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• First cut !

  sebsplane • 12/11/2020 at 19:19 • 0 comments

  Back to Fusion360...

  With all due respect for open-source projects, i had a hard time using Freecad v0.18 to do what i wanted... But it helped me a lot to grip the basics notions of  CAD and CNCs. So back to fusion 360:
  

  This time, it was much easier to scale things up : 

  1. import svg (had to rescale it even if it was defined in mm ,weird)
  2. extrude the shape by clicking on them to match my plywood thickness
  3. create a job
  4. create a 2mm tool 
  5. select the edges i wanted to cut in the first pass : all the >2mm holes and create a 2d contour
  6. configure the number of passes ( 2 of 1.8mm each in my case )
  7. run a simulation to see everything running fine
  8.  added a drill pass to cut the 2mm cable holes
  9. repeat all the steps 3-7 to add the outside contour cut
  10. post process my gcode file and voila !

  Know your limits

  So let's fire GRBL candle and plug the cnc : after the origin setup , i send the gcode and start to see the magic :

  Unfortunately , things started to go wrong in the last step : the outlines cuts. For some reason , the bit started to go down wayyyy deeper than what i expected: 6mm instead of 1.8 ! After a second of hesitation, i see that the machine still want to cut at this depth, so be it ! I'm so close to having my first part, lets see... yes ! first part finished! it goes to the second one ...Oh no! the upper Y axis limit is hit ! ABORT ! 
  

  I was way too greedy on the size of my work area : they said 3018 so 30cm x 18cm workspace right? Not quite on my machine :)
  

  Lets do a rescue Gcode to save the remaining profiles :

  what? it also hit the X axis limit !?! what a noob !
  

  In the end i managed to get 2 profile out of my first cut, not that bad...

  At least it's enough to start testing some assembly schemes :

  Number one seems to be too twisty to be usable, number two is okay but with a 27mm spacing, i'd need 37 of them to complete my meter long arm! Maybe i'll go number three with 800mm-ish length /36mm spacing and 22 of them. We'll see...

• CADs, how do they work?

  sebsplane • 12/10/2020 at 19:47 • 0 comments

  From Blender ..

  As soon as this idea popped up in my head , i had to immediately materialize it somewhere. It happens that i've been occasionally using blender for more than 10 year now and i'm familiar with a lot of its shortcut to model objects::
  With this first model i totally forgot about the basic principle of the tentacle : it has to have a central shaft to be articulated! Plus the spines are upside down,  and the spine profile lacks in details, but at least it gave me an idea of how it could look...
  

  To freecad...

  
  So how do i translate this into a physical thing i can (automatically) manufacture?
  

  Looks like i need a CAD software! How about freecad? I followed the first tutorial https://wiki.freecadweb.org/Tutorials and it seemed very powerful at first :
  
  

  But thing were a bit complicated on the bezier side: so much things on the toolbar ! Do i need to constrain all the things ? how can i constrain handles? What are those green stuff displayed everywhere? seems to indicate the stiffness of the curve or something...

  To Inkscape...
  

  So i decided to work bezier curves with inkscape instead on which i'm much more familiar. After a quick svg import, i managed to generate a tool path for my snowflake and run a simulation , nice !

  so i think i can scale this process to get my 24-ish plywood pieces for the lamp! Lets try it ,model everything in inkscape :

  and then import it in freecad :

  Starting from here things get complicated, for some reason , when i try to convert these shapes to sketches, the axis are inverted ,  i cannot remember the process to make the holes , i need to get back to the tutorial... Same for the toolpath, i have trouble selecting the shapes i want to cut, i dont understand where my tools are saved ...
  

  So much for an intro to CAD !

• building the machine

  sebsplane • 12/07/2020 at 21:50 • 0 comments

  here is the 3018 pro kit upon reception:

  The assembly guide is okay, the parts are well packaged and the assembly fairly quick (3h for me). 
  As my first CNC it looks clean and sturdy, i don't expect to cut metal with it (yet!)

  the first cut was really satisfying , here is a christmas decoration after 8 min of cut, 200mm/min in 1.6mm plywood with a 1.5mm diamond bit. This first project was the opportunity to learn about the basics of cad and cam and was a good introduction to the work to come!
  

• Idea genesis

  sebsplane • 12/05/2020 at 19:47 • 0 comments

  Seaching on the web for diy lamp projects, i had a look at heliox's lamp which had the dimensions / functionalities i had in mind :

  
  
  I hesitated big time on what machine i wanted  to get into digital fabrication  :
  3d printers looks amazing but their slow pace and their use of plastic is a bit of a show stopper for me ( unless i managed to get a full precious plastic (https://preciousplastic.com/ ) filament production line , i don't want to create more plastic waste than i currently do). 
  Another obstacle is the price and maybe the learning curve ...
  

  So i set up my mind on buying a 3018 CNC which seems to have a good community around it .
  

  I did my first intership in a rail factory where they had this massive CNC for cutting the rail profiles and it left me a lasting impression .

  Plus i have a few  woodworking ancestors , so cnc cut plywood would be my choice !

  Now regarding the design, I found the following website fascinating and well documented on how to create amazing mechanical tentacles :

  https://www.poormansguidetoanimatronics.com/blog-1/2018/5/12/the-wonderful-world-of-tentacles-part-1
  

  so let's get started!

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