<div style="width:40%; float:right"> <video width="100%" autoplay loop controls muted><source src="https://i.imgur.com/qEuKq2J.mp4" type="video/mp4"/>Your browser does not support the video tag.</video> <legend>"The B-axis spinning under angular jog command."</legend> </div> <h1>Wildcard Week - 4-Axis Subtractive (Mill Turning)</h1> <h4>Wednesday 16 May, 2018</h4> ###This week Was do whatever the heck you like week. Actually, it was a lot more specific than that, but in principle this week was an experiment to see what people would explore given the choice. Traditionally, this week's class was reserved for composite work, In past lives I'd already done quite a lot of work with composites working on the racing team. We experimented with many different methods and cores for carbon fibre and fibreglass, namely pre-impregnated sheets, wet-lay and vacuum infusion. Our team had made flexure springs out of carbon and carbon-kevlar weave and even experimented bonding carbon with 3D printed titanium inserts. That was a very expensive time. It's also quite a time consuming exercise, sanding and bogging large moulds for days at a time. Sometimes we would get bridging or delamination, and had to fix voids by syringing filler-resin mix into our painstakingly careful layup. We used to save up our beer cans to use as resin pots, and occasionally a can would start to get hot and we'd banish it to the outside area for cooling off. One time someone placed a block of metal in front of the hot-air element of our scratch-built autoclave conducting heat through a screw in the insulation well above auto-ignition temperature of the wooden enclosure. The box caught fire and the part hadn't quite reached the resin liquification temperature yet! Funny enough being the only firefighter on the team, when they saw the box smoking they ran inside to get me and "investigate"! Putting out that fire was actually one of my first jobs on the team, and possible the fastest ever way to make it out of the 'rookie-zone'. Those years were the most incredible and valuable experiences of my time at university, and I went on to manage two electric racing teams before finally graduating. Anyway, given that there wasn't much I needed to build that involved composites, and not much I was looking to explore without exhausting a small nation's GDP worth of carbon fibre I decided to check out some other options. I was quite excited about textiles, and there was even a <a href="http://archive.fabacademy.org/2018/labs/fablabspinderihallerne/students/peter-dahl/week17.html">student from Spinderihallerne</a> (in our regional review group) growing mycelium material this week. The problem with Fab Academy is that I always find myself continually behind with what I want to experiment with. That's a good problem of course, however this semester had just tipped to the pointy end and I needed to get my shit together pronto. I had just started my global evaluation, and upon the first round of feedback I conceded that this week would be largely a documentation week with something light-weight for the wildcard assignment task. <div style="width:100%; float:left"> <div style="width:33%; float:left"> <img src="media/week17/carbon-fibre-clipboard.jpg" style="width:100%; float:left; padding:5px 5px 5px 5px;"/> <legend>"The carbon fibre clipboard my mate Rowan made for me one night, when we were bored and we had a big box of carbon scraps. He used vacuum infusion and then I sanded it back with 1200 grit."</legend> </div> <div style="width:33%; float:left"> <img src="media/week17/carbon-fibre-monocoque-infusion.jpg" style="width:100%; float:left; padding:5px 5px 5px 5px;"/> <legend>"A vacuum infusion carbon fibre monocoque made for an endurance vehicle that we raced in Manila, Philippines. The entire vehicle ended up weighing around 48kg."</legend> </div> <div style="width:33%; float:left"> <img src="media/week17/carbon-fibre-racecar.jpg" style="width:100%; float:left; padding:5px 5px 5px 5px;"/> <legend>"I didn't actually do this carbon work but it was one of my favourite cars in the workshop. The whole car weighed about 220kg and featured in-house spun carbon tube wishbones and flexure suspension."</legend> </div> <div class="row"> </div> <div style="width:33%; float:left"> <img src="media/week17/carbon-fibre-glass-side-pods.jpg" style="width:100%; float:left; padding:5px 5px 5px 5px;"/> <legend>"A fibreglass and carbon fibre side pod I worked on in 2012."</legend> </div> <div style="width:33%; float:left"> <img src="media/week17/monocoque-mould.jpg" style="width:100%; float:left; padding:5px 5px 5px 5px;"/> <legend>"The mould for the vacuum infusion monocoque above. Looks a bit like rocket surgery 🚀"</legend> </div> <div style="width:33%; float:left"> <img src="media/week17/carbon-fibre-monocoque.jpg" style="width:100%; float:left; padding:5px 5px 5px 5px;"/> <legend>"The 2008 (same as above) car on stands."</legend> </div> </div> My method of choice was 4-axis machining, since I would likely need it later and Frosti (the instructor in FabLab Vestmannaeyjar) had bought an indexer (4th axis) for the shopbot and had been meaning to assemble it for some time. I figured it would be an excellent way for me to get comfortable with the Shopbot, since I'd really stayed away from it this whole course. ###I have to set up my own goals this week What would make this week successful? I'll be happy if I could turn something into a round shape. For bonus points I could wrap a profile pattern around a cylinder, but given the lack of bonus points floating around in the schedule nearing the end of Fab Academy I don't really think I'l make it. Before we start, we had to assemble and align the indexer. ###Setting up the indexer (B-Axis) ####Only one mill bit was harmed in the making of this write-up ######But it was pretty impressive Setting up the indexer was quite a task. Since the shopbot was already commissioned in it's position, I was hesitant to move it away from the wall to make space or un-mount the control boxes on the front of it. As it was, there was only enough space to get around the machine on the wall-side. So we decided that we would drop the indexer through the bed of the shopbot, and this saved us from having to use the rack/pinion/rail extensions. Frosti found a jig-saw lying around, so I cut the far end of the bed out but still maintaining enough length for a standard sheet (2440mm) The installation from there was reasonably straight forward, in order to minimise movement of the machine's legs when inserting the fasteners for the indexer brackets we simply unbolted only one row of bolts at a time. That way we could get the indexer brackets past the end legs of the machine without removing them. The control box was simple to understand - there was space for two more motor drivers and the headers for them just plugged straight into the motherboard. See below for an illustrated recount of my journey with the indexer. <div style="width:100%; float:right"> <img src="media/week17/shopbot-indexer.jpg" style="width:33%; float:left; padding:5px 5px 5px 5px;"/> <img src="media/week17/shopbot-control-box.jpg" style="width:33%; float:left; padding:5px 5px 5px 5px;"/> <img src="media/week17/shopbot-control-board.jpg" style="width:33%; float:left; padding:5px 5px 5px 5px;"/> <div class="row"> </div> <legend>"The shopbot indexer, installed through the bed of the shopbot and inside the X-most leg of the machine. The control box and harness, whilst messy, was pretty easy to get my head around."</legend> <img src="media/week17/x-zero-headstock.jpg" style="width:33%; float:left; padding:5px 5px 5px 5px;"/> <img src="media/week17/x-zero-tailstock.jpg" style="width:33%; float:left; padding:5px 5px 5px 5px;"/> <img src="media/week17/x-zero-headstock-coordinates.jpg" style="width:33%; float:left; padding:5px 5px 5px 5px;"/> <div class="row"> </div> <legend>"Aligning the indexer after installation. You just touch the bit to the sides of the headstock and tailstock, and check for deviations. You do this for both the X- and Z-directions, and shim the brackets to get them aligned if necessary. We didn't end up needing any."</legend> <img src="media/week17/z-zero-headstock.jpg" style="width:20%; float:left; padding:5px 5px 5px 5px;"/> <img src="media/week17/z-zero-tailstock.jpg" style="width:20%; float:left; padding:5px 5px 5px 5px;"/> <img src="media/week17/z-zero-tailstock-coordinates.jpg" style="width:20%; float:left; padding:5px 5px 5px 5px;"/> <img src="media/week17/inches-to-mm-tolerance.jpg" style="width:20%; float:left; padding:5px 5px 5px 5px;"/> <img src="media/week17/inches-to-mm.jpg" style="width:20%; float:left; padding:5px 5px 5px 5px;"/> <legend>"As you may be able to tell, I came down a little fast on the tailstock (sorry Frosti!) and smashed up a single flute cutter. The alignment was within an accepatble margin, after doing the conversion from the values stated in the instructions that were sent with the indexer.<br>Have I ever mentioned how absolutely retarded the imperial measurement system is?"</legend> <div class="row"> </div> <img src="media/week17/shopbot-5-axis-yay.jpg" style="width:33%; padding:5px 5px 5px 5px;"/> <legend>"Hooray! The indexer was installed and after changing some settings (it's all outlined in the instructions they sent us) the B axis was enabled!"</legend> </div> ##How to Turn Something Into a Round Shape ###(and make already round things smaller) ####a picture-book of that time I did that So welcome, to this special edition of ***"How to make (almost) anything, round!"*** Today we're gonna turn a rectangular section that I found in the dumpster into a round section with flats. A classmate <a href="http://archive.fabacademy.org/2018/labs/falabvestmannaeyjar/students/birita-idali/">Birita</a> helped me to set up and we both did our "mild-card" week assignments on the indexer. Well, my assignment was pretty mild, but her part turned out really cool looking. (get it? 'turned' out 🤣) Thanks to a call with Wendy, I found some <a href="http://www.shopbottools.com/ShopBotDocs/files/WrappingRotaryIndexer.pdf ">Shopbot Documentation</a> for wrapping machining jobs with the rotary indexer. It was a great start to getting comfy with the new system, and especially nice to refer to since I'm still building up my Shopbot confidence and self esteem in general. Before you start, they (the Shopbot man) tells you to add the post-processor. Unfortunately the ones that shipped with this version of Shopbot were in barbarian units, so <a href="http://www.shopbottools.com/mSupport/drivers.html">here's the link</a> to where you can get official post-processing files coherent with sophisticated measurement standards. (Last updated in 2016) It took Birita and I a while to figure it out but you can zero the Z-direction to the centre (of the B-axis) if you know the height of your part. You simply touch the top of the part, then rotate B-axis 90-deg and touch the part again. Divide the difference between these values by two and you get your centreline, assuming your part is round. If you have a non-symmetric workpiece or if you're not sure you got it straight you can just zero to the headstock height. Either or. For zeroing the X-direction, you can just touch the left and right of either the headstock or the workpiece (if the workpiece is symmetrical). Once again just divide this by two and you get the centreline of the B-axis in the X-direction. For the Y-direction you just start anywhere along your length, making sure you won't hit the headstock or tailstock of the indexer. A very important thing to note is that the B-axis spins around before starting a cut, so make sure to **lift the tool well above the part** before starting! (We didn't do this btw, but we noticed it could be a problem) See below for 8-part pictographic of this adventure. <div class="row"></div> <div style="width:100%; float:left"> <div style="width:50%; float:left"> <img src="media/week17/rounding-test.jpg" style="width:50%; float:left; padding:5px 5px 5px 5px;"/> <img src="media/week17/wrapped-job-setup.jpg" style="width:50%; float:left; padding:5px 5px 5px 5px;"/> <legend>"The V-carve gadget allows a couple good options. The instructions do a great job at explaining each of these options (for once) so it only took an hour to get my head around what was going on. Pictured is setting up the job."</legend> </div> <div style="width:50%; float:left"> <img src="media/week17/indexer-gadgets-vcarve.jpg" style="width:50%; float:left; padding:5px 5px 5px 5px;"/> <img src="media/week17/create-rounded-toolpath.jpg" style="width:50%; float:left; padding:5px 5px 5px 5px;"/> <legend>"The rounding methods depend on the type of workpiece you're using. Rastering is best for rectangular sections, since the corners of the stock will come off evenly. Optimised works for this as well, so long as your rectangular section is aligned to 0 degrees. Pictured is configuring a toolpath."</legend> </div> <div class="row"></div> <div style="width:50%; float:left"> <img src="media/week17/wrapped-toolpath.jpg" style="width:50%; float:left; padding:5px 5px 5px 5px;"/> <img src="media/week17/post-processing.jpg" style="width:50%; float:left; padding:5px 5px 5px 5px;"/> <legend>"After you calculate the toolpath it is displayed unwrapped. You then go on to post-process the job (the indexer *.pp file in millimetres is available at the <a href="http://www.shopbottools.com/mSupport/drivers.html">Shopbot website</a>)."</legend> </div> <div style="width:25%; float:left"> <img src="media/week17/finished-rounding.jpg" style="width:100%; float:left; padding:5px 5px 5px 5px;"/> <legend>"My part didn't come out so amazing, but I wasn't too stressed. The part being so long and machining it thin with a broken bit meant that it bent a lot while machining. I measured a run-out of around 1mm, which could have been a combination of factors such as centre-ing of the job within the indexer fixtures and B-axis zeroing."</legend> </div> <div style="width:25%; float:left"> <img src="media/week17/birita-wrapped-toolpath.jpg" style="width:100%; float:left; padding:5px 5px 5px 5px;"/> <legend>"Here's an example of the awesome types of things you can do with the indexer. This was made by fellow student <a href="http://archive.fabacademy.org/2018/labs/falabvestmannaeyjar/students/birita-idali/">Birita í Dali</a> shortly after we used mine as a test."</legend> </div> </div> <div class="row"></div> ##More complex toolpaths After our <a href="http://archive.fabacademy.org/2018/labs/falabvestmannaeyjar/mechanical_design/index.html">awesome machine week</a> where we got Frosti's original Mantis project and added a 4th axis to it, I set out to try the Fusion CAM for 4-axis machining. The deities of project management frowned upon this and I didn't end up finishing, mainly because Fusion 360 doesn't actually output 4-axis CAM (as far as I can tell). <div style="width:100%; float:right"> <img src="media/week17/cnc-test-crayon-2.jpg" style="width:30%; float:left; padding:5px 5px 5px 5px;"/> <img src="media/week17/cnc-test-crayon.jpg" style="width:30%; float:left; padding:5px 5px 5px 5px;"/> <img src="media/week17/4-ax-mill.jpg" style="width:25%; float:right; padding:5px 5px 5px 5px;"/> <img src="media/week17/4-axis-g-code.jpg" style="width:25%; float:right; padding:5px 5px 5px 5px;"/> <img src="media/week17/fusion-cam-preview.jpg" style="width:25%; float:right; padding:5px 5px 5px 5px;"/> <img src="media/week17/fusion-cam.jpg" style="width:25%; float:right; padding:5px 5px 5px 5px;"/> <img src="media/week17/fusion-preview-settings.jpg" style="width:25%; float:right; padding:5px 5px 5px 5px;"/> <div class="row"></div> <legend>"I thought it would be a fun idea to do a practice run with a crayon. It's likely that this was a terrible idea. We will never know."</legend> </div> ## Design Files There's actually no real design files for this week. The job was the tutorial from the instructions from Shopbot, and it depends on what stock you're using anyway. I know, it sounds like I'm making that up, right? V-carve basically generates it very quickly, and most of the work went into zeroing the machine and measuring stuff out. The VERY basic files that I used are in <a href="design-files.html">Design Files</a> for this week, but it really can't be used for any other situation.