Double Eagle M906C - Internal upgrades / tinkering

[Colin Allen]

11 hours ago, RostokMcSpoons said:

Yeah I've resisted the temptation to do it before, but the guns rate of fire has dropped recently (not by much, but enough to show up when testing using my chrono)... I'll swap the motor first

That is the best thing to do; stick a decent motor in there and see how it goes.  If you changed the spring to a stronger one, that could explain the reduced ROF.

[RostokMcSpoons]

After yesterday's skirmish where the motor got very toasty thanks to a lot of burst-fire and semi-auto spamming, I thought I'd try swapping the motor out of my Scarab (which shoots at an impressive RoF, very smoothly), into my DE, to replace the famously 'ok-ish' Chaoli grey thing.

 

Here's the motor I took from the Scarab, it's a Classic Army '31000' High Torque motor.  

 

Well, the swap went ahead easily enough in physical terms.   At first I had the motor height set (I think) too high, so the motor wasn't running much faster than the Chaoli.  But I lowered it out and the RoF increased quite impressively. 

It still got hot quite quickly.   I also had problems with multi shots when in semi, and overrun in full-auto too.  Is the 31000 TPA too much for my gnu?  It's got an M105 spring in there and shoots at ~330fps with 0.20g, with some hop applied.
I can try some further experimentation with the motor height, but I won't if that motor is just too much for it. 
Backing off to a 7.4v is definitely an option too (though currently I only have one which will fit in the PTS stock - and I'd rather keep that for my SIG)

 

[Fatboy40]

If the "31000" value refers to RPM then I think that's a bit too fast a motor.

 

DE say that the stock motor is 19k RPM (but not at what voltage), I'm running AK2M4 XT 22 TPA ones that are 22k RPM on 11.1v and get a very snappy trigger (due to the better magnets etc.), so 31k RPM is going waaaaay beyond what the stock RPM is.

[RostokMcSpoons]

I just put it all back together and chrono tested the RoF, it's 18rps with the 11.1v. It's plenty snappy enough with the 7.4v for semi auto, but although I didn't test that on my chrono, I'd estimate it at about 12-14rps.

 

I think the 31000 refers to TPA, turns per armature, and the higher number gives more torque and less rpm.  But this is really my first foray into messing with motors so I'm at the bottom of the leaning curve!

 

This time when I installed the motor I started with the adjustment screw far in, to the point the EFCU wouldn't let the gun fire, and then loosened it off until it sounded healthy.  A bit more loosening might allow that really high RoF that seemed to cause trouble.  The trade off of having the mechanical resistance is the heat getting generated.  It still gets hot after not many shots

Edited July 9, 2023 by RostokMcSpoons

[Fatboy40]

15 hours ago, RostokMcSpoons said:

I think the 31000 refers to TPA, turns per armature, and the higher number gives more torque and less rpm.  But this is really my first foray into messing with motors so I'm at the bottom of the leaning curve!

 

I'm very happy to be corrected by others but to have 31,000 turns of copper wire on an armature would mean that the wire would be microscopically thin  (bending the laws of physics kind of thin). I've not disassembled and serviced an electric motors since I used to race RC cars, but it really can't be TPA.

 

It has to be RPM, but who knows at what voltage so lets assume 11.1v so they can put a nice high number on their packaging  So, I'm still leaning towards it just being too fast a motor, and we've no idea how efficient the Falcon controller is regarding braking the motor so we only get a single gearbox cycle (but as it's made to a very cheap price point I'm going to assume it's nowhere close to as good as say a GATE Titan). A manufacturer like GATE may even publish figures for how high an RPM is supported, so that active braking can occur effectively, and we could use this as our yardstick for the Falcon as well.

[RostokMcSpoons]

it's odd I can't find 31000 Classic Army motors to look at the spec sheet. 

( Edit: I can find a product page, but not many specs : https://www.airsoftgi.com/product/NON-Retail-Package-Classic-Army-Speed-Torque-31K-Motor-Long-34144/ )

 

But another google turned up this list:
 

• 16 TPA / 31,000 RPM
• 18 TPA / 28,000 RPM
• 22 TPA / 25,000 RPM
• 28 TPA / 19,000 RPM

 

So I'm thinking you're right, it must be a 16 TPA motor spinning at 31,000rpm that I've now got in there.

Which I don't want - the 22 TPA is definitely what I should be after - more torque, traded for a little less speed (and heat?) ... so it's this one (as per your recommendation) isn't it?

 

https://www.ak2m4.co.uk/xt-high-torque-motor-22tpa-long-fan?search=22tpa

 

Bonus for having a fan that might keep it cool too!

Problem is I shouldn't be spending actual money until I get a new contract, but luckily I won't be playing for another 3 weeks so I've got a bit of time.

 

Edited July 10, 2023 by RostokMcSpoons

[Fatboy40]

34 minutes ago, RostokMcSpoons said:

... more torque, traded for a little less speed (and heat?)

 

Well, the magnets in the Chaoli motor etc. are so crap that the XT motor we're talking about is marginally faster than the stock motor (worth one or two extra RPS) and has substantially more torque. Also I'm finding it quite a lot cooler as well  

[ak2m4]

What frustrated me hugely in the past was 99% of motors on a website would give the RPM but never the voltage.  Some older spec pdfs used 8.4v nimh.  In the end I actually purchased a chrono rotation thingy (the name escapes me now) so I could measure motors and find out the rpm.  I switched to the XT motors with the little plastic fan on due to the high number of failures with Rocket and ZCI motors when used with 11.1v.  Heat is indeed a killer.  The brushes on the XT contain a little more silver than normal apparently, not sure if that really affects anything.

 

Oh ask a Chinese motor factory that you want a "something TPA" motor, they won't have a clue what you're talking about 🙂

 

Do DE have vents in the motor grip base plate?

Edited July 10, 2023 by ak2m4

[RostokMcSpoons]

22 hours ago, ak2m4 said:

 

Do DE have vents in the motor grip base plate?

 

Yes they do, which made me very happy to see your motors have a fan to take advantage of that

[RostokMcSpoons]

I've recently bought a Titan 7.4v battery off the classifieds here, and trying that in the gun with the high speed motor in place was pretty good.  Yeah, the RoF is 'sensible' rather than 'exciting', but the semi auto response is still good, and most importantly the motor stayed cool after a bit of semi and short burst spamming.  If I don't get around to grabbing the 22tpa motor in time for the next skirmish, I'll run with this configuration.

[Leo Greer]

Is the Scarab CA motor ferrite or Neodymium?

 

Ferrite motors are almost always either 28 TPA, or, more commonly, 32 TPA. This is because the weaker magnets need more turns in order to produce any kind of torque.

 

To clarify, TPA does not actually dictate torque by itself--wire thickness, wrap tightness, etc, all play factors, as well as how strong the magnets themselves are. However, in general, the higher the TPA, the higher the torque.

 

Neodymium motors typically have much lower TPA due to having much stronger magnets. For example, a 40K motor might be 14 TPA, and a 25K motor might be 22 TPA. Note that these are averaged unloaded speeds--the motor speed changes, sometimes drastically, depending on how the specific motor is made, the batch of magnets, and even where the motor falls on the averaged scale.

 

For example, SHS high torques are known run at around 35K unloaded and 16 TPA. However, SHS (manufactured by ChiHai Shenzhen) doesn't always use magnets with the same strengths. Neo magnets have different "N" ratings (most common is N35H, stronger but rarer are N52, and everything in between), that control their strength. Thus you can never be 100% sure of the speed of what you're getting (and speed may vary somewhat by individual motor).

 

Different brands (ASG, Tienly, etc), may use magnets of different strengths. For example, Tienly uses N52, which is one of the reasons Tienly motors are more expensive. Thus, a Tienly with the same TPA as the SHS will be stronger and run cooler at the same speeds.

 

All that to say, the Scarab motor (if it's neodymium), is probably 31K unloaded speed. Speed under load is less, so doing calcs based off the unloaded speed will give results that are too high. 30K is actually a very normal motor speed, and should produce an ROF of about 18-19 on an 11.1v battery. For example, the original TM EG1000 gave 18 when chronoed on 11.1v (technically in between 12.6v and 11.1v, but I'm approximating, not running exact calcs). This means that the original TM long motor, borrowed from the photocopier industry, is about 30K. 30K should not be too much for your stock gun, especially on 7.4v.

 

This is assuming the Scarab 31000 is actually a 30K motor and not something random.

 

For example...

 

More than one brand of RIF use Neo motors with weak magnets that distort the "balance". For example, Krytac's 30K Neo motor (sold incredibly overpriced online), does run at 30K approx on 11.1v, but the magnets are very weak. Thus, the TPA is not 16. It could be 25 TPA for all I know. Weaker magnets means more TPA needed to limit the motor to the same equivalent speed.

 

Arcturus currently sends all of their new stock guns out with a 24K 23TPA Neo motor that actually performs more like a 30K, giving 20+ RPS @ 1.6J on 11.1v. Thus, we have a 23TPA 30K equivalent... the magnets are weaker.

 

At the other end of the spectrum, Tienly puts out a 50K motor that uses ferrite magnets. It's 9TPA, using the strongest ferrite magnets available for the purpose.

[RostokMcSpoons]

Yeah I can't find the specs for the motor.  Maybe it's written on the body of the thing itself, but it says '31000'.  'high torque / speed', and that's all I can remember without taking it out of the gun to check.

 

It's an old, discontinued motor, judging by the few product pages I found for it out there.

 

Anyway, the plan remains to buy an XT from ak2m4 and put the CA motor back in the scarab (where it runs cool on 11.1v), but it can work on in the DE as a backu, on 7.4v

 

I've been burning through too much ammo on game days when I'm using the DE on full auto, so really i need the semi auto to work nicely, and a lower RoF isn't the end of world either!

[RostokMcSpoons]

A bit concerning, my beloved "ever-reliable" gat has decided to go a bit "un-reliable"

 

It's currently got a Vapextech 7.4v battery plugged in, but I've tried with alternative 7.4v and an 11.1v.  
I've also swapped out that high-speed + high torque Classic Army 31k motor back to the original grey lump.

 

The symptoms remain the same:

 

Plug in the battery.   1 vibration (good!  gun is ready)

Fire a few shots on semi.  Can be fine.  And then it'll either over-run and fire a couple, or it won't fire.  I'll get two beeps (System code: "Module stuck")

Fire a few shots on full auto and it'll typically fire 3 rounds before stopping and doing the two beeps.

Resetting the trigger and trying again after a couple of seconds always results in a successful shot, so it's not completely buggered.  But it's very far from full health too.

 

The only previous problem I've had with the gun was with the battery connector extension lead getting loose - but it's not that as I got the 1 vibration when I jiggled the lead and it reconnected.  Now it's well taped together, and the single vibration doesn't happen - just the double error code beeps.

 

Having just painted it, I wonder if paint could've crept in somewhere it shouldn't.  When the gun doesn't fire it sounds like the spring moves under power, perhaps going to no tension, or full tension.  Next trigger pull makes it fire.

 

Any ideas?  Does the poor thing need pulling apart for it's first ever service?
Or has the motor getting hot been a symptom or cause of a MOSFET problem?

 

Edited August 22, 2023 by RostokMcSpoons

[Fatboy40]

Even though it doesn't state it anywhere the motor getting hot in the DE M900's is the small amount of active braking it does, and the crap Chaoli motor exhibits this as the horrible heat. 31k for a motor seems a bit too fast as well? (it's only a little old DE with a Falcon where we can't tweak the amount of braking).

 

Maybe it is time to crack the gearbox open and use a cotton bud with a tiny amount of IPA to clean the optical sensors?

Also to add to this thread my son's moved from his upgraded Firehawk to his M906C permanently now.

 

I moved his Maxx Model M4A-PRO to it and swapped to a Maple Leaf 229mm inner barrel and 60 degree MR bucking, using the Maxx solid concave nub, an M105 spring plus XT 22 TPA high torque. Played in a forest yesterday and the range on 0.32g is crazy good.

 

@RostokMcSpoons I wish we lived a bit nearer to each other so we could have a game and be Double Eagle nerds 🤓

[RostokMcSpoons]

29 minutes ago, Fatboy40 said:

Even though it doesn't state it anywhere the motor getting hot in the DE M900's is the small amount of active braking it does, and the crap Chaoli motor exhibits this as the horrible heat. 31k for a motor seems a bit too fast as well? (it's only a little old DE with a Falcon where we can't tweak the amount of braking).

 

Maybe it is time to crack the gearbox open and use a cotton bud with a tiny amount of IPA to clean the optical sensors?

Also to add to this thread my son's moved from his upgraded Firehawk to his M906C permanently now.

 

I moved his Maxx Model M4A-PRO to it and swapped to a Maple Leaf 229mm inner barrel and 60 degree MR bucking, using the Maxx solid concave nub, an M105 spring plus XT 22 TPA high torque. Played in a forest yesterday and the range on 0.32g is crazy good.

 

@RostokMcSpoons I wish we lived a bit nearer to each other so we could have a game and be Double Eagle nerds 🤓

 

 

Yup, cheers mate, a nerd-fest would be good!  I'd love to compare the range I get with my stock barrel + stock hop unit + Omega nub + Macaron 50deg bucking, to see if I could justify paying for the same upgrades.  The XT 22 TPA motor is still in my AK2M4 shopping basket!

 

But in the meantime - good advice... yes I'm thinking the optical sensor is dirty and it can't detect the braking point properly any more.  At least, that's what I'm hoping it is - better than a failing Falcon unit?
 

[Dan Robinson]

Fingers crossed dude.   I've just bunged a random spare spring in mine now it's a steady 347 fps with stock everything else.

 

Won't be at Spec Ops this weekend now though. 

[RostokMcSpoons]

Right so I've taken my beloved apart and cracked open the gearbox.

I've opened up the control unit, all the sensors looked clean, and the wiring intact.  The gearbox itself has more grease than I expected so a lot of the stuff has the usual black gunk coating it.

 

This is where I might have made a mistake.  The only stuff I had to hand for cleaning was acetone, and I used some on the o-ring on the piston head  When I put it back in the cylinder to check compression, I was rather aghast to find there wasn't any! Now without any grease on it I wasn't expecting much, but did the acetone shrink it???  Anyway I put in a spare o-ring, added a bit of grease, and the compression was perfecto.

 

I've cleaned off the gunk on the piston and tappet plate, and added some fresh grease.

 

Before I put more of it together, is there anything else I should check?

Edited August 23, 2023 by RostokMcSpoons

[Dan Robinson]

Pretty certain acetone will eat orings,  unless they're a special type.

[RostokMcSpoons]

Thanks Dan.

Idiot does idiot things, will try to learn lesson 😋.  Compared to the o-ring I replaced it with, it looked like it had gone on a diet, but the total diameter of the whole thing was perhaps slightly bigger.  Maybe it was just really needing that grease, but if acetone hurts the o-ring them it's for the best I've replaced it (unless it turns out to be too chunky!) 

 

I'm a bit concerned that given a lack of obvious things-gone-wrong, that I've not fixed my gun, and a new control unit will be required.  Anyone know where I can source one? 

Edited August 23, 2023 by RostokMcSpoons

[RostokMcSpoons]

A somewhat bizarre issue has arisen during re-assembly this morning:  The gearbox is now a stupidly tight fit in the lower receiver, to the point where the fire selector is entirely binding up on the inside of the receiver, and won't budge from 'safe' when everything is back in place.

 

Now, it has to be said that muggins here did at one point try to knock out a pin that's actually fake  so a punch was applied to the outside of the shell and tapped with a hammer a couple of times, before the penny dropped.  However I didn't smash the hammer, the lower receiver still looks absolutely straight, and it was a tight fit anyway.   Maybe I've budged it by some tiny amount though.

 

Any good ideas on how to improve matters?   I did have a quick go with a flat file but frankly it just makes the receiver look a mess on the inside without really shifting much material.   I do have a cheapo dremel but frankly that's always seemed to do sod-all too when I've tried it before.
Or I could try to widen the top of the receiver by using some wedges to lever it apart - but that seems a bit drastic and with potential for drastically buggering it?    

 

What say you, oh Great Hive Mind?

 

Edit: In the absence of any answers, and any patience on my part, I went looking for my Dremel (which I'd put away as it seemed to be shit), couldn't find it, so instead levered the shell away from the in-situ gearbox with a screwdriver.   It loosened it up ever so slightly think - the metal is just about sturdy enough to resist my fairly gentle efforts - I don't want it to break.   Gives me some confidence my hammering on a pin punch didn't bend it.   It's still really binding up though.

Anyway, I decided that before I spend more time on it that I'd test the electrical side of the equation with the gearbox out of the receiver by plugging in a battery, and connecting the motor.   I didn't know if it'd be a useful test, but as it turns out - it was.    It's doing the same thing as before:  Good vibration on plugging in the battery, but full auto won't spin continuously, and spamming in semi-auto gives me the two beep error every now and again.

 

Bugger.

 

So it looks like the excessively hot motor fried the circuitry (or the dying circuit caused the excessively hot motor).

Edited August 24, 2023 by RostokMcSpoons

[Dan Robinson]

Circuitry in the FCS?

 

As for the selector,  could the heat have warped something that shifted once you took it apart? 

[RostokMcSpoons]

Yeah I guess there could be a dry solder joint in the FCS with all that heat but there's nothing visible, no scorch marks from a burnt out item.

 

As for the selector, I dunno, it was a tight fit before, but it's too stable now to have just changed with a bit of heat.  A bit more levering and maybe a polish on the inside and it'll be ok.

 

I've sent off a contact form message to Double Eagle asking what might be wrong and where I can buy a replacement unit if I need one... And I sent a message to Will at Spec Ops.  Maybe he'll know as they have 904's as rentals.  And maybe he'll have a boneyard gun I get the control unit from.

[ak2m4]

@RostokMcSpoons I have spoken to DE recently about buying spares, even with a large purchase order for AEG's but the owner replied they aren't interesting in selling spare parts.  Maybe they have a different deal with their existing suppliers or wholesaler but for me kinda took the shine off the company a bit.  They can fit an aftermarket ETU right?  Or even a standard trigger block.  I'm sure one of the major dealers has spares though, crazy not to.

Edited August 25, 2023 by ak2m4

[Fatboy40]

@ak2m4 When I bought my first DE M900, being a bit of a nerd, I went down a rabbit hole finding out as much as I could about "Double Eagle". When you spoke to them was it with "Fujian Qing An Precision Machinery", or another name they go under?

 

They're a big company, making their real money from cheaper toys / knock off Lego Technics things (some of which are actually really impressive, the construction vehicles they do).

[Fatboy40]

12 hours ago, RostokMcSpoons said:

I've sent off a contact form message to Double Eagle asking what might be wrong and where I can buy a replacement unit if I need one...

 

And I sent a message to Will at Spec Ops.  Maybe he'll know as they have 904's as rentals.  And maybe he'll have a boneyard gun I get the control unit from.

 

FYI I've never had any replies from DE when using their website form, however they have a Facebook presence and do reply (eventually) to messages you send to them on that (and their parent company is on LinkedIn).

 

Red Alert in Newbury also use DE M904G's as rentals so they may be worth a punt (Skullchewer on here could maybe ask for you).

 

Worst case scenario a GATE Titan v2 will drop straight in (with no need to replace the trigger, but the Maxx Model trigger for example have a tougher trigger spring).