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NscrupulousModefiler

Advice needed: suitable solenoid for remote mag-release?

Getting close to finishing the Hushpuppy and ticking things off my list for things to improve in the bullpup format... It's turning out to be a quite handy (if heavy!) little weapon, but one thing that's still niggling and will inevitably draw fire from the bullpup nay-sayers is the mag release. I can lengthen the existing one to make it functional for this version, but the fastest mag-change system I can work out means you really need to have your thumb around 2 mags at the same time - the mag release ideally needs to be activated by your index finger. I could work up a mechanical solution but it would be a lot of faffing... I'd be keen to try a solenoid for the next iteration of the build.

Questions then:

1. Has anyone gotten this to work before? I've searched here, NerfHaven, Reddit and the net generally, but no joy. Maybe my search is too narrow?

2. Needing about 5mm travel, but what I really need to know is how much force the solenoid will have to be capable of. Noticing their rating decreases with travel ... so they're less strong at max. extension?

These are what's readily available locally. All 12v, the stronger ones are quite heavy, and all are bloody expensive. I can get the same cheaper from Aliexpress, but ideally I'd prefer stay with 2S in the build so would prefer 6v if it'd be grunty enough. Can work around either push or pull action.

Any advice or comments welcome!

OldNoob

Use a micro servo instead, lighter, lower power demand, can run off a control board, use it to move the current release lever.
Personally I would use the Rayven/Stryfe type design, despite not liking reaching behind my grip to release mags. If you have to go back there to remove the mag it's no fuss to mechanically operate a lever. I never drop my mags out, despite being able to, as I feed the next one from my off hand so you gain nothing by adding mechanical complexity via a remote release.
Minky

I am going to give a roller catch a go on the Bull pup I've got on the drawing board at the mo (months away, sigh).  In conjunction with a big guide skirt I hoping it'll be practical for quick changing by my shoulder...  But don't do that,  this sounds much more interesting!
NscrupulousModefiler

OldNoob wrote:
Use a micro servo instead


Thanks ON. You thinking something like this? Is there any way to make a servo-type action work without a control board? (ie: just on/off actuation?)


Minky wrote:
I am going to give a roller catch a go ...


Intriguing... how does that work? Worked it out  Wink That could be a good simple solution!
OldNoob

Yeah, those. You need a controller to tell it how far and when to move.
NscrupulousModefiler

OldNoob wrote:
You need a controller to tell it how far and when to move.


Damn... Sensors are picking up a crash-course in RC electronics on the horizon. Wink
SSGT

EDIT

Topic moved to Q&A and New Members.

SSGT


Servo motors are usually made up from a normal DC motor, a potentiometer (which is used to determine the shaft position) and a small board. The board is fed a PWM signal from the controller which tells the servo what position you want the shaft to be in. The board compares this to the current position, which is determined by the voltage output of the potentiometer, and if it doesn't match it spins the motor in the correct direction until it does. Depending on the individual servo it may be possible to simply feed it a constant "on" or "off" signal to force it to the limit of it's rotation in either direction although, since the min and max pulse width is usually around 1ms and 2ms respectively, it's quite possible that if you supply a signal outside of it's range the servo will try and move past it's mechanically limited range and either strip gears or just run the motor at stall constantly. If you'll be running a microcontroller anyway you can still do without a separate board, just feed the servo a PWM directly from an output pin of the microcontroller and keep it within the specced pulse range of the servo (as I say, normally a pulse between 1 to 2ms in length and at a frequency of 50Hz although this may vary).

I personally would run a mechanical mag release if possible though. A long bar to the front may work, as would a roller catch, but to be honest, if it were me, I'd probably also just keep the current mag release - it'll be more reliable and means you wouldn't need a pack installed just to release a magazine. I know a lot of people use their dominant index or middle-finger to release magazines but I almost always use my off-hand thumb to depress or slide mag-release catches anyway (I sometimes use dominant index finger with Retal/EAT style mag-release but have never used middle-finger with Stryfe/RS/Rayven style mag release).
NscrupulousModefiler

Thanks for all the detail SSGT. One way or another if I did run an electrically driven release I'd absolutely require a back-up manual release as well - locking the servo's gears to the mechanism would be asking for trouble. Given my limited experience with microcontrollers it's not likely to appear in a build just yet... the solenoid seemed like an achievable mid-level measure. There's lots I've learned from this build though that'll hopefully be incorporated into a cleaned-up v2.0; a fully mechanical system will probably give me the best result as long as I start building it in on the "ground floor". On the other hand... if done right, Minky's roller-catch idea might be just the ticket...

I'll try and post pix or a vid in the next few days of the mag-change system I'm using, just to clarify why I'd want to use the off-hand index finger activating a front-mounted release switch...

Cheers! Nscrup.
Minky

Hey, if you want to do the R&D I'm more than happy with that! I'm nowhere near trying it myself yet and I've got a feeling that if it's as easy as i think it should be everyone would be doing it. I came up with it when watching Walcom's vid on the Paradigm Shift and I was trying to work out how he did the two stage mag wells (read up later and he used a different method).  My only concern with it is that the roller has to extend enough to hold the mag in a consistent position but without being far enough out to potentially flip the top dart... So have fun with that!
NscrupulousModefiler

Old thread, but just posting here as an epilogue to the discussion and because I haven't got enough photos yet to warrant starting a whole new one.

Quick 'Tater-Cam vid of the mag-change system for the Hushpuppy. Installed the extended mag-release and it actually works MUCH better than expected, so no need for any of the electric solutions. The roller-lock still bears exploring though I reckon. This routine works nicely for my Rayven as well... if no-one's seen anyone using a similar system, I'll work up a proper demonstration thread with pix and vid.

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