helical gears and piston teeth

[laminkiaHD]

hello guys, I´m typing from Mexico with this problem, i installed this gears ( http://rsov.com/product.php?langId=1...=4758&cateId=0 ) with this piston ( http://shop.ehobbyasia.com/shs-reinf...r-ebb-aeg.html )in a cyma cm046 with m120 spring, 11.1v lipo and a matrix magnum 3000 motor. The problem is that the first tooth (from left to right) of the piston breaks and i replaced twice! always with the same effect.

My main concern is if my configuration is not correct at all, starting with the gears, are those high torque o high speed? because i really dont understand about ratios...

i used to run this configuration with a m130 spring and never had issues, only the fact that my rof was very very slow even with lipo, thats the main reason i downgraded to m120 spring and it really increased my rof and nice internal sound. But then stripped twice...


please can somebody help?


greetings from Mexico

[m102404]

I'm going to guess that your piston is not returning completely forward fast enough and that the sector/half gear is rotating really fast and hitting the not-quite-forward-enough piston...smacking into the rack and eventually breaking it (maybe right away, maybe on a burst of full auto, etc....)

The description of the gears say "high speed"...."high torque" gears will usually be in the 20+:1 ratio. Yours are in the high speed ratio range.

Using a stronger spring will result in the piston returning fully forward faster...using a high torque gear setup will result in the gears rotating "slower"...using a slower motor will turn the gears slower...etc...

[ILLusion]

You're using the incorrect torque and spring combination. That gear set is considered an ultra high speed gearset, meant to be used with springs no stronger than an M100 or even M90.

How you got it to function fine with an M130 is beyond me... but what you're experiencing is sometimes called "current torquing".

When the gears are undertorqued to crank a heavy spring, the motor draws a huge load of current to get enough power to crank that heavy spring. You'll burn out your motor and battery real fast this way, as well as literally burning holes through your trigger contacts from the huge current arcs. With the M130 spring, you were probably completely maxing out the motor's capability of current draw, which is why it was turning so slow. When the spring finally releases, the motor is drawing so much power at that point, that the sudden release of built up potential energy will then become a huge excess of kinetic energy, which rotates the motor (and the gears) at insanely fast speed. It's turning so fast, that it's causing the sector gear to strike your piston before it's even had a chance to reset. A head on collision like this, as you can imagine, is extremely stressful, and your piston isn't built to take that type of impact. Something will have to give. Thankfully it was your piston teeth and not your gears.


Lower your spring more, or get a different ratio gear set. You SHOULD be using a 1:22 (or something similar) ratio gear set to crank the springs you're trying to turn.

Edit: What m102404 said, but in not such a clear and concise manner.

[m102404]

LOL..."sudden release of built up potential energy will then become a huge excess of kinetic energy"

cool story bro

(Illusion's tops at this stuff...take special note at what he's posted)

[ThunderCactus]

How slow was your ROF exactly?
Granted you were putting way too much load on your motor, but with an 11.1v LiPo your ROF should be no less than 1200rpm at the very least, and with high speed gears should be up in the 1600-1800rpm range.

As stated, buy proper gears and a proper spring for those gears
Get a full tooth piston instead of a half rack
Shim your gears properly
And install a MOSFET switch since your LiPo is going to destroy your trigger contacts