E03: Computer-controlled cutting

This week is about computer-controlled cutting. I did several projects to get experience with the laser cutter and vinyl cutter. These include photo laser-engraving on acrylic and wood, a laser-cut business card, a vinyl cut 'Fab-Team logo' for a sticker (and T-shirt), two laser-cut lamps made of cardboard and two press-fit constructions: an acrylic jewelery tee and a spaceship (for my son's birthday party).

Notes from lecture + comments:

This week is about computer-controlled cutting. Machines used are the laser cutter and vinyl cutter.
    Assignments:
  • 1. cut something on the vinil cutter (custom sticker for your laptop, origami, etc.)
  • 2. Design, make, and document a parametric press-fit construction kit
    - Make Joints! However - don't make the whole project and then make the joints.
    - make not just simple joints, make strong joints.
    - You need a parametric design! You need to use one of the parametric tools.
    - Optional: Make something that you can be transformed (in order to make it multifunctional).
    Nice examples (I have found):
  • http://www.instructables.com/id/Press-fit-Construction-Kit/
  • http://www.instructables.com/id/3D-Puzzle-Maze-CNC/
  • http://fab.cba.mit.edu/classes/4.140/section.Architecture/people/Saulnier/pages/pressfit.htm
  • http://infosyncratic.nl/weblog/2008/09/16/press-fit-geodesic-dome/
  • http://aaminadesigns.co.za/?tag=laser-cut
    Notes on laser-cutting:
  • When lasering, material goes somewhere (techniques: burn, melt, evaporate, ..)
  • Lasering always eaves a kerf
  • NEVER leave the Laser unattended.
  • Let the laser outgazing (after cutting!)
  • Periodically clean the lens!
  • Only lasercut material you know
  • Parameters: power, speed, frequency
  • Frequency - if it is too high you put too much energy in one place
    Notes on Cardboard:
  • - Tune the lasercutter power in order to not cut through.
  • - If you can bend it, it is good material.


How to MAKE it

At the FabLab Kamp-Lintfort we have a Epilog Fusion 60Watt Laser. The machine has a work space of 1000mm x 700mm.

For (vinyl) cutting we have a Summa S120 Cutter and a Sillouette Cameo.


MAKE something with the vinyl cutter - a sticker

Download




MAKE a spaceship

For my sons astronaut-birthday-party he wished to have a real spaceship to play with. Happily I could convince him that a real space ship might be too big for our living room but I promised to do my very best to create an alternative.
May plan was to make a scaled version out of cardboard.

At the end we assembled all parts to get a 'real spaceship'. And the kids love it :)

Download







MAKE press-fit lamps

I used Rhino to create the body of the lamp and 123D Make to turn it into a 2D built plan. For the material I choose cardboard (leftover of some packaging).

A press-fit spherical lamp

Download


Another press-fit lamp

In Rhino I created a sphere, subtracted (boolean difference) a second and third sphere to concave the object. Finally, I subtracted a cylinder (for the cable fairlead). 123D Make needs a solid object for slicing (horizontal & vertical).
In 123D Design you first have to define the 'manufacturing settings' (i.e. material size, thickness, slot offset and tool diameter). After that you can select the 'construction technique'. I choose radial slices as my favour. The parameters enable to instantly manipulate the slice distribution, direction, etc. You will be surprised about the results and the shape you get.

In principle, the laser cutted nicely (Speed: 20; Power: 90; Frequency: 30). But because the cardboard was not perfectly flat (it was cambering in the center), I had to complete a few spots manually, which was not a big deal, as the cuts have been almost through.
Assembly took less than 10 minutes.


Download


MAKE a press-fit jewelery Tree

I used Adobe Illustrator in oder to draw a jewelery tree. I made two cutouts at the trees bottom and created two stands with cutouts, too. They should press-fit together at the end. For the material I choose 3.7mm white acrylic. Therefore I made the cutouts 3.7mm wide.

I made some simple cuts in order to find the appropriate parameters for the laser. This was quite easy, so I started to cut all the parts. However, while assembling them it turned out, that the cut of the laser was too thick. As a consequence, the stand was quite wiggly.

Thus, I had to find the proper sizes for the cutouts - as 3.7mm did not work.

Finally, 2.8mm fits. Thus, the cut of the laser (with the given parameters) has a thickness of 0.45mm.
At the end, the jewelery tree fits together and my niece liked it. I also made her some rings out of acrylic, too.

Download


Additional laser-cut/engraving projects

The following picture shows a group of coal-miners. Here a a photography was rasterized for engraving on acrylic and wood. The two materials were put next to each other onto the work space. For the engraving I used the same parameters.

We (Adriana, Luiz and I) also made businesscards using a simple sheet of gray paper. While engraving, the top layer disappeared and the brown-coloured core became visible.

2D Parametric Design - using Fusion 360

In the previous case I did a spaceship using 123D Maker and Illustrator to generate a 3 dimensional model. This time, I wanted to study more the construction of joints. I checked some references for joints and also you can visit this article in the Maker Magazine which presents different kind of joints:

Some of these parameters you can modify in 360 Fusion in the panel: Modify > Change Parameters. Otherwise, you can look in the timeline in the bottom panel of the fusion window, and modify independently each feature.



I began with the construction of a sketch from one bottle, thinking in the diameter and tolerance between each bottle. After it, I extruded the first three surfaces.



IMPORTANT: When your are doing a mirrored model, generating the whole model, you may work with the origin point and the origin point planes, in order to orient the symmetries in the same origin.



I proceeded to mirror the second part of the bottles, and join it using a boolean operation. You can find it in 360 Fusion in the panel: Modify> Combine > choose Join. Afterwards, I did a perpendicular support in between the three sheets, for this I designed a screw joint using two tabs and an extra tab for the external part of the joint. The extrusion of this part is in the origin. In order to conserve the symmetry, you can extrude the object using a symmetry factor, in this case I used the parameter “Mat” (Material Thickness) / 2. When generating this part you can see that there is an intersection of two bodies solved using a boolean operation. In this time instead of using a joint I used the CUT tool, IMPORTANT: If you are using cut option in the boolean operations, don’t forget to click the option: “keep tool”, for keeping both bodies.

In the same form, I designed the lateral part to hold the object, as you can see in the pictures. I did the mirror of the five boolies, generating the other half of the model and making the space for four bottles.



The final part of the model is the design of the holder, generating the legs and also the intersection of the other support. There is no clearance in the intersection. I considered a clearance only in the screws joints of 0,5 mm.



To generate a sketch for all the parts, I made a flat of all the components using the tool Align and moving all the pieces in the same top origin plane.



I did a new sketch to project the sketch of the bodies. Finally, I exported it in DXF format, in order to have the vectors and cut it in the Illustrator program, which is the compatible program for our laser cutter EPILOG FUSION.



When opening this data in illustrator, you can see that the lines are “exploded”, which means you have to join it in order to have a nice contour.



I did a test of the joints, in order to verify, if there is a need for clearance between the joints. I worked with MDF 3mm this time, giving more stability and durability to the model. I didn't have the need to use chamfers for my model.



After it, I proceeded to cut the whole model in the laser cutter using 8% Speed, 100% Power and 20% Frequence. I had an error in the generation of the body of the holder because I didn't consider the taps in the bottom and the top part. In this case, I should enlarge this joint 5 mm.

Finally I built and joined all the parts! It works very well, a bottle holder for wine and beer!



Here you can also see a video of the laser cutter working:






Take Away's

It was so impressive to see how easily you can make something big within few steps easily. The laser cutted lamp is the best example. By just applying boolean operations on solid objects (here: in Rhino) you can create awesome objects, which than can be sliced (here: 123D Design) and cutted. Within a few minutes you can assemble it and make it a real object.
Cardboard is a wonderful material, not just for prototyping. You can create really cheap models that look awesome, too.