Choosing lithium battery brand...

[overkill]

An inverter large enough to power a 1600W demo hammer weighs around 5.6Kg and is quite bulky (going on a 2Kw model for a safety margin). It would be far better to fit a brushed or brushless DC motor onto the hammer mechanism.

[maddox10]

Why bother? RC brushless motors come up to 10 kw packages in affordable* form.


Not the first roboteer that makes his own batterypowered tool from a 240V mains machine
(it's very easy to fit a 50mm outrunner in the body of a cheap anglegrinder), working that route should be a lot cheaper and inside the rules.

*affordable is a fluid term, different for everybody.

The cheapest way I see is to replace the AC motor with a series wound startermotor from a junkyard.

[Limitaneus]

All excellent points. Thank you very much! I admit that my electrical engineering knowledge could be written on the back of a postage stamp in quite big letters, but my fiancée's old flatmate Tim apparently builds and flies multi-rotor helicopters (I intend for both to be team members, assuming they're willing, of course). He can handle that - I have a pronounced spasm in my right arm, which I fear will not mix well with soldering irons, TIG welders, or precision cutting equipment. =]

Thanks again for helping me out. My overall plan is to follow maddox's advice and disembowel the demo hammer accordingly, then shock mount it as well as I possibly can, The central idea behind the weapon is to couple active damage from the hammer strikes (the 230V hammer I've been looking at strikes at 2000bpm) with the sheer amount of strikes through the metal chassis of the target spreading vibrations through the bodywork and knocking stuff loose inside. Hopefully it won't also deafen everyone in the building, but who can say? =]

[Yatcatcher]

Perhaps look at air hammers as an alternative? Possibly from a DC compressor or even from low pressure CO2? Not sure how practical it is but cheaper and maybe lighter.... https://www.amazon.co.uk/Silverline-...rds=air+hammer weighs 735 grams....

[Limitaneus]

That's an interesting idea, Yat. Given how light they are, I'm almost envisioning a bank of them on a kind of jaw-like setup, clamping onto the opponent from the top or sides (I've often wondered why more vert crushers didn't use additional horizontal clamps to properly corral their victims) and hammering away on them until something comes loose inside. I'd kinda love to see that sort of thing on Battlebots, actually - let's break Deadblow's record for most hits in a match! =]

[typhoon_driver]

bear in mind that if you clamp onto an opponent and vibrate away, the same vibrations will be going back through your machine. Need to design it accordingly

[Limitaneus]

Indeed. I envisaged a very steep wedge at the front, say 50-60 degrees, with the horizontal clamps mounted fairly low on the robot to hem the opponent in and the multiple air hammers on a bar coming down from over head. Ideally, this would direct the vibrations down through the opponent and into the complicated, sensitive, electronicky things, of which I am assured the opponents will have several. =]

[katch]

the more processes, the more batteries, wiring, power you use.. and weight, so you forfeit weight in your hammer i guess. 100kilos seems a lot in heavies, but having weighed up armour its a lot harder than you think to keep it down.

[Limitaneus]

Weight was never really a concern - the moving bar (think Mousetrap rather than, say, Arnold Arnold Terminegger) was a mount for air hammers, which are fairly tiny. Like, the one linked in this thread previously weighed ca. 800 grams. The idea is much more clamp than hammer. I agree it's probably overcomplicated, but it's definitely unique - even if it is beyond my engineering skills at the moment.

The previous sentence implies I have any engineering skills; this would be what we in the trade call a "big fat porky pie". =]

[katch]

Are you thinking of putting Air hammers inside each pincer !! that' be quite cool to see.

[Limitaneus]

I wasn't initially, but that would work too! A couple of little ones mounted on the grabbing claws, plus ca. 5-6 on the bar coming down from the top. With that amount of vibration power, something'll probably get shaken loose... plus the paintwork'll be completely ruined. Which is of course the most evil damage it's possible to inflict. =]