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AoE,shaving teeth, audio ROF, tappet plate bearings: how-to **UPDATE**

I decided to put together a a crash course in response to emails and pm's. These are but a few of the techniques t I have been using in my builds. These are items I feel havent been covered enough and I welcome anyone else to add to it.

It will cover :
AoE or Angle of Engagement
Removing/shaving piston and sector gear teeth
tappet plate bearings
audio ROF testing

Part one

AoE or angle of engagement refers to the angle of the first tooth on the sector gear as it comes into contact with the pickup tooth on the piston. Here is a picture before adjustment:
http://img75.imageshack.us/img75/5659/100_2828Medium.jpg
Note the poor alignment angle of the sector gear. In order to correct this a shim or buffer material must be used to move the piston body back. The goal is to align the piston so it contacts the first tooth on the sector gear with the most surface area possible.
Here is a pic of the piston head with a shim.
http://img75.imageshack.us/img75/3429/100_2829Medium.jpg
I use a 2 part nylon washer although only one is pictured, a smaller one to fit he piston head post and a larger one to match the size of the head. The larger fits around the smaller washer and they are not stacked. This is the less desirable of the two options as the strength of the piston assembly is compromised. The prefered method is to add rigid foam or soborthane rubber to the piston or cylinder head. It is available from a couple different websites and is worth the $10 for a 4x4 sheet. I use the 1/8" 70 hardness with great results.
Here's a pic after AoE adjustment.
http://img75.imageshack.us/img75/1830/100_2837Medium.jpg

Part Two

Removal of piston/sector gear teeth

There are 2 reasons to remove teeth on the piston and sector gear , pick-up timing and short stroking.
Pick up timing refers to the aligment of the piston and sector gear as stated in part one to provide optimal surface contact and avoid interference which leads to piston/gear failure.
Short stroking is done to increase ROF. By removing teeth from the sector gear the psiton is not drawn back as far thus creating a shorter cycle time which equals higher ROF but a lesser FPS. Removing the corresponding teeth on the piston is not necessary but the teeth are strictly dead weight at this point so I remove them.
Here is a picture of a AE piston that has had the second to last tooth removed, the third to last shaved to avoid contact with sector gear's 2nd tooth, and two teeth have been removed of the front to allow for a shorter stroke.
http://img75.imageshack.us/img75/608/100_2832Medium.jpg
Removal of the second to last tooth is an must for any thing other than stock IMO, I prefer to shave down the third to last tooth rather than removing it totally. It usually only needs to be trimmed a little bit to avoid contact with the sector gear. Before anyone asks it is an Airsoft Elite aluminum piston modified to take a Deepfire titanium rack . Also only one of the piston head shims is installed at time of picture.

Part Three

Tappet plate bearings

In my opinion this is one of the most looked over areas of the gearbox. I have tried sanding and polishing the rails of the tappet plate but I have never been satisfied with the drag that the design seems to produce. The way I address the problem is by adding a few single bearings to the sides of the tappet plate. Depending on the tolerances of different setups the width of the tappet plate might need to be thinned out to allow for the protruding bearings. I prefer to use the small bearings in a leftover piston head or spring guide. Any bearing will do as long as it fits the rails of the gearbox with out binding.
http://img75.imageshack.us/img75/5550/100_2838Medium.jpg
http://img75.imageshack.us/img75/6613/100_2840Medium.jpg
Note how the bearing does not protrude from the top or bottom of the tappet plate only the sides. I drill the holes in the tappet slightly larger than the bearings to allow them to roll. When assembling a little dab of grease will keep them in their place. It will take a few tries to get the fitment just right but the resulting smoothness is well worth the trouble. I am seriously toying with the idea of dong this on the rails of the piston. It is something I am going to try tomorrow and I will post up ROF test results.