04. Computer Controlled Cutting¶

After being introduces to two new cutting techniques of Vinyl Cutting and Laser Cutting, it was going to be an exciting week. This week was about exploring the machines and testing their limits in terms of materials, intricacy as well as its limitations.

Machines used for the assignments:¶

Roland DX-24 Vinyl Cutter

SIL Manufacture Laser Cutter

Epilog Laser Mini

Group Work¶

We started with group work by testing different parameters on various materials. More about it can be found here

My role here was to gather all the materials and testing out the template made by my colleagues.

Laser Cutting using Fusion 360 and Slicer¶

Step 1:
One of the softwares that intrigued me during the research was slicer which comes as an extension of Autodesk Fusion 360. This software is designed specially for laser cutting complex organic forms. Hence, I went to Fusion and stared making an organic model of a bench.

Step 2:
Once the model is ready, click on the Add-ins option and go to Fusion 360 app store. There search for slicer and one can download its installation file from there.

After this, go to Make>3d print and under that, select custom as your print utility and select the installation file that was previously downloaded as the application. This will install Slicer in the Fusion 360. It can now be found under ‘make’ menu.

Step 3: Once Installed, open the 3d model in Slicer and change the parameters to get the 2d file for cutting. These parameters include

(1). Construction Technique : Select the technique you wish to use like interlocked slices(90 degree interlocking), Stacked slices(Layers in one direction), Radial(One central axis and radial components interlocking them), Folded panels(Surface development using triangular faces).

(2). Depending on the construction technique, select other parameters like number of parts in x and y direction, the notch, and the slice direction.

(3). It also gives the flexibility to enter the material dimensions including thickness and gives the 2d plans composed on the sheet accordingly.

(4). Once the parameters are set, a dxf file can be exported with numbering for sequence of assembly.

(5) This dxf file can then be imported in RDWorks which can then be dowloaded into the laser cutting machine(SIL manufactured in this case).

Settings Used¶

Cutting : Power : Min 60 Max 65 Speed : 15 cm/s

Engraving : Power : Min 15 Max 20 Speed : 200 cm/s

The final laser cut product is shown below:

The material used here was recycled 2.7mm MDF. Since the kerf was not considered, certain parts of the assembly did not fit properly (they were slightly loose).

Later on, I found out that the kerf can be added in the material settings which would then be considered in the output file.

Plotter Machine¶

Plotter Machine is a very different than laser cutting, where a sharp blade is used for cutting a thin surface(Generally a Vinyl Sticker) unlike laser Cutting where a lasr beam is used.
The machine at FabLab CEPT is Roland DX-24.

The process of cutting and vinyl application is explained below:

(1). I started with downloading a jpeg image which I used as a base file for creating my graphic for cutting on a vinyl paper. This file was then opened in Inkscape and converted into a vector using Trace bitmap command.

(2). This vector was then exported in ‘eps’ extension and imported in CutStudio which was then used for sending this vector to plotter as an outline.

(3). Before sending the file to the plotter, make sure the settings of the plotter are as desired.
- The origin - Pen pressure (Here, the pen pressure used was 150gf for a 180 gsm vinyl paper). Click on test to cut a small circle and sqquare to check if the pressure works properly. - Make sure the width of the roll is not less than the width of the document.

(4). Once the settings of the plotter are in place, send the file from CutStudio to the plotter using cutting button on the software. Here, go to the properties of the plotter, and click on ‘Get from Machine’ and before exporting the file to the plotter.

(5). The machine will not cut the outline of the graphic on the vinyl paper.

(6) Once it is cut on the plotting machine, carefully remove the unwated areas from the vinyl. Try applying the force is the direction parallel to the paper rather than perpendicular to make this process easier.

(7). Once the extra vinyl is removed, put a bigger transfer tape on the vinyl, and press it properly so there are no or few air bubbles. Carefully remove the transfer tape and the vinyl, onto a hard surface(Here,transparent acrylic) where you want to stick the vinyl.Again after pressing hard, remove the transfer tape and the vinyl should stick in place.

Comb Exercise - Kerf Calculation¶

The idea behind this exercise is to make slits of varied sizes in a material to calculate the best possible kerf value in optimum settings. Having known that the kerf value for an mdf is anywhere between 0.1 and 0.2, I chose to make six slits in a circle of 0.05 difference in slit width. Hence, the widest one was of material thickness and the smallest one of material thickness minus 0.25.

The material used here was 2.7mm recycled MDF. The file was generated using AutoCAD 2018 with slits of 2.45mm to 2.7mm.

When importing the above file into RDWorks, the problem I faced was with text. RDWorks didnot read text from dxf AutoCAD generated dxf file. The solution to this is converting the text into vector lines using txtexp command in AutoCAD before exporting the file as dxf.

Once this was solved, the dxf can be imported in RDWorks which can then be sent to the laser cutter.

Settings used¶

Cutting : Power : Min 60 Max 65
Speed : 15 cm/s

Engraving : Power : Min 15 Max 20
Speed : 200 cm/s

Here, after cutting, I realised that the pieces were too loose. i.e. the kerf was more than 0.25.
On further analysing, I found out that because the laser cutter was used to cut a thicker material before, the focus was set accordingly and hence wasnt correct for 2.7mm MDF. Also, since the material was recycled, it was slightly curvy and not completely flat.

Thus, I got a fresh material, MDF of 4.2mm thickness, prepared a file for that thickness, transferes it in RDWorks, and prepared for Laser Cutting. This time I made sure all the settings were correct before going ahead with cutting.

Setting used¶

Power : Min 65 Max 70 Speed : 15 cm/s

With the slits ranging from 3.95mm to 4.2mm in the 4.2mm MDF, the best fit was in 4mm slit. Hence, the kerf was 0.2mm.

This learning along with the same 4.2mm MDF was further used for making the components of parametric design exercise.

Parametric Press-Fit Construction¶

After the Press-Fit experiment in slicer and making the comb for Kerf calculation, I was all set for making my parametric design.

The idea was to integrate a *parametric living hinge into my design. The software I wanted have used is Fusion 360. This is the process I followed:

(1). I started with making basic shapes of my press-fit. My choice was circle and two semi-circles connected by a living hinge.

(2). Next I assigned a variable to the diameter of circle. The same parameter was also applied to the diameter of semi-circles and the distance between them(also, the length of living hinge).
The lines, which were going to be repeated for living hinge were given the size of ‘diameter*0.75’ and placed at the opposite ends of the living hinge.

Increased the diameter to 80, and it was working fine.

(3). Text task was to make the parametric living hinge. My idea was that the number of cuts should increase when I increase the length of the hinge. But, one limitation of Fusion 360 is that parameter are only in distance(here, mm) and hence you cannot assign parameters to number of repetitions. Thus, I decided to give 10 slots on each side(total 20), equally spaced along the length. The parameter I used for rectangular pattern was ‘Diameter*0.95’for the extent of repetition, since the length of the living hinge was equal to the diameter and 0.95 would space it in a way that opposite lines are equally spaced.

(4). Next was adding the slots in the circle and semi-circles. For that, a slot was sketched on the circle as shown. The length of the slot was given the dimension as ‘diameter/4’ and the width as ‘Thickness-0.2’ where thickness is the thickness of the material and 0.2 is the kerf.

This was then repeated 3 times for the semicircular shapes and 6 for circular shape using circular pattern tool.

(5). It was time to test the file with different parameters. I tried increasing and decreasing the parameters in different combinations and it worked perfectly.

You can then select the sketch, and export it in dxf format.

(6). The dxf file was then opened in RDWorks and copied multiple times for cutting multiple pieces and then sent to the lassr cutting machine.

Settings used¶

Power : Min 65 Max 70 Speed : 15 cm/s

(7). The resultant pieces fit well with each other. The thing that amazed me the most was the flexibility of the Living hinge.

(8). I tried making the below structural arrangements to test the flexibility of the hinge module.

Thus, even though MDF is now a very flexible material, laser cutting it in certain ways can be very effective in achieving flexibility.

Laser Cutting on Rice Paper¶

For one of my interior projects I tried using laser cutting on rice paper, which is slightly thicker than normal bond paper.

Settings used¶

Power : Min 12 Max 15 Speed : 25 cm/s

Because of the Thickness of the material and the intricacy of the graphic, high speed and low power was used.

Note: I have tried laser cutting on the same paper before but didnot get results anywhere close to this time. There were a lot of burn marks on the back of the paper, which was significantly less this time. The reason being, the machine i used previous time was of 36”X48” bed size while this time, it was 36”X24” which was almost the size of rice paper. Since the paper covered the bed, the paper was vaccumed onto the bed by the exhaust which gave much better result!

The Original Files¶

-Vinyl Cutting Graphic
-Parametric Press-Kit Modules
-Slicer File
-Comb for Kerf Calculation
-Parametric Press-Kit Modules

Group Work¶

The Group Assignment was to try out different materials and setting on laser cutting machine. The group page can be found here