Featherweight Database

[fwsorg]

Big pulleys stand up to more punishment from Eds whirly bit as he put it.

[robjones]

Ive messed about with diddy pulley on feathers (eg BlacknBlue)and watched other feathers for ages and I decided to go for BIG ONES!! They only weigh 400g each and take a beefy 13mm v belt. It never comes off or slips due to the huge surface area of contact. With the blades needing to be bolted on I needed something substantial in order to take the punishment (An EV Warrior @ 36v). Its worth remembering that the pulley itself adds to the MoI (Possibly both pulleys do?)
The mounting is aluminium and the inner shaft is 20mm titanium. Sadly it all weighs 12.7 Kg so I may have to run it with just one 500g blade not two, unless I can make savings elswere.

[stu]

How about using 8v batteries.
Im sure others would agree!

Mr Stu

[geoff]

Rob, That is one nice looking bit of kit.
Having played with many types of belt / pully arangements for weapons drive, the one thing we have learned is that it is always handy to have a little slipage in your drive train. Think on this.. You manage to bring that EV to a dead stall @ 36V any idea what the stall current is? ...Trust me, its a SERIOUS number of amps!!
Its more than possable to weld relay contacts shut (with all the embarassement that causes when you discover that you cant turn your weapon off!!)
Not to mention the excess loading on your battries, increasing the very real chance of some high quality pyrotecnics!:sad:
Yes, you will gain a little MoI from the bigger pullies, but it is only a little. For what its worth I would set that up with just enough slack in the belt that if you were to lock the blades, the EV is JUST capable of slipping the belt.
A far as reducing the 0.7Kg are you using Ni-CAD or Ni-MH batts.? Remember 36V of Ni-Cad weighs around 2.8 - 3Kg but 36V of Ni-MH will come out somewhere around 2.1Kg.
Oh yes, just one other thing..Just how thick are those polycarb body panels? :wink:

Regards,
Geoff.

[stu]

Thicker than your polycarb pannels, so go back to your Astro flight!

Mr Stu

[robjones]

LOL!
The panels are 6mm polycarb. But Im hoping that nasty spinners will be kept away by simple side bars like in big CHIP. Ill need lots of spares!
Im going to be testing the weapon once Ive have hardened the blades. If things get difficult I can run it on 24v, or use a small solenoid, or do what we do with our other spinner BlacknBlue - namely cut the motor just before every hit.
The power at the moment is 3 x 2100mAh, 12v NiCAD in series. I have loads of other types to try out. 2100mAh may not be enough for a battle.
It may well be that the 2WD design with the blades well away from the robots centre of turning mean that the weapon wont stall anyway-glancing cuts and tears only, especially at 6000rpm.

[dragonmaster_1]

Looks good Rob. Cheers Geoff got the green belt. DragonStrike Nearly done just got the electrics to do. Running my EV on 24v. Latest pic on profile. Tiamat coming on nicley latest pics on web site.
Regards Tony.

[robjones]

Thanks Tony
DragonStrike looks a very strong robot! Is that steel all over?

[dragonmaster_1]

No its not steel its 6mm Ali with 10mm poly bulkheads the bar is 2kg and 30cm long 6cm wide and 2cm thick steel. Power 2x 3300 NI-MH. Drive 14.4v Drill motors.
Tony.

[geoff]

Lookin good so far Tony