Based on the DIN 2221 standard, among others, OHO has established a series of stages in which the satisfactory completion of this project was carried out
1. Feasibility study
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Materials, components
Required materials & components can be sourced or replaced locally?
✓ Yes
All the materials can be located with some ease, in hardware stores, parts stores and/or junkyards
Previous theoretical case, showing the exploded view
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Manufacturing processes
Required manufacturing processes can be povided locally?
✓ Yes
In a small workshop, all the processes required for manufacturing can be achieved
Example showing the processes involved
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Specific training
Is specific training for manufacturing necessary and can be provided?
✓ Yes
Especially when it comes to heat treatment for the blades
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Sustainability
Do all materials and processes meet the sustainability criteria?
✓ Yes
It is observed that both the materials used and the manufacturing processes are sustainable from an economic, social and environmental point of view
2. Market analisis and requirements
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Market analysis
Analysis of the current products on the market:
* Price [USD]: 237
* Source: ebay
* Country: USA
* Price [USD]: 243
* Source: ebay
* Country: USA
* Price [USD]: 100
* Source: mercadolibre
* Country: Venezuela
* Price [USD]: 363
* Source: mercadolibre
* Country: Venezuela
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Requirements definition
Definition of the main technical data (size, capacity, power...):
- Maximum sheet thickness [mm]: 3
- Maximum round bar diameter [mm]: 13
- Maximum plate or angle thickness [mm]: 5
- Cutting length [mm]: 150-180
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Optimal functions and features:
Definition of necessary/optional functions and features
- High hardness steel blade: Shear is required to have hardened steel blades
- To screw on a metal bench: It is preferred that the machine includes its own support structure
3. Search & analisis DIY technologies
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OHO Search engine
Customization of the OHO search engine
A search for similar or related equipment was carried out in our repository, obtaining some equipment that can be used as a reference
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Manual search
Searches were also performed within Google, Youtube, special websites etc., getting, among others, the following results:
* Title: Homemade shears for sheet cutting
* Views: 280000
* Likes: 4900
* Comments: 285
* Maximum sheet thickness [mm]: 3
* Maximum thickness of plate [mm]: 3
* Cutting length [mm]: 205
* High hardness steel blade: Yes
* To screw on a metal bench: Yes
This example will be used as the main reference machine
* Title: Leaf Spring HACK - Metal Cutter
* Views: 486000
* Likes: 5800
* Comments: 162
* Maximum sheet thickness [mm]: 2.5
* Maximum thickness of plate [mm]: 2.5
* Cutting length [mm]: 200
* High hardness steel blade: Yes
* To screw on a metal bench: Yes
* Title: Homemade metal shear
* Views: 331000
* Likes: 3200
* Comments: 123
* Maximum sheet thickness [mm]: 3
* Maximum thickness of plate [mm]: 3
* Cutting length [mm]: 130
* High hardness steel blade: Yes
* To screw on a metal bench: Yes
* Title: Manual Sheet Shear
* Views: 236000
* Likes: 4600
* Comments: 215
* Maximum sheet thickness [mm]: 3.6
* Cutting length [mm]: 200
* High hardness steel blade: Yes
* To screw on a metal bench: Yes
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Networking
This section refers to contacting partners, associated organizations and experts
Since the cases found on the internet provide enough information, it was not necessary to search for reference equipment in this way, it can be useful when working with unusual equipments
4. Development & documentation
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Analisis of functions & structures
From analyzing the operation and parts of the main reference machine and the rest of the examples obtained, a first list of components for the shear is generated
During this process, some measurements of the parts and assemblies, essential for the design, are extracted
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Technical solutions
The OHO development team also proceeds to design and determine the engineering problems that arise, in order to obtain a quality product that can be manufactured with Appropriate Technologies
One of the solutions generated by the technical team was the inclusion of some bushings in the joints, this to ensure that these joints do not get stuck and enough tightening to support the loads
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Technical documentation
There is an internal and self-managed Gitlab repository, where the preparation of plans, exploded views, the final parts list, details and annotations, among others, are controlled at a formal and technical level
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Peer-Reviews
Before continuing with manufacturing, a group of experts was convened to verify the plans and generate observations, in order to optimize the design and prevent errors during later stages
5. Manufacturing, tests and improvements
- Workshop
Determination of the workshop for manufacturing: Among the most important aspects to be fulfilled by the manufacturing workshop, we have:
- It does not require industrial or specialized processes such as plastic processing, CNC machining, complex chemical processes, among others
- It has basic tools for working with metal and wood at a non-industrial level
- It has measuring instruments appropriate to the processes, such as: vernier, tape measure, thread counter, gauges, etc.
- Includes painting equipment such as compressor and spray gun
- It is a space large enough and ordered for manufacturing, assembly and painting operations
- It has qualified personnel in basic and intermediate works with metal, wood, painting, among others
- Some parts or processes that are not available may be purchased or ordered from more specialized stores and workshops
- Purchase
Purchase of materials and components: From the list of parts, the amounts of materials to be required from local suppliers were totaled
- Structural profiles
- Fasteners
- Special profiles
- Metal plates
- Consumables
- Manufacturing of prototype
Fabrication according to specified quality standards: The manufacturing process is oriented according to the order of the assemblies in the parts list and their assembly logic, this is shown in the various stages of the manufacturing video:
- Tests and improvement
Module tests, system tests, improvement of components: Some tests were carried out on the equipment, to verify the correct adjustment of the parts and the efficiency in its operation.
- Lateral slack: Apply moderate force on the lever, from left to right and vice versa, alternately. The plates do not tilt
- Example of real use: Making cuts of the samples of plate and sheet
- Visual detail of the cut: Straight shape of the cut, Straight edge, no burrs
- Updates of technical documentation
Updates of plans, parts lists, assembly instructions:
- The main plates (2.1 to 2.3) were manufactured in a thickness of 12mm, which is sufficient, instead of the 16mm initially proposed
- Modification in the length of the bushings, according to the new plate thicknesses
- Pieces 2.5 and 2.6, manufactured in 1/2" square bar, available in the workshop
- Mobile blade (piece 2.7), with dimensions adjusted according to the leaf spring piece achieved, recovered material
- Plans are expected to be updated with these changes, in order to have accurate information regarding the equipment manufactured
6. Certification DIN Spec 3105
- Formal audit
Verification of the completeness of the documents:
- Parts list
- Drawings of all parts and assemblies
- Assembly instructions
- Optional documents, technical notes
- In the image, it can be seen that this verification is complete, except for the previous corrections, which refer to the final update of the blueprints
- Assignment of reviewers
Search and assignment of peer-reviewers with sufficient expertise:
- Peer-reviews
Realization of the peer reviews, technical clarification, improvements: In process
- Certificate
Issue of the certificate: In process
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