In my last post I described many changes and goals I was seeking to achieve with a redesign of the X-Carriage for the Gemini 3D printer.
Admittedly this process has taken much longer than I ever anticipated, which has been disappointing.
After the first working prototype of the Gemini that I created in early 2015, I figured it would take me at most a couple of months to get everything optimized and a new revision of the 3D printer running and printing.
Little did I know how much I had really tasked myself with and the learning curve that I would have to experience. Redesigning the corexy mechanism and the frame took relatively little time, I figured I was well on my way to a more refined machine.
Using SketchUp for the design turned out to be a major time suck for the project. I had to go through a great number of concepts and revisions to get all the electronics to fit into the smaller space I had allowed for when I redesigned the corexy mechanism and frame layout.
Making dimensional and part-placement changes with SketchUp entails a ridiculous investment in time, manually editing vertexes and shapes to compensate for SketchUp’s primitive modeller. It’s not that you cannot make complex models in the program so much as the amount of extra work that is required to make those objects exportable as manifold STL files. At some level of complexity it becomes nearly impossible, and I found that I could make objects mostly manifold and then run them through Netfabb to fix the remaining glitches. Thankfully I’ve been doing most of my slicing with Cura and it’s fairly good at fixing most minor STL file glitches. Slic3r, despite it’s major improvements over the years, is still generally inadequate at compensating for the most minor of manifold issues within STL files and more often than not crashes entirely when loading models exported from SketchUp.
Over the summer I got busy with other projects and also suffered from some health issues which prevented me from making any major progress on this particular design. Too be honest, I also got fed up with SketchUp and the overwhelmed with the challenges of coming up with a working model for the X-Carriage in it.
I took many months off to learn OpenSCAD and make some items with my 3D printers which were not other 3D printers.
By October 2015 I thought I was ready to start back at it – and I started where I left off in early Summer and recreated some of the core portions that did work in OpenSCAD. Once I got the basics going, I then took another break. I was actually fairly stuck and temporarily out of ideas. Work and health issues took precedence, my employing company was acquired and there has been a transition period ongoing and I was in nearly constant pain from RSI. I won’t focus too much on the RSI, but suffice to say I invested my time and money into changing many aspects of my ergonomics and lifestyle to heal from years of damaging behaviour and I am happy to say that I’m am mostly pain free and able to once again focus some time on this project.
As the fall season transition into Winter, I had managed to build a modular parametric code framework for the X-Carriage in OpenSCAD. I took advantage of a couple of free days during the Christmas holiday season to pound out some rough test pieces and print them to get a feel for how it might all work together and how to best compensate for the absolute math of OpenSCAD dimensions and the reality of extruded plastic. I got side tracked by some fanciful designs before I managed to reign myself back to reality and come up with the modular compact carriage concept I’ve detailed in the past few posts.
I am happy to say that today marks a milestone where I have all the electronics mounted within a printed assembly and mounted to the robot. I see many points of the models that I would like to improve on aesthetically and some minor modifications for part fit and placement, but it’s together well enough to start wiring things up to the Smoothieboard and start some movement and heating tests later today.
Based on the current design I can now finalize the placement for the build platform, relative to the nozzles, and create the final missing part or two for the filament pushers. After the trials of the past year, I loath to put a date on when I expect the Gemini revision 3 to be actually printing objects – but I think it might be safe to say “soon”.
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