4. Computer-Controlled Cutting - Week 3


4.1. Assignments

Computer-Controlled Cutting

group assignment:

  • do your lab’s safety training

  • characterize your lasercutter’s focus, power, speed, rate,

    • kerf, joint clearance and types

individual assignment:

  • cut something on the vinylcutter

  • design, lasercut, and document a parametric construction kit,

    • accounting for the lasercutter kerf,

    • which can be assembled in multiple ways,

    • and for extra credit include elements that aren’t flat

4.2. Group Assignment

4.2.1. How to use our laser

  1. Setup Ventilation output on window IMAGE

  2. Turn the vent on

  3. Turn the chiller on

    • behind a tube

    • first it lights up red and beeps 3 times but turns green after it IMAGE

  4. Flip the switch for the laser cutter -> laser not on, separate switch

Now the Laser is ready for Usage.

  1. Turn on light on the side-panel

  2. Adjust leveling

    • use acryl-distance holder to set the distance between laser and bed to it (until it scratches the laser a bit)

    • buttons on the right side IMAGE

  3. Set the local origin

    • on the front-panel there is a switch to turn on adjust laser -> PRESS IT

    • now use the laser to set the local origin, if needed

    • ‘Esc’ Button on the top panel returns to local origin

  4. Choose uploaded file on machine to print (also upload and start is possible in RDWorks)

4.2.1.1. Additional Notes

  • left side of the bed is flat -> use for testing/configuration

  • Use ‘Frame’-Button on top panel to lookup the frame of the file to cut

  • ‘Esc’ cancels programm

4.2.2. Parameter

4.2.2.1. General Infos

  • Focus : Point in Space, where focal point of the lens is and so the cut of the laser the cleanest

  • Power : Power on the laser used for cutting/engraving strength : -> to strong == burn : -> to weak == no cut/not visible engrave

  • Min/Max Speed : exact max and min speed for laser-movement : -> to slow == to deep engraved/to much cut or burning : -> to fast == no/to low cut/engrave

  • Rate : For engraving the distance between the different lines/dots

  • Kerf : Part that is burned away : -> Diameter of the laser beam : -> needs to be calculated on model creation/design

  • Joint clearance: : -> even though the

  • Software: RDWorks IMAGE

4.2.2.2. Determining values for our cardboard

For determining the values, we used following 3 methods:

4.2.2.3. Kerf

For determining the kerf, we used 10 equidistant Rectangles (e.g. 1cm) and cut them out. Now if wee look at the sides of the rectangle, because of the kerf the sides of it are reduced, all halve of the kerfs total distant. IMAGE VISUALISING KERF That means, if we put all squares together like shown above and measure the total length, the kerf sums up 10 times, so we can calculate the kerf with this simple equation:

(total length - expected length)/10

IMAGE MODELLINK

4.2.2.4. Joint clearance

For determining the joint clearance, we used a comb-like structure with different widths around the thickness of the cardboard (in our case, 3mm). But smaller then the thickness of the cardboard is sufficient though ;D.

IMAGE MODELLINK

Then, after cutting, we used a piece of cardboard, clamped it in the comb and test, how good it holds/ if it goes in at all. IMAGE

4.2.2.5. Speed and Power

For determining the optimal speed and power configurations for cutting and engraving, we used a matrix, where each cell has a different setting for speed/power:

IMAGE IMAGE VIDEO

There we also found out, that over 30% power was overkill for engraving, where values lead to much smoke, and this is no good, as we learned.

IMAGE MODELLINK

4.2.2.5.1. Determined Parameters

General

  • Kerf: 0.3mm

  • Joint clearance: 2.6mm

Cut:

  • Speed: 30mm/s

  • Power: 50%

Engrave (Lines):

  • Speed: 300mm/s

  • Power: 20%

  • Distance: 0.2mm

4.3. Individual Assignment

4.3.1. Vinyl-Cutting

For Vinyl-Cutting I decided for the logo of our local hackspace, so I used the original image and created an outline of the font for path-creation:

IMAGE DXFFILE

Then I First tried out our CRICUT Cutter but the software used for uploading the path was so bad, that it rearranged the font completely wrong and used every path piece in the preview. I could have worked around it by handcraft it back to the original state, but I find this to be to stupid, so I used our other cutter.

IMAGE

With the other cutter, there was no problem. I chose matt black for the cut, made it almost exactly the size of the print and lay it on around machine zero and started cutting:

IMAGE VIDEO

Then I removed the negative form:

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Placed the transfer film on it:

IMAGE

And pulled the logo of:

IMAGE

At last I just put it on a piece of acryl and have little stand:

IMAGE

4.3.1.1. Machine Settings

IMAGE IMAGE

4.3.2. Laser-Cutting

For Laser-Cutting I designed a Bone-like structure which can be used to design little skeleton-like creatures or little structures. I parametrised the length, width, the slit width and depth and for the rib the tip - distance from the center.

Bone

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Single Side Bone

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Rib

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Path

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Then I used The RDWorks Software to arrange and created copies of it.

IMAGE

Then I uploaded the file to our Laser, chose a suitable position on the cardboard, framed it (meaning draw a bounding box around the area) to look, if it fits and started the print.

IMAGE VIDEO

The outcome is pretty decent, but I should have designed them a little bit bigger, but should be possible with the parameters:

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4.3.2.1. Remarks

  • when uploading the file from our lokal PC connected to the lasercutter and then starting from the machine, some weird end-code happens that it want’s to drive over zero and a nasty sound comes (because he crashes into the wall)

    • in our case, one time the coordinate system completely changed, so zero was not in the usual spot for the machine but ist was in the middle of the plane somehow, resetting fixed it

4.4. Notes

  • in freecad export as .dxf -> user technical drawing and ‘insert view’

  • upload raw project files!