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After several months of trawling forums, the RioBotz handbook and google, myself and two of my friends are ready to start building Big Dave 3, our first Heavyweight robot.
Where we're at:
We have the basics of a design in Autodesk Inventor. We're intending to get each of the plates (there are 8 main plates) cut out of 7075-0 aluminium. We have yet to decide on a material for the drum, which we're intending to get cut in sections and then bolt together to save cost & machine time.
We've selected drive & weapon motors. Alien 8085's and Turnigy T203T's respectively.
Drive: 5:1 via spur gears. Wheels are 11x7.10-5 GoKart tyres, driven with a keyway'd 25mm axle. We're hoping to get axles made up from a local lawnmower racer.
Weapon: 6:1 via toothed pulley. 95% of full speed is just a hair under 11000RPM.
Batteries: 8 x 8400MaH LiFePO4 batteries.
Things we're slightly worried about:
Unfortunately, it's just a screen grab with none of the gearing shown, because trying to render something with that much detail screws up my laptop!
Next steps:
Buy everything once we're 100% happy with the design.
Find a waterjet/laser cutting service, as well as a local machine shop/school/university that will allow us to cut pockets in our plates.
Design & Print the battery housing.
Start assembling!
Drive Test & Tune.
Weapon Test & Tune.
Armour.
Trivia: Back in 2004/5, we built/helped to build several autonomous robots for the "MicroMouse" competition: Lil' Dave, Dave, Big Dave & Big Dave 2. Thought we may as well continue the naming tradition.
Where we're at:
We have the basics of a design in Autodesk Inventor. We're intending to get each of the plates (there are 8 main plates) cut out of 7075-0 aluminium. We have yet to decide on a material for the drum, which we're intending to get cut in sections and then bolt together to save cost & machine time.
We've selected drive & weapon motors. Alien 8085's and Turnigy T203T's respectively.
Drive: 5:1 via spur gears. Wheels are 11x7.10-5 GoKart tyres, driven with a keyway'd 25mm axle. We're hoping to get axles made up from a local lawnmower racer.
Weapon: 6:1 via toothed pulley. 95% of full speed is just a hair under 11000RPM.
Batteries: 8 x 8400MaH LiFePO4 batteries.
Things we're slightly worried about:
- Weight! Autodesk puts the framework (seen below) at 89Kg. Once we add in the bolts and electronics, I would image that would put us about 95Kg, without armour. The obvious solution to this is to mill pockets in the side and back plates, which could save us a good 10-15Kg. However, the machine time for that would be crazy expensive.
- Weapon Drive - we're intending to use a toothed belt that's slightly overtensioned (.5mm), which might tear when the drum hits something.
- Clearance, Clarence. There isn't that much room between the edges of the tyres and the side plates, nor is there much room between the drive motor and the gears. When running inverted, there's a 5mm ground clearance.
- Bearings. None of us have the slightest clue how to design bearing housings in the side plates in a way that doesn't need machine time.
Unfortunately, it's just a screen grab with none of the gearing shown, because trying to render something with that much detail screws up my laptop!
Next steps:
Buy everything once we're 100% happy with the design.
Find a waterjet/laser cutting service, as well as a local machine shop/school/university that will allow us to cut pockets in our plates.
Design & Print the battery housing.
Start assembling!
Drive Test & Tune.
Weapon Test & Tune.
Armour.
Trivia: Back in 2004/5, we built/helped to build several autonomous robots for the "MicroMouse" competition: Lil' Dave, Dave, Big Dave & Big Dave 2. Thought we may as well continue the naming tradition.
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