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d_dan

How to prevent overspin without upgrading spring

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I'm currently having an issue with overspin when using a m100 spring when using an 11.1v 15c lipo I get overspin. Any suggestions as to how to prevent this?

 

I cant go over 328FPS so any help or directions are welcomed.

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Run 7.4v instead of 11.1v possibly

Better option would be Fit a mosfet with active brake.

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Better option would be Fit a mosfet with active brake.

How do you know thats the better option?

 

Have you ever fitted or used a mosfet with active brake?

 

Do you know what motor he has inside?

 

Active braking increases motor stress and if he has a cheap naff motor it will get very hot and die quickly.

 

Be careful with advice especially when it involves someone else's money.

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Hey guys,

I have a Krytac 30k High torque motor & standard gears from the Krytac trident gearbox

 

Ideally I want to increase the ROF in the long run also.

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Hey guys,

I have a Krytac 30k High torque motor & standard gears from the Krytac trident gearbox

 

Ideally I want to increase the ROF in the long run also.

 

If you want a higher RoF and you already run an 11.1v LiPo then you're going to need lower ratio gears (probably 13:1).

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How do you know thats the better option?

 

Have you ever fitted or used a mosfet with active brake?

 

Do you know what motor he has inside?

 

Active braking increases motor stress and if he has a cheap naff motor it will get very hot and die quickly.

 

Be careful with advice especially when it involves someone else's money.

 

OK let me rephrase that In my Opinion that would be the better option.

 

I have fitted and used a MOSFET with active brake, I currently have one on my MP5 thats running 11.1v and I've not had a problem

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tbh - how about you give us more info

 

gun in question, well more to point barrel length, motor you are actually using coz most stock std motor shouldn't over spin on low burst 11.1v

what is your actual rof & fps blah blah blah

 

you will not get a full size AK flying along above 25rps without over spinning

even if you you put in a m120 and short stroke loads you will be down on volume so SS longer barrel guns are not really that viable

 

you can get to 20rps deffo - maybe 25rps without too much overspin starting to take place

30 - 35rps can be done with medium length barrels & a bit of SS

 

is the gun really overspinning - or you seeing nozzle retract so assume serious overspin is taking place - not

a few people confuse nozzle retracting with overspin - and others confuse misfeed with firing 2 bb's - the first bb got stuck - blank fired followed by another bb = 2 bb's come out - must be double firing, ergh no it is misfeeding still

 

sorry not doubting you at all but some people get confused with double firing/misfeed/over spin etc....

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Okay,

So trying to touch on everyone's questions and comments.

 

It's a Krytac LVOA. (Running a M100 spring) << What I believe is the culprit (When using an 11.1v, I causing overspin due to the match up) although it works fine with 7.4v

The Krytac's have a fet but no active break so this will need to be swapped out for something else (I use an AB on my current main but I'm happy to spend some extra money to get a really tight setup linking to the trigger if there are options worth exploring.

 

Krytac LVOA spec to note.

  • Inner barrel Length 387.5mm
  • 30k Torque motor.
  • Spring M100
  • FPS - 320
  • ROF 15.8 on 7.4v 25c

 

In relation to overspin I am seeing the piston moving to a position that is beginning to compress the spring again.

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Right - so you are getting 16 rps on 7.4v 25c

so that equates to 24rps on 11.1v 25c (16 x another cell or 50% or 16 x 1.5 = 24rps)

 

In fact you probably hitting 22-23rps if using a 11.1v 15c tbh

 

In fact you probably have a lower spring in there if Krytac seals are pretty good

coz m100 = 328fps based on 350mm barrel so you could be hitting 340fps a m100

 

Anway what you refer to overspin.....

 

yes if you start to see the piston in the inspection/rear window of box that means the piston has travelled aprox 20mm - 25mm from rest as it just just starts to appear in window......

 

Yup if the piston starts to show in rear window = yup overspin.....

 

Now remember on full stroke you still got 25 - 30mm more retraction/compression of spring

so it isn't OMG rebuild required asap

plus is this gun firing like this on a fresh off charge 11.1v ???

but after a while from say a fresh 12.6v it starts to behave itself a bit better at 11.1v ???

(remember on 11.1v you gotta change lipo before she hits 9v (3v min charge alarm for each cell)

 

More than live-able if the piston is not well into window

end of day fire a few shots on 7.4v to stop this "slight" to moderate overun

 

People pay bundles for this pre-cocking feature ffs

 

Sounds like it is live-able to me if it isn't running way into window and beyond on fresh lipo

 

Further down the line you can beef it up with say a 2 maybe 3 short stroke speed setup but tbh

leave it as it is - if it ain't broke don't try to fix it

 

keep her sensible like you are on 15c 11.1v - warning 30-40c 11.1v's pack a lot more punch possible too much for UK markets

Reckon you are fine tbh - would be suprised if you getting crazy overspin as it should be under 25rps

 

If you still concerned take a pic but if it isn't well showing in rear window it is fine in my book on a fresh 11.1v lipo

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As SD said if you are only getting slight overspin leave it alone. A lot of guns get slight overspin on a fresh battery its only when it starts double firing its an issue.

 

Very few guns actually require an AB fet and most people who have them would be better served with a non-braking fet as AB fets shorten motor life. So fitting one to a gun that doesn't require it is kind of daft as you are gaining nothing except a bill for a new motor sooner than is necessary.

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Agreed - not had to bother with an AB fet yet

hey I'm a poet & didn't even know it

 

I know a few on here use them but if a gun is starting to double fire it is talking to you

Do not fit an AB to cure or reduce a double firing gun that is running too fast imho

coz if she is starting to double fire you are highly likely to be pushing too fast in its present state risking PE or PME or smashing f*ck out of stuff when you unleash a burst on full auto

yes you might be ok with AB using semi only and it slowing the gun asap to avoid risk

but full auto the risk will be there once more

 

To me fitting an AB to stop double firing is like fitting a m120 to get fps up to 350 rather than fix the pi$$ poor air seals instead

 

As stated - I know a few use AB's and higher end ECU mosfets have AB - some can adjust the AB too

but as Trigger said - think most guns will never really need AB

I bought some posi fet's to make up a 3034 with AB but as of yet - nahhhh not bothered with any AB

 

for the record - I have smashed f*ck out of stuff taking the pi$$ - my recent victims were in a gun hitting 40rps

and that was only just starting to double fire but a 35c 11.1v still smashed f*ck out of it in a 30 sec auto burst

piston was about halfway in window so to speak - it was SS 3 teeth so piston releases right at end of window - so it was getting close to releasing the piston again on each stroke......

that was SS, lightened, strong spring blah blah blah - thought I got my homework correct but - ergh nah I failed (again)

Hence these guns when pushed do talk to you - ignore at your own risk...

 

You very likely do not have any real overspin like I was being stupid pushing and pushing it so you should be fine

finish your gun up at end of day on 7.4v to leave gun and spring parked nicely & you will be golden I reckon

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Any suggestions of tell tale signs of pending danger when im out placing?

 

I picked up a new 7.4 today so ill give it a go with both and see how I get on.

 

What about fitting DSG's, reducing stroke and increasing spring strength? Or am I asking for trouble

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Any suggestions of tell tale signs of pending danger when im out placing?

 

I picked up a new 7.4 today so ill give it a go with both and see how I get on.

 

What about fitting DSG's, reducing stroke and increasing spring strength? Or am I asking for trouble

 

You have a nice gun, use it with a beefy 7.4v, 9.6v or 9.9v LiFe (ergh LiFe's are not all that imho)

or a mild 15c lipo should be fine

 

You can't DSG coz they are for only 250-300 absolute max barrels

 

SS - that stuff is way way down the line....

Ya gun has a mix of plastic/metal tooth rack, 18:1 gears and a bloody great basic 3034 mosfet cleverly fitted

 

Later on when she needs a service you can look into other options if you wish

but for now - don't bother messing with a nice gun - you will only make it worse trust me

This is the point of buying a decent gun in first place - it works well right out of box

 

If your piston is still behind the window - ie not showing clearly then you are fine

 

pic of gearbox (AoE no corrected btw) but shows how much the piston would be pre-cocked if you can start to see it window

 

IMG_2869.jpg

 

So if you see piston in window the thing is about half way pre-cocked

 

But light springs are often used on slightly longer barrels to keep fps to UK spec

But lighter springs will over run with more juice or powerful motors

hence hard to get a full size AK above 25rps & still be under 350fps with a full cylinder of air for 455/469 barrels

 

As long as it it ain't in window you got nowt to worry about - use 7.4v to park it properly at end of day

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Thanks for all the feedback guys.

Gonna take this out for a spin on Wednesday evening try the 11.1 and 7.4 in the order advised and see how I go. If there is trouble at least I know something has to be done. if not ill hold on until service time.

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how about getting a WBB and then fitting an M150 spring, the 30k motor will be able to cycle it on an 11.1v LiPo and you'll then not have any overspin issues!

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how about getting a WBB and then fitting an M150 spring, the 30k motor will be able to cycle it on an 11.1v LiPo and you'll then not have any overspin issues!

Making a wbb work well on an aeg is never that simple because volume not just pressure is an issue, but it is worth it when its all working right.

The Ultimate cnc 30k motor would be better its a bit torquier and doesn't lose trigger response as much with a heavy spring.

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The Krytacs were designed to be able to pull an m150 spring and my SPR had no issues with the Orga 6.23 WBB and shot at pretty much bang on 350 fps with it so I imagine that the CRB would be fine too.

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The Krytacs were designed to be able to pull an m150 spring and my SPR had no issues with the Orga 6.23 WBB and shot at pretty much bang on 350 fps with it so I imagine that the CRB would be fine too.

Thats interesting because when I tried the same thing with my crb it was all over the place. I had poor consistency with the fps and accuracy. I did plan on trying to get it working properly but killed it before I had chance. I also found that the 30k motor did slow a bit with a heavier spring, not much but enough to bug me when spamming the trigger. The Ultimate motor performs better and is only £60 so cheaper than than the krytac 30k if anyone with a 20k wants to upgrade.

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Aye... I wish I'd done more research on motors before buying the 30k Krytac one, lesson learned though.

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Took the LVOA out for a spin last night.

With a 7.4v and the m100(at least thats what I think is in there) it felt a little underpowered so I cant wait to chrono it this evening.

 

Anyway on to the important bit....

Tried an 11.1v and after 3 shots on semi she locked up, I managed to get it free by switching to auto thankfully.

Went back to semi and tried a few more shots but within 10-15 rounds she has started to double fire so I decided to drop back in the 7.4v right away.

 

I am secretly hoping the chrono results from tonight are poor and ill try a heavier spring and the 11.1 yay!

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FPS wise it could be hitting say 300fps on a m90 spring but still shooting ok

TM's are similar

 

But m90 would explain a bit why the overspin but lock up on semi raises a concern

but think if PE took place you would of ripped more crap on auto trying to clear it

 

Think on semi you may have hit the dead zone where cut off lever is just raised a smidge that impedes the switch trolley etc....

(BUT hard to say as I haven't got a crystal ball and "usually" when a gun fires a bit quicker it will complete the semi cycle better)

 

But yeah you gotta get the thing chrono'd properly to narrow down the guesswork

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