One question, one answer thread TECHING QUESTIONS ONLY

Discussion in 'Gun Building, Modifications & Repairs' started by Adman234, Oct 9, 2011.

  1. Cbg133

    Cbg133 Member

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    So, question on MOSFETS and precocking.

    The anti reversal latch keeps the gears from spinning backwards correct? That means if you remove this latch, your gears will spin freely in both directions.

    And a MOSFET can be programmed to precock right? Where the piston head is pulled backwards, just before the last sector gear disengages, then when you pull the trigger it finishes off the cycle.

    Does this mean, if you set a MOSFET to precock, and remove the reversal latch, that the gears will then just slowly unwind because there is no reversal latch to stop them? Or is that reasoning incorrect?
     
  2. aotsukisho

    aotsukisho Well-Known Member

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    You want to leave the ARL in anyway, because preventing the spring from decompressing through the drivetrain requires the motor to be constantly powered. Passive braking (shorting the motor leads) cannot provide sufficient braking force at low speed, so the motor will have to be in a constant state of powered stall. Stall current is the maximum the motor draws, therefore lots of heat from every component in the system for an extended period of time.

    I don't technically know the answer to your question but the only other alternative is highly undesirable so I will say yes you should leave the ARL in. Also, don't undersize your battery as you are stalling the motor with a much larger starting torque (peak amp draw) than a normal, non-precock gearbox.
     

  3. Wingman703

    Wingman703 Moderator Staff Member Moderator

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    Depending on how the mosfet is programmed, it can either hold that anti-reversal force until the battery is unplugged(which would constantly drain your battery and stress your motor), or it does its burst of reverse polarity and stops(which is how I am aware of all precocking mosfets operating). However, the gear reversal is NOT a slow or gentle process. That big spring you have powering the piston decompresses like it normally does with only the drivetrain drag slowing it down. You also break stuff like that, tappets, pistons, and sector gears can and will receive damage.
     
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  4. Lefse

    Lefse Well-Known Member Supporting Member

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    I have seen how severe the damage from a missing or faulty ARL can be, that thing is there for a reason. The tappet plate is designed to withstand the force of the tappet spring, not the main spring, if the ARL doesn't stop the gears from reversing it can be subjected to a big portion of the energy stored in the main spring. You do not want this to happen, this can also do significant damage to the piston.

    With cycle detection you can technically run the gearbox without an ARL, like in a Scorpion Evo, but I still wouldn't trust it 100%.
     
    kazuchan, -Spitfire- and Wingman703 like this.
  5. aotsukisho

    aotsukisho Well-Known Member

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    Got a couple one-shot questions that I have not seen answered with all kinds of search terms...

    1. What's the difference between the different gear sets for versions of gearbox? I've seen the whole V2/V3 and V6/V7 but it seems like the only difference is size of the spur gear?

    2. Also related to gear sets, I have two sets of V2 compatible gears where one has normal looking sawtooth ARL ratchet faces and another where the bevel's flat teeth go straight to the beveled teeth that interact with the pinion gear. Can ARLs interface with that as well?
    [​IMG]
     
  6. Wingman703

    Wingman703 Moderator Staff Member Moderator

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    They are completely different ratios and in most cases will not interchange between gearboxes or gearsets.

    The bevel pictures is a SeigeTek bevel and yes, the ARL catches those extended bevel teeth. You can not mix SeigeTek bevels with other brands due to the teeth count.
    Seigetek does the majority of the gearing between the bevel and spur gear(thus the amount of teeth) where as most other brands do the gearing between the sector and spur gear.
     
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  7. kazuchan

    kazuchan Member

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    my SRC baga yaga ( combat master ) got broke magazine lip. Where I can find the replacement ? I hear some rumors it same like TM magazine hicapa
     
  8. aotsukisho

    aotsukisho Well-Known Member

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    It's based off of a Hicapa so I would assume any Hicapa feed lips would fit in it. If you know people with other brand Hicapas see how their mags feed in your pistol if you're unsure.
     
    kazuchan likes this.
  9. Raven1st

    Raven1st Well-Known Member

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    I’ve noticed a few brushless AEG motors pop up on the usual oversees discount retailers and I’ve been wondering...

    Anyone know if any of them would work with a 26v lipo, and if not, if there are any components I could swap out of the ECU to make it work with 26v lipo?


    I have reasons for needing this.
     
  10. Wingman703

    Wingman703 Moderator Staff Member Moderator

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    Only one way to find out Raven.

    DO IT

    FOR THE FLAMES
     
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  11. Raven1st

    Raven1st Well-Known Member

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    *Dragonforce intensifies*

    That kind of project would be a very slow burn, this ain’t like first time when I had all my weekends free to sit at a tech bench, I got adult stuff now.

    Last I checked my 6s lipo was lookin’ a little puffy.
     
  12. aotsukisho

    aotsukisho Well-Known Member

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    Brushless motors have strict maximum RPM limitations, exceeding them can see the rotor fragmenting with destructive results. Because these AEG brushless retrofit units only care about power being applied, you can easily make a simple MOSFET switch using an appropriately rated component. I've done motor controller add-ons in the past to piggyback an existing controller to a higher voltage - with a BUK453-50B MOSFET I was able to drive a motor at up to 10s lipo as long as the motor is clamped with an appropriate kickback diode.
     
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