swiss cheesing a piston?

[sniperiain]

anybody ever donee this to their piston? also the piston needs to have the rear teeth removed and short stroked if its super crazy?
i heard that it makes it lighter there for making it go forward quicker if your firing at somin like 32RPS.
anybody done it and if so is it worth doing?
on this video at about 1:44 onwards
http://www.youtube.com/watch?v=mo2L1gbzSfY
if the mods delete this vid then heres a pic but you cant see to well

[magic_golem]

Re: swiss cheesing a piston?

ive done the swiss cheesing to a few pistons, never really noticed a huge difference but i wasnt going for a high rate of fire, i just wanted the piston lighter so the gears had a little less work to do but after looking at the idea on paper i saw it as a waste of time, reducing the weight of the piston by about 5 grammes, doesnt really compare to the force still required to compress the spring.
having said that i do still grind out most of the 'channels' on each side so that there is as little point of contact with the casing and so as little friction as possible.
short stroking can seriously increase your rate of fire, drops your fps though, if you thinking of doing that, go read up some more online as not only will you need to re-make the rack gears on the piston (although you can buy ones premade with less teeth, just count them) you will also have to gat a vice and grind teeth off of your sector gear too, as if you just remove teeth off the pistion and not the sector gear as well, the piston will hit the now 'extra' teeth on the sector gear.

hehe that was alot, hope that helps you.

Anyone else had much luck with swiss cheesing their pistons? lol ive done it to an mp7

[sj_asc]

Re: swiss cheesing a piston?

It really depends on the setup, in all the testing ive done, i haven't really noticed much of a difference between the standard and modified part, you can see it more when measuring in RPM, but as far as sounding noticeably faster it isn't there, and nor should we expect it to be.

The primary purpose of weight reduction would be to reduce the piston assembly return time in order to prevent out of time engagement, not just ROF as we know it. Lightened piston assembly's (the piston, piston head + base block) generally are much more effective when paired with ported cylinders (ideally 1/2 or half ported) so the piston can be released to gain speed for half of the return without the resistance of compression which slows it down.
However, it will not work the same for non ported cylinders, long barrels and heavier bbs, really high hop setting without the use of a stiffer spring, because you run the risk of premature sector to piston tooth engagement.
A heavier piston assembly is better for increasing muzzle energy with heavier bbs.

"swiss cheesing" is a good approach to building a more efficient high speed setup because it will allow you to get away with the use of a lighter spring, but passing 30rps, you will need to step up the spring rate and or reduce the pistons stroke distance.