4. Computer controlled cutting

Browse through the NuEval Handbook to review the evaluation criteria.

Group Assignment

Safety Training

Characterize your lasercutter’s focus, power, speed, rate, kerf, joint clearance and types.

Anna

Power and speed characteristics

We made a power speed parameter test for the group assignment. As you can see I loaded 12 color profiles in one go. Previously Andri did a similar project for his group assignment. He has to make 25 or more separate cut files. Overall, not sure color mapping is easier or faster, but it is interesting.

The top row of this document is the power and the vertical row is the speed. In the top row the color used all other color are to be set to 0.

See Andri Semundsson page for the previous project.

Andri Semundsson site

File 1 File 2

Evert

Kerf test

In Inkscape we made a square box 100 x 80 mm with 8 lines plus the outlines an cut it out then we measure the gap than was in the hole made after cutting, we measure that gap as 2,69mm then we divided in that number with the number of the cutting lines or 2,69/10 that gives oss a kerf about 0.269mm

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Comb test

This test is to measure how much thikness ekstra the kerf cuts from the material We used MDF 4 mm material in this test we made some parametric drawing in fusion for this test we draw a kind of comb and made some lines in it that in the middle was set to material thickness and then we added or subtract 0.05mm for each slot that we moved In the end i found out the material was hangin togeather wherer we had the material thickness -0,15mm

Albert

Power and DPI test

This test is to understand the effects of gray scale on etching power. This also included a test on the effect on etching from changing DPIs. In Inkscape, a grid varying of gray scale was created.

DPI test card

To prepare for the laser printer, the 100/200/400 DPI squares were moved to separate layers, also retaining the 600 DPI layer including the text. A border was adde to all four layers (also the 600 DPI), which kept the individual layers aligned. The 600 DPI layer border was made as a 0.02 mm red line (which is need to make the cut.)

On the FLR Epilog Printer, I sent each layer to the printer in the order 100, 200, 400, 600. As I was using 4 mm timber, the recommended settings for the lab were used. This included:

For the raster:

• Speed: 60%
• Power: 100%

For the vector:

• Speed: 11%
• Power: 100%
• Freq: 500 Hz

For each round, the DPI slider was adjusted.

Parameter settings box, including DPI slider

This resulted in the following card:

Final greyscale and DPI test card

While sequential printing is time consuming. This resulted in a nice stand alone reference card.

The file used for this work week04_dpi_card.svg (includes layers).

Magnús

Joint tests.

We made a set of test joints based a set of joints Neil showed on Wednesday’s lecture:

• The FreeCAD Joints:

  

• The recreation:

  

First thing when designing parametrically is narrowing down on the required parameters. In this case they are:

Parameters

Parameter Name	Unit	Expression	Description
MatT	mm	4 mm	Material Thickness
JFlex	mm	2 mm	Joint flexible element thickness
TLen	mm	30 mm	Total Length
TWid	mm	30 mm	Total Width
JDep	mm	TLen/2	Joint Depth
SnapD	mm	MatT/3	Diameter of snap in snap and flexure joints.
Kerf	mm	0.18 mm	Kerf
FingNum	none	8	Number of fingers in finger joint.

The Sketch

The Joints are done in Autodesk Fusion. First step is sketching out each joint. Here’s the joint for the pinned assembly:

Things to note here:

• The width of the horizontal slots is calculated using the formula:

  • (Material Thickness / cos(45 deg)) + Material Thickness
  • In the file: “MatT / ( cos(45 deg) ) + MatT“
  • This makes the slot hug the pin at a 45° angle so it’s a snug fit. The kerf is only applied on the other axis.
  • The kerf is only applied where necessary, Inside the the joints but not the total piece size.
  • Doing the kerf in the Fusion parameters instead of afterwards using Inkscape means you can adjust that part of the design without offsetting the entire file and changing the total size.

Here’s the pin joint assembled in Fusion:

And here it is after cutting and assembling:

Cutting

Starting off by projecting all the joints into a sketch and exporting the sketch to Inkscape as a .DXF. Double checking the scale and adjusting the stroke to 0.20mm and the stroke paint to Absolute red: 255,0,0 RGB. Nesting them to maximize material usage.

The final arrangement was this: (Stroke width adjusted for visibility)

After cutting the pieces fit together nicely. The finger joint got loose after a bit of wiggling, But that’s mostly the MDF rubbing away. The snap joint definitely had some issues but that’s the MDF crumbling rather than deforming.

Here’s all the joints together:

Here are the project files for the joint tests:

Program Used	Description	File extension	Link
AutoDesk Fusion	The Joints	.f3d	link
Inkscape	Cut file for joints	.svg	Link

Individual Assignment

• Talk about what you did for the group project
• Add a link to the group page
• Include images

Design, lasercut, and document a parametric construction kit

• Create something that can be assembled in different ways.
• Review examples from previous students.
• Demonstrate and describe parametric 2D modelling processes.
• Talk about the laser cutter(s), what brand, specs, how to use the machine, how to get the machine ready. What settings do you use (numbers with units) -Talk about laser safety, -Do not leave the machine while it is running, always keep an eye on the machine -Make sure the exhaust is turned on -Do not use the machine if you are tired -Do not use the machine if you are alone in the lab

Important!

Must be parametric!!

Cut something on the vinyl cutter

• Create a 2d design and cut on the vinyl cutter
• Explain how you created your design
• Talk about the Vinyl cutter, what brand, specs, how to use the machine, how to set the knife cutting depth.

Note

• Link to the group page
• Include you design files
• Include a hero shot of your results

NuEval

• Go to the NuEval Dashboard and check off the items on the checklist that you believe are ready for evaluation.