Multi shot. On semi 🤣

[Egon_247]

It comes in waves, doesn't it?

It's all hunky dory and you're dinging people on the field with your "different to an M4" pew and then it lets you down. 🤣

 

So. Aug. It's a tm v3 with non tm gears in it and a 28k warhead. It runs on a 7.4v unless I'm in a daft mood, then the 11.1 comes out to play ...

 

So on semi, it's lobbing 2 or 3 out the barrel. Not actually firing per se, just kinda throwing them out. 

 

I've changed the hop rubber in case it wasn't holding on properly, but no joy.

 

Would my thinking be right in that if there was slack in the bushes, it may not be activating the cut off lever, as semi also doubles up as full auto, when on the 11.1v?

 

Nothing physically changed other than the hop rubber, so I'm thinking something is worn. 

 

Dropping the box out, I can move the shafts in the bushes and they just look a bit sloppy to me.

 

@ak2m4 will be getting a visit shortly I think, but I thought I'd ask the collective first....

 

I have heard things about the feed tube too but I think that was just not feeding at all.

 

 

[Cannonfodder]

Edit: ignore me, I didn't read the post properly 

Edited June 20 by Cannonfodder

[Hotweeweejef]

What’s the discharge rate of the 11.1?

 

My Krytac Trident SPR does this and I have concluded that it’s the batteries causing the issue…

 

So, I accidentally bought 25C instead of 20C 11.1s and the higher discharge rate seems to cause the motor to overspin on semi, causing the exact symptoms to you describe. 
Using a 20C 11.1 and I have next to no issue…

Now I say next to no issue because a fully (100%)  charged 20C will cause the problem also, but significantly less often and the problem goes away once the battery has discharged a bit. 
 

Hopefully it’s the same issue for you and not something trickier. 

[Pseudotectonic]

what gears?

[Egon_247]

7 hours ago, Pseudotectonic said:

what gears?

18:1, two teeth off the release side.

[Rogerborg]

11 hours ago, Hotweeweejef said:

Using a 20C 11.1 and I have next to no issue…

 

Except that you're trying to draw more current than the battery can provide, which will, best case, heat it up and shorten its life, or worst case spark it up.

[Sewdhull]

Yeah, using your battery to tune your gun shouldn't be a thing. You are deliberately stressing the battery but that's up to you.

 

It's not the batteries causing the issue, it's your setup causing the issue.

 

If you are getting multiple shots on semi it's either overspin or worn cut off lever. Overspin seems unlikely.

 

 

Edited June 21 by Sewdhull

[Egon_247]

I still have the issue on a 7.4 20c. It's not overspin (unless the arl is catching on the gears, hmmm) I'm going to rebuild it shortly anyway, might need a new switch carrier if it's not disconnecting the semi properly.

[Pseudotectonic]

11 hours ago, Egon_247 said:

18:1, two teeth off the release side

uh oh

 

could be the problem

[Colin Allen]

Just to get some clarification, could you put up a video of this "lobbing 2 or 3 out the barrel. Not actually firing per se, just kinda throwing them out."

Is the gearbox cycling twice or are two shots coming out on one cycle?

5 minutes ago, Pseudotectonic said:

uh oh

 

could be the problem

Yes, that could be problematic.  I would have taken two off the pickup.

[Egon_247]

Yeah, I'll get a vid tomorrow,I've had a beer now and likely to hate it more if I fire it now .🤣

[Hotweeweejef]

22 hours ago, Rogerborg said:

 

Except that you're trying to draw more current than the battery can provide, which will, best case, heat it up and shorten its life, or worst case spark it up.

Ah ok. Could you elaborate on this for me please? Still pretty new to this Lipo battery business. 
 

I’ve always used the 11.1 20c with that rif (as I did the previous owner I assume as that was the battery supplied with it) and 95% it functions fine (except the occasional double feed/over spin when the 20c is 100%) The problem was me purchasing a couple spare batteries and not checking the specs fully and ending up with the 25c. 
 

Genuine question, so hopefully that doesn’t read as me being arsey, because I’m really not 😂 

Like I say, still pretty new so keen to learn. 

 

[Rogerborg]

On 21/06/2024 at 18:30, Pseudotectonic said:

uh oh

 

could be the problem

 

D'oh, yes, I missed that.

 

One hail-Mary to try is drilling a very slight detent into the top of the hop chamber, directly above the feed tube.  A few gentle-pressure turns with a 6mm drill bit put up the feed tube, just enough to create a little inverted dimple that BBs can seat into.  This fixed, or seemed to fix, a similar issue on my MP5K, although as with anything airsoft it might just have been sorted by another round of disassembly-reassembly.

 

(Detouring...)

 

 

11 hours ago, Hotweeweejef said:

Could you elaborate on this for me please? Still pretty new to this Lipo battery business

 

No worries, and you're right to ask because it's not obvious.  What your gun is telling you is that the motor can draw enough current to over-spin, and will do so if the battery can supply it.  By using a lower-C battery to fix that, you're now in a situation where the motor is trying to draw more current than the battery can provide.  It's probably marginal, and many players are likely in the same situation without even realising it.  However, you might find is that the battery heats up with use.  It's not likely to become seriously toasty, but it'll be shortening its life to some extent.  I mean, it's really not a huge deal in the grand scheme of airsoft lifetimes or costs, but I'd keep an eye on it for any signs of puffing up or alarming overheating.

 

The tl;dr version is that ideally you want a battery that can comfortably supply more current than the motor can draw, and that you fix the double-shots another way, e.g. checking for a worn cut off lever, using an active-brake mosfet (although this then increases strain on the motor), or even by a mechanical bodge like limiting the trigger travel so that the trolley can disengage faster (I've used a blob of hot-melt glue between the trigger contacts to achieve this).

[Egon_247]

Sorry guys, no video, she's had me building a patio all day. 😒

[Sewdhull]

On 22/06/2024 at 08:43, Hotweeweejef said:

Ah ok. Could you elaborate on this for me please? Still pretty new to this Lipo battery business. 
 

I’ve always used the 11.1 20c with that rif (as I did the previous owner I assume as that was the battery supplied with it) and 95% it functions fine (except the occasional double feed/over spin when the 20c is 100%) The problem was me purchasing a couple spare batteries and not checking the specs fully and ending up with the 25c. 
 

Genuine question, so hopefully that doesn’t read as me being arsey, because I’m really not 😂 

Like I say, still pretty new so keen to learn. 

 

If the motor spins too fast the spinning system doesn't slow down before it cycles again.

 

When a battery has current drawn from it the voltage the motor sees drops, the motor speed drops and the spinning system slows down earlier, perhaps before the next cycle. The amount of slow down is dependent on the internal resistance of the battery and the energy lost is dissipated as heat instead of in spinning the gears in the battery. Dissipate enough heat in the battery and as roger says it gets warm and possibly so warm it splodes.

So it becomes important to have your gun fire correctly in the first place and not use the battery to handicap it.

[Egon_247]

On 21/06/2024 at 18:30, Pseudotectonic said:

uh oh

 

could be the problem

 

I get where you're coming from, and that's what i thought, but it was firing perfectly before....

I haven't done a video as I'm knackered and we have a full on audit at work, so not high on the priority list.

 

I did some digging and also some thinking....at my age i have to plan these things..

I recently started using midcaps. I'm not a fan of them as they feel horrible. However, i do wonder if the midcaps have mangled the feed tube into the hop. They've never fed right and as i was short of mags, i kept trying them just to see if it was me being a hicap slob.

So, when i get off shift on Thursday, I'm going to strip it down and have a look at the tube, nozzle and hop, to see if they're all playing nicely together. 

I have ordered a metal feed tube anyway, as I've modified pretty much every thing else on this thing, so why not. And I've heard good things about them. 

The "dent" thing in the top of the hop chamber might be a good move too. I'll see what happens on Thursday..

 

 

Edited June 25 by Egon_247

[Egon_247]

Ok. So first up, bugger.

Tooth missing from the sector gear. I'd short stroked the pick up but it looks like it short stroked the last tooth on the release side all on its own...😒🤭

[Egon_247]

And just to add insult to injury, the warhead base has had its positive wire chewed up getting it in and out of the aug. Hanging on by about three strands. Have removed it and thrown it down the garden. 

[Colin Allen]

3 hours ago, Egon_247 said:

Ok. So first up, bugger.

Tooth missing from the sector gear. I'd short stroked the pick up but it looks like it short stroked the last tooth on the release side all on its own...😒🤭

It seems that you need to restart the build.

[Egon_247]

1 minute ago, Colin Allen said:

It seems that you need to restart the build.

Yup. Just finished raging and looking at other solutions