Gearbox question.

[AngryViper]

Will there be any problems if I run 13:1 gears, M120 spring, and a SHS High Speed motor? Is there anything I need to upgrade in the gearbox so it can handle this build? Certain I should get/ stay away from?

[pestobanana]

There will be a lot of problems, that is a terrible setup. Get away from that motor. Use a high torque motor.

You will have to shim your gears properly, add a sector delay clip, and short stroke to correct tappet timing. You will have to make sure your gun is feeding 100% up to speed or you will strip your piston in no time at all.

[Bellerophon]

That motor will not have the torque to pull that spring, especially not with that gear ratio. High speed motors spin quickly, but this speed comes at the expense of torque, any kind of load (such as a spring) will slow it down immensely or or most likely stall it. I wouldn't pair a speed motor with any spring heavier than an m100 and stock gears (18:1). High torque motors don't spin much slower, but they can pull heavier springs on lower gear ratios without slowing even under the heavier strain.

High RoF builds are very tricky, you've got to do a lot of research and get a lot of practice diagnosing and fixing gearbox problems before attempting one. In general, you can't just drop in 'more powerful' parts and expect it to work, either you will notice no benefit or more likely your gearbox will tear itself to pieces.

I HIGHLY recommend reading this guide before you go spending any money. It'll likely cost more than you think, both in money and effort, but I can personally attest it's extremely satisfying to get it working. I can post details of the ~35 rounds/second build I'm working on, if you're curious.

[wind_comm]

by comparison, ~35 rps is child's play nowadays. the motor in question definitely doesn't have the torque, but 13:1 and m120 isn't even hard.

getting there will cost you much more than you think, but can be done for less than everybody else thinks. the parts are available, proven, and some are even dirt cheap. the question is always going to be the person doing the work.

getting to the "promised land" of over 30 rps isn't even the hard part. any half-wit tech can do it nowadays (I did it literally by accident before the final parts revision of my rifle), but the end result is that the guy comes back because it shoots like crap. doing a gearbox is only one part of a tuning package.

[Bellerophon]

Originally Posted by wind_comm

~35 rps is child's play nowadays.
...
any half-wit tech can do it nowadays

Hey! I resemble that remark.

[Stealth]

Originally Posted by Bellerophon

Hey! I resemble that remark.

In what way?

[lurkingknight]

sorbo and a steel rack piston. Proper modification for AoE correction...


Don't really need to adjust the stroke... all my guns are full stroke 110s or 120s. Short stroke a 120 to get it under 400 fps and avoid overspin, yes. But 110s on full stroke don't overspin terribly.

[Bellerophon]

Originally Posted by Stealth

In what way?

Mostly the bit about being a halfwit tech. Despite all odds, my build is running, so I'm happy. It's not fieldable yet, there's still lots to do, but at least I can enjoy the lovely BRRT sound it makes.