Hot wiring

[SnakeDoctor87]

So guys,

 

I recently went to Warzone in coventry and took my G&G Firehawk. Which now doesnt resemble a firehawk at all.

Anywho I wasnt happy with the performance, sluggish response, cycling slowly when using 3 round burst - despite having a Perun drop in MOSFET and ETU.

 

I'll start off my saying this is more of a process diary for me, i think better when I put my thoughts on paper/screen. But and advice/suggestions are more than welcome.

 

Anywho, I decided to change out the standard gears from 18:1 to 13:1. Probably over kill in hindsight with an ASG boost 40k. Now I'm suspecting this is actually a high speed motor despite Bullseye Country Sport listing it as a high torque. Cause although I'm getting what I want out of the build, the moment I start firing the gun the wires near the battery get hot quickly. Especially at the Tamiya connection. Not burny hot but enough for you to notice it after a couple of shots. After a while the battery will then start to get warm. So somewhere there is resistance and I ent that good with electrics.

 

The Perun uses low resistance wiring so for it to start getting warm this quick something is up.

 

The shimming is fine, minimal play with no rubbing and freely rotates numerous rotations when screwed closed and rotated with my finger when testing. Im also using a madbull internal kit, cylinder, cylinder head, piston and nozzle. The piston was tight on the tracks so modified it so it moved freely along the tracks in the gearbox.

 

The motor sits in the grip quite well although the gearbox hole and pistol grip hole are off centre by a couple of mil. So could be changing the angle it sits on the bevel slightly and creating more friction that standard. Although the motor adjustment adjusted fine with no noticeable grinding or straining. I adjusted till it whined then quarter/half turned it back until it sounded nice.

 

The battery I used in testing is a Nuprol 7.4v 1300mah stick with 20c single and 52c burst. I forgot to mention the Perun is also fused with a 30a fuse. As wired by Perun.

 

Not sure on the spring I think its either an m90 or m100 and I havent been able to chrono before or after the build so not sure on fps yet (my brother on law and I share the chrono)

 

Overall the build turned out how I wanted it to, its snappy, responsive and sounds much better than it did previously and I had a lot of fun putting it together. But I dont want to risk using it until the heating up issue is sorted.

 

Sorry for the length, thanks for reading did you got this far.

 

Rob.

[EDcase]

I'm no expert but it does sound like the battery is underpowered.  You might need a 25c minimum for that build.

Couple of questions that might help others diagnose the problem:

 

Does the motor get warm/hot?

Did you test the shimming and piston travel with the gearbox fully tightened up?

[SnakeDoctor87]

Hey, yeah shimming and piston travel was tested. The motor im not sure about. Was the next thing I was gonna check tbh.

 

So how do the battery specs work? Im a little unsure about the c count.

[Rogerborg]

Higher C is better, and should stay cooler.  The limit should be the sink (motor) not the source (battery).

 

Sight unseen, I'd suspect the motor, if for no better reason than I've just had a motor short internally and get finger-burning hot, and also heat up the wiring and battery.  I'd pop it out see if it's causing heat anywhere when running under no load.

[SnakeDoctor87]

Cheers Roderborg,

 

I'm gonna get a better battery and test the motor like you suggested.

[Adolf Hamster]

Asg 40k has enough torque to be called "high torque" but its also very fast and very power hungry.

 

If you increase the wiring gauge/replace the tamiya with an actual connector it might only acheive letting it draw enough to kill the fuse/battery

[ak2m4]

I imagine the amp draw with 13:1 and the ASG 40K is super high, if you have a meter, stick it on and see what numbers you're getting

[Les]

Just to rule it out- if you connect everything up but don't fire, is there any heating?

Could be a wiring short, or wire rubbed through and touching on something rather than a mechanical problem?

 

[SnakeDoctor87]

Hey guys,

 

Thanks for the new replies.

 

I have tested the motor all hooked up and only the motor got warm while not cycling the gearbox. I think i may have shimmed the bevel too tightly. I was following a negative airsoft vid on doing spur first and I didn't cater for the motor height. 

 

4 minutes ago, Les said:

Just to rule it out- if you connect everything up but don't fire, is there any heating?

 

 

No nothing when idle, cheers for the tip though.

 

1 hour ago, ak2m4 said:

I imagine the amp draw with 13:1 and the ASG 40K is super high, if you have a meter, stick it on and see what numbers you're getting

 

I do have one but dont really know how to use it. It came with the soldering iron I bought lol I have bought a 25c battery to see if the higher c will keep the temps down.

 

1 hour ago, Adolf Hamster said:

Asg 40k has enough torque to be called "high torque" but its also very fast and very power hungry.

 

If you increase the wiring gauge/replace the tamiya with an actual connector it might only acheive letting it draw enough to kill the fuse/battery

 

I think the wiring is already 16 awg, Sorry unsure about wiring too.  The perun was pre-wired with low resistance wiring. The motor did have trouble going into the gearbox hence why I think I've shimmed the bevel incorrectly, I've already nicked the existing cabling which I discovered this morning so need to repair that to rule out shorting. I do intend to change to deans though as I've had endless connection issues with tamiya on all my guns so ill have a Deans swapping day at some point.

 

Thanks guys, I'll keep updating after every change I make incase you guys think something I don't.

[Adolf Hamster]

Yeah likely the connector is the bottleneck atm.

 

Sadly a higher c battery wont help the wires overheating, possibly make that worse, although at least its more likely to handle the motor.

 

Remember amp support is a factor of both the c rating and capacity, so lower capacity at a higher c rating aint necessarily more current.

[Rogerborg]

6 hours ago, Adolf Hamster said:

Sadly a higher c battery wont help the wires overheating, possibly make that worse

 

Only if the battery is currently limiting what the motor can draw.  That's not a situation I'd like.

[Adolf Hamster]

11 hours ago, Rogerborg said:

 

Only if the battery is currently limiting what the motor can draw.  That's not a situation I'd like.

 

Hard to be sure, but if any combo can do it then its an ask 40k on 13:1

[Lozart]

If the wiring is getting hot, it's because there's too much current for the size/makeup of the wiring. Changing the connector from Tamiya to Deans isn't the solution, if anything it would make it worse. If the connector was acting as a bottleneck then IT would get hot, not the wiring (if it's getting hotter than the wiring then you really do have a problem).

 

Basically it sounds like the motor is pulling more current than the wiring can handle on account of the combination of that motor and that gearing.

[SnakeDoctor87]

So i suppose the question or decision is do i swap back to the og motor which was a g&g 18k motor and keep the 13:1 or stick with the 40k motor and go back to the 18:1 i had before. Or just go back to the setup originally. 18:1 with the 18k motor but use the 25c battery i now have. The reason i was changing was cause i wanted snappier trigger response but the 3 round burst struggled. But i suppose that was down to current draw and there not being enough from the 20c battery? Maybe, im piecing together what you guys are telling me.

Im not above admitting defeat, but i also want to get this working so im happy with my aeg when i next use it, but also dont want it exploding in my arms either so a compromise between what im building is needed.

 

[Adolf Hamster]

2 minutes ago, SnakeDoctor87 said:

So i suppose the question or decision is do i swap back to the og motor which was a g&g 18k motor and keep the 13:1 or stick with the 40k motor and go back to the 18:1 i had before. Or just go back to the setup originally. 18:1 with the 18k motor but use the 25c battery i now have. The reason i was changing was cause i wanted snappier trigger response but the 3 round burst struggled. But i suppose that was down to current draw and there not being enough from the 20c battery? Maybe, im piecing together what you guys are telling me.

Im not above admitting defeat, but i also want to get this working so im happy with my aeg when i next use it, but also dont want it exploding in my arms either so a compromise between what im building is needed.

 

 

 

if the goal is trigger response then the 2 things you want are pickup speed and precocking.

 

precocking is all in the mosfet (depending on which version you have you may need to change, perun offer units but i'm more familiar with the gate stuff) and in terms of motors i'd say shs high torque at the budget end, or if you want to spend then a warhead standard.

 

the problem with the likes of the 40k is as well as improving response time you're also getting a much higher rof and current draw.

 

the other thing is to ensure things like shimming/aoe (note aoe=/=massive amount of sorbo) are well setup so everythings spinning free and easy.

[SnakeDoctor87]

Cheers,

 

The aoe is spot on and shimming is much better now ive gone back through it. The bevel height is much better so the pinion isnt being squished. Which would have cause friction and im guessing more current draw. I just put the gear box back together, along with a 25c lipo connected with deans. I repaired the wiring with heatshrink so theres no worry for it shorting out which could also have been a possibility after finding exposed wiring below the motor armature. I just ran the gearbox under load and theres no instant warming even after a solid amount of shot through single and 3 round burst. Im gonna test it more tomorrow before work as its late now and i dont want to wake my boy up. But fingers crossed/touch wood all your combinations of thought have helped me fix my gun. I will let you all know after i fully test as i have appreciated all your input and learnt loads more than i was expecting through doing this process so even if i do have to go back to the og build it was still worth it.

 

Thanks all 🙂

[Adolf Hamster]

it's a steep learning curve.

 

if it's any consolation, it took about half a dozen stripped pistons/gears and 2 nearly killed batteries before i learned the 40k was not the way.