Modifying the tappet plate for better air seal

[Skladfin]

I've recently come up with the idea for better airseal.

Could I mill/sand off 1 or 2 millimetres off the front of the tappet plate, which would theoritically cause the tappet plate to hit forward farther than usual. This would result in better seal between the hop up rubber and the air nozzle because the nozzle could reach slightly farther.

Not sure if this has been done before. However, I believe this could cure those "nozzle not reaching rubber" problems that some times cause loss of FPS for as much as 70FPS.

any ideas, middle fingers, and cash donations welcome.

EDIT: So yes, I found, this indeed DOES work very well! No risk of causing misfeeding, gearbox jam, or any other problems.

Originally Posted by Skladfin

I just tried this personally on a client's gun

gained back 45 ish FPS.

The trick is to do the flashlight-under-hop-up-unit trick to keep checking whether the nozzle fully meets the hop up rubber or not. I think someone on here had a picture explaining how to do this neat little trick.

Originally Posted by Arnies Forums Member

Done it to my M14, as I was getting loads of [lost air] up to 150fps in 1 case sanded 1mm off the front of the tappet plate re installed it, tested it and gained all the fps back plus a little extra.

On closer inspection and comparison of the hop rubbers on my barrel out of my SOC16 against the M14 revealed the sealing lip was a nats doodah shorter on 1 than the other, 1 is a Guarder black, the other origin unknown (believed TM).

[coach]

I'd worry about the integrity of the tappet plate where you've milled it down. can it handle the stress being thinner? is 1 or 2mm's going to make a sufficient difference?

Anyway, I say go for it. try it and see. you may have stumbled across a brilliant idea.

I guess a slightly longer nozzle would interfere too much with the BB feed path?

[Crunchmeister]

In theory, this could work. As coachster said though, I'd be worried about the tappet plate handing the stresses it sees by being thinner. But no better way to find out than try it. And if it doesn't work, at worse you're out of a $10 part.

[venture]

Never use a nozzle that is >1mm +/- the stock nozzle.

If it is too short you will get multiple bb feed problems.
If too long it will interfere with one bb feeding.

[PRELUDE]

instead of modifying the tappet plate, maybe you can try putting a layer of thin tape around the nozzle. the layer must be thin enough in order for the nozzle to still fit into the the hop-up chamber... hence a better seal.

applying something around the nozzle will not change the integrity of the tappet plate. also, it will not change the distance/position of the nozzle for improper bb feed.

[ThunderCactus]

How about asking me to machine custom stainless air nozzles that are .3mm oversize?

[m102404]

Sand off a couple of milimeters? Isn't the thickness of a regular tappet only a couple of milimeters to begin with?

[Skladfin]

Originally Posted by Crunchmeister

In theory, this could work. As coachster said though, I'd be worried about the tappet plate handing the stresses it sees by being thinner. But no better way to find out than try it. And if it doesn't work, at worse you're out of a $10 part.

Yup, that's one of my worries as well. My other hypothesis is that if it's 5mm to begin with and can handle numerous amount of shock, then another mil or two wouldn't really cause any stability problems. However you are right, it's only a $10 part and I should just try it. Down side is that right now I don't have an AEG to try this with lol.

Originally Posted by venture

Never use a nozzle that is >1mm +/- the stock nozzle.

If it is too short you will get multiple bb feed problems.
If too long it will interfere with one bb feeding.

I don't think you understood my idea here. Theory is that the nozzle will only reach farther when it shoots out like it should, nothing to do with nozzle length itself. When the tappet plate is pulled back, it's still the same clearance without modification.

Originally Posted by PRELUDE

instead of modifying the tappet plate, maybe you can try putting a layer of thin tape around the nozzle. the layer must be thin enough in order for the nozzle to still fit into the the hop-up chamber... hence a better seal.

applying something around the nozzle will not change the integrity of the tappet plate. also, it will not change the distance/position of the nozzle for improper bb feed.

That's a good idea, but it only works if the nozzle is already making contact with the rubber. My idea is if the nozzle is outright not reaching the rubber and therefore air is lost inside the hop up chamber. Good idea though, this is what people do for their VSRs.

Originally Posted by ThunderCactus

How about asking me to machine custom stainless air nozzles that are .3mm oversize?

Would work, but that could cause misfeeding problems :P

Originally Posted by m102404

Sand off a couple of milimeters? Isn't the thickness of a regular tappet only a couple of milimeters to begin with?

You are right, it's not very thick to begin with. 1mil or 2 mil is just a figurative number. I will probably sand off just enough to make a good contact relative to the tappet plate thickness.

[Azathoth]

Wouldnt it easier to sand down those MM's from the inside of the gearbox where the base of the nozzle will strike the inside front of the gearbox?

[yuhaoyang]

I thought the nozzle already pushed the BB up very near to the protruding notch in the hop-up bucking... wouldn't moving the BB further forward cancel out the hop-up effect?

[coach]

Originally Posted by Azathoth

Wouldnt it easier to sand down those MM's from the inside of the gearbox where the base of the nozzle will strike the inside front of the gearbox?

yes but no. I'd much rather a tappet failure than a catastrophic gearbox failure. ie crack.

Originally Posted by yuhaoyang

I thought the nozzle already pushed the BB up very near to the protruding notch in the hop-up bucking... wouldn't moving the BB further forward cancel out the hop-up effect?

hopup nub is still further forwards. that, shouldn't be an issue.

[Azathoth]

Originally Posted by coachster

yes but no. I'd much rather a tappet failure than a catastrophic gearbox failure. ie crack.



hopup nub is still further forwards. that, shouldn't be an issue.

Actually I think it would better taking the matierial of the gearbox. The failure point is not in the nozzle slot but the side walls near the cylinder head.

Another option is to grin out a groove in your nozzle and place an O ring inside it. Their is a DIY guide at filairsoft.

[Con Murder]

I like azathoth's idea of shaving the mechbox. BUT I would try the tappet plate first (this is assuming you have a seal problem, not a working AEG) just to ensure it was a solution, and then wait for the tappet to fail before shaving. Now to make it more complex, if the tappet mod held out for say 4-6 months I most likely would just keep modding tappet plates. I never want to do anything that might compromise my mechbox integrity.

[m102404]

Why not shave a bit off the "lip" of the hopup unit where it contacts the face of the mechbox shell? Integrity of the mechbox/internal parts is still intact..and hopup units can be swapped if you botch it.

It would still bring the the nozzle closer to the lips of the hopup rubber...and most times there's enough play in the magwell/magcatch to allow the mag some wiggle room.

Hopefully you're only looking for <0.5mm.

Otherwise...take a longer nozzle with a similar body profile and turn/shave it down...or make a custom one from scratch.

The last custom one I had made was made out of derlin and didn't take too long. (cost me a case of beer though)

[ThunderCactus]

.3mm doesn't cause feeding problems, I made a custom air nozzle for my 249 already