If one standard has to be chosen, then it should be metric. I would prefer finding a system that is dimension-agnostic.
A vehicle/furniture/machine construction kit should include crossbracing. Either plate triangles or space-frame characteristics.
Skid steer is practical on 1) small vehicles or 2) giant vehicles with no room for giant steering systems. With the LifeTrack's current wheelbase, it can be skid steer only as long as it remains light. Load the thing up, however, and skid steer won't work.
As best I can tell, FeF doesn't have any fields yet, let alone oa farm. So there's no need for the tractor to actually do any agricultural work. The money seems to be going towards the fabrication tools.
I interpret the LifeTrack as a proof of concept. The current design is a dead end, but it illustrates a point.
Bootstrapping has a discussion of parallel-rail frames. Personally I think they're a better idea than the current 3-way square tube construction technique.
At the moment, my concept is a single unifying modular system for all the vehicles and most of the machines. For example, start with a rectangular frame of whatever size is appropriate (try to standardize frame dimensions). Then bolt on one of a family of suspension/propulsion units (double wishbone, tank treads, etc). Then drop a mission-specific cab and or tool on top of the frame (vehicle body, loader arm, etc).
I think we'll get closer to a system like that as we more clearly define the requirements for all the different missions it needs to function in.
mrsquish was talking about electric tractors and it inspired a thought. The latest videos from FeF show them having to add 1000 pounds of weight to the back of the tractor so it can carry a big pallet of bricks. Well, based on what people are saying about electric tractors, why not convert the LifeTrac to electric drive? Electric motors would be direct replacements for hydraulic motors (maybe a little bigger) and 1000 pounds of batteries would give it all the torque and/or running time a farm could possibly use. It won't work as well during the winter, tho.
http://www.youtube.com/watch?v=ufLpGGf7TWs
http://www.evmaine.org/html/farm_tractors.html
I can't find it now, but I remember analyzing the size/weight of nickel iron batteries and calculating that a power-cube sized battery bank would weight right about 1000 pounds.
This.
http://grabcad.com/library/wheel-support-life-trac
This design should have won. This is how the "universal rotor" should work. The current design makes zero sense, particularly now that exotic couplers are being added to it. http://www.youtube.com/watch?v=QZ8D7AHczlQ The quick connect assembly now as at least two, maybe three, couplers between the motor and the wheel. It's going to be harder to machine sprockets and double chain then to durn an axle on a lathe. All this does is make the component even larger and even harder to mount. It needs to get smaller, not bigger.
That assembly Flaviano modeled is exactly how all existing construction equipment connects the wheels and motors (when it isn't a single solid axle). It is the best possible compromise between all the different requirements.
"You said, however, in an earlier comment that the current LIfetrac design is a dead end."
> I meant the way the frame is built. Bolting together tubes is great for prototyping; not so great as a permanent design choice. No one ever needed to demonstrate a tractor frame. It was the performance of simple/cheap motors, bearings and the power cube that needed to be demonstrated. As the design is refined it will most likely go through at least one major redesign of the basic structure, abandoning the bolted-together-tubes approach.
> I agree that the "tractor" is really a Bobcat. Most likely a design iteration will include increased modularity so it can be changed from a Bobcat type layout to a tractor type layout. Skid steering was merely an easy first approach.
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