Jefftron Leviathon and pre-engagement issues on Specna E10

[Alimcd]

Good afternoon everyone, I’m new around here so be gentle with me.

I picked up a Specna E10 recently that I swore to myself I’d leave stock as a loaner gun. One thing lead to another and it ended up being little more than a metal body for the usual suspects from AK2M4 and Socomtac. 
 

I loved the idea of the Jefftron Leviathan and popped one in with a 13:1 gear set, asg M95, Infinity 35000. The power is bang on at c.340 and the ROF is great at 34rps but the issues are two fold.
 

After a few games, I’m getting error messages that state high-current and over-spin. At this point it goes into protection mode for a few minutes, I’m assuming this is temperature related. The mosfet diagnostics state that the Semi auto and motor start current are pretty high  at 80a+, I’m using an 11.1 2600 mah 30c battery in there that should be fine, right? The amperage seems surprisingly high, the shimming is fine and the bearings have been changed from the stock specna ones (they failed 1000rds in on stock internals prompting this whole build) to some Retroarms ones. Everything spins freely and the lateral play is c0.05mm on each axle. The only factor that I figure could have changed is that the specna pistol grip is the devil’s own and maybe the motor height has wandered, greatly increasing the resistance. Thing is, it SOUNDS like a well set up AEG, it doesn’t sound like it’s struggling.

Ive got active break turned up to full to counter the over spin, could this be a factor in it over heating? 
 

I like the Binary trigger, they do a lot of semi-only games at Finmere and Matt has ok’d binary during semi games as long as “I’m not a dick”. I don’t spam the trigger, but it’s doing a lot of rounds in semi. Again, is the relatively high draw of the motor start up my issue?

Next up, pre-engagement. I don’t use the full auto often, in fact on the current set up it’s set to 5 round burst on auto, but with the ROF set to anything over 26/28rps I’m getting a significant reduction in power and the resulting decrease in range is hilarious. This was my first high speed/response build and I’m clearly learning the ropes, should I be considering taking some teeth off the sector gear? 
 

I bow to your superior knowledge and experience and hope I’ve missed something really obvious. Like I said, it’s not a wanker gun and I don’t want to use it to hose people, it would be nice to get similar range when sending a burst downrange as semi shots and even nicer if the flipping thing would not decide that it needs to take 5 to chill out in the middle of a game!

 

[Zarrin]

Quite a few mosfets call for no more than 20-25C rated batteries - though I couldn't see the recommended rating on the Leviathan website spec sheet. Maybe test on an 11.1v 20C and see if that clears up the heating/board errors? Maybe also test on a 7.4v and 9.6v nimh if you have any to eliminate possibility of high voltage issues.

 

[Davegolf]

With an empty gearbox fit all your gears, you should be able to spin the sector gear one whole revolution if shimming is good.

Then you can rule that out for sure.

Active breaking will make insane heat build up, more heat in electronics means more resistance which means more current... which you've guessed means more heat!

That is a very fast setup you have there, personally I would swap that motor for a 22000, runs way cooler and stil see mid 20s ROF or run a 7.4V - that's the fast fixes.

I think ROF over 20-25 is pointless.

Pre engagement fix with your current setup will involve short stroking and a stronger spring, but this will make your 35000 work pretty hard on Semi auto.

Short stroking requires teeth removed from both the Sector and piston.

Learning can eat a few parts ?

Always aim aim for the best mechanical setup - minimal or no active brake.

This is done using the right mix of voltage, motor, gear ratio and spring strength.

 

[Alimcd]

Thanks for the help guys, I’ve got a 20c 11.1 kicking about somewhere, I might try and torture test with that and see if I can force it to over heat. That way I can eliminate the battery from being the cause of the issue.

Shimming-wise, with no piston/motor in the sector gear is quite happy to spin for a complete revolution if not more. That was one of the confusing elements, it didn’t sound like an AEG that was under stress once I had rebuilt it. The stock gearbox sounded awful and when opened up the motor height was way too high and the gears were SUPER tight. Worst part was that there wasn’t any lubricant and the stock ported cylinder was so roughly finished that it  had sliced the piston’s O-rings into ribbons. Not what I had expected from Specna after such polished social media content. cue Bill Murray meme
“Externals are ok though, which is nice”

I had some mother’s Auminium polish on my desk at the time so I polished the rails of the gearbox just to try and eliminate any potential friction. Probably overkill but I hadn’t tried a high ROF build before and was going for the “throw shit at the wall and see what sticks approach”

Dave, totally agree regarding ROF. My initial idea was for a demon response for semi-auto and the option of a burst mode that would put 3-5 rounds down range super quickly. I think I’ll be resolving a lot of issues if I just drop the pretty stupid notion of having a 30+ ROF and concentrate on finding why it’s overheating with semi/binary. If I can achieve 20-25 on a 7.4, it’s going to cause less stress to everything and still give me what I’m after for burst-wise

The more I read, the more times I see active breaking to be the cause of issues. I’ve had a Gate Nano AB fail spectacularly, scorch marks on the PCB! Thats has got to be a thermal issue too?

 

[Sitting Duck]

M95 producing 340 means great compression & bearing/spacer inside piston plus bearing spring guide

or likely a slightly stronger than labelled spring as the E10 is a titchy barrel

Seems to be like a FireHawk 140mm or something, no more than 200mm

so doubt if spring really was a m95 or 313fps rated spring in a titchy barrel

Probably @ 28rps you are starting to get PME where the piston & sector are starting to catch on a full stroke

which might explain qwirky results where the stroke/volume is being screwed up producing weird shots/results

- pretty lucky you haven't ripped the rack out - keep firing on full auto & something will go I'm sure

 @25rps you will be getting overspin & potential double firing without Active Braking

and this really is the gun talking to you & 25rps is about the limit you can push a full stroke UK 350fps gun

sure AB will prevent/reduce the overspin & double firing on semi...

BUT on 3 round burst or 5 round burst those 4 shots will be cycling close to the limit all the same

As others have said you need a stronger spring that will give you say 380~395 or a true m115~m120

then take off the first two or three teeth off pickup side of sector gear, the FIRST 2 or 3 teeth that engage piston

IF your last/release tooth on sector gear is same size you can leave the teeth on piston rack

it is if your last/release tooth is larger then you MUST take off the matching amount on rack

though most remove the teeth on rack just to be safe, though if the last tooth is same it clear & release OK

If experimenting taking off two, then three or you take too many off sector, you can just use another sector & not need a new piston/rack

As you are using a 13:1, then you need a 13:1 sector

But if you was using a 16:1 set, then very likely a reg 18:1 sector from a std set should work as ratio is down to the step/spur gear

Anyway - you are cycling too fast on a full stroke

Either set ROF on fancy mosfet to say 75%

or

Look to Short Stroke a couple of teeth with a slightly stronger spring

or

run it on 7.4v on a 40c Lipo to give you say 25rps aprox

VERY VERY VERY ROUGH RPS CALCULATOR....

MOTOR SPEED (in 1000's or K), divided by ACTUAL gear ratio, then multiply by 10 will give a ROUGH RPS on 7.4v 25c

EG: 35 (35,000) divided by 13.5 (probable actual ratio) = 25.6 rps

for 11.1v's multiply the 7.4v figure by 1.55 or 55% increase, it isn't really 50% coz gun is cycling so extra cell is a bit more boost than 50%

25.6rps x 1.55 = 40rps expected rps on 11.1v - especially a 30c one

BUT I'm only getting 34rps ???

Well it is only a ROUGH guide and the variation could be your shimming/motor angle and also some loss due to fancy mosfet

(Don't care what manufacturers say, some response is lost in those electronics over bare bone thick wire on a 3034 with no breaks/fuse etc...)

The ROUGH guide does work in most cases give or take a couple of rps on a UK spec gun

higher 400+ or DMR stuff will have a slightly lower rof with heavier spring blah blah blah

on a 30k motor:

30/13.5 = 22.2rps which many use on 7.4v

So as said, you should have chosen a 22k or 25k absolute max if running on 11.1v

25/13.5 = 18.5rps then on 11.1v or x1.55 = 28.7rps

or there abouts ffs

(stock setups on weak 18k & 18.65 will give you 9.65rps so add a bit on as it is an easy pull ratio to make 12rps)

I said it was a ROUGH calculator, easy on the motor gearing figures need a bit more added on

or insane DSG's you gotta take some off even shimming was perfect on ceramics etc....

But it does kinda give you a rough idea in a large ballpark so to speak

bearings/bushings actual motor performance (and they can/do vary on same motor/batches)

plus ultra thick wiring, if using lame 20c or beefy 30c+ LiPo's (some LiPo's are not same as other makes)

(Oh and don't bother expecting this to work on a stock supplied 8.4v NiMah on small Tamiya,

this rough calculator is for LiPo's on deans blah blah blah, what people should be using in their tweaked setups blah blah blah)

Boring anorak post nearly over.....

Yeah you are pushing it and that is why you are getting grief

Twenties is plenty on a SSG

& if you get 22~24rps, then you hardly notice it not hitting 30rps

& you can set pre-cocking for a bit better response & not need hardly any AB

If I can achieve 20-25 on a 7.4, it’s going to cause less stress to everything and still give me what I’m after for burst-wise

 

[Alimcd]

I’ll check that spring again. The barrel is, as you say, only about 150mm. I popped an MP5k cylinder in there so it would be appropriate for the length of the barrel and there’s a bearing at both spring guide and piston end. Compression is good with fresh O-rings on the piston head. I can’t press it in with a finger over the cylinder head.
 

I remember a slightly raised eyebrow when my chrono read 340, I think this was due to getting lower than expected results and I may have swapped the spring for something stiffer at the time To experiment. I like the ASG springs as they’re colour coded and therefore idiot-proof but I may have been a pillock and left the Specna (quoted 380) spring in instead. It would certainly explain why the motor is heating up!

ill double check the spring tonight and report back.
 

The fancy mosfet ROF is for whatever reason not directly proportional, ie a drop from 100-95% takes it from 34 to 28.6 so I’ll have a play around with it.

Thanks for the ROF prediction guide, very logical and makes perfect sense. I’ve screen shotted it to keep it to hand!

 

[Davegolf]

We've all been there, more for the challenge i think than anything making ROF lasers but when you get back to the game, 20 RPS is just beautiful in an AEG, great trigger response for Semi and tight accurate burst fire.

Yeh I have a tricked out MP5K with 150mm barrel, awesome compression on a SS M120 = 305 FPS

So suspect diff spring rate or ASG springs are a little high ?? You do have double bearings though too.

Consider yourself educated @Sitting Duck has written... novelled ??

I prefer 18:1, 22000 and 11.1v, so much get up and go from a standstill, quieter and motor rarely even gets luke warm!

This is pulling a full stroke MS135

View attachment 55660

This is is a standard TM with M85 spring lol!

View attachment 55661

 

[Sitting Duck]

I’ll check that spring again. The barrel is, as you say, only about 150mm. I popped an MP5k cylinder in there so it would be appropriate for the length of the barrel and there’s a bearing at both spring guide and piston end. Compression is good with fresh O-rings on the piston head. I can’t press it in with a finger over the cylinder head.
 

I remember a slightly raised eyebrow when my chrono read 340, I think this was due to getting lower than expected results and I may have swapped the spring for something stiffer at the time To experiment. I like the ASG springs as they’re colour coded and therefore idiot-proof but I may have been a pillock and left the Specna (quoted 380) spring in instead. It would certainly explain why the motor is heating up!

ill double check the spring tonight and report back.
 

The fancy mosfet ROF is for whatever reason not directly proportional, ie a drop from 100-95% takes it from 34 to 28.6 so I’ll have a play around with it.

Thanks for the ROF prediction guide, very logical and makes perfect sense. I’ve screen shotted it to keep it to hand!

"Normally" a M100 is 328fps

now when that if fitted to a 455mm AK you will get more

&

when fitted to a MP5k you get a bit less due to creep/loss

Also a bearing spring guide adds about 15fps due to a little more spring compression from bearings over a std plain guide

(though you loose a bit of power, volume to be exact when correct AoE so a bearing spring guide usually offsets this)

Cheapo China guns come with a massive heavy alloy spacer inside usually 8~9mm

as the piston's teeth is 3mm pitch that is effectively 3 more teeth of compression than no spacer

& a bearing inside piston or on piston head is about 4.5mm or another 1.5 teeth compression than bare piston

So with all those variables it is easy to see why a genuine M100 spring can give 300~350fps in another gun

and that is without great/piss poor seals or mis-labelled springs etc....

Hence people tend to stick to a particular spring make than risk playing the typical Chinese lottery on too many parts

Or, if knowing the gun shoots a smidge hot, then remove spacer(s) or Short Stroke option maybe

(or vice versa, add a small spacer to bump the fps up a bit, as long as it doesn't hit the spring guide on full retraction)

TBH - it don't matter what spring is in there, if you got good seals & fps is about right that is all that matters

I was just saying it sounds a bit strong for a genuine m95, that's all

So many many ways to skin a cat and loads of variables on these poxy toy guns

@Davegolf has one of them fancy hook test meters - niiiiicccceeeeeee

I got one of them RC testers as my test meter is ergh just a cheap test meter

View attachment 55662

is my actual one, but anything will do...

View attachment 55663

a bit cheaper, run on full auto for say 5 secs and check the amps/draw

a really efficient build and good shimming draws less amps which means less heat and longer battery

Motors normally draw up to 80amp on initial start up for a few nanoseconds, but soon settle down to say 15 or so

(depends on gearing & motor)

30k is about my limit to run on 7.4v & 13:1 SS 2 or 3 teeth etc... is a very good snappy base build

you can often chuck a mosfet in maybe and run a lame 13rps gun to 20rps on 11.1v if on a tight budget

But always worth checking the amps to see just how efficiently you built it & it's running etc...

Some fancy bastids like Titan will give you this info on screen, but a meter tells you on any gun

(plus it "can" help you find the sweet spot for motor height - in conjuction with sound it all makes)

((depending on how well you set bevel/motor height in the first place of course))

PS - we only know some of this knowledge or slight wisdom coz we've all made numerous

(and plenty) of balls ups, learning from our mistakes (wisdom)

Plus we are all still learning, I know I am, doing stuff slightly different to things I was doing a year or two ago

always trying to squeeze maximum performance & efficiency from each subsequent build etc...

I'd say you did a reasonable job compared to my first few attempts that were complete disasters

(the first three were fucked completely and the next few were far from good let alone great rebuilds)

 

[Davegolf]

Haha yes I'm lucky to have one of them fancy hook test meters for work ?

Yes certainly a good first ballsy build @Alimcd and you clearly have some good fortune seeing as you got away with not blitzing your piston ?

 

[Alimcd]

Thanks for all the insight, it’s great fun having a little project gun like this. When it’s purring away at 20-25rps and being electrically reliable I’ll be a particularly happy bunny.

I’ve ordered a 22,000 motor due to Corona cabin fever. It’ll give me a few more things to fiddle with anyway!

I’m hugely appreciative for the help and look forwards to many more fuck ups going forwards. Here’s a little piccy on the Specna anyway, it’s basically a pistol. I can feel the more Milsim inclined already adding me to an ignore list!

View attachment 55666

 

[Davegolf]

But at least you have an L85 above it, not another AR... yawn ?

Although yours is hot little guns like that are ace indoors, def have a soft spot for SMGs ?

View attachment 55673

 

[Alimcd]

The L85 is the “just leave it alone gun” so if the others that I’ve buggered around with fail, I’ve still got a stock ICS that’s perfectly fine. All it’s had is a gate NanoHard popped in to save the contacts! I thought it would be ironic to have an L85 as my Ol’reliable

Loving that MP5K!

 

[Davegolf]

The ICS L85 is a great gun, nice gearbox too. I've had 3, only have my first one left, but it's in bits lol as it became a self contained HPA project ?

I did not leave it alone ?

Going back to a previous comment of yours - I agree cabin fever is 'spendy' lol, just ordered a load of guts to pimp yet another gearbox, just can't leave it alone!

I imagine @Sitting Duck crafting away at something as we speak haha!

 

[Alimcd]

HPA looks pretty interesting, I think I’ll just get my head around AEGs for now! 
 

Looking forwards to trying that 22,000 it could be the solution to both the PME and the overheating. Thanks for the advice guys

 

[Sitting Duck]

HPA looks pretty interesting, I think I’ll just get my head around AEGs for now! 
 

Looking forwards to trying that 22,000 it could be the solution to both the PME and the overheating. Thanks for the advice guys

TBH - just try a decent 7.4v....

22,000 x 1.55 = 34,100

your present motor is a 35k supposedly on 8.4v (7.4v fully charged, each 3.7 cell can hold up to 0.5 extra volts = 4.2v)

so a 7.4v = 8.4v fully charged or a 11.1v = 12.6v

the 1.55 or 55% value for 2 cell > 3 cell calculation so speed rps will be running nigh on the same

YES the AMPS from the 22k will be lower but due to Voltage the Watts will vary....

eg: 35k draws say 19 amps on 7.4v so a full Lipo = 19 x 8.4v = 159.6 Watts or say 160 Watts

now 22k on same 13:1 say 12.5 amps (guessing tbh), 12.5 x 12.6 = 157.5 Watts - not a lot of difference eh ???

I based this guess on similar builds & @Davegolf 10.4a on a m135

though I feel you must have a m110 at least & your gear ratio of 13(13.5) over a 18(18.65) is about 1.38

So basing on a smidge lower of 10a x 1.38 = 1.38 possible reading, maybe round it down a bit

(I've had a really low 25k ferrite 13:1 SS 3 teeth build draw 11.75 @ 335fps)

So did a kinda guess in the middle of a neodym 22k being around 12.5-ish

could be 12amps, doubt if it would be 13amps but your shimming might be a whisper smidge out so 12.5a is my figure

12.5a x 12.6v is not far off the Wattage of say a 19a x 8.4v - though this could be 20a x 8.4v = 168 Watts but not THAT much difference

Don't matter, but might save you £40

Just saying you might be OK just on 7.4v and perhaps a higher capacity as you should gain some space on a 2 cell than a 3 cell LiPo

FFS, this Corona Isolation bollox better end soon if the highlight of my day is doing mathematical airsoft predictions

My calculations could be completely way way off the mark and is intended to only be guide, it does not reflect the true actual readings you may or may not get as each gun is individually different plus....

Your gun is at risk if you do not keep up servicing or other loans secured upon on it

charges & indemnities may apply & you should always seek professional advice

any advice given is regulated by the amount of alcohol I have consumed

Sitting Duck is not affiliated with any other species of water foul or any other poultry or KFC

Full T&C's available on request - if I can be arsed depending how long this corona or thread goes on for

 

[Davegolf]

Remember maths is fun kids ?

 

[Sitting Duck]

Remember maths is fun kids ?

I have asked somebody to give them the once over to see if they are about right

Unfortunately she is self isolating with Corona 25 as she is high risk & has type 3.5 diabetes....

 

[Alimcd]

With all the measures taken by treasury, we’ll need her unique mathematical mind as chancellor by the end of this!

Also, SittingDuck. I haven’t completely ignored your advice. I’m going to try a 7.4 in there as well first.

I’m working from home and had eBay open in another window. Got a proper ball-achey task come in and thought, sod it, why SHOULDN’T I have a 22,000 as well. Complete the set...

 

[Sitting Duck]

sod it, why SHOULDN’T I have a 22,000 as well. Complete the set...

Yeah, I got like that with loads of things like consoles, peew peew's etc...

doesn't hurt to have a spare "just in case...."

Now I finally admit I have a problem....

I have no more fucking room to hide them from Mrs Duck

agreed - your money - your gun/motor & all that

Me personally I'd use a 22k/22tpa mainly for higher stress build say a DMR or DSG perhaps on 11.1v

For reg AEG I tend to go with 7.4v on a balanced 30k/16tpa

Others might use a Higher Speed 40k+ on std gears to achieve the snap, but that can draw more amps

(though if you don't spam loads a higher speed motor is OK, just going nutz will create more heat)

It is all down to personal preference, budget & your circumstances

Admit I was using faster motors at first, but found they (the motor) or they gun didn't last too long

Now I tend to stick on a 25k to 30k, but no faster for me on 7.4v

I stick on 7.4v coz it is generally cheaper and space saving over a 11.1v

(not always true, HobbyKing do some deals at times where a 25c 11.1v block LiPo is cheaper than similar 7.4v)

https://hobbyking.com/en_us/rhino-2200mah-3s-25c-lipo-pack-w-xt60.html?queryID=7bd535558be7b9d8aedbbec64c6dc4eb&objectID=83948&indexName=hbk_live_magento_en_us_products

 

[Alimcd]

I must confess that the quality of Lipos is something I have less than zero knowledge about. I just used the same company that I used to buy Nimhs off back in the day, componentshop. 
 

I’ve been using these

https://www.componentshop.co.uk/11-1v-2600mah-25c-continuous-discharge-cranestock-lipo-battery.html
 

and have just noticed that they aren’t 30c as thought but 25c. Are these infamously crap or worth sticking with?