Starting Point

[RogueTwoRobots]

Re: Starting Point

Looks like a nice start to a build.
If you ask Kane nicely, I'm sure he'll happily move this to another section of the forum. Or better yet, don't hesitate to start up a build thread for it, that way you could keep all these pages of research seperate from the building of your machine.

For an axe, I've seen a couple in B&Q that are quite similar to what Avenger uses. They have a fibreglass handle too so won't risk splitting as mentioned in the electric axe guide page. They may be a bit short though, depending on the design of your robot body.
Alternatively, you could make your own, maybe with a bit of steel box section as an arm and a shaped piece of Hardox or something to make the axe head.

Actually just remembered seeing something a while back that I thought would make a good robot axe. Ice axes used in climbing. They had a funky shape to them and the handle was metal (with some plastic coating over it) so would be sturdy enough bolt to. Their strength in general should be good as they have to support people dangling from them. I think they can be quite expensive though.

I may be about to contradict myself here actually. Found a pic of what I was thinking of:
http://gearflogger.typepad.com/photos/u ... sanano.jpg

Not sure how well the axe head/attachment would hold up. Might be fine for axe hits, but copping a blow from a horizontal spinner could be damaging. Plus that one is £85 :shock:

[typhoon_driver]

Re: Starting Point

Lol I wouldn't bother with an ice axe. Those are designed for being thrust into ice surprisingly enough. They are generally very light and sharp pointed. Great for climbing with, not so great for robotic combat. Making an axe head would be easy enough. What kind of weight were you looking for? I've got some nice 20mm hardox pieces kicking around somewhere that would make a lovely featherweight axe head

[zoll]

Re: Starting Point

I will confirm this first but I believe the batteries are new and unused if this makes a difference?

Thanks for the offer of the hardox but I've never worked with hardox before and probably dont have the equipment to either so will probably have to go for a ready made axe.

[psycho_fling]

Re: Starting Point

id still charge the batts seperately sounds like you have the chargers to cope

for the axe id go for an off the seld one thats what i have, buts like 1metere plus in length might have to cut it down abit

[typhoon_driver]

Re: Starting Point

If you have an idea of weight and dimensions in your head I'd be happy to cut and weld something up. Cheaper and stronger than a store bought axe

[zoll]

Re: Starting Point

Just a bit of an update, Gary has made me an axe as per his last post (thanks again). I will be home from uni next weekend and so can get back to work on it, get the axe fitted and working.

Bits remaining to do; get some power leds, make removable links and find some circuit breakers.

On the last point on tht list im still slightly confused. If I buy circuit breakers designed for the home from a hardware store, they are designed for AC current, if i put these in a dc circuit do they take twice the amps to cut out. i.e if I wanted to limit a circuit to 50A DC would a 25A AC circuit breaker be the right thing to use? Further for a dual controller that can handle 50A per channel does this mean I need to limit the current going into it to 50A or 100A?

Will hopefully get some pictures up when I get home and will start a thread in the build section.

[typhoon_driver]

Re: Starting Point

No problem, you're welcome. Got the cash ok so it should be in the post today or tomorrow. Just remember, you will probably have to shorten the axe arm!

I wouldn't bother with circuit breakers instead just look to use some automotive fuses if you are worried about drawing too much current. They are cheap as chips and come in various ratings. Also a bit lighter weight wise.

http://www.technobots.co.uk/acatalog/Sh ... s_422.html

If you go down the automotive fuse route then you can put a 50A fuse on each channel of the controller. If you use a 100A fuse or breaker then technically one channel could still draw over 50A allowing one side of your speedo to blow without your safety feature stopping it happen so in answer to your question, throw a 50A whatever on each channel of the speedo.

[zoll]

Re: Starting Point

Just a quick question, how long should a 100-220mA charger take to charge 3800Ah batter. and is it fine to just change the tamiya connection on the end for a deans connector?

[typhoon_driver]

Re: Starting Point

for a rough idea divide the capacity by the charge rate, ie 3800/200 = 19 hours and yes its fine to change the connector just make sure the polarity is correct for your setup.

[zoll]

Re: Starting Point

Ah no wonder they seemed almost dead after 5 hours charge lol

[typhoon_driver]

Re: Starting Point

Yeah I'd highly recommend getting a charger that can charge at an amp or two. It will become invaluable during events.

[zoll]

Re: Starting Point

Just the problem that i'd need 4/6 chargers depending how many battery packs i need >< which im guessing would be £100 atleast

[zoll]

Re: Starting Point

What do you think to these http://cgi.ebay.co.uk/Intelligent-1-...item1c0b5a5722

[zoll]

Re: Starting Point

Managed to do a bit of building today, had a few problems... made a test rig for the axe and it just destroyed itself without the full axe even attached, wood ripped of the base... might have to learn to work with metal sooner then i was planning lol

Second problem I'm running a victor 883 as the speed controller for the axe it works fine off 21.6V (3x7.2V) but if i try to run it off 28.8V (4x7.2V) it doesnt come on. The victor is rated up to 30V so I thought 28.8V would be ok but prehaps not?

[daliad100]

Re: Starting Point

Try checking the current drawn when the axe fires