I know there are many, many guides on how to adjust and correct the AoE, some are probably a good bit better, but this is just my go at it.
We're going to say you can get to this point from one of the Numerous guides on how to take apart a gun, in this case, an M4. Now, what's nice about AoE is that it can be adjusted in any gearbox, not just M4s. Every gearbox has a piston/gears and this mod will work for every gearbox.
Alright, the picture isn't all that great, but it's good enough to see what I'm talking about. That first tooth on the Sector Gear, the on at the top, see how it is hitting the first tooth on the piston, the really big one on the left? This is called improper Angle of Engagement, or AoE.
Think of it like a knife, the reason knives cut stuff is because they come to a point, and all that pressure is applied at the point of the blade. If you try and cut with the wrong side of a knife, it won'tg cut because it's not sharp, and the pressure is spread out. The same principle applies with AoE, just backwards. Because the gear is engaging the piston at a point, it will wear down that tooth until it just can't grab it any more. Adjusting the AoE is where you make the first tooth of the gear line up evenly with the first tooth of the piston. You spread out the pressure along the whole tooth, instead of that small point.
This is a picture of the damage that bad AoE can do to a piston.
This is what it should look like, or about what it should look like. It's not quite perfect, but it has been adjusted. Perfect AoE will have the first tooth of the Sector Gear lined up and parallel with with the first tooth of the Piston. If you notice, it's a little off. Now, this is still better from the first example, but not perfect. I left it as is, because this M4 is a loaner shooting 320fps in a stock gun, not very challenging at all.
Now, to push the piston back, you'll need a spacer of some sort to allow for the piston teeth to mesh correctly with the Sector Gear teeth. I used the stock rubber padding and some mouse pad foam to allow me to achieve the proper spacing.
Here's my mouse pad, I've already used it a few times, obviously.
I start by taking the cylinder of the gun and pressing it into the mouse pad. Pressing it hard enough to make an impression on the foam. Like this:
Then I cut the circle out of the foam.
Next, I use a hole puncher to put a hole in the center of the circle to allow for proper air flow into the air nozzle. The hole that you put into the padding at this step should end up being right over the air nozzle hole.
A picture of the foam pad over the cylinder head, note that you can easily see straight through the air nozzle.
Next, I remove the rubber padding out of the back of the cylinder head. It's kind of hard, and messy, but do-able. Just be sure you scrape out as much as you can and try to get the rubber pad off in one piece.
Next, you replace the rubber pad with the foam pad that we made earlier.
*note* It is a good idea to trim up the foam pad so that it fits better into the cylinder head.
For reference, this is the glue I use:
And now glue the rubber pad back onto the foam. The reason I do this is because the foam is soft and gets torn up very easily, the rubber pad helps to protect the foam so that it lasts longer.
A Side view:
The padding needs to be just right so that the first tooth of the piston and the first tooth of the Sector Gear are parallel to each other, You need to test this with your spring in. Foam Compresses under pressure, what the angle of engagement is without the spring will be different from the angle with the spring. Be warned, and be careful, you can screw up a piston if you don't check to make sure it's correct.
Alright, now if you'll notice, after putting in the padding, when you try to turn the sector gear it will hit the second or third tooth on the piston instead of the first:
Simply remove them, I use a dremel now that I have one, but I used files before that.
And now you'll notice that it all meshes correctly, and when the sector gear turns, it comes into contact with the first tooth of the piston first, and not one of the other teeth.
That's how I adjust my AoE.
I realize several of these pictures are rather sub par, so I want to invite anyone who cares to to one up me and make a better guide. We'll probably post many different ones. There are many ways to adjust the AoE, this is just one way. It is also rather late for me, so, please, let me know if I have misspoken, or made some sort of critical error. Thanks guys.
An update, but this time using sorbo padding as an example. The process is very similar to the foam, except I find that sorbo is strong enough that it doesn't need the rubber pad to protect it.
This is what it looks like after about 30k rounds. Yes, it took a few tries to get the hole right in the middle of the padding. Ended up looking like some triforce knock-off, but it still works.
This is what the cylinder head looks like from the side. You can see the sorbo is glued right on top of the rubber padding. Just be sure it is cleaned of all grease to be sure that the glue will do it's job. It doesn't need to be perfectly cut, as long as it fills up most of the cylinder head, has a hole for the air port, and evenly fits into the cylinder, then you are golden.
Edited by airborne101, 12 August 2011 - 10:23 AM.