Machine

Capabilities of the Metal Laser Cutting machine and a summary of sheet and rotary cutting.

Kern LC50 LaserCell

Machine Capabilities

Kern LC50 LaserCell

The Fab Lab high-powered laser cutter is a Kern LC50 LaserCell with a 400w CO2 laser installed. It is a fully enclosed system with a 1300mm x 1270mm cutting area. It also has a rotary unit for cutting round stock up to 750mm long by 100mm diameter.

The machine is capable of cutting a range of metals and non-metals. It can cut up to 4mm mild steel, 2mm stainless steel, 1mm aluminium and 0.6mm brass. These are the types of metals we stock at the Fab Lab, but the machine is not limited to cutting only these materials. It can also cut or engrave a range of plastics, wood and stone up 25mm thick.

Sheet Cutting

Sheet Cutting Metal

What can be achieved using the Kern LaserCell's Sheet Cutting function that other XY-axis machines cannot?

• Capable of processing not only metals, but thicker materials and larger sheet sizes.

• High level of detail for surface engraving on hard materials such as stone or steel.

• Capable of processing a range of fabrics, great for highly accurate and complex pattern making.

• Achieving a flame polished edge on Acrylics up to 24 mm thick.

• Compared to CNC machining, nesting is more efficient and sheet wastage can be reduced by using the Kern. This is due to the tooling characteristics of a CNC router, compared to the 0.1 mm thickness of a laser beam.

Example: Folded Sheet Metal

Elephant Stool by Myra Kosen and Ivy Lee, ExLab 2019

The Elephant Stool explores the potential of using a single sheet of material, cut and scored, that can then be folded to form a functional piece of furniture.

See the Ex-Lab website to find out more about Myra Kosen and Ivy Lee's Elephant Stool.

ExLab: Experimental Design Lab

For more information on folding sheet metal, see the page "Post-Processing Metal"

Post-Processing Metal

Example: Acrylic (Flame Polished Edge)

Enfold by Dan Parker, ExLab 2017

Enfold’s rounded square trope was laser-cut and heat-formed from a single sheet of clear 6mm acrylic. Shimmering apertures were developed parametrically for both structural and aesthetic purposes. Laser cutting the 6 mm acrylic achieved a flame polished edge finish, which maintains the material's visual iridescence and how it refracts light.

See the Ex-Lab website to find out more about Dan Parker's Enfold coffee table.

ExLab: Experimental Design Lab

Example: Leather Patterning

Compact Disk Chair by Gareth Price, ExLab 2018

The Compact Disc Chair (or CD Chair) derives inspiration from the Japanese art of Origami and the kinetic process of folding. This kinetic furniture piece has two modes: unfolded and folded. The material finish of the furniture piece is a 2mm red dyed cow leather hide. The leather was laser cut to create the individual pieces as well as the small holes used for sewing the hinges by hand. These stitched hinges enable the folding to occur and provide an intricate detail to the otherwise minimal design.

See the Ex-Lab website to find out more about Gareth Price's Compact Disk Chair.

ExLab: Experimental Design Lab

Example: Engraving on Leather

Example: Engraving on Stone

Rotary Cutting

Rotary Cutting Metal

Cutting a Stainless Steel tube on the Kern LaserCell rotary unit

Sara Tan's ExLab project using laser cut stainless steel tube and intersecting tubes.

How the Rotary Axis works

The rotary mode works with 2D rhino curve geometry rotated around a 3D rotary axis, based on input settings of the pipe circumference. The chuck spins the tube whilst the laser head moves along the rotary axis.

Rotary Axis Diagram

Machine and material limitations

Each machine and the material you choose have limitations which affect the fabrication process and impact on the design. You will need to understand the following items whilst preparing your file to achieve a desired result.

Machine

The rotary stage can hold a maximum tube length of 700mm while the maximum cut area is 650mm. Clearance zones are necessary so the laser head will not collide with the chuck or support cone.

Materials

The Fab Lab stocks tube that has a thickness of approximately 1.6mm. This can vary slightly due to the way the product is made.

The tube is suspended at each end, multiple cuts across the length of a tube will weaken its structure causing slouching. This can create inaccurate cuts since the material is now off-axis. You may want to consider splitting the geometry into multiple pieces or designing the cuts to maintain the strength of the tube. Smaller diameter tubes suffer from slouching more than larger ones.

Slouching in tube can impact on the final cut result

If you desire to use materials such as timber dowel, tubular perspex or other tubular metals with varying thicknesses, please read the alternative materials page and contact the Fab Lab before purchasing.

Preparing your 3D model

Download the template file - This file includes the appropriate clearances and the unrolled tube stocked by the Fab Lab for reference.

When creating any 3D geometry to be fabricated it is best to work in 1:1 scale. Model the size of the actual tube you will be cutting in rhino, including the correct thickness.

The two examples identify a 3D and 2D working method and display a number of common design strategies to help you understand some of the finer fabrication details when working with rotary cutting.

Example project 3D

3D Project outcome

You can take the methods used in the example and apply it to achieve many tube cutting outcomes. This project outlines:

• Intersecting tube of varying sizes

• An angular cut through a tube

• Some relevant commands

• Designing with tolerance

Create your tubes

Draw and extrude

1. Draw the circles using the _circle diameter tool. See the available diameters. For this example we have chosen 101.6mm and 25.6mm.

2. Extrude the curves to the desired length. Be sure to toggle _Solid to NO this will ensure the object is tubular.

Arrange the geometry

The tubes have been arbitrarily placed for this example. Your design may require specific placement.

• Use the Gumball Tool to arrange geometry.

• Use the move ,rotate , Rotate3Dcommands for more precise placement of the geometry.

Subtract the geometry

Splitting the geometry

Using the Split command, you can cut holes in the intersecting geometries.

1. Select the geometry you want to cut into, in this case it is the larger tube.

2. Type in Split

3. Select the 'cutting' geometries, in this case it is the smaller tubes and the plane.

4. Hit enter

5. Your geometry is now modified, you can see the holes and slice cut into the tube.

Thickness and tolerance

If making slotted, intersecting or piercing geometry you will need to consider the thickness of the material and the position of the laser head when it cuts the geometry.

The laser is cutting vertically toward the rotary axis, resulting in a slanted cut on the cylindrical surfaces.

OffsetSrf to create material thickness

You will need to inspect your geometry for collisions. Give your geometry the material thickness, the Fab Lab stocks 1.6mm tube.

1. Duplicate your geometry so you have a copy (you may come back to this)

2. Use the OffsetSrf command and toggle _solid to YES, type in an offset distance (1.6mm).

   • Click the object to change the offset direction.

3. Measure the intersecting geometries (see diagrams below)

The thickness will cause a problem when inserting the smaller tube if not considered.

There are multiple ways to edit for tolerance and can be an arduous process.

1. Go to your original copy of the geometry

2. Select the smaller tubes and OffsetSrf, use the tolerance measurement from the previous steps.

3. Split your geometry using the new slightly larger tubes.

4. Repeat the OffsetSrf to double check your 3D model is free from collisions.

5. Your geometry is ready to be unrolled.

Unroll your geometry

Using the unrollsrf command you can turn a tube into a flat 2D surface.

The dimensions are the tubes outer circumference

1. Select the tubes outer surface and type unrollsrf

2. S surface geometry will be generated.

3. Using theMake2D command, create curve geometry from the surface(s).

4. Your geometry is now ready to be placed in the template file.

Place the curves inside the cutting zone with the correct unrolled pipe boundary. If you have multiple tubes of varying sizes, keep reading or skip to 3.3 Multiple Pipes Required.

Example project 2D

You can also experiment with creating curve geometry in 2D to develop a rotary project.

Draw 2D geometry

Use the template file's unrolled tube boundaries for reference. Draw your 2D curve geometry within this area.

• The Y axis is the outer circumference of the pipe = to one full rotation of the pipe or 360 degrees.

• The X axis is the length of the pipe, the max length is 650mm.

Create a tube

• Create a tube with your chosen diameter.

• Use the UnrollSrf command to get a 2D surface.

• Move the surface into the boundary, overlay with the curve geometry.

Project curves onto tube

Use FlowAlongSrf command to project curves onto a tube.

• Select your curve geometry and type FlowAlongSrf.

• Select an edge (near corner) of the unrolled surface.

• Select an edge of the pipe you want to 'project' onto.

Review the model in 3D

• Select the tube and Split with the curve geometry.

• Move the object and rotate if required - using Gumball tool or Move commands.

• Use the OffsetSrf command and set to the desired material thickness.

Clean up the file

• Your geometry is ready - delete any surfaces / non-required objects.

• Arrange your curves into the cutting zone of the rotary template.

• Set your curves to the appropriate cut order layers.

• Ensure to update your material, thickness and other details.

Adapting the Rotary Template

Clearance zones

The rotary template includes clearance zones on either side of the cutting zone. This is due to the chuck mechanism that holds the cylindrical stock in place at each end. The laser head can’t move through these clearance zones as it will collide with other parts of the machine. Please place your geometry only in the cutting zone.

Unrolled Pipe Templates

It is important to know the diameter and corresponding circumference of your cylindrical stock before setting up your file. We have provided a number of unrolled pipe templates to the right of the Rotary template. These sizes are based on the diameter of steel tube we stock. Select the correct unrolled pipe layout for your desired material and place it into the cutting zone. You can then proceed to add your unrolled 2D curves onto the template.

If you are supplying your own cylindrical stock and it's diameter does not match one of the templates provided, you must edit the Y-axis dimension of your unrolled pipe so it is equal to the stock circumference.

Multiple Pipes Required

If you require more than one pipe cut just copy and paste the base template for the number of pipes you need. Rename your material type and thickness/ diameter, student name and sheet number/s.

File Setup

CUT Order

When setting up your file You must differentiate between your CUT curves by placing them on the green CUT-Primary or blue CUT-Secondary layers. This places your curves in a cut order, allowing us to cut out any internal geometries first before cutting larger external geometries.

Nesting (for Rotary Mode)

For rotary mode, you should aim to nest (order the cuts) from right to left as the tube is held and secured on the left hand side. For example if you cut all the way through the tube on the left before cutting geometry on the right the tube may fall off the rotary axis, or the structure may be compromised and shift out of line before all cuts have been completed.

Allow a 30mm clearance zone between objects, this area is required when the support cone needs to be moved to re-support the tube. Don't worry if you can't do this 100% correctly, our technicians are great at navigating through cuts and changing the cut order and nesting if they have to. It's a tricky one to comprehend.

Interlocking Nesting

Some designs may interlock enabling the tube to keep its structure reducing the need for separation and clearance zones. This method can reduce the amount of cuts required and save material. Some interlocking designs may require extra internal cuts to 'unlock' from one another see Internal Cut Wastage for more information.

Internal CUT wastage

In order to remove some unwanted internal cut areas you need to slice up the scrap geometry into multiple cuts, otherwise some internal parts won’t come out due to the curvature of the tube. This part needs to be taken care of when preparing your 3D model otherwise you may have issues later on.

Waste cuts should be made on the Primary cuts layer.

Post Processing

Depending on the material you have cut you may require some post processing work. Metal items will usually need cleaning, polishing and potentially painting/finishing.

For tips on elevating your laser cut project to the next level, read our guide to Post-Processing Metal:

Post-Processing Metal