Gearbox question.

[Deleted]

Okay, so after hours of google searches and a good 12 hours working on my gearbox, I'm at my wit's end.

My setup:

V3 Gearbox
7MM metal bushings
13:1 SHS Gears
14 tooth (7 metal) SHS Piston
M120
SHS High Torque Motor
9.6V Battery
Lonex Silent Piston Head
Everything else stock.

So the issue I've been having with my gearbox is that the motor will turn the gears back, but only to maybe one or two teeth. I first diagnosed this as an issue with the spring being too heavy, so I swapped down to a M90-M100 spring that I found from an MP5 to fix this issue. The gearbox would then cycle perfectly after I adjusted AOE, until eventually it started to lock up too. What I saw was that the piston was also broken (back teeth broken), so I swapped the original piston to an SHS one and fixed AOE again for it to work. So my question is how come it continues to keep locking up? I made sure my shim job was done correctly and even had it confirmed with a lot of other people as well, so shimming may be out of the question, the wiring is fine and so is the AOE. From what I understand SHS High torque motors can hold up an M120 easily, so what is the issue? Could it be a bad battery? I am running a normal 9.6V NiMH battery 1600MAH, but I made sure it was fully charged before testing. Could it be a bad motor? I'm not sure how to test this. Do you recommend a lipo for this gearbox to actually work? I'd rather not have blistering high speeds over 30rps.

Any help would be greatly appreciated thanks!

[X]

Aug 31, 2013 14:13:44 GMT -5 @albertngoo said:

Okay, so after hours of google searches and a good 12 hours working on my gearbox, I'm at my wit's end.

My setup:

V3 Gearbox
7MM metal bushings
13:1 SHS Gears
14 tooth (7 metal) SHS Piston
M120
SHS High Torque Motor
9.6V Battery
Lonex Silent Piston Head
Everything else stock.

So the issue I've been having with my gearbox is that the motor will turn the gears back, but only to maybe one or two teeth. I first diagnosed this as an issue with the spring being too heavy, so I swapped down to a M90-M100 spring that I found from an MP5 to fix this issue. The gearbox would then cycle perfectly after I adjusted AOE, until eventually it started to lock up too. What I saw was that the piston was also broken (back teeth broken), so I swapped the original piston to an SHS one and fixed AOE again for it to work. So my question is how come it continues to keep locking up? I made sure my shim job was done correctly and even had it confirmed with a lot of other people as well, so shimming may be out of the question, the wiring is fine and so is the AOE. From what I understand SHS High torque motors can hold up an M120 easily, so what is the issue? Could it be a bad battery? I am running a normal 9.6V NiMH battery 1600MAH, but I made sure it was fully charged before testing. Could it be a bad motor? I'm not sure how to test this. Do you recommend a lipo for this gearbox to actually work? I'd rather not have blistering high speeds over 30rps.

Any help would be greatly appreciated thanks!

What brand is the gun? Mainly asking to establish what brand the motor is.

Sent from my XT1080 using proboards

[MayhemXXXFrosty (AndrewMp5k)]

Well he's using a SHS High Torque motor, so the stock brand motor won't matter.

Are you using a quality 9.6v battery, or is it one of those crappy green/blue/yellow/black/whatever batteries that come with the gun?

[Deleted]

Sorry if my information isn't full enough, umm the brand of the gun is a JG G36c, and the battery is a G&P 1600Mah 9.6

[X]

Aug 31, 2013 17:18:00 GMT -5 MayhemXXXFrosty (AndrewMp5k) said:

Well he's using a SHS High Torque motor, so the stock brand motor won't matter.

Haha.. Duh... Didn't read closely enough. I'll just stop talking now...


Sent from my XT1080 using proboards

[Puma1]

I had the same type of problem on a JG m4 s-system I was working on for a friend. He had shimmed the gears too tight, and it added extra stress that the motor couldn't pull. This caused it to start spinning backwards, and activate the anti-reversal latch. Granted, he was using an M130 on a high speed, so the little added stress was enough to wreak havoc.
Using a high torque motor, however, leads me to believe that this isn't the problem you're facing.

Have you checked all of your gears for missing teeth or anything of that sort?

also, make sure no parts of that broken piston are left in your gearbox.

Ctres may be able to help you out, as he knows a lot more than me.

[Deleted]

My gears don't seem to be missing teeth, I tried comparing the old failed piston and the new one and I can't see any difference either, I believe it is down to the piston however because without it the gears move fine.

[ctres]

I'll pretty much echo what puma said about shimming, but maybe I can clarify a bit. The way I see it is in a reasonable build, and yes yours is very easonable and totally doable, and assuming that all your electrical and mechanical components function properly then there are really only two major reasons you would run into the issue you are having.

1.Dead or weak battery
2. Excessive mechanical resistance, such as too tight of shimming.

I would venture to guess that you are having a combination of the two. Your battery is very far from ideal for that kind of power hungry setup, but I find it unlikely that the battery would be able to pull it at all, so maybe your battery is just dead.

On the other hand, assuming your battery is fine and can pull your setup, you could have various issues with the mechanical parts that could create too much resistance. Remember that using high speed gears lowers the ratio so it is already increasing the load on the motor similar to installing a stronger spring. The more demanding the setup, the more noticeable issues such as shimming become. Too tight of a shim job could definitely be the problem, but it could be other fitment issues like the piston being too tight in the gearbox rails.

Adding more mechanical resistance via stronger spring, faster gears, or extra tight shimming will all cause of the motor to draw more current, so if the battery can't supply it then the gun won't be able to cycle.

My first recommendation would be to try the gun with a nice powerful lipo or very large nimh. It doesn't have to be high voltage, it just needs to be able to supply a lot of amps. If that cycles the gearbox then that should tell you a lot. The noises it makes will tell you a lot about your shimming.

[Deleted]

Thanks, I think I'll go that path first with upgrading to a LiPo. I did find out a bit of the issue was the SHS piston being a little bit wider than the original piston, making it get stuck in the rails... like literally unmovable. But yeah I will look into a LiPo, hopefully a 20C 7.4V Tunigery will work with the setup in mind.

[MayhemXXXFrosty (AndrewMp5k)]

If the SHS piston has rail clearance issues, then if I were you I would take the O-Ring off the piston head and put the gearbox back together with just the cylinder setup and the piston (so cylinder, cylinder head, tappet plate and nozzle along with the piston). Then tilt the gearbox like a teeter-tauter back and forth to see if the piston slides back and forth fine. If not then you may have to shave the piston's rails to get it to glide better. Also if you didn't, lube your piston rails as well as the gearbox rails so it cuts down on friction resistance.

[ctres]

Yep, I always test just like Mayhem said. If that is your problem, then you can either get a new piston or just sand the rails to make it fit.

Just remember that if you go with an 11.1V lipo your ROF will be pretty high, like approaching 40rps. I hope you have corrected AOE and taken the necessary precautions to protect against pre engagement. I'd personaly stick with a higher torque motor like a JG blue in that setup.

[MayhemXXXFrosty (AndrewMp5k)]

Not to mention, if you haven't eliminated your friction situation (as in your gearbox keeps locking up). Eventually running an 11.1v you will run into a train wreck of a situation more then likely than with a 9.6v. So better to work it out with your 9.6v and find/fix the issue then to jump into an 11.1v hoping it will solve it.