4. Computer controlled cutting

This week is about computer controled cutting with the vinyl cutter and the laser cutter

Research

Part of te assignment is parametric design. So I followed a tutorial by Ian Southwell on youtube.

I thouhgt I followed his step by step well, but something went wrong. I tried several times, but I could not get into dmension mode to change the dimension. With the help of Sjoerd I found the solution.
• Go to the sketch in the Browser
• Right mouse click
• Choose Edit Sketch

The lasercutter

We use a BRM CO2 Lasercutter 500W with a bed from 160 x 110 cm. It’ water cooled.

Safety first

• Never leave the space within the red tape when you are working with the laser,
• Keep the lid closed, when the laser is running
• Keep the pink waterspray at hand in case of flames (there are no electronics under the bed, so no safety hazzard)
• No rubber, MDF of PVC in the Laser Cutter. • Avoid very detailed drawings to be cut and high power becaus of fire risk.

Software

• The cutter uses Lasercut 5.3. You can use file formats DXF and Adobe Illustrator CS2

• Save your DXF file on the desktop of the Laser cutter computer or in FabFiles, make sub file with your name.

• Go to File and Import your DXF file

• Check dimensions with Size tool.

• DXF and CS2 sometimes change the size. Resize if necessary.

• Zoom out to check if the drawing is centered on the working tabel.

Go to Edit in the toolbar and choose Centre to table if necessary

• Zoom in & select all.

• Tools > Unite Lines. This removes unnecessary dots in the sketch witch saves time cutting.

• Set mode, speed and power in the window at the right hand side of the screen. For this job (cardboard apr 2.6 mm) I used cutting mode, speed 50 and power 60.

• When ready go to the bottom of the window and click on Download. The file is send to to the lasercutter

• In the pop up window click Delete all to remove previous files and then click Download Current (that is your file)

• Turn laser on 1. Turn key clock wise 2. Push green button, the machine is on 3. Turn switch clock wise, the laser is now on.

• Put material on bed

• Adjust focus of the laser. Unscrew the upper ring at the nozzle. Place focus wood under the nozzle. Let the nozzle touch the focus wood. Fasten the upper ring. Remove the focus wood.

• Set starting point with u, d, l, r arrow buttons. Choose your starting point avoiding material waste as much as possible. Then press Anchor and press Enter

• Press Test (if the machine does not respond, press ESC and then Test) The laser nozzle will follow the outline of the sketch. If necessary adjust the position of the material of adjust the starting point. Run Test again.

You are ready to cut

• Turn on Ventilator

• Press start

When the job is done:
• Wait for a minute to let the ventilator remove the fumes
• Turn the ventilator off
• Turn the laser off (switch number 3)

Laser Cutter Assigment

For the laser cutter assigment we heave to make a press fit card board kit. I got inspired by House of Cards designed by Charles Eames. As a kid I played a lot with it.

I chose for cards of 60 x 100 mm. First I made a paper pencil sketch to calculate the meassurements.

Then I went to Fusion to create a first digital sketch for parametric design.

I changed the parameters in the Change Parameters menu.

For the slots, the most important for the press fit part of the assigment, I chose 2,463 mm. This is the best with for the 2.6 mm card board and the kerf we measured in the group assigment.

When I tried to change the dimensions in the sketch by the changed parameters I got an error notification about over constrain.

I could not figure out what the problem was so I started over. This time I used the parameters direct in the demensions. I got no error notifications.

But when I changed the parameters the hole sketch got bigger. There was something wrong in the sketch.

My neighbour a mechanical engineer helped me out. It appeared that all the dimensions in my sketch were linked. So if one dimension got bigger it ‘pushed’ the other dimensions and the whole sketch got bigger.

For the new skecth I started with just a quarter of the sketch

witch I mirrored vertically and then horizontaly.

I set the outer dimensions of the whole sketch at 60 x 100 mm.

Then I changed the dimensions of the slots and the outer dimensions stayed on 60 x 100

Just to make sure that setting the dimensions over the whole lenght and width would have done the trick at my original sketch I made a simple sketch. Again I got the over constrained notification, when I clicked OK, the driven dimension appeared.

Now when I changed a dimension in the sketch from 30 to 50 mm, the outer dimensions stayed the same.

Tme to cut! (See above)

This is a press fit result.

Althoug the inspiration I used is a perfect simple design, my assignment was not up to standard. It looked to much like a finger joined box (sorry Mr. Eames)

I decided to add a equilateral triangle as a second shape. Due to the dimensions of the rectangular the dimensions of the triangle had to be 100 mm. That left only one side for two slots. The other sides got one slot.

First I calculated the dimension and put them in the parameters.

Then I drew the triangle using the parameters (the names) instead of entering every dimension value separately. That worked fine.

The cutting went like clock work.

The combination of the rectangular and triangle is great.

As a bonus I cut out the silhouette of the car for my final project and glued it together to a 3d model.

The Vinyl cutter

The Vinyl Cutter is a Roland Camm-1 Servo.
It runs on AI. Save as AI CS2. Save on USB stick.

• Make sure the handle at the back is down.

• Insert the vinyl. Make sure it is aligned properly

• Adjust the position od the wheels according to the width of the vinyl. The wheels should be on one of the white markers.

• Adjustthe position of the knife.

• Click power on
• Knife is detecting the width of the vinyl.
• Push Origin till the display stops blinking
• You’re good to go.

• Open file and save in FabFiles or subfile with your name.
• Click File > Document Setup > Document Artboards to crop

• Click Print > Placement select lower left dot. • Click Print

• Transfer the sticker to transfer tape
• Stick the sticker to the targed surface.

Vinyl Cutter Assigment

I wanted this assignment to have something to do with the final assignment. So I chose to make the sticker a silhouette of a Renault 4. I want to use this model for the car I’m going to build.

I created the drawing in AI, with a 1 pt line. Based on a technical drawing I found on the internet.
Then I followd the steps discibed above.

Problem & Solution
I thought the drawing was okay, a 1 pt AI CS2 drawing. The cutter however saw the 1 pt line as an inner and outer line, so he made a very thin cutout instead of a single cut.

I solved the problem by puting the line on ‘No Line’ in the drawing and filled the shape 100%.

This time the result was good. I used a transfer sheet to get the sticker of the vinyl sheet and unto my note book.

As you can see there is a tiny flaw in the rear wheel. where the sticker didn’t come of the transfer sheet propperly.

The group assignment Joint clearance

In order to test if our cuts are squeeze fit we decided to make a measuring tool. The material we would cut is about 3 mm thick so I made a tool to measure thickness from 3.2 mm to 2.8 mm in steps of 0.5 mm

I decided to make the tool in Fusion 360.

• I saved the file as .dfx and tried to open it in AI, because the cutter sometimes has problems with Fusion 360 DFX files.
• AI could not open the file.
• I then opend the file in Inkscape.
• The sketch was a bit damaged so I had to do some additioonal drawing and I had to add the meassurements.
• I saved the file as a Desktop Cutting Plotter (AutoCAD DXF R14) .dxf

• I took the file on USB stick to the Laser Cut Computer
• I downloaded the file directly from the USB stick, but then the Cutting software didnt open it.
• So I put it on de desktop first.
• I still had to do some editing: one line had moved.
• I mannaged to get the drawing in order.

• I stopped the cutting when I realized I had made a miscalculation. I used the full width, instead of the width minus the kerf. Besides the numbers were small and being cut out so evntualy the wood would have ignited.

• I went back to Fusion to create a new tool.
• First I did a recalculation: the serie as mentioned above but substracted by th kerf of 0.137 mm.
• I drew the tool line by line. That was not a succes: some lines weren’t there. • New strategy: I used the line tool continouesly, entering the various dimensions and it worked.

• Back to the laser cutter
• The numbers were lost in the DFX conversion because I forgot to change the numbers in to vectors.
• We cut the tool twice and wrote the meassurements manualy

• Now we had a tool to use the right width for the cardboard we were going to use for the 2D modeling assignment.

Link to the group assigmnment

Files

Renault 4 silhouette
House of cards Triangle
House of cards Rectangle
Joint Clearance Tool