MIE243. Group Design Project September 2014

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Vincent Johns
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MIE243 Group Design Project September 2014 Note: We will be posting a frequently-asked-questions document at the end of Week Two.

Sample reports and CAD drawings will be posted around Week Six to Week Eight. GROUP SIZE IS STRICTLY FOUR TO SIX PEOPLE.

The goal is to create a complete design which could potentially be developed into a working prototype through a detailed design process.

1 MIE243 Group Design Project September 2014 Note: We will be posting a frequently-asked-questions document at the end of Week Two. Please attend the tutorial in Week Two to get a general overview of the project first before worrying too much about specific questions. We know there is a lot to take in here. Sample reports and CAD drawings will be posted around Week Six to Week Eight. GROUP SIZE IS STRICTLY FOUR TO SIX PEOPLE. PROJECT HOBBY CNC MILLING MACHINE The aim of this project is to develop an advanced conceptual design for a hobby-level CNC milling machine. The goal is to create a complete design which could potentially be developed into a working prototype through a detailed design process. Such hobby-level designs have recently become quite popular online, especially with the advent of other related tools, such as home 3-D printers and rapid-prototyping suites. If you have a relatively complete design, this could become a very interesting home project to build! Design Goals The goal of this project is for your group to produce a completed conceptual design for your own CNC milling machine. Note that in doing so, your design need not be unique just for the sake of uniqueness; rather, the goal is for you to follow and document a formal and rigorous design process. This process leads to a design which, hopefully, meets a set of engineering requirements that you must first write using the general problem description. If the design contains similar elements to existing designs, it may simply be the case that

2 such design elements are the best general-purpose solutions available. What is not acceptable is wholesale copying or minor modification of complete existing designs you must start your design process from scratch, and document the process as you complete the design. By its nature, this problem is open-ended and free to be interpreted by your group. You may decide to design a more high-performance, high-end machine, or a low-cost, simple-toproduce product. You may choose to cut multiple materials, or a single material. Any choices to this end are acceptable, so long as they are (i) justified in your report, and (ii) consistent across your complete design (i.e., do not target low-cost specifications and then build the entire machine out of needlessly expensive materials/components, for example). To receive the best grade, you do not necessarily need to create the most ambitious design. Designing something for the sake of being complex or complicated is not the focus a documented, detailed, and well though-out, yet simple design which meets the requirements you create will work just as well. We will explain more about our expectations and the details of the project primarily through the weekly tutorials. During these tutorials, your group will have one-on-one access to the TA, who can help you by following your progress from week to week. As suggested in the syllabus, try to make full use of these tutorials bring your work with you so the TA can guide you and answer questions. Additional Constraints and Hints The primary constraints in this project are as follows: (i) (ii) (iii) You must produce a hobby-level product; it should be a complete design that does not require access to exotic or expensive materials to build. It should fit within a home workshop or small workspace. The exact dimensions will be left to your group to decide, but be aware the effect these may have on the capabilities of your machine and the difficulty of its design. You are strongly recommended to research existing designs before starting your own. Likewise, the exact capabilities (materials worked, accuracy/resolution, cutting speed/feed rate allowed, etc.) of your machine are also open. You should comment on your choices, however, as there is an inherent trade-off of design effort vs. capability, and also cost/design complexity vs. capability. Report Style and Content The main goal of this project is to create a complete conceptual design that is ready to enter the detailed design phase. Note that the result of this project would be a good example to use to demonstrate your design and CAD skills to a potential employer, and is also good practice for MIE490/1 (Capstone) in fourth year. The group size for this project is four to six; we cannot accommodate smaller groups due to the number of reports this would generate, and more importantly, because of the workload for you. If you are having trouble finding a group, please contact the instructor and they can assist you. The general style of

3 the deliverable for this project will be that of a proposal or engineering report to a company about a product that you have designed. It should consist of the following sections: 1. Introduction and Research You should begin by examining the current state of the art in home and hobby-level CNC milling machines. Pay particular attention to the size, construction, and capabilities of the commercially available alternatives. Since you are required to make a complete design, you will also have to do additional research into some particular parts of the design. For example, you may want to investigate the different general types of machines (axis layout, tool attachment, etc.). While you do not have to be concerned about the electronics elements of the design, you should investigate the size and placement of important components such as motors, and the inherent limits on accuracy and range of motion/cutting area. You must also ensure that your mechanism can be driven by real-world motors (i.e., no part requires unreasonable torque or force). 2. Engineering Specifications After careful research, you should write a set of engineering specifications for your design. This would outline important conceptual choices, such as the overall size, operating principle, estimated cost, and capabilities that your design will attempt to achieve. These specifications should be related to your general design goals, as justified earlier. Remember, a more complex or more unique design is not necessarily going to get the best mark. Rather, the best specified, described, and targeted design will. 3. Candidate Designs Using your engineering specifications, you must produce engineering sketches or rough CAD drawings (your choice) of at least three potential designs that will meet your engineering goals. These sketches do not have to be detailed or complete, but should include some of the more critical dimensions (ex., the overall footprint of the machine and major components). Recall from class that the primary use of a candidate design is for comparative selection. Use your designs to select a final candidate that is most likely to succeed in meeting the specifications you have created. The above three components would typically comprise a project proposal in an engineering environment. For the sake of reducing your workload, we will have you simply include them in the final report, rather than having you submit a separate document. In capstone (fourth year), these will be spread across the PR (Project Requirements) and DR (Design Review) documents, taking roughly the first half of your fourth year. The remainder of this course s report must include the following: 4. Design Analysis and Description From your candidate designs, you should select one that you consider to be the best conceptual design. For this design, you should explain why you have chosen it, and describe in detail its operation and features. Particular attention should be given to explaining your choices of mechanisms, materials, and components (i.e., types of bearings, shafts, gears, etc.). For your description, you should make specific reference to drawings of your proposed design.

4 5. Drawings To accompany the description of your design, you must produce a set of professional assembly drawings from your 3-D CAD model which follow standard technical drawing conventions. Parts must be identified using numbers that are used in a parts list. You must include one complete assembly drawing of the entire design presented on a single page. You should also include additional drawings to detail complex assemblies and important sub-systems. You will submit these 2-D drawings along with your model files electronically with your report. Details of the hand-in process will be posted later in the term. Grading Criteria: OVERALL, YOUR ASSEMBLY DRAWINGS MUST ALLOW QUICK AND COMPLETE UNDERSTANDING OF THE DESIGN, THROUGH MINIMAL EFFORT AND IN THE LEAST POSSIBLE TIME. Since this is not a detailed design project, exact dimensioning, tolerances, fits, etc., of actual parts will not be possible. However, rough dimensions should still be included, as you should be able to realistically size most parts, even if exact numbers are not available. Design elements where fit or tolerance is critical should also be identified, even if exact numbers are not available. Note also that it is not necessary to produce the part/working drawing for each component (i.e., every bolt, screw, etc., does not need a separate drawing, as you are not determining the dimensions of these parts by calculation in most cases, and many are standardized, with drawings available from the manufacturer). However, your final design should be as detailed as possible you should consider the placement and sizing of parts such as mounting bolts, bearings, etc., in as logical and realistic a way as is possible. Standardized sizes for these parts should be used whenever applicable. If there is one part which is critical to your design (or for which you have placed significant design effort, such as a custom cam, gear, etc.), then it would be a good idea to include a separate drawing for this part. Finally, you are strongly encouraged to include isometric views in your report, so that you may better explain your design and its operation. The format for the report is open, but it should be professional and concise, yet complete. There is no minimum or maximum page limit. The only restriction is that all written pages should be 8.5 x 11 in. All pages and drawings should be neatly arranged and presented, and hand-in will be electronic (details posted later). Your report should make direct reference to your drawings, and must include a list of references to any external works used. Copying an existing design with minimal or no modification will not be tolerated; we have extensive knowledge of what is available online and elsewhere.

5 The grading scheme for the project is as follows: Research, Engineering Spec., and Candidate Designs 5% Detailed Design Explanation of Device Operation 2% Justification of Component Selection 6% Assembly Drawing 3% Supplementary Drawings 2% CAD Models 3% Design and Process Quality / Completeness 4% Total 25% Due Date: Dec 3 rd, 2014

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