<h1>Applications and Implications</h1> <h4>Wednesday 23 May, 2018</h4> ###>>>>> Fast Forward >>>>> ####(If you've just joined us) So for the first half of Fab Academy I was planning on building a power generation unit (Mini Power Plant), but since coming to Vestmannaeyjar and realising how un-challenging it would be to make a turbine spin around (one of the windiest places in the world) I decided to act upon a real problem my Instructor, Wendy, and I had while back in the Dubai SuperFabLab. The problem was that we needed to <a href="assignment08.html">re-bed the ShopBot</a> and to do so we needed a large diameter drill bit and a way to make square holes for the dome-headed bolts we were using. I was inspired by some specialised drill bits I'd used on the racecars in the past, and instantly started researching into a method for drilling using an eccentric spindle. <img src="media/week18/6pc-Titanium-Coated-Woodworking-Saw-Drill-Bit-Carpenter-Wood-Plastic-Metal-Hole-Grooving-Saw-Drill-Bit.jpg_640x640.jpg" alt="Side-ways drilling bits Bunnings (slot drilling, titanium)" style="width:25%"/> <legend>"Sideways drilling bits I was inspired by, I've used them many times and always impressed. Perfect hole drills but they also happen to be tougher and can drill a slot in a pinch. Source: <a href="https://www.aliexpress.com/item/6pc-Titanium-Coated-Woodworking-Saw-Drill-Bit-Carpenter-Wood-Plastic-Metal-Hole-Grooving-Saw-Drill-Bit/2048910125.html">AliExpress</a></legend> I'm always looking for ways that my work can be relevant in space, and so I checked out some of the power tools used on the ISS. Here's a cap I took from one of the recent EVA live-streams featuring the very tool I've been influenced by: <img src="media/week18/iss-eva-space-tool.jpg" alt="Torque tool from the ISS EVA live-stream" style="width:50%"/> <legend>"Space has some demanding requirements, one of those is building rugged multi-purpose equipment to save weight and reduce overheads for completing mundane activities."</legend> I had a weekend spree on Fusion and begun designing some bulk-drawings for what my device is going to look like: <div> <img src="media/week18/rocket-surgeon-1.jpg" alt="Some drafts of the rocket surgeon" style="width:50%; float:left"/> <img src="media/week18/rocket-surgeon-2.jpg" alt="Rocket surgery, polar hand-held CNC machine" style="width:50%; float:left"/> </div> <img src="media/week18/rocket-surgeon-early.jpg" alt="Early designs of the head assembly." style="width:50%"/> <legend>"Early designs of the head assembly and power-drill style enclosure." </legend> I tried a few configurations of where exactly the stepper motors should go, and I settled that they should be as far back in the handle as practical because of their weight. I have also had a go at two slip-ring designs to get electrical connectovity to the rotating head assembly and neither look promising at this point. I'm still looking into it. I'm calling it "<strong>The Rocket Surgeon</strong>". This comes from the <a href="https://blog.oxforddictionaries.com/2017/05/24/malaphors/">malaphor portmanteau</a> of the sayings "It's not rocket science" and "It's not brain surgery". As it happens "Brain Science" is already a thing, and in any case I do hope one day to do something in my life that could be considered "Rocket Surgery" 🚀 <img src="media/week18/dummy-fit.jpg" alt="Early designs of the head assembly." style="width:50%"/> <legend>"Dummy fit using the laser cutter to give me an idea of packaging and grip comfort." </legend> --- ###This week's assignment The assignment for this week is to spec the final project and answer a couple questions regarding how I approach the design. This ones a pretty cool one, because I've done a lot of startup stuff (lean canvas, hackathons, etc.) before and being able to justify your invention/product is one of the most exciting challenges of building things! <legend>"Assignment: Propose a final project that integrates the range of units covered..."</legend> And answer a bunch of questions like: + **What will it do?** *The Rocket Surgeon is a hand-held CNC machine configured in polar co-ordinates. The polar co-ordinate format could be considered like a power-drill on the end of a power-drill.* + **Who's done what beforehand?** *The nearest examples I could find related to portable small-format CNC machines were the <a href="https://handibot.com/">Handibot</a> and the <a href="http://www.pocketnc.com/">Pocket NC</a>. It will also have some semblance to the DNA of a <a href="https://www.milwaukeetool.com/Products/Power-Tools/Drilling/Magnetic-Drills">Mag Drill</a>.* + **What will you design?** *I'll design the platform for the machine - the electrical and mechanical layout. At the end of Fab Academy I will have a manually controlled eccentric power drill, which will form the basis of a CNC-controlled machine.* + **What would you do if someone asked for 10,000 of them?** *I'd build a startup around it, offer some friends jobs and get on with it.* + **What materials and components will be required?** + **Where will they come from?** + **How much will it cost?** + **What parts and systems will be made?** + **What processes will be used?** |Parts |Source or Self made? |Cost(AUD)|Process(es) |Additional: | |--- |--- |--- |--- |--- | |Spindle |Huaqiangbei Markets |$16 | | | |ESC |Huaqiangbei Markets |$18 | |Mystery brand | |Milling bit |Carbide Depot |$3 | | | |Stepper Motors |Jameco |$19 | |Qty:3 | |Stepper Driver |Carl-brand |$3 |Circuit-milling |A4953 drivers | |Lead-screws |Found it |$3 | | | |Rail-tube |Found it |$7 | | | |Enclosure |Carl-brand |$40 |3D-printed | | |Control boards |Carl-brand |$4 |Circuit-milling |ATmega328P | |Batteries |? |$20 | | | |Power-converter |Carl-brand |$7 |Circuit-milling |Capacitors,inductor,mosfet | |Limit switches |Carl-brand |$4 |Circuit-milling | | |Shaft couplers |Carl-brand |$0 |Printed or machined| | |Primary head bearing|Carl-brand |$0 |Printed or machined| | |Gearbox |Kevin, open-source |$0 |Printed or machined| | | | | | | | + **What tasks need to be completed?** *The majority of the circuits required have been built, now it's time to design the mechanical assembly and do some test fits. I've tried a few of the linear axes already and now to build the big bearing for the theta-axis and mount it all in it's enclosure. I'll try to summarise what needs doin in the schedule below.* + **What questions need to be answered?** *See infrequently asked questions below.* + **What is the schedule?** *Eeep. I got a few weeks to put it together.*<br> *I'm not a believer in Gantt charts, I've never seen any respectable projects stick to their Gantt chart. Some WWII general once said "No battle plan ever survives contact with the enemy." That's not to say there shouldn't be a plan, I just don't think highly of the Gantt approach.* |Task |Time |Done? |Outcome | |--- |--- |--- |--- | |Assemble electrical |2 Days |Done |Assembly took forever, had to compromise with two-layer board (See <a href="assignment12.html">Output Wk</a>) | |Test electrical |1 Day |Done |Most features working, some features need re-design (See <a href="assignment12.html">Output Wk</a>) | |Administer changes elec. | | | | |Design mechanical | | | | |Print mechanical | | | | |Assemble mechanical | | | | |Test mechanical | | | | |Final adjustments | | | | + **How will it be evaluated?** *I'll be happy if I can mill a circle into wood for now :) *<br>*In all seriousness though, the thing to be said about design is that it will never quite look as good as it did in your head. This reality comes about because of the real world pressures of timeframes, cost and the limitless design pathways. Let's face it, this is just another assignment after all.*<br> *So with that in mind, success to me will be measured by: sufficient technical complexity, assembly stiffness, feel (completeness), ease of use and wow-factor.* ####Infrequently asked questions: + **So uhh.. What is it you're building again?** *Basically a power drill that can machine holes up to 50mm diameter into soft materials, and then potentially machine rectangular holes up to 50mm diagonal.* + **Will it have comparable machining tolerance to a CNC Machine?** *No* + **Do I care?** *Also no* + **Are you planning to change the world with it?** *I would never try to change the world overnight, but I do hope to build tools that give people more options. For me the main thing to aim for is building things that enable the next generations of innovation. I think this has a good chance at contributing to that.* + **Can you MAKE ALMOST ANYTHING with it?** *Actually you probably could. I have aspirations to use it as a machine that can make small parts, in particular round parts like shaft couplers which have been an ongoing limitation of machines within the Fab Lab suite.* + **What about Kickstarter?** *Actually I don't think much of Kickstarter. Many projects promise a lot and don't scale well. Not to say it doesn't work, but it's notably hit and miss. I'm much more familiar with traditional startup practice and there's rarely a good reason that crowd money is better than equity (unless it's significant crowd money), and there are a lot of different attachments to consider in both cases.*<br>*At this stage I'm open to anything, but from the outset I'll admit that I'd be pretty weary of a kickstarter push if I wasn't able to raise money through traditional avenues.* ####Rough Component Plan <img src="media/week18/architecture-output-ctrl.png" style="width:50%; float:left; padding: 5px 5px 5px 5px" alt=""/> <img src="media/week18/architecture-power-stage.png" style="width:50%; float:left; padding: 5px 5px 5px 5px" alt=""/> <img src="media/week18/architecture-input-ctrl.png" style="width:50%; float:left; padding: 5px 5px 5px 5px" alt=""/> <legend>"Some initial architecture concepts that would be required for the power stage, output-ctrl stage and input-ctrl. For time management there's a lot that won't be included on this diagram, but keeping them here for future work."</legend> Focus on the things that matter.