Double Eagle M906C - Internal upgrades / tinkering

[Colin Allen]

22 hours ago, Herrgh said:

 

I used long thin metal files which meant I could only tackle the job from certain angles. This resulted, try as I might to avoid it, in other parts of the gearbox in line with the file also getting a very light sanding, but this shouldn't really effect anything. 

I sometimes use a hammer and small chisel to remove them.

[RostokMcSpoons]

Hi guys, been a while since I've been around these parts... A combination of being skint through trying out a lower-paid job (in a much better one now thankfully), knackered knees and ankles, and worst of all a bad case of tinnitus caused by a grenade going off right next to me in a very confined doorway in the last game i played... meant I've not played for months. 

Luckily the tinnitus has eased off back to where it used to be, so as long a as i wear ear-pro i will try again.

 

Anyway, glad to see the thread is being useful still!

 

My beloved m906c has also decided to do something bad to the Falcon ETU again.  I think the damned things are very heat sensitive, so a poorly shimmed gearbox or a badly adjusted motor, or just a lot of single shot spamming can cause it to fail.  

So these updates are good info 👍

 

My alternative thought is to go for one of those drop in hpa engines ... I'll wait until someone beats me to it so i can crib from their experience 😋

Edited May 10 by RostokMcSpoons

[Herrgh]

Hello gang,

 

Solink 35k motor arrived yesterday, which I immediately slotted into my M906C. A superlative improvement over the stock motor - the gun is now very snappy, very responsive, a semi-auto spamming machine. So me happy. 

 

However, I have a slight conundrum now.

 

On semi, FPS hovered around 265 on 0.25g.

On auto, FPS hovered around 300 on 0.25g.

 

(All this with no precocking or active braking - the only setting I've touched is the Perun's ROF reduction, maxed out) 

 

Huh.

 

Adding 2 steps of active brake on Semi mode via the Perun, has now brought the semi FPS up to 300, same as auto. I am at a loss as to what is going on.

 

I think there must be a little bit of overspin or something? Is the piston coming to rest after each semi shot some place in the cylinder that is robbing it of air volume?

 

Edit: and why only on semi? My googling suggests usually it's the other way round (auto has lower fps) I think due to premature engagement? 

Edited Friday at 13:24 by Herrgh
clarification

[Adolf Hamster]

1 hour ago, Herrgh said:

Edit: and why only on semi? My googling suggests usually it's the other way round (auto has lower fps) I think due to premature engagement? 

 

you are correct the stereotypical symptom is higher energy on semi, with pme skipping teeth and resulting in the piston not being drawn back fully giving a lower energy in auto after the motor has spooled up.

 

the other way around is a tad more mysterious, and especially that it can be cured with a different precock setting.

 

the only thing i can think is that at your initial 2 steps of precocking, the tappet plate hasn't been fully released, meaning the order of operations is tappet plate releases then fire, with the snappy brushless able to wind the piston back and release before the tappet has had time to get fully into battery. with more precocking it's stopping after the tappet release meaning it's in battery and all the motor is doing is winding the piston back a little before it sends.

 

but if that were the case, you'd expect the lower fps to also occurr in auto, as i doubt the motor from a standing start is going to be faster from tappet release to piston release than the same motor already wound up to full chat.

 

1 hour ago, Herrgh said:

I think there must be a little bit of overspin or something? Is the piston coming to rest after each semi shot some place in the cylinder that is robbing it of air volume?

 

it's worth noting that precock is just controlling the amount of overspin, and in terms of air volume a fully precocked piston has more time to fill itself with air than it will under full auto conditions, so you'd also expect it to give more energy than auto if the cylinder refill time was a factor.

 

 

[Herrgh]

6 hours ago, Adolf Hamster said:

the only thing i can think is that at your initial 2 steps of precocking

 

My bad, I've actually set SEMI to have just 1 (not 2) step of Active Braking. Precocking (I think) tries to get the spring to stop at the rearmost position ready for the next shot but I have not turned that on in any way for either SEMI or AUTO. At the moment the gun is set up thusly:

SEMI

Active Braking - Level 1

Precocking - Off

ROF Reduction - None

 

AUTO

Active Braking - Off

Precocking - Off

ROF Reduction - Level 5

 

I've just tested adding some ROF reduction to SEMI, just in case that was the common denominator, but obviously that has had no effect on FPS in that mode. I've shot off an email to Perun in case they have any insight into this weird problem, but I'd still like to know what the underlying issue is (even though thanks to the Perun it's no longer an issue).

[Herrgh]

Disregard everything I broke it 

[Herrgh]

Disassembled the whole thing - turns out:

• The piston head has detached from the piston. No damage. This is probably cos I didn't use threadlock.
• The nozzle lips that let it sit in the tappet plate have broken along one cardinal edge, but I have an XT POM-based replacement that I wanted to use anyway, so I will install that.

Will put it back together better than I did before and give an FPS report once it's done.

[Adolf Hamster]

23 hours ago, Herrgh said:

My bad, I've actually set SEMI to have just 1 (not 2) step of Active Braking. Precocking (I think) tries to get the spring to stop at the rearmost position ready for the next shot but I have not turned that on in any way for either SEMI or AUTO. At the moment the gun is set up thusly:

 

Active brake on its own is supposed to prevent overspin, which could be thought of like a natural pre-cock, but can often have the unintended effect of stopping the box too soon giving trigger lockups as the cutoff timing does take into account a little bit of overspin.

 

Typically i tend to reccommend using ab and precocking together or not at all, although it could be argued a precock setting without ab probably wont harm anything.

 

Ofc none of that has anything to do with the energy output, but i see you've got to the bottom of that mystery.