Piston tooth count and AOE

[LazzurusMan]

After on all, it's me again with ANOTHER question that'll hopefully help me to get my Sig sorted.

It's been 5 years since I started working on it proper, I NEED to get it done.

 

So I have a 15 tooth piston that I've used a Dremel on to reduce the size of two of the teeth for aoe, AND I removed two teeth on the pickup end to short stroke it.

 

I need to replace it as I can't get the piston head off as I glued the thread and the head of the screw is now pretty chewed up, and just wondered, as I'm correcting for aoe and short stroking anyway, would it matter how many teether the rack on a new piston has?

[Adolf Hamster]

for short stroking removing the release teeth isn't really necessary, it's just something people like doing for neatness but outside a fractional weight saving it doesn't actually make a difference.

 

for aoe it'll depend on how everything goes together, but as long as it's picking up smooth without clipping any teeth then it's good.

[LazzurusMan]

So I managed to get the piston head off and put a couple of washers on it, but the aoe still isn't right and there's no more space for washers on the piston. Anyone know any other tricks I can use? 

Picture of my current aoe, is it bad enough that I HAVE to correct it?

[Davegolf]

There’s nothing wrong with that really.

If you are running a 450fps spring or DSG then I would make it better though.

The easiest AOE method is fit an airlab sorbo pad to the cylinder head. Does 2 jobs in 1 go

[Adolf Hamster]

  On 30/06/2022 at 18:56, LazzurusMan said:

So I managed to get the piston head off and put a couple of washers on it, but the aoe still isn't right and there's no more space for washers on the piston. Anyone know any other tricks I can use? 

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lemme guess- running out of bolt space? you can sortof get away with running a longer bolt.

 

  On 30/06/2022 at 18:56, LazzurusMan said:

Picture of my current aoe, is it bad enough that I HAVE to correct it?

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it's not perfect, but it would work if you aren't pushing for speed, but given the motor that's gonna be driving it along i'd be tempted to get it a bit further back (so the full face of the tooth is hitting the full face of the piston).

 

  On 30/06/2022 at 19:03, Davegolf said:

The easiest AOE method is fit an airlab sorbo pad to the cylinder head. Does 2 jobs in 1 go

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listens to the distant reee-ing of negative airsoft

 

usually i'd be against just blanket dropping sorbo into a gun as often it can end up over-correcting, but given the aoe seems to need a bit more than the usual spacing it may well be called for here.

[ak2m4]

why don't you add 1 or 2 more shims to the piston head?  you said there's no more space for washers, how come?

[Davegolf]

Most AEGs want 4-5mm depending on squishyness 

[LazzurusMan]

  On 30/06/2022 at 20:14, ak2m4 said:

why don't you add 1 or 2 more shims to the piston head?  you said there's no more space for washers, how come?

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The piston head has a bit of metal that protrudes into the piston where the thread for the bolt is. If I add more shims to it, the bit with the thread no longer goes into the piston. At that point I'd be relying entirely on the bolt to keep the piston head on, and be creating a weak point.

[Adolf Hamster]

  On 30/06/2022 at 20:20, Davegolf said:

Most AEGs want 4-5mm depending on squishyness 

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That sounds like at least 2, even 3mm too much.....

[Davegolf]

I always remove the rubber disc from inside the cylinder head 😉

[Adolf Hamster]

  On 30/06/2022 at 20:47, Davegolf said:

I always remove the rubber disc from inside the cylinder head 😉

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Ahh, that would make a difference....

[ak2m4]

  On 30/06/2022 at 20:31, LazzurusMan said:

The piston head has a bit of metal that protrudes into the piston where the thread for the bolt is. If I add more shims to it, the bit with the thread no longer goes into the piston. At that point I'd be relying entirely on the bolt to keep the piston head on, and be creating a weak point.

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Good longer strength steel screw works for me.  Never had any problems personally.  Your AOE doesn't look too bad, maybe just leave it.

Edited July 1, 2022 by ak2m4

[LazzurusMan]

Took off all the shims I put on, put a rubber washer on the piston head and screwed it tight (I suppose if that's a weak point it'll be cheaper than replacing a whole gear set etc) and my aoe is pretty much spot on. 

Thank you all, I'm one step closer to getting her on the field again!

 

Now to solder the new wires and rebuild for testing.