Voltage Modded Stampede problem... It keeps going, and going, and goin
Posted 22 April 2014 - 06:46 PM
I did a basic voltage mod to my stampede, connecting a run-of-the-mill 8 "AA" battery holder from RadioShack into the battery tray. When I load it with 8 standard alkaline "AA" batteries (for a total of 12v), it runs just fine, no issues. However, when I up the voltage by replacing some of the standard batteries with "AA" Trustfires, the darn thing just won't stop firing. I slide the battery tray into the blaster, and everything seems fine. I pull and hold the trigger and it rattles off the rounds like a champ. But when I release the trigger, it doesn't stop firing. The trigger itself isn't stuck in place, it physically releases into it's "relaxed" position, but the motor keeps churning. If I only replace one standard battery with one Trustfire, it will eventually wind down and stop firing after several seconds. But if I replace 2 or more standard batteries with 2 or ore Trustfires, then the thing keeps firing non stop. I have to physically pull out the battery tray from the gun to get the motor to stop cycling.
Any body seen this problem before? Any suggestions?
Posted 22 April 2014 - 07:19 PM
Now, since I didn't answer your question, here we go. That's a normal problem with Stampedes. There is a spring-loaded cam that is part of the cycle control system, and when you up the cycle rate too high, the cam doesn't have time to move out of the way before the bolt is already forward again and into the next cycle. Either lower your battery voltage or upgrade your spring.
Posted 22 April 2014 - 07:20 PM
Edited by Xenomorph1320-D, 22 April 2014 - 07:21 PM.
Posted 22 April 2014 - 07:55 PM
When you pull the trigger on a Stampede, a white lever coming from the trigger compresses a switch, engaging the motor, which moves the plunger. The plunger holds down the switch until the cycle is completed; holding the trigger down will make the cycle repeat itself, which is what gives the Stampede the ability to fire full-auto. If the system is running to quickly, the switch-lever can't move back to it's original position, which causes the runaway.
Edited by Mully, 22 April 2014 - 07:58 PM.
Posted 22 April 2014 - 09:31 PM
azrael, though I do have an upgraded replacement spring (for the plunger), I haven't put that in the gun yet.
snakerbot, Mully, and Xenomorph1320-D: Thanks much for pointing out the bit about the pushrod switch that works with the trigger. To your question Mully, I was trying a maximum of 2-3 Trustfires with all the other slots filled with standard "AA"s. So I wasn't going crazy with those.
Xenomorph1320-D, I tried your suggestion of replacing the spring that operates the pushrod switch. Unfortunately, none of the ballpoint pens I have around here were big enough in diameter to fit around the pushrod. BUT, out of curiosity, I scrounged around and came across a spare tactical rail lock button from a section of tac rail that I removed from the stampede as part of an exterior mod to the shell. That button spring was just about the same diameter and length of the spring that came off of the pushrod, but had a stiffer tension than the original pushrod spring. Soooo... with a little finagling I managed to put that button spring on the pushrod and get the little locking clamp back on to the rod. And what do ya know... it friggin' works. I can use 2 Trustfires in the battery configuration and it stops firing the way it should. 3 Trustfires are still too much, making it run too fast for the new switch spring to shut it off. But the ROF from 2 Trustfires + 6 standard ""AA"s is pretty sweet.
Maybe I'll get my grubby hands on a NiMh battery eventually that I can use to improve and clean up the battery configuration, but for now, the Trustfires are doing the trick.
Thanks again everybody.
Edited by stoicclown, 22 April 2014 - 09:35 PM.
Posted 23 April 2014 - 01:11 AM
I can run mine off 4s/16.8v, with a LiPo battery, with around 9-11kg spring resistance, FWIW.
You're absolutely going to need to put in the upgraded spring if you up the voltage. That will honestly probably solve your problem. Run is 3s, with the new spring.
Posted 23 April 2014 - 08:06 AM
Edited by stoicclown, 23 April 2014 - 08:07 AM.
Posted 24 April 2014 - 02:58 PM
I ran my Rayven off a bench top power supply just to see how much current it drew, but it was well within the max for the R/C car battery pack I run it off of.
Don't forget the motor torque is related to current. If your batteries can't source enough current, that may account for a larger drop in RPMs after each shot. I'm not an engineer so I can't really back that up but it is consistent with my crude understanding of electronics and motors.
Edit: Whoops, forgot which gun we were talking about. If you don't have enough current, your motor isn't going to be able to crank through the cocking phase as quickly, as the peak current draw will be when the most force is applied, right before the plunger is released. I was thinking of a flywheel gun when I was talking about RPM drop after each shot.
You can poop in my toilet anytime champ.
Posted 29 April 2014 - 09:13 AM
i don't understand why everyone in this particular thread is hating on trustfires, its what i have used in my stampede since day one. I don't think I've ever actually fired a stampede with D's in it... I run 4 unprotected 14500's and have never had a problem. they charge in decent time and have a great run time. to combat your gun continuing to fire, there are two options that work pretty well and are easy to do:
1. modify the trigger mech (easier): there is a white lever that runs up from the back of the trigger to the bottom of the plunger tube. when the gun fires, it rotates counterclockwise and holds the trigger switch /on/ until the plunger tube retracts, enabling single fire. simply cut or sand the nub off so that it stops interacting with the plunger tube.
2. move the trigger switch (more involved): if you are a little more inclined to doing stuff and things to the internals of your blaster, take out the white lever explained above and its housing. underneath you will find a switch- move this to right behind the trigger and dump in some hot-glue to hold it in place. you may have to re-solder some longer leads to the switch, i don't remember if it will reach with stock wiring but my guess is no. while doing the soldering, un-solder all of the other electronic locks and improve the response time and fire rate of your blaster as well.
both of these options will solve your problem- however, it also means you need to learn to use the gun again. if you hold down the trigger for too short of a time, you will load a dart and not fire. this can quickly lead to jamming issues. simply practice firing until you learn how long to hold the trigger down to fire- remember to have a loaded clip as dry firing with the voltage mod can severely harm the blaster.
hope this helps.
edit: a few little things.
Edited by PBZ, 29 April 2014 - 09:16 AM.
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