Wed 21 Nov 2012
Smart Mob – Open Source Backhoe Design Review
Posted by Aaron
Review the Design for the Open Source Backhoe
Collaboration is the very core of our work. Join us in reviewing the new design for the open source backhoe by clicking the link below. People from all over the world are free to comment and make suggestions before we build the next prototype. If the design is a success, we’ll be ready to document it and release it openly for use all across the planet. Your comments now can help make that happen.
(click on the image to go to join the Smart Mob)
Participate in the Smart Mob
The design review period is open for the next week or so. At any time, feel free to click on the image above or follow this link to join the online collaboration environment:
You can download the CAD files here to view them locally:
OSE – Backhoe – Design Review.zip
The files require the VariCAD viewer – download it here:
VariCAD Viewer (Windows, Mac, Linux)
Global Village Construction Set Design Specifications
Our design needs to balance a number of different elements that include:
- Ease of fabrication
- Modularity
- Affordability
- Lifetime Design
- Performance
Marcin is preparing a detailed paper covering the specifications in detail, and you can read our current vision of our design parameters here.
Current Design Process
This design was modeled by Lenny-Wayne Patterson, a remote machine designer that we have been working closely with for a few months now. Lenny-Wayne has a background as a mechanic, machine designer, and fabricator, and he has been an excellent contributor to the development of the Global Village Construction Set.
We began the design process of the backhoe earlier this year through a GrabCAD challenge. This was the winner that was selected from 19 entries:
(click image to view all of the design images and download the files)
Lenny-Wayne stepped up to prepare this design for fabrication and so that it would fit the general requirements for the Global Village Construction Set. He modeled the boom after the GrabCAD contest entry:
This design path was abandoned, because it called for the use of welds and the boom shapes are irregular. We decided to move in another direction using bolts and rectangular pieces, because this makes the components easier to fabricate and possibly easy to interchange in a lego-like fashion with other machines in the GVCS package. In theory, one machine can be disassembled and another can be built using a subset of the very same pieces.
Lenny-Wayne took the design in another direction and brought this to the table:
This iteration was a major step forward in terms of aligning with the Global Village Construction Set design specifications. Lenny-Wayne pushed the design further by squaring up the remaining irregular shapes and simplifying the boom. Here is the current model that we’re asking the community to review:
Computer Donations
We would like to ask the OSE community to donate any computers of mid-to-high-quality. Lenny-Wayne is using an older machine that can’t really keep up with the work, but he has a lot of experience and skill that will help us develop many machines in the future.
If anyone would like to donate laptops or desktops to Open Source Ecology, please email me at aaron at opensourceecology.org.
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November 21st, 2012 at 4:22 pm
The challenge with the one cylinder on the bottom of the boom is that it will drag in the dirt and the cylinder rod may be damaged. How about extending the boom length and fitting that cylinder on top of the boom?
November 30th, 2012 at 4:04 pm
I agree with Marcin, I would not have any of the cylinders in an area that will be dragged through earth. Also where is the power for the cylinders coming from. I just see the pistons and no activators, lines, hoses, or controllers besides the actual console of controls.
January 17th, 2013 at 12:47 am
Boom components are usually “triangular” in shape with the but end towards the operator and the pointed end pointing away from the operator. This balances out strength, weight and the operating stresses of the machine.
Although I commend OSE for its vision, many of the machines featured on this website are already in existence and have been designed by highly qualified experts. some of the OSE designs are wide of the mark of being both feasable and practical but I like the fact that this new approach can lead to some very interesting results.
This back hoe requires a tractor for its support which makes for an expensive set-up. There are stand alone back hoes on the market that use one pair of wheels and one pair of legs for support. The machine is towed with any small vehicle and once in location can be manouvred independently by using the back hoe arm to “lift and push” itself around.
Also the standard back hoe both here and in industry has a working arc of 160-180 degrees which is not ideal. the alternative in industry is the 360 degree machine which can turn a full circle and can dig and load a vehicle for soil transport.
You now have an opportunity to improve back hoe design and aim for 270 degree swing on the boom:-
Get rid of the square frame and side-shift mechanism and position the support legs further back with the boom pivot sitting above the legs. fix boom pivot to a support bracket that is at one corner of an equilateral triangle and you can achieve 270 degree working arc.
You can reduce cost by doing away with the hydraulically operated legs and use manual adjustment using a tube with a series of holes sliding through a slightly larger tube and secured with a pin( like an axle stand). If the support arms for the legs could be swung through about 90 degrees side to side the operator can position these in the optimum location for the type of work he or she is doing.
I would also counterbalance the boom with the operators seat, engine and hydraulic pump. The counter-balance could also incorporate a container that could be filled with local material-i.e. soil, bricks, water bottles etc which would mean a lighter machine for transport and a heavier machine for stability and better visibility and less neck strain for the operator.
Good luck
Sam Osborne
January 18th, 2013 at 12:57 pm
I assume either each cylinder would attach via quick attachment hoses to the hydrolic system of the LifeTrack or there would be a junction box of hydrolic quick connectors on the mounting block.