I gave up. What's wrong with my build?

Hi… recently, I’ve built my 3rd gel blaster. the 2 other build was successful with stable 330 FPS.
the 3rd build use the same cylinder & piston set as the previous 2… the different is 3 teeth trimmed from sector gear and piston, reversed delayer chip, high speed motor and mosfet active braking.
With the optimal volumetric ratio, It only get 240-250 FPS… checked for leaks on cylinder & piston set everything was fine. I’ve tried changing the cylinder to bigger ratio and still getting the same FPS. Can anyone guess whats the problem here ? Thanks.

What blaster is it? What spring, gears, gearbox are you using? What is the barrel length and cylinder port? While at it, what motor, mosfet, tappet plate and nozzle are you using?

I am guessing you are using m100 as that typically achieves 330fps, and if you are running it short stroked, you should expect a loss of around 45fps, give or take depending on the barrel length and cylinder, usually short stroking two teeth, requires the next spring up to get the same fps, again, give or take depending on the cylinder, barrel, spring.

You also mentioned a high speed motor, so a loss in fps from a previous perfect setup is more likely tappet plate and nozzle related. It can be pme, though if you have 3 teeth missing this should be unlikely with an m100, unless you are above 30rps.


Possibly the delay chip/tappet timing :thinking:
Need to check it all by rotating the gearbox whilst split in half and check that tappet/nozzle travel is all functioning correctly :+1:

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To confirm you said the difference is the 3 teeth trimmed and the swapped delay chip, motor and active break?

  • I doubt the high speed motor and active break would do it unless the high speed motor was changing the timing with one of the other changes.
  • trimming teeth: this could definately do it. For a start you are no longer pulling the piston back the full length, changing the amount of air you push forward and depending on where the port it you could be losing VE ratio, creating a suction effect in the barrel because there isn’t enough air you have changed the cylinder and no change so I assume this is not the cause. The other thing that could be happening is depending on which side of the sector gear the teeth were taken, the piston could be being released before the nozzle fully engages the t-piece, creating a momentary leak and reducing the air going into the barrel. Short stroking also doesn’t make use of the full spring load so this will effect the piston velocity with less force being applied to it.
  • delay chip reversed: this could change the timing of when the tappet is released and when the nozzle engages the t-piece. If it is being released late and hasn’t formed a seal on the t-piece before the piston is released it will leak air for a short time and you may not have the air to fill the barrel.
    All else being equal to the other builds these are the things I would check for first: When you have the gearbox apart, rotate the gears and check the tappet is released well before the piston and the nozzle engages the t-piece and seals. If it isn’t a different tappet may be required or changing the delay chip back around/removing the delay chip depending on blaster and gear combinations (unspecified).
    If this is all happening at the right time, then you may need to step up the spring to get the piston moving fast enough.
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