2kg sure beats 8kg to do the same thing with nicads =), well just go nuts with the revs on the beater, also at this stage were considering a beater with only 1 arm/part that actually hits other robots instead of the traditional 2, may be tricky to balance but this should give the opportunity to get the other bots further into the blades b4 contact is made, and therefor make better contact and therefor more damage sound like a good idea?
i pressume traditionally beaters only spin at about 1000rpm is there any reason we cant just go nuts and aim for like 8k, only restriction i can see is balancing the weapon

im pretty sure dylons would hit at least 3000rpm and the motor behind that isnt really that powerful (700w at best).

if you cad it up and its center of mass lies on the central axis go for it problem with one tooth style weapons is they dont have as much energy as a two toothed type because you need to use a disproportionatly (how the hell do you spell that lol) massive counterweight to balance it out.

balancing the weapons isnt really that hard either. mine needed 50 grams of weight taken out of the rim to balance it and still spun it past 5000rpm just fine.

what motor is it anyway? sounds like the 5330 axi. if your using two of those at 48v im pretty sure your frame will bend itself up from the torque alone (jks)
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www.demon50s.com - Minimoto parts
http://www.youtube.com/user/HyzerGlen - Videoooozzz

You should read the section on drum / beater design in the Riobotz book. A "typical speed" would be around 3 to 6K rpm and some nutter in the States reckons that 40K is working for him. A one sided beater would be a good idea in theory, but it will weigh more, so you have to balance the weight gain against the effectiveness. Your motors will do around 10,000 rpm with no load @ 40V, so a reduction of between 2:1 and 1:1 would be where your aiming for.

Remember that with a brushless motor and ESC, you can spin the weapon at any speed you want, its full proportional control. Most people just go 100% all the time, but it makes sense to lower the RPM if you think the match needs more turning ability or you need longer running time.

oh btw, whats the biggest sweetest charger for charging A123's? bad habbit can get me one at cost price, so im just going to get the best one that i can find because this is somthing ill use past this robotics project

okay guys time too spend a weekend on the bot again, i need a bit of help with my materials selection, can somone put me onto a site with metal properties and stress strain curves for common metals and different thicknesses? at this stage were looking at using stainless but im not sure what mix or thinkness too use. im still cading at this stage and im really not shure how im possibly going too predict the weight, at this stage our bot is looking like itll be 350 x200x 300mm is this roughly the right scale? ill get a cad up soon but at this stage think of pussycat, with a beater on the bottom, that runs tiped over all of the time, with a 250kv weapon motor, 2 24v bosh drive motors, running at 40v =) should be fun

http://www.matweb.com/ is a good place to start for metal properties; if they don't have the details, they will have a link to a site that does. Nobody uses stainless for new bots unless they get it for free. S Steel may have a reputation for 'toughness', but its other properties make it lower performance than most steel. You would be better off with Hardox or Bisalloy and Bisalloy would probably be cheaper too. Go for at least 3mm hardened steel if you have an active weapon and 5 to 8mm if you do a wedge.

I still think you will run into trouble with a 40V supply, its just asking for trouble!

2 4000mah 30c 6s packs on the way from Hobby King!!!!!!!! WOOP WOOP!!! 2mins at 5328W and 44.4v here we come !!!!!

Don't forget to post a spin-up video! 5KW is all very well, but matches do go for 3 minutes - what's the plan for 2:00 to 2:59?

Hoping for a less then 2 min knockout
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Tim Team Reaper.

5kW is on demand, i doubt it will be pulling that much once the beater is upto speed. should have heaps of capacity for 3 mins, considering most ppl seem to run 2200mah a123's without any problems

have you got a good charger?
its gonna be harsh to charge them batteries straight after a fight so spares would be reccommended
but man thats alot of powah!
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http://au.youtube.com/user/crustydemonsully

The day I stop giving 100%, is the day I stop competing

here are some teaser pics of our robot now that we have started building
its a beater ifyou cant pick it, going to be driven by that brusless motor
[img]http://www.robowars.org/forum/album_pic.php?pic_id=1513[/img]
[img]http://www.robowars.org/forum/album_pic.php?pic_id=1512[/img]
[img]http://www.robowars.org/forum/album_pic.php?pic_id=1511[/img]

Last edited by Jtepper on Sun Nov 15, 2009 8:25 pm; edited 3 times in total

god damn LOL

what company did the cutting on the frame panels? any extra armour over that?

looks good
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www.demon50s.com - Minimoto parts
http://www.youtube.com/user/HyzerGlen - Videoooozzz

we sent a letter to online laser bendigo asking nicely if they would sponsor us, and they did it for free from 5mm mild steel offcuts, so that we can check if all the parts fit together properly, then we are going to do a final one from bisalloy
There will be 2/3mm (havnt decided yet) polycarb plates over the top just to keep crap out more than armour.

You would be better off without the polycarb and adding more steel on the outer panels; those struts are not going to last against another good spinner. Looking at the front of the frame, the beater is going to be absolutely massive! Are you sure its not a lightweight?