[chbot] electonics & motor current question.

[Mikael Stewart]

The stall torque of a brushed DC motor will vary with commutation angle and 
depend on the number of armature poles. It sounds like the gun was designed 
for the motor to build up some speed and momentum before engaging, so it 
should have some mechanism to stop rotating after the last shot. Otherwise 
it should have been designed so that the minimum torque seen at stall be 
enough to charge the next shot.

How old is the gun?

Regards,
Mikael



----- Original Message ----- 
From: "Carl Ranson" <carl.ranson at gmail.com>
To: "chbot" <chchrobotics at lists.linuxnut.co.nz>
Sent: Friday, March 05, 2010 9:36 PM
Subject: [chbot] electonics & motor current question.


> Ok, so i've been asked to diagnose a fault with an airsoft gun.
>
> basically a motor drives a gear-train to pull back a piston against a
> big spring. the final gear has half of its circumfrunce covered with
> teeth, so that it drives the piston for half it's cycle and then quickly
> lets go of it.
>
> the problem seems to be if you hold down the trigger too long, it
> re-engages the piston.
> So starting with the piston engagd it seems that the motor/battery isn't
> strong enough. it draws upwards of 17A.
>
> my question is this...
>
> given a motor/gearbox that usually draws <3A at 9V , is it possible that
> the same arangement, starting from a stall where the piston is engaged,
> wouldn't work at 16A.
>
> my hope is that i can demonstrate the battery supplied is insuffiet so
> they don't have to return the whole  system under the consumer
> guarentees act.
>
> Cheers
> Carl .
>
> _______________________________________________
> Chchrobotics mailing list Chchrobotics at lists.linuxnut.co.nz
> http://lists.ourshack.com/mailman/listinfo/chchrobotics
> Mail Archives: http://lists.ourshack.com/pipermail/chchrobotics/
> Web site: http://kiwibots.org
> Meeting Dates:
> Wed 17 Feb 2010 6.30pm
> Wed 21 Apr 2010 6.30pm
> Wed 16 Jun 2010 6.30pm
> Wed 18 Aug 2010 6.30pm
> Wed 20 Oct 2010 6.30pm
> Wed 15 Dec 2010 6.30pm
>
> When replying, please edit your Subject line to reflect new content.