Well with a large majority of NSW bots being boxes, hitting a corner doesn't seem to hard to me
_________________
https://www.halfdonethings.com/

Thanks Glen I'll look into that.

Cheers, Aaron.


I'm now confidant about my weapon motor selection, and have changed the fiction drive setup slightly. It now has extra gearing(with a couple of spur gears) and 40mm Colson. Its now running @ 36V, and should have a peak power of around 2500Watts(3.4HP). All under 3000RPM.
_________________
Imagination is more important than knowledge. Knowledge is limited. Imagination encircles the world.
Albert Einstein.

i forsee lots of gyro issues.
schweet.
_________________
Mechanical engineers build weapons, civil engineers build targets

Issues = fun?
_________________
Imagination is more important than knowledge. Knowledge is limited. Imagination encircles the world.
Albert Einstein.

fun for other people
IE your bot wont want to turn corners with the wep spinning
_________________
Mechanical engineers build weapons, civil engineers build targets

At least he won't need a gyro to go in a straight line
_________________
https://www.halfdonethings.com/

very cool design!!!! Best of luck with it!!!

I am finally getting somewhere with the drum, and it's all getting done locally just around the corner from work. The drum is being made from mild steel(rolled) and the teeth will be welded on, which will be mild steel as well. Then the hole thing is being heat treated(Hard). It doesn't look like it will cost to much ether.

I'm sourcing other bits and bobs, and should start construction soon.

Also the drum will be spinning under 2000RPM now, but still with the same peak power(2500watts, 3.4 horses).
_________________
Imagination is more important than knowledge. Knowledge is limited. Imagination encircles the world.
Albert Einstein.

I had a good chat with Andrew @ http://www.fastelectrics.com/default.asp about the Neu motors. He was very helpful.

He has sent me some test data on a couple of Neu motors, and is very keen for me to select the correct motor the first time!


Hes an email he sent me:

Trent these are dyno test from a brake dyno

Read from left to right and assume as you move right more brake is being applied

I have include the 1910 test so you can see how things change as wind and voltage change

With fewer winds the rpm/v increases and the motors torque output per amp decreases at a proportionate rate

As winds fall and voltage increases the efficiency hump moves to the right or to higher amperage and higher watts out.

However in a motor with fewer winds the extra power is due to the increased speed of the motor, not extra torque

The torque produced per amp is actually less (ie twice the rpm/v= ½ torque per amp). So either a gearbox, more amps or a mix of both is required to obtain the same torque at the output shaft





I did some ruff calculations, and worked out that my drum would have about 3850 J.

But it seems to be too late in the day for me to take in the info he has sent me, so if anyone has any comments or conclusions from the email, say so.

Also I have been happy with my selection of motor and gearing before contacting Andrew, but now its just a bit of information overload. So any insight into that info would be appreciated.
_________________
Imagination is more important than knowledge. Knowledge is limited. Imagination encircles the world.
Albert Einstein.

seems pretty good. would be interesting to see the full graph so you could see the wattage at stall. looks like it could hit 3000w which would be impressive for a tiny motor.
_________________
www.demon50s.com - Minimoto parts
http://www.youtube.com/user/HyzerGlen - Videoooozzz

Well considering that watts out = rpm x torque I can predict that the power out at stall will be 0.
_________________
Get Some!!!

Secretary of the Queensland Robotics Sports Club inc.

damn you thermodynamics!
_________________
www.demon50s.com - Minimoto parts
http://www.youtube.com/user/HyzerGlen - Videoooozzz

Dont forget to allow for aerodynamics and drive friction as well.

A brake dyno isnt spinning a lump of steel with teeth around in the air.

Ok, the teeth may be small, but the tip speed is high
_________________
Great minds discuss ideas. Average minds discuss events. Small minds discuss people

I like the top graph, since Chuck has a 1910 at 22V . It can't fail to be spectacular in some way or other - an explosion will be almost as good as a fast spin up.

My take on this is that you need to consider the gearing very carefully to match the load to the motor and battery pack. There will be a target RPM you want to hit with the drum and a motor RPM/power output that will stop everything burning out. I have been keen to get more torque and less speed.

BTW: what did Andrew say about supplying the 1910 motors? I'd be in the market for a spare.
_________________
Australian 2015 Featherweight champion
UK 2016 Gladiator champion

Thanks guys I'll hopefully be looking @ it all in more detail tomorrow.

Nick, supply is no problem if your prepared to wait a little while. Also I believe the prices quoted to me were good, from Andrew.

After speaking to Andrew after work yesterday(about 6:00) and learning from that convo, he then also sent me no less than three emails before the end of the day. Very helpful.

What I'm interested in @ the moment from you guys is, what you do when looking @ similar tables above in relation to the voltages from your battery packs.
What I mean is, Andrew was looking @ the A123 batteries @ there sag voltage(about 2.6V) not 3.3V. When you guys look @ a motor do you match it to the sag voltage or the nominal?

If these terminologies are not correct, please correct me.
_________________
Imagination is more important than knowledge. Knowledge is limited. Imagination encircles the world.
Albert Einstein.