Reinforcing a gearbox

[Qlong]

I don't understand how a pipe band would ever prevent a gearbox from cracking, in fact it would only increase the stress on the metal frame.

Increasing the stress on the metal frame, that is the intention.

By applying stress in compression on the frame, the tension stresses on the mechbox caused by the spring and piston will be unloaded to the steel band. Since the bands are designed to be used in high tension applications, it has a significant less chance of fracturing than a zinc alloy.

The strongest mechbox I have ever heard of being made was a mechbox CNC milled from a steel billet from one of McMaster's Mech. Engineering shops. The steel billet wasn't cheap.

I just don't understand why he took off the guide rails for the piston... somethings going to go very wrong...

It seems like he took it off and replaced it with a stainless steel plate to unload the stress from the front of the mechbox to the rear, since the majority of V3 mechbox breaks from the top, I'm pretty sure the plate is doing most of the work and not the carbon fibre.

What about a nylon/other high strength polymer to replace the metal? Nylon is very durable and has excellent abrasion resistance.

Polymers usually have very low yield strengths than metals, the strongest ones today barely reach the strength of aluminum alloys. Polymers also have a very high ductile to brittle transition temperature meaning they are more likely to fracture at cool temperatures than metals.

Comparing Nylon to metals, Nylon would have very poor relative wear resistance. Wear is not the issue in this case, it is the strength and toughness of the material.

I think I might have convinced my self to test the steel band on one of my already broken mechboxes.

[ThunderCactus]

Originally Posted by tylamarre

I think the strongest gearbox you could ever create would be with a laser cutter and a block of steel.

Actually that's an un-informed idea. The heat of the laser creates hardened areas and scale all over. At the very least you'd have to temper the whole thing and have it all buffed, and the laser only cuts in a possible 5 axes from a fixed point so it would have to be machined after anyway. In order to get the complete mechbox, you'd need a 5 axis EDM. And even then, money money money.

Quite frankly, steel is overkill for a mechbox unless your planning to go above 600fps on a V2 mechbox. And then you'll have to re-invent the piston to handle those stresses, and use a 4 gear system to get enough torque to move it lol

7075 aluminum would handle 500fps no problem in the exact dimension of current V2 mechbox design, given they put radii everywhere there's a sharp corner.

Anyway, they did actually used to have CNC mechboxes. I believe pro-win made them, and someone in Canada made a few as well. The reason they're not around anymore is because they're unnecessary.

A good tough-as-nails G&P mechbox with a sorbo pad will withstand prolonged abuse

And if your REALLY paranoid about it, get a CA249 with the huge block of a PGC mechbox lol