• Hi Guest. Welcome to the new forums. All of your posts and personal messages have been migrated. Attachments (i.e. images) and The (Old) Classifieds have been wiped.

    The old forums will be available for a couple of weeks should you wish to grab old images or classifieds listings content. Go Here

    If you have any issues please post about them in the Forum Feedback thread: Go Here

Overspin/Double-firing on first cycle only

J

jem

Members
Joined
Aug 28, 2023
Messages
11
Reaction score
3
Hi all,

Recently did some work on my Specna SA-H02 (416). First gun I've taken apart, definitely a learning experience.

I'm noticing some double-firing (occasionally triple-firing) in semi-auto, but only on the first trigger pull after connecting/disconnecting a battery.

Thinking this is just a little overspin caused by the 11.1v batteries I'm now using, and the Aster's AB is just taking a second to kick in after that first cycle.

Does this sound reasonable an assumption?

Changes I made:

- Installed a Gate Aster v2, following Gate's video and documentation

- Reshim of the stock gears, following Chupacabra Outdoor's video exactly

- SHS piston, rocket cylinder head and nozzle

- SHS motor

- Cleaned the entire gearbox and shell with hot, dish soapy water and relubed following TheAirsoftTech's video, using Superlube

Thanks!

 
Last edited by a moderator:
What have you set up on the Aster? Is there precocking on semi?

 
Lozart said:
What have you set up on the Aster? Is there precocking on semi?
Click to expand...


Sorry, meant to include this!

I've tried Active Braking on both Adaptive and various manual levels, no difference in the overspin on that first cycle.

I did play around with both manual and auto pre-cocking but noticed no difference in the overspin with it on or off. It's off for now.

Also set a 20 RPS limit, though this unsurprisingly didn't change the overspin either.

 
Auto precocking could cause this.

When it first powers up it doesnt know the timing of the system, so intentionally overruns on the first shot to time it, then from that info it can set a more appropriate precocking timer.

 
Adolf Hamster said:
Auto precocking could cause this.

When it first powers up it doesnt know the timing of the system, so intentionally overruns on the first shot to time it, then from that info it can set a more appropriate precocking timer.
Click to expand...
Interesting! thanks.

This still happens even with precocking disabled though

 
When you shimmed the gearbox, did you make sure that the sector gear cam is still reliably being seen by the Aster sensor? It may be a bit borderline.

 
Lozart said:
When you shimmed the gearbox, did you make sure that the sector gear cam is still reliably being seen by the Aster sensor? It may be a bit borderline.
Click to expand...


Good point, but surely the issue would occur more randomly in that case than just the first trigger pull after a battery's connected? ?

 
Good point, well presented.

Does it do it with a 7.4v battery?

 
Lozart said:
Good point, well presented.

Does it do it with a 7.4v battery?
Click to expand...


Thanks!

I'm yet to test this (all my 7.4v are Tamiya, don't have the means to rewire them right now and a friend's borrowing my adapter...)

Will try to remember to post the results when I get to it :)

 
What's the SHS motor out of interest?  Be careful with that Adaptive AB setting and 11.1v, can easily spanner a motor.  As Loz says try with a 7.4 and well worth getting a basic soldering kit for the battery connector conversion.

 
jem said:
Does that not just use a regular v2 gearbox? should be the same no?
Click to expand...
Yeah the gearbox is the same, but the grip covers the whole gearbox so when the motor is installed you can't see it where the pinion meets the bevel.

I cobbled some tube etc together to position the motor, shimmed the bevel then I'll sort motor height in due course. Maybe this eve...

 
Braking a brushed motor creates at least as much damage as running it.

Voltages will be higher (limited by the speed the magnetic field collapses at) and you are effectively shorting the motor for varying periods of time(MOSFET switching on and off) and that energy all turns into heat.

Brushes don't like it either.

Higher torque motors suffer more since they produce more braking torque.

 
Sewdhull said:
Braking a brushed motor creates at least as much damage as running it.
Click to expand...


Surely if the motor has a hard brake instead of a soft break that's going to impact the motor quicker?  I'm just going on what I've seen in the past ten years.  I'd say 90% of the motor returns / failures I've had from customers have been caused by the Titan adaptive AB feature, or at least that's the one thing they all have in common.  Perhaps it's something else that's going on with the feature.

 
Yes hard braking will be worse for the motor than softer.

Running any brake also means there's less time for the motor to cool between instances of running.

Because motors are enclosed cooling can be an issue anyway.

Brushes have a hard time as well as the armature windings.

Most neodymium magnets will permanently lose magnetic strength(even after they have cooled again) if they get near 80C which will increase the current the motors run at, because the back EMF which limits voltage will reduce and therefore current will increase at the same revs making the motors heat up even quicker.

Once the motor is out of its design parameters it will go south quickly.

Ferrite magnets tolerate around 3 times that temp.

The best setting is none, but if you need it, the weakest braking is the next best.

Even in the cold the motor can get very warm in use as your hand tends to warm up the grip limiting heat transfer away from the grip, which has poor thermal transfer from the motor because it's surrounded by air anyway.

Not running your motor hard is the key to motor longevity I think.

 
You must log in or register to reply here.
Back
Top