When I lent my services to a collegue who was working on a film about 12 years ago, I was introduced to the world of cnc. I remember watching this huge machining centre milling out a slab of mdf and turning it into a fantastic set of gears. I knew that it would have taken me hours to achieve the same thing with traditional power tools. I decided then that I would invest in a cnc router for my own business Oxenham Design. At that time I could turn on a computer, but even to check email seemed like a crazy set of operations. I persevered and learned every piece of relevant software I could get my hands on. I am now fortunate enough to be using Vectric's ASPIRE software, and Techno cnc routers, which has helped us to create some amazing projects, both in part, or in full. I thought that this blog would be a great place to share "behind the scenes" adventures with the software, materials and equipment we use, as well as the projects we build.

Wednesday, 19 December 2012

3D Unwrapping (made easy!)

We finished the other 2 parts of the Molson Hockey Games, but the time was getting so tight, I was really unable to get any decent photo's for posting :( It can be quite a job to remember to stop and take them all the time!

I get alot of emails inquiring about "un-wrapping" 3d geometry for planar cutting on our Techno. In-fact, the last 2 jobs featured the use of this for a couple of pieces, the Monopoly hat, and the sides of the Plinko game ramp.
Some Cad software has this ability built into it, right out of the box. Other programs, like Sketch-up have 3rd party 'add-on' plugins, which do work. We do our full 3d modelling mostly with Hexagon, which is solely a polygon modeller. This can have it's draw-backs when trying to lay geometry flat out. Trying to unwrap it in programs like Corel are impossible to do, as they don't support 3d geometry.
Enter our little secret!
We actually use 2 programs for this. One is called Pepakura designer. This was developed for making paper models from 3d polygon-models. It's a nifty package, but it's geared toward printing on sheets of paper with tabs, that you trim out, fold, and glue up. We have actually done this for creating printed texture maps, for applying to large 3d models we have machined. The draw-back is it doesn't account for any material thicknesses.
That's where a little power-house piece of software comes in. It goes by the name of "LaminaDesign"

 It was developed by Paul Haeberli, and it does it's job exceptionally well! It hasn't seen alot of developement action recently, but hopefully my assertive nagging will have an impact!
It's interface is not complicated, but packs a bunch of useful features. Upon install, there is a text file in the main installation folder, which allows well documented options for tweaking the software's behavior.
I thought I would unwrap a simple model to show you how the process works, and how simple it really is.
This is the basic model created in Hexagon. It's pretty simple as a shape, but figuring it out as a flat would be nightmarish! Especially the fact that it's tapered.
I exported the model out as an STL and dragged it into LaminaDesign. The red lines are the deviations in the geometry, which LaminaDesign assigns as cut lines.
If I explode the drawing at these settings, I would get a whole pile of parts and pieces. If I wanted to laser cut this from clear acrylic, with faceted edges, this would be amazing. You even have the choice of adding numbers to the parts, with snap-off tabs. However, I want a continuous sheet. Maybe I plan on cutting this from .060" styrene, and only want 1 single join. No problem!
I would select the draw tab from the main menu, then select the delete icon. Now I just have to rotate around the model, deleting all the red cut lines. You do have to be a little intelligent on how you determine the join though. You can also choose the pencil icon to draw your own custom cut line. This is very well documented in the online manual, so I won't go into it here.
I have deselected all the lines, except for the seam at the top of the shape, and one single line where the unwrapping will split apart from.
BAM! Here is the shape flattened out! I can choose from the dropdown menu's if I want the numbered parts or not, or the size of the numbers. But in most cases for cutting on our Techno, it would be wasted time.
This is now where the material thicknesses come into play! I can assign a material thickness from the menu, as well as add my own material via the settings file in the install directory. You can also assign how flexible your material is, resulting in slight geometry changes based on if it's really stiff or not.
You also have plenty of options for joining the pieces as well. From finger joins, straight joins, tabs, stitch holes, etc. The nice thing is that in the image above, I chose finger join, and it takes into account the material thickness assigned to it for the finger-depth!

I can now save out the job, which Lamina Design writes to a folder, containing a PDF file, as well as a vectored DXF. It also saves out the job and materials information as well. You can assign a sheet size as well, and import that into Aspire, or Corel, or any vector editing software.

So there you go! Unwrapping made easy by smart software developers. Man I love computers!

1 comment:

  1. Thanks for the post on 3D wrapping.