3. Cutting Stuff

But within the law - no animal was harmed

Hero Shoot of the Week

HeroShoot

Figurines not to size! They were the only at hand.

Summary

This is how I used the laser cutter to create a parametric assembly kit for D&D games. I made several design and calculation errors. And the final design is still not perfect.

This weeks music was

This week I discovered this music and listened to it while laser cutting.

Work Process

Machine introduction

In my FabLab we have (at the moment) two laser cutters. There are two new BRM on their ways but we got some delivery issues...

So how we use it at FabLab ULB. We are using the FabMan reservation platform. After it was reserved, students can scan a QR code to unlock the power supply to the laser cutter.

Security

For security, there is a fire extinguisher next to the entrance door. There is also a fire blanket just above the extinguisher.

Each Laser cutter has also the big red button (that students are generally afraid to use... So we always show them how to use it when they are trained).

Than as the electricity goes through the FabMan bridge (I hope I remember to add a pic), we can monitor the electric consumption. This allows that when the laser is active, it requires the user to push a button (on the bridge) every 10min to check if they are physically present. Otherwise the bridge deactivate so no more current and no more laser. But than it is also a lost work. (Yup, it works just as a Big Red Button)

Epilog Fusion Pro 32

It is our current industrial Laser Cutter of our FabLab. Here are some characteristics:

  • 60W CO2 Laser
  • 80x50cm
  • 30cm Z
  • autofocus (plunger system)

They also provide a Material Settings Sheet

To control it we use the program Epilog Software Suite that was given by the company that made the laser cutter.

When I am lost, or have a doubt I can also check the Manual (As was said in the MicroController recitation: Read the F*cking Manual)

Setup

I will be mostly using the Epilog as Lasersaur is quickly broken by our students.

Lasersaur

Here are some characteristics:

  • 100W CO2 Laser
  • 120x55cm (it was shortened by 5cm by the students user error...)
  • 10cm Z
  • manual focus

It needs a big overhaul (new cables and co). I was thinking to do it after the new BRM lasers are put in service and when there is less demand (and of course after the FabAc)

Introduction

Bas made a quick introduction on how some working process. He also did a quick intro for OpenSCAD. He showed us how simple shapes can do complex logos.

For example the (old) twitter logo:

Twitter

Starting with Computer

Before cutting

Before cutting I need to know the best parameters to cut:

  • frequency
  • power
  • speed

So I started working on a simple square series. Each square has a different color so I can experiment with different parameters.

I am using RGB color system:

  • R = Power: 0-100%
  • G = Speed: 0-100%
  • B = Frequency: 0-100%

Note that the % is for the reference on the laser cutting interface but I am using the same values for colors, so I never go beyond 100-100-100 on the color scale (it goes up to 255).

To not waste time with making lots of square I used the clone tool of InkScape and the following video to understand how to color them differently.

! Object > Selector and CSS -> delete outline setting

So I wanted to color it automatically within the Clone Tool but couldn't figure it out.

FabAc GPT GPT1
GPT2
GPT3
GPT4
GPT5

Well. I managed to do something... But not the thing that I wanted. :/ Lets hope chat has an idea on how to do it.

Here is a screenshot of the Epilog Laser Cutter interface:

Screenshot

Results

Frequency:

Frequency Results

To be honest I do not see any difference...

I will take 50% as it is the default parameter when I import the SVG into the Epilog program.

But what is interesting is that the sound that the laser cutter emits is different for each frequency.

Power & Speed:

Some of the settings are definitely too powerful and a flame is created.

But this is the process to see what Power and Speed can be used for what.

Power_Speed

Kerf

I started with creating the Design for the Kerf experiment. For that I created a simple parametric design in FreeCAD. I did not wanted it to be just a simple kerf...
So instead I added some holes to convert them into keychains. I still need to find what I want on it...

Kerf_Design

Than exported it into a flattened SVG, imported it into InkScape to add color (order of the cuts) and to possibly add text or raster image.

Results

The first parameter tested was S20 P60 F50.
It is an almost success.

Second try I took S20 P65 F50.

Same results. I am missing a fraction of a mm.

3rd try I took S15 P65 F50. And it worked. It cut through!

Kerf Result

After several measurement with a caliper, the kerf is around 0.9mm for 10 cuts.

And now I have 9 temporary keychains on which I can write.

Joint clearance

So for joint clearance I made a teethed object with FreeCAD. Fixed the hight and distance between the teeth.

Than with the excel table I made a series of clearance test.

CAD

Parameters

I also subtracted the Kerf for each joints.

So the input parameters are the:

  • Material width
  • Tested joint clearance
  • Kerf

I had some issues with this one. One time I forgot to add the kerf. A second time I had a typo (double negative) in the excel sheet...

Results

For this I cut out my file (after converting to SVG with the LCInterlocking FreeCAD plugin) and a simple cube / rectangle.

And S17 P63 F50 seems to work too.

Joint Result

And somehow I managed to mix up the + and - sign in InkScape...

Different types of joints

This picture was showed in Neil's class:

Joints

I am putting this here so I can find it later on if I need it.

Parametric construction kit

So my initial idea was to improve on Lena work. But looking at it I could not figure out what could I add to it...

I also play D&D so after FabAc I will replicate her work.

After the communion to home and with a good night sleep.

I got how I could improve it.

I want to create some new tiles and modify some of Lena's tiles.

Well....

That wasn't long...

She did not give the original Fusion file. So I cannot use her parameters to improve on it. I guess I will need to start from scratch.

My D&D Tiles

So I started working on it in Fusion. I choose Fusion so I can share with my engineer friends who also play D&D. In Fusion it is easier to work on the same projects at the same time.

So a D&D tile is 25mm. I started with that. Than created a joint type in a separate file that I could work on independently.

One issue that I found is that the parameters are not shared between bodies/files. FreeCAD is better on this point (or maybe I just do not know that it is possible in Fusion).

So I have a series of parametric files.

Construction Kit

Now I just need to go to the FabLab and cut some. But it is the weekend... I don't want to...

To convert my Fusion files into SVG I installed the Origin plugin. It works for me as I also have an Origin CNC.

For some reason, one of my parametric design doesn't want to be exported into SVG. It is the one where I repeat the basic tile. Neither with the plugin (which works really well with other designs) and neither exporting it with DXF (there are lines that appears).

For now I am cutting what I can cut and I will see later (if I still have time) why it does not want to cooperate.

While cutting I also made some adjustment, as the joint that I was using was too small and broke easily. As it was a parametric design it was easy to correct.

joint

I feel like, I also need to create more variants (diagonal corner, flexible parts, etc.). I will do them one day for D&D, that is for sure, but will I have time to do it before the next FabAc chapter ? Time is running short.

I definitely want more variants and also more joint variants. While building my tower I realized that the T joint I am currently using is not the best for the floor connectivity.

Tower

At least it is sturdy.

I just noticed that my joint is too long and creates a space between my tiles. This will be a problem as if I do other tiles that are twice the length, the joint holes wont match. The correction is easy but I will do it after FabAc as it would be (I think) quite a long testing.

FabAc GPT

Do you know how can I do a flexible laser cut design in fusion 360 ?


GPT5
GPT5

I made a flex wall (I still need to cut it. It might not be that flexible) with the help of FabGPT. It is really an inefficient model... I will need to find a better way to do it. Maybe the flex model should be added via InkScape ?

So my flex part is definitely not good. It does flex but it does not flex strait. It spirals a little. It also has a weak point. I broke the first cut instantly.
This still needs work...

Tower2

At least I have something. I am not totally proud. This still lots of work before it can be used on a real D&D table.

I am currently testing different joint length to see which one is the best.

Joint Test

On the left is the 0.5 mm gap between tiles.
Right is the 0 mm gap between tiles.

If I want to use it with other tiles that do not have this gap included in the base design, I should use the joint that leaves 0 mm gap.

This is also the new Flex design that works better.

Flex Wall

But it still needs some tinkering as it is hard to bend (and I did not put in the joint holes either).

For final project

For my final project I already did a parametric object to cut with the laser.

Plaque

But this should be cut out with something more solid (like mdf) than cardboard.

Learning Outcome

Half of the time I misspell clearence...

Up until now, I never used to work with kerf and joint clearance. But I never needed to either. It was quite a new experience as I needed to include it into my parameters.

I also never did any cuts that resulted into a flexible part. I knew we could do it but never did it myself. And I never expected that the S design would not only flex, but also spiral down...

After review with Henk, he said that the laser source might be at its end. I contacted the Epilog Support. We will see what will happen next.

Digital Files and Links

Assignment Check

  • group assignment:
    • do your lab's safety training
    • characterize your laser cutter's
      • focus
        • autofocus, hehe, i am cheating
      • power
        • Done
      • speed
        • Done
      • rate (frequency)
        • Done
      • kerf
        • Done
      • joint clearance
        • Done
      • types
  • individual assignment:
    • cut something on the vinyl cutter
      • Done
    • design, lasercut, and document a parametric construction kit,
      • accounting for the laser cutter kerf,
        • Done
      • which can be assembled in multiple ways,
        • Done
      • and for extra credit include elements that aren't flat
        • Done