building a gun from scratch anyone do it

[m102404]

Originally Posted by MatzelleJ08

I'm putting it on the front..it will look sick but I should get the largest battery power..I just have no clue what battery size is good..and if I get to powerful will it break the gearbox..but gun looks sick

I'm sorry to hear that...my kids are sick at the moment as well. One has a runny nose and the other threw up last night.

Anyways, like I said, you'll have to know the dimensions of your battery box and find a battery that will physically fit.

The battery power won't break your mechbox per se. If you're internals are not done well, you're like to see it fail shooting it with any battery.

There's lots of good battery FAQ's on this forum, but here's my basic understanding and short form version:
- Even though they might have the same rating (e.g. 1.2v 1400mah), small cells (aka minis, 2/3A) do not have the same "guts" as larger cells (aka large, subC). Bigger cells have deeper reserves of power to draw from. A battery pack made up of large cells should be good for a day's game, whereas a mini-pack with the same "numbers" will be good for a half day. That is a very rough generalization, but it does match up with my experience. That said...a lot of rifles use minis and guys just swap their batteries when they die.
- Each cell of a pack is typically 1.2v, with some maH rating (e.g. 1100, 1200, 1400, 4200, etc...). Add up the number of cells to get the total voltage (i.e. an 8.4v pack is made up of 7 cells). The maH (roughly the capacity) is not added up.
- Roughly, the larger your mah rating, the longer your battery will last before it dies. That is rough, because how many times has it been charged, the temperature, the power of the spring load, the efficiency of the wiring and motor all affect how long it'll last. Minis last half a day, large packs a whole day.
- Most packs are 8.4v and 9.6v (the 9.6v has one more cell than a 8.4v pack). In general, you are physically restricted by the dimensions of your rilfe/box of what battery size (cell and voltage) you can use. I won't try to explain the physics and electrical details, because I'll mess it up and then McGuyver will lace into me...but essentially the 9.6v battery will result in a higher rate of fire (i.e. more shots per minute and faster semi-auto trigger response).

Again, any poorly assembled mechbox will break no matter what battery you hook up to it. Any mechbox undergoes more strain if you're firing long full auto bursts.

A battery won't break your gun. The person who assembled it, or the person pulling the trigger breaks it. (baring just plain bad luck with a parts failure).

So armed with that knowledge...get the dimensions of your battery box and look around on ehobby, airsoftparts.ca or anywhere else that sells battery packs. You could also post the dimensions (inside dimensions, not the outside of the box) and post a picture of it, that might help others to help you.

Have fun!

[lupo]

Originally Posted by m102404

Again, any poorly assembled mechbox will break no matter what battery you hook up to it. Any mechbox undergoes more strain if you're firing long full auto bursts.

A battery won't break your gun. The person who assembled it, or the person pulling the trigger breaks it. (baring just plain bad luck with a parts failure).

This is not entirely true. If you upgrade a mechbox and run it with matching parts then yeah you wont have a problem. But if you choose to run a mechbox with lower end parts and over match a battery (say like running a 10.8 or a 12volt) you will kill the box. I have seen it happen plenty of times , and done it on purpose just to see how long stock parts will last. Typically what happens when you apply too much voltage is that the piston , gears and bushings just cant take the rpm. Usually whatever plastic parts you have (bushings or piston) melt or in the pistons case gets out of sync with the gears and usually ends up loosing teeth.
And on the note of building a gun from scratch. I have built 1 G3 , 2 mp5a5's 2 m4a1's and 2 SPR's. All varrying from stock tm parts all the way up to the SPR's that were small tm parts with the bulk being systema and armalite. Experience and having lots of parts kicking around helps alot.

[m102404]

Originally Posted by lupo

This is not entirely true. If you upgrade a mechbox and run it with matching parts then yeah you wont have a problem. But if you choose to run a mechbox with lower end parts and over match a battery (say like running a 10.8 or a 12volt) you will kill the box. I have seen it happen plenty of times , and done it on purpose just to see how long stock parts will last. Typically what happens when you apply too much voltage is that the piston , gears and bushings just cant take the rpm. Usually whatever plastic parts you have (bushings or piston) melt or in the pistons case gets out of sync with the gears and usually ends up loosing teeth.

Thanks lupo,

I thought that in the context of this thread and from the tone/nature of the questions posted from the OP, my answer was appropriate. I was not referring to "super guns" running extreme voltages, more to the typical realm of 8.4 and 9.6v batteries. In my post I was referring to any poorly assembled mechbox and intended to use the term "poorly" to refer to any number of things that would compromise a mechbox (i.e. loose/tight shimming, bushing material, piston length, etc...). I think even a mechbox poorly assembled with top grade parts is at a higher risk of failing than a well built one with stock parts, especially (or more so) when pushed hard and fast by a big battery. I might be thinking of things at extreme ends of the spectrum, and over extending it to make a point.

I've purposely destroyed mechboxes (boredom + too many parts on hand = stupid) to see plastic bushings melt/crack/elongate under both light and heavy loads (is surprising how long plastic bushings will last, but when they go...wheee!), with both small and big batteries. I've also seen & heard-of good pistons torn to shreds by Herculean motors pushed by big batteries (so I know the point you're making). Haven't pushed 12v...and don't know if I want to...the way I play I'd be out of BBs so fast that I'd always be at the respawn point reloading!

The only constant that I've found is that you cannot make a bullet proof mechbox (yes we all know the PTW's are the best...we're not referring to them... ). You can make them really, really, really robust and they can last 10's or 100's of thousands of rounds...but I think that even a "perfect" one will fail eventually. Pushing fast and hard just shortens the time between failures. (I may be restating your point here...sorry) I'm of the opinion that that balance of the whole system (mechbox/spring/piston/gears/etc.., motor, battery, magazines) is more important than hitting a set FPS or ROF, if you want a reliable weapon.

Your point of high voltage (10.8-12v) batteries tearing up mechboxes is very valid but I thought that "level/complexity" of build was out of scope for this thread and adopted a beginner/mid-level perspective in answering it.

Still...it'd the person that plugs a 12v battery into their rifle that breaks it...don't blame the battery! Nayh!

[MatzelleJ08]

So what battery should I get with the

Systema 120 complete gearbox

And I would use a systema magmum motor

[m102404]

Without any regard to posts #14, 16, 17 or 18 in this thread, get any of the following:

This one comes with a strap:
http://www.canadiantire.ca/browse/pr...08474396672453

Or one of these:
http://www.airsoftparts.ca/store2/in...&cPath=117_119

http://search.stores.ebay.com/eHobby...665468QQsofpZ0

[Hectic]

I put a small strip of duct tape about three layers thick on the right side of my upper receiver to correct the off centerdness of my VLTOR CAVS worked like a charm.
so as you can see a shim is anything you can use to shim something

[Hectic]

wow I'm gonna get me one of those batts that ought to increse the ROF a bit eh.
[QUOTE=m102404;631238]Without any regard to posts #14, 16, 17 or 18 in this thread, get any of the following:

This one comes with a strap:
http://www.canadiantire.ca/browse/pr...08474396672453

[Skladfin]

Yo sup G, my gun's so Sick yo~ we shud totalli hooook up sometime bra~~

sorry I just had to do that.