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Milled blocks designed in Sketchup

3D Printing & Imaging
Milled blocks designed in Sketchup

Recently, I had a class of 7th graders designing in Sketchup. One of the projects is to accurately design a block of 2″ x 2″ x 1.25″. These designs were then converted to G code with Millwizard by an 11th grader who then milled them in the high school across the street on a Taig Micromill. This was a fun project that helped illustrate the concepts and processes of separating the design from the manufacture of objects.

The way it worked out was that the middle schoolers would make some designs, and share them with the high schooler. If the files were designed correctly, proper size, no overhangs, then they would be converted to code and milled. He was able to process 4 files in one class period by cutting in 2 inch insulating foam. Then, the next time I met with the 7th graders, I gave them the blocks they designed.

Parts from this project could be fabbed on a variety of tools including Shopbot, Makerbot and mill. So you don’t have access to any CNC tools in your program? The designing part of the project could work fine if paired with a manufacturing system like Big Blue Saw, Shapeways, 100kGarages, Thingiverse, and Ponoko.

This is a new project that worked well in several ways: Students got to do design work on the computer. The designs had authentic criteria, when the designs were done, another student had the responsibility to manufacture them, the manufacturing process had some deadlines, and the parts were delivered to the original designing students. All involved got a taste of various parts of the distance manufacturing services. Everybody seemed to have a good time, kids got to learn about design and manufacturing and have a custom part of their design delivered to them.

The block you see above, and these others, is unfinished. Next steps for the part would include finishing. The foam can be sanded with a fine grit paper, then painted with a mixture of white glue and water, and after drying can be sanded again and painted with a variety of paints.

How are you using the manufacturing and design process with your students? How do students get their designs out of the computer? Not every school has access to a mill or other fabrication tools, so what are some ways that students can get their hands on the parts they’ve designed?

12 thoughts on “Milled blocks designed in Sketchup

  1. kirkologist says:

    Could you please talk a little more about how you set up the lesson for the 7th graders?

    1. Chris Connors says:

      Initially, I pointed them to the software, which has been installed on their computers all semester. I gave them a few periods to experiment with it in a loosely structured way. They found the Warehouse and figured out how to download other people’s models. They bumped into scale problems where, for instance a doghouse was about the right size, but the dog downloaded was taller than the house.

      I showed them how to do simple things like make shapes and then use the Push Pull tool to extrude them up and out, using the Move tool to pull a center line of a cube up to make a pitched roof.

      The milled block project came in after they had started on a house. In that assignment, also pretty loose, they were to make a shape that looked like a house. I let them choose how their house would look.

      Pitching the lesson included working with the high school student to develop a design envelope for the parts. We settled on a few criteria, including 2″ x 2″ x 1.25″ and no overhangs in the shape. He designed up some sample blocks and milled them. We now have the manufacturing part down to 4 of these blocks being milled in one class period of about an hour.

      In preparing the files for the mill, they needed to know how to make shapes to an accurate size. The process I used was very similar to, which was written after the fact.

      Once the parts started coming back to the 7th graders, we got to see which designs looked better than others, and did some improving on the designs. The designing and milling phase will run for about two weeks.

      At some point, I will bring in a Makerbot to fab up the parts right there in the lab. That should be fun.

  2. cranky_EE says:

    Actually if you did a little more work developing a lesson plan, this could be a dandy lesson in vocabulary.

    Covering things like, you know, the difference between criteria, requirements, specifications, etc.

  3. Stunmonkey says:

    You should be able to get that material, in that size range, to easily machine on a Taig much faster (10x) than that and with much better surface finish.

    I really love the idea of the project and what you are teaching. I have taught tech subjects to similar age groups and one glaring lesson is that if the subject equipment or process appears too arcane and complex, or the results too abstract, it is actually a sharp turn-off for the kids not an invitation to learn more.
    Please look into the machining issues, you should be able to turn out a gang run of the whole classrooms models in one class period easily, and with smooth sharp detail. I have machined coin dies and surface mount pc boards on Taigs, they are capable of amazing detail and finish and can run well past 1000 mm/min in soft materials.

    BTW, a Makerbot would take quite some additional time. A Makerbot, while very cool to demonstrate for different reasons, is not the unit for producing student work. It very likely couldn’t put one unit together in a class period much 20 or 30-odd students worth of units.
    I’d say stick to the subtractive machining for the purposes of your production demonstrations.

    1. Chris Connors says:

      Yours are some great directions to lead the project in future iterations. I expect to do it again with two different groups of students in the coming semester. One group will be a fresh batch of middle schoolers, and the other will be high schoolers in an introductory computer use class. The high schoolers will be in the same room as the mill.

      What are your settings for motor tunings on your Taig? It sounds like we should revisit that aspect of setup to make cleaner products.

      Agreed that the Makerbot will likely be too slow to make large projects quickly, but having the ability to do additive fabrication of custom designed parts on the desktop will be an excellent draw for motivating students.

      As stated above, this is a new project, very much in development. If you have links and resources that could improve it, pass them along!

      1. Stunmonkey says:

        Sure thing Chris. I can even email you optimized setup files, I keep generic ones for the most common type of machines I get called to do work on. A lot depends on the motors, their coil wiring system, and your driver. I can tune anything, but I need to know the system parameters first.
        If there is a way to contact you let me know. I may even have some better motion control pieces to donate if yours are not up to snuff – I have lots of perfectly good industrial grade stuff as used pulls, as they aren’t approved for re-use in critical environments and so usually just get tossed.

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