far to get full hopup, and even if it did somehow bottom out, just put a thick nub between the arm and hop rubber...

What Drakker is talking about with the Mnub is that your hop arm isn't pressing on it flat. It's pressing at an angle because it's so thick. Easier solution is to just make the Mnub shorter until the arm presses down on it pretty much flat.

The PDI chamber just absolutely is not designed for flat hops. Or convenient operation. Actually it really only serves to eliminate ONE issue (left/right hop bias) in an over-engineered and frankly, unnecessary manner.
If they're going to use O-rings, it needs to be higher tension and needs to be mounted right at the end of the arm for maximum tension.
Hop window needs to be longer and squared.
adjustment is just a huge pain in the ass and it needs to be TDC'd anyway so screw O-rings altogether.
and there's no positive alignment for the inner barrel. You just kind of eyeball it and lock it in place with set screws.

[Showe22]

feedback note:

After receiving an AA hop up chamber in the mail today, the AA arm does not travel as far as the stock hop up arm does. While I have yet to test out the chamber with a TDC mod (or install a TDC mod on my Gspec), it seems as if the TDC mod would work better with a stock chamber. Results to come in the future.

[ThunderCactus]

The arm only has to travel about 1mm to get beyond the max range you'd need for a flat hop.
Just use a harder nub, and if you need the arm to sit higher, use a thicker nub.