Axe mechanism

[razerdave]

Axe mechanism

73 joules is not a lot :S

[Mouldy]

Axe mechanism

Gord- Are you using the same fan motor in your hammer that you used in Arggh?

James and Grant...dont know what You mean by cost effective...I bought you one of the fan motors you destroyed so you owe me lol

[nick]

Axe mechanism

At 73 Joules a conventional electric feather will already be beginning to jump. For many opponents it is a damaging level of energy. Feather hammers are handicapped in two ways compared to their heavier counterparts. For a given weight they cannot make as high a energy to weight as a heavy without generating more power to weight, as there will be less time in which to generate it. This *is* somewhat possible for motors and gearboxes which can increase in power performance as they get smaller, but is more of a challenge for available batteries which put more sharp limits on performance.

With pneumatics so much power can be made available, unless you are stuck with low performance components it is not in my mind even an issue, pneumatics scale down remarkably well. Given the need and motivation it is possible to construct pneumatic parts in a heavy capable of reaching hundreds of kilowatts of power. The second disadvantage is that gravity is a less significant effect the smaller you are, so jumping becomes a problem even with a reduced energy. It is easy for feather to lift other feathers, they dont have to move things as far so the stresses are less.

There are a couple of ways to generate more energy, the simplest is often to increase stroke or shaft length. Neither are totally problem free. It isnt worth increasing the head mass much so you need to concentrate on power. Secondly more volts, it works best to really punish the motors and the batteries. If you havent thought of overvolting your probably just not trying.

If you use a toothed belt or chain drive, plausibly you might be able to handle shock energy elastically in the tensioners, and avoid a clutch - if you are careful. The tensioners have to be sprung low friction rollers for a timing belt or sprockets for chain.
The effect on the overall energy shouldnt be too great. If you can cut your own sprockets it might be possible for you to make a torque shaping linkage. However with only one ratio per position, you cant get much of a retract jolt, the same effect is there for elliptic gears except you wont have the shock absorption either. This kind of torque shaping mechanism can be used to reduce jumping to a degree. Shaping mechanisms work efficiently with sprung energy storage, though too much use of these mechanisms can cause trouble in self-righting (and possibly retract). The former might be less of an issue in a feather.

Nick.

[kinforester]

Axe mechanism

Dave - Yes I am using the same motors as Aaargh! but at a higher voltage. Ive designed it to take upto 32 C cells,whether i use that many will just be down to testing.

GORD

[razerdave]

Axe mechanism

To tension the drive chain for the axe, cant a use a piece of self lubricatin plastic like George fransis does for Chaos 2s drive chain ? saves the weights on spring loaded ones

[nick]

Axe mechanism

It depends on how much power you expect to waste. That depends on how much tension you are putting on the belt or chain. At low tension such a light setup will be better, for relatively heavy tension it might not and a plain nylon roller for a belt need not be heavy. One problem with toothed belts is getting enough width to make the idea viable. I havent really looked into how well it would work out in practice.